Merge all three apps into one repository

86 files changed, 5158 insertions, 0 deletions

diff --git a/merchant-terminal/.gitignore b/merchant-terminal/.gitignore
new file mode 100644
index 0000000..796b96d
--- /dev/null
+++ b/merchant-terminal/.gitignore
@@ -0,0 +1 @@
+/build
diff --git a/merchant-terminal/.gitlab-ci.yml b/merchant-terminal/.gitlab-ci.yml
new file mode 100644
index 0000000..4c03405
--- /dev/null
+++ b/merchant-terminal/.gitlab-ci.yml
@@ -0,0 +1,36 @@
+merchant_test:
+  stage: test
+  only:
+    changes:
+      - "merchant-terminal"
+  script: ./gradlew :merchant-terminal:lint :merchant-terminal:assembleRelease
+
+merchant_deploy_nightly:
+  stage: deploy
+  only:
+    refs:
+      - master
+    changes:
+      - "merchant-terminal"
+  script:
+    # Ensure that key exists
+    - test -z "$DEBUG_KEYSTORE" && exit 0
+    # Rename nightly app
+    - sed -i
+      's,<string name="app_name">.*</string>,<string name="app_name">Merchant PoS Nightly</string>,'
+      merchant-terminal/src/main/res/values*/strings.xml
+    # Set time-based version code
+    - export versionCode=$(date '+%s')
+    - sed -i "s,^\(\s*versionCode\) *[0-9].*,\1 $versionCode," merchant-terminal/build.gradle
+    # Add commit to version name
+    - export versionName=$(git rev-parse --short=7 HEAD)
+    - sed -i "s,^\(\s*versionName\ *\"[0-9].*\)\",\1 ($versionName)\"," merchant-terminal/build.gradle
+    # Set nightly application ID
+    - sed -i "s,^\(\s*applicationId\) \"*[a-z\.].*\",\1 \"net.taler.merchantpos.nightly\"," merchant-terminal/build.gradle
+    # Build the APK
+    - ./gradlew :merchant-terminal:assembleDebug
+    # START only needed while patch not accepted/released upstream
+    - apt update && apt install patch
+    - patch /usr/lib/python3/dist-packages/fdroidserver/nightly.py nightly-stats.patch
+    # END
+    - CI_PROJECT_URL="https://gitlab.com/gnu-taler/fdroid-repo" CI_PROJECT_PATH="gnu-taler/fdroid-repo" fdroid nightly -v
diff --git a/merchant-terminal/build.gradle b/merchant-terminal/build.gradle
new file mode 100644
index 0000000..594cab3
--- /dev/null
+++ b/merchant-terminal/build.gradle
@@ -0,0 +1,76 @@
+apply plugin: 'com.android.application'
+apply plugin: 'kotlin-android'
+apply plugin: 'kotlin-android-extensions'
+apply plugin: "androidx.navigation.safeargs.kotlin"
+
+android {
+    compileSdkVersion 29
+    buildToolsVersion "29.0.3"
+    defaultConfig {
+        applicationId "net.taler.merchantpos"
+        minSdkVersion 26
+        targetSdkVersion 29
+        versionCode 1
+        versionName "1.0"
+        testInstrumentationRunner "androidx.test.runner.AndroidJUnitRunner"
+    }
+    buildTypes {
+        release {
+            minifyEnabled true
+            proguardFiles getDefaultProguardFile('proguard-android-optimize.txt'), 'proguard-rules.pro'
+        }
+    }
+
+    compileOptions {
+        sourceCompatibility = 1.8
+        targetCompatibility = 1.8
+    }
+
+    kotlinOptions {
+        jvmTarget = "1.8"
+    }
+
+    testOptions {
+        unitTests {
+            includeAndroidResources = true
+        }
+    }
+
+    lintOptions {
+        abortOnError true
+        ignoreWarnings false
+    }
+}
+
+dependencies {
+    implementation "org.jetbrains.kotlin:kotlin-stdlib-jdk7:$kotlin_version"
+    implementation 'androidx.appcompat:appcompat:1.1.0'
+    implementation 'androidx.core:core-ktx:1.2.0'
+    implementation 'com.google.android.material:material:1.1.0'
+    implementation 'androidx.constraintlayout:constraintlayout:1.1.3'
+    implementation "androidx.recyclerview:recyclerview:1.1.0"
+    implementation "androidx.recyclerview:recyclerview-selection:1.1.0-rc01"
+
+    // Navigation
+    implementation "androidx.navigation:navigation-fragment-ktx:$nav_version"
+    implementation "androidx.navigation:navigation-ui-ktx:$nav_version"
+
+    // ViewModel and LiveData
+    def lifecycle_version = "2.2.0"
+    implementation "androidx.lifecycle:lifecycle-extensions:$lifecycle_version"
+    implementation "androidx.lifecycle:lifecycle-common-java8:$lifecycle_version"
+
+    // HTTP Requests
+    implementation 'com.android.volley:volley:1.1.1'
+
+    // QR codes
+    implementation 'com.google.zxing:core:3.4.0'
+
+    implementation "androidx.swiperefreshlayout:swiperefreshlayout:1.0.0"
+
+    // JSON parsing and serialization
+    implementation "com.fasterxml.jackson.module:jackson-module-kotlin:2.10.2"
+
+    testImplementation 'androidx.test.ext:junit:1.1.1'
+    testImplementation 'org.robolectric:robolectric:4.3.1'
+}
diff --git a/merchant-terminal/proguard-rules.pro b/merchant-terminal/proguard-rules.pro
new file mode 100644
index 0000000..f1b4245
--- /dev/null
+++ b/merchant-terminal/proguard-rules.pro
@@ -0,0 +1,21 @@
+# Add project specific ProGuard rules here.
+# You can control the set of applied configuration files using the
+# proguardFiles setting in build.gradle.
+#
+# For more details, see
+#   http://developer.android.com/guide/developing/tools/proguard.html
+
+# If your project uses WebView with JS, uncomment the following
+# and specify the fully qualified class name to the JavaScript interface
+# class:
+#-keepclassmembers class fqcn.of.javascript.interface.for.webview {
+#   public *;
+#}
+
+# Uncomment this to preserve the line number information for
+# debugging stack traces.
+#-keepattributes SourceFile,LineNumberTable
+
+# If you keep the line number information, uncomment this to
+# hide the original source file name.
+#-renamesourcefileattribute SourceFile
diff --git a/merchant-terminal/src/main/AndroidManifest.xml b/merchant-terminal/src/main/AndroidManifest.xml
new file mode 100644
index 0000000..f52995f
--- /dev/null
+++ b/merchant-terminal/src/main/AndroidManifest.xml
@@ -0,0 +1,56 @@
+<?xml version="1.0" encoding="utf-8"?>
+<!--
+  ~ This file is part of GNU Taler
+  ~ (C) 2020 Taler Systems S.A.
+  ~
+  ~ GNU Taler is free software; you can redistribute it and/or modify it under the
+  ~ terms of the GNU General Public License as published by the Free Software
+  ~ Foundation; either version 3, or (at your option) any later version.
+  ~
+  ~ GNU Taler is distributed in the hope that it will be useful, but WITHOUT ANY
+  ~ WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
+  ~ A PARTICULAR PURPOSE.  See the GNU General Public License for more details.
+  ~
+  ~ You should have received a copy of the GNU General Public License along with
+  ~ GNU Taler; see the file COPYING.  If not, see <http://www.gnu.org/licenses/>
+  -->
+
+<manifest xmlns:android="http://schemas.android.com/apk/res/android"
+        xmlns:tools="http://schemas.android.com/tools"
+        package="net.taler.merchantpos">
+
+    <uses-permission android:name="android.permission.NFC" />
+    <uses-permission android:name="android.permission.INTERNET" />
+
+    <uses-feature
+            android:name="android.hardware.nfc"
+            android:required="false" />
+
+    <uses-feature
+            android:name="android.hardware.telephony"
+            android:required="false" />
+
+    <application
+            android:allowBackup="true"
+            android:fullBackupContent="@xml/backup_descriptor"
+            android:icon="@mipmap/ic_taler_logo"
+            android:label="@string/app_name"
+            android:roundIcon="@mipmap/ic_taler_logo_round"
+            android:supportsRtl="true"
+            android:theme="@style/AppTheme"
+            tools:ignore="GoogleAppIndexingWarning">
+        <activity
+                android:name=".MainActivity"
+                android:label="@string/app_name"
+                android:screenOrientation="landscape"
+                android:theme="@style/AppTheme.NoActionBar"
+                tools:ignore="LockedOrientationActivity">
+            <intent-filter>
+                <action android:name="android.intent.action.MAIN" />
+
+                <category android:name="android.intent.category.LAUNCHER" />
+            </intent-filter>
+        </activity>
+    </application>
+
+</manifest>
diff --git a/merchant-terminal/src/main/ic_taler_logo-web.png b/merchant-terminal/src/main/ic_taler_logo-web.png
new file mode 100644
index 0000000..e3b8075
--- /dev/null
+++ b/merchant-terminal/src/main/ic_taler_logo-web.png
diff --git a/merchant-terminal/src/main/java/net/taler/merchantpos/Amount.kt b/merchant-terminal/src/main/java/net/taler/merchantpos/Amount.kt
new file mode 100644
index 0000000..17ddd61
--- /dev/null
+++ b/merchant-terminal/src/main/java/net/taler/merchantpos/Amount.kt
@@ -0,0 +1,48 @@
+/*
+ * This file is part of GNU Taler
+ * (C) 2020 Taler Systems S.A.
+ *
+ * GNU Taler is free software; you can redistribute it and/or modify it under the
+ * terms of the GNU General Public License as published by the Free Software
+ * Foundation; either version 3, or (at your option) any later version.
+ *
+ * GNU Taler is distributed in the hope that it will be useful, but WITHOUT ANY
+ * WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
+ * A PARTICULAR PURPOSE.  See the GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along with
+ * GNU Taler; see the file COPYING.  If not, see <http://www.gnu.org/licenses/>
+ */
+
+package net.taler.merchantpos
+
+import org.json.JSONObject
+
+data class Amount(val currency: String, val amount: String) {
+    @Suppress("unused")
+    fun isZero(): Boolean {
+        return amount.toDouble() == 0.0
+    }
+
+    companion object {
+        private const val FRACTIONAL_BASE = 1e8
+
+        @Suppress("unused")
+        fun fromJson(jsonAmount: JSONObject): Amount {
+            val amountCurrency = jsonAmount.getString("currency")
+            val amountValue = jsonAmount.getString("value")
+            val amountFraction = jsonAmount.getString("fraction")
+            val amountIntValue = Integer.parseInt(amountValue)
+            val amountIntFraction = Integer.parseInt(amountFraction)
+            return Amount(
+                amountCurrency,
+                (amountIntValue + amountIntFraction / FRACTIONAL_BASE).toString()
+            )
+        }
+
+        fun fromString(strAmount: String): Amount {
+            val components = strAmount.split(":")
+            return Amount(components[0], components[1])
+        }
+    }
+}
diff --git a/merchant-terminal/src/main/java/net/taler/merchantpos/MainActivity.kt b/merchant-terminal/src/main/java/net/taler/merchantpos/MainActivity.kt
new file mode 100644
index 0000000..0c6bdfa
--- /dev/null
+++ b/merchant-terminal/src/main/java/net/taler/merchantpos/MainActivity.kt
@@ -0,0 +1,123 @@
+/*
+ * This file is part of GNU Taler
+ * (C) 2020 Taler Systems S.A.
+ *
+ * GNU Taler is free software; you can redistribute it and/or modify it under the
+ * terms of the GNU General Public License as published by the Free Software
+ * Foundation; either version 3, or (at your option) any later version.
+ *
+ * GNU Taler is distributed in the hope that it will be useful, but WITHOUT ANY
+ * WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
+ * A PARTICULAR PURPOSE.  See the GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along with
+ * GNU Taler; see the file COPYING.  If not, see <http://www.gnu.org/licenses/>
+ */
+
+package net.taler.merchantpos
+
+import android.content.Intent
+import android.content.Intent.ACTION_MAIN
+import android.content.Intent.CATEGORY_HOME
+import android.content.Intent.FLAG_ACTIVITY_NEW_TASK
+import android.os.Bundle
+import android.os.Handler
+import android.view.MenuItem
+import android.widget.Toast
+import android.widget.Toast.LENGTH_SHORT
+import androidx.activity.viewModels
+import androidx.appcompat.app.AppCompatActivity
+import androidx.core.view.GravityCompat.START
+import androidx.lifecycle.Observer
+import androidx.navigation.NavController
+import androidx.navigation.fragment.NavHostFragment
+import androidx.navigation.ui.AppBarConfiguration
+import androidx.navigation.ui.setupWithNavController
+import com.google.android.material.navigation.NavigationView.OnNavigationItemSelectedListener
+import kotlinx.android.synthetic.main.activity_main.*
+import kotlinx.android.synthetic.main.app_bar_main.*
+
+class MainActivity : AppCompatActivity(), OnNavigationItemSelectedListener {
+
+    private val model: MainViewModel by viewModels()
+    private val nfcManager = NfcManager()
+
+    private lateinit var nav: NavController
+
+    private var reallyExit = false
+
+    override fun onCreate(savedInstanceState: Bundle?) {
+        super.onCreate(savedInstanceState)
+        setContentView(R.layout.activity_main)
+
+        model.paymentManager.payment.observe(this, Observer { payment ->
+            payment?.talerPayUri?.let {
+                nfcManager.setTagString(it)
+            }
+        })
+
+        val navHostFragment =
+            supportFragmentManager.findFragmentById(R.id.navHostFragment) as NavHostFragment
+        nav = navHostFragment.navController
+
+        nav_view.setupWithNavController(nav)
+        nav_view.setNavigationItemSelectedListener(this)
+
+        setSupportActionBar(toolbar)
+        val appBarConfiguration = AppBarConfiguration(nav.graph, drawer_layout)
+        toolbar.setupWithNavController(nav, appBarConfiguration)
+    }
+
+    override fun onStart() {
+        super.onStart()
+        if (!model.configManager.config.isValid() && nav.currentDestination?.id != R.id.nav_settings) {
+            nav.navigate(R.id.action_global_merchantSettings)
+        } else if (model.configManager.merchantConfig == null && nav.currentDestination?.id != R.id.configFetcher) {
+            nav.navigate(R.id.action_global_configFetcher)
+        }
+    }
+
+    public override fun onResume() {
+        super.onResume()
+        // TODO should we only read tags when a payment is to be made?
+        NfcManager.start(this, nfcManager)
+    }
+
+    public override fun onPause() {
+        super.onPause()
+        NfcManager.stop(this)
+    }
+
+    override fun onNavigationItemSelected(item: MenuItem): Boolean {
+        when (item.itemId) {
+            R.id.nav_order -> nav.navigate(R.id.action_global_order)
+            R.id.nav_history -> nav.navigate(R.id.action_global_merchantHistory)
+            R.id.nav_settings -> nav.navigate(R.id.action_global_merchantSettings)
+        }
+        drawer_layout.closeDrawer(START)
+        return true
+    }
+
+    override fun onBackPressed() {
+        val currentDestination = nav.currentDestination?.id
+        if (drawer_layout.isDrawerOpen(START)) {
+            drawer_layout.closeDrawer(START)
+        } else if (currentDestination == R.id.nav_settings && !model.configManager.config.isValid()) {
+            // we are in the configuration screen and need a config to continue
+            val intent = Intent(ACTION_MAIN).apply {
+                addCategory(CATEGORY_HOME)
+                flags = FLAG_ACTIVITY_NEW_TASK
+            }
+            startActivity(intent)
+        } else if (currentDestination == R.id.nav_order) {
+            if (reallyExit) super.onBackPressed()
+            else {
+                // this closes the app and causes orders to be lost, so let's confirm first
+                reallyExit = true
+                Toast.makeText(this, R.string.toast_back_to_exit, LENGTH_SHORT).show()
+                Handler().postDelayed({ reallyExit = false }, 3000)
+            }
+        } else super.onBackPressed()
+    }
+
+}
diff --git a/merchant-terminal/src/main/java/net/taler/merchantpos/MainViewModel.kt b/merchant-terminal/src/main/java/net/taler/merchantpos/MainViewModel.kt
new file mode 100644
index 0000000..3fe472d
--- /dev/null
+++ b/merchant-terminal/src/main/java/net/taler/merchantpos/MainViewModel.kt
@@ -0,0 +1,51 @@
+/*
+ * This file is part of GNU Taler
+ * (C) 2020 Taler Systems S.A.
+ *
+ * GNU Taler is free software; you can redistribute it and/or modify it under the
+ * terms of the GNU General Public License as published by the Free Software
+ * Foundation; either version 3, or (at your option) any later version.
+ *
+ * GNU Taler is distributed in the hope that it will be useful, but WITHOUT ANY
+ * WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
+ * A PARTICULAR PURPOSE.  See the GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along with
+ * GNU Taler; see the file COPYING.  If not, see <http://www.gnu.org/licenses/>
+ */
+
+package net.taler.merchantpos
+
+import android.app.Application
+import androidx.lifecycle.AndroidViewModel
+import androidx.lifecycle.viewModelScope
+import com.android.volley.toolbox.Volley
+import com.fasterxml.jackson.databind.DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES
+import com.fasterxml.jackson.databind.ObjectMapper
+import com.fasterxml.jackson.module.kotlin.KotlinModule
+import net.taler.merchantpos.config.ConfigManager
+import net.taler.merchantpos.history.HistoryManager
+import net.taler.merchantpos.history.RefundManager
+import net.taler.merchantpos.order.OrderManager
+import net.taler.merchantpos.payment.PaymentManager
+
+class MainViewModel(app: Application) : AndroidViewModel(app) {
+
+    private val mapper = ObjectMapper()
+        .registerModule(KotlinModule())
+        .configure(FAIL_ON_UNKNOWN_PROPERTIES, false)
+    private val queue = Volley.newRequestQueue(app)
+
+    val orderManager = OrderManager(app, mapper)
+    val configManager = ConfigManager(app, viewModelScope, mapper, queue).apply {
+        addConfigurationReceiver(orderManager)
+    }
+    val paymentManager = PaymentManager(configManager, queue, mapper)
+    val historyManager = HistoryManager(configManager, queue, mapper)
+    val refundManager = RefundManager(configManager, queue)
+
+    override fun onCleared() {
+        queue.cancelAll { !it.isCanceled }
+    }
+
+}
diff --git a/merchant-terminal/src/main/java/net/taler/merchantpos/NfcManager.kt b/merchant-terminal/src/main/java/net/taler/merchantpos/NfcManager.kt
new file mode 100644
index 0000000..09c1470
--- /dev/null
+++ b/merchant-terminal/src/main/java/net/taler/merchantpos/NfcManager.kt
@@ -0,0 +1,233 @@
+/*
+ * This file is part of GNU Taler
+ * (C) 2020 Taler Systems S.A.
+ *
+ * GNU Taler is free software; you can redistribute it and/or modify it under the
+ * terms of the GNU General Public License as published by the Free Software
+ * Foundation; either version 3, or (at your option) any later version.
+ *
+ * GNU Taler is distributed in the hope that it will be useful, but WITHOUT ANY
+ * WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
+ * A PARTICULAR PURPOSE.  See the GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along with
+ * GNU Taler; see the file COPYING.  If not, see <http://www.gnu.org/licenses/>
+ */
+
+package net.taler.merchantpos
+
+import android.app.Activity
+import android.content.Context
+import android.nfc.NfcAdapter
+import android.nfc.NfcAdapter.FLAG_READER_NFC_A
+import android.nfc.NfcAdapter.FLAG_READER_SKIP_NDEF_CHECK
+import android.nfc.Tag
+import android.nfc.tech.IsoDep
+import android.util.Log
+import net.taler.merchantpos.Utils.hexStringToByteArray
+import org.json.JSONObject
+import java.io.ByteArrayOutputStream
+import java.net.URL
+import javax.net.ssl.HttpsURLConnection
+
+@Suppress("unused")
+private const val TALER_AID = "A0000002471001"
+
+class NfcManager : NfcAdapter.ReaderCallback {
+
+    companion object {
+        const val TAG = "taler-merchant"
+
+        /**
+         * Returns true if NFC is supported and false otherwise.
+         */
+        fun hasNfc(context: Context): Boolean {
+            return getNfcAdapter(context) != null
+        }
+
+        /**
+         * Enables NFC reader mode. Don't forget to call [stop] afterwards.
+         */
+        fun start(activity: Activity, nfcManager: NfcManager) {
+            getNfcAdapter(activity)?.enableReaderMode(activity, nfcManager, nfcManager.flags, null)
+        }
+
+        /**
+         * Disables NFC reader mode. Call after [start].
+         */
+        fun stop(activity: Activity) {
+            getNfcAdapter(activity)?.disableReaderMode(activity)
+        }
+
+        private fun getNfcAdapter(context: Context): NfcAdapter? {
+            return NfcAdapter.getDefaultAdapter(context)
+        }
+    }
+
+    private val flags = FLAG_READER_NFC_A or FLAG_READER_SKIP_NDEF_CHECK
+
+    private var tagString: String? = null
+    private var currentTag: IsoDep? = null
+
+    fun setTagString(tagString: String) {
+        this.tagString = tagString
+    }
+
+    override fun onTagDiscovered(tag: Tag?) {
+
+        Log.v(TAG, "tag discovered")
+
+        val isoDep = IsoDep.get(tag)
+        isoDep.connect()
+
+        currentTag = isoDep
+
+        isoDep.transceive(apduSelectFile())
+
+        val tagString: String? = tagString
+        if (tagString != null) {
+            isoDep.transceive(apduPutTalerData(1, tagString.toByteArray()))
+        }
+
+        // FIXME: use better pattern for sleeps in between requests
+        // -> start with fast polling, poll more slowly if no requests are coming
+
+        while (true) {
+            try {
+                val reqFrame = isoDep.transceive(apduGetData())
+                if (reqFrame.size < 2) {
+                    Log.v(TAG, "request frame too small")
+                    break
+                }
+                val req = ByteArray(reqFrame.size - 2)
+                if (req.isEmpty()) {
+                    continue
+                }
+                reqFrame.copyInto(req, 0, 0, reqFrame.size - 2)
+                val jsonReq = JSONObject(req.toString(Charsets.UTF_8))
+                val reqId = jsonReq.getInt("id")
+                Log.v(TAG, "got request $jsonReq")
+                val jsonInnerReq = jsonReq.getJSONObject("request")
+                val method = jsonInnerReq.getString("method")
+                val urlStr = jsonInnerReq.getString("url")
+                Log.v(TAG, "url '$urlStr'")
+                Log.v(TAG, "method '$method'")
+                val url = URL(urlStr)
+                val conn: HttpsURLConnection = url.openConnection() as HttpsURLConnection
+                conn.setRequestProperty("Accept", "application/json")
+                conn.connectTimeout = 5000
+                conn.doInput = true
+                when (method) {
+                    "get" -> {
+                        conn.requestMethod = "GET"
+                    }
+                    "postJson" -> {
+                        conn.requestMethod = "POST"
+                        conn.doOutput = true
+                        conn.setRequestProperty("Content-Type", "application/json; utf-8")
+                        val body = jsonInnerReq.getString("body")
+                        conn.outputStream.write(body.toByteArray(Charsets.UTF_8))
+                    }
+                    else -> {
+                        throw Exception("method not supported")
+                    }
+                }
+                Log.v(TAG, "connecting")
+                conn.connect()
+                Log.v(TAG, "connected")
+
+                val statusCode = conn.responseCode
+                val tunnelResp = JSONObject()
+                tunnelResp.put("id", reqId)
+                tunnelResp.put("status", conn.responseCode)
+
+                if (statusCode == 200) {
+                    val stream = conn.inputStream
+                    val httpResp = stream.buffered().readBytes()
+                    tunnelResp.put("responseJson", JSONObject(httpResp.toString(Charsets.UTF_8)))
+                }
+
+                Log.v(TAG, "sending: $tunnelResp")
+
+                isoDep.transceive(apduPutTalerData(2, tunnelResp.toString().toByteArray()))
+            } catch (e: Exception) {
+                Log.v(TAG, "exception during NFC loop: $e")
+                break
+            }
+        }
+
+        isoDep.close()
+    }
+
+    private fun writeApduLength(stream: ByteArrayOutputStream, size: Int) {
+        when {
+            size == 0 -> {
+                // No size field needed!
+            }
+            size <= 255 -> // One byte size field
+                stream.write(size)
+            size <= 65535 -> {
+                stream.write(0)
+                // FIXME: is this supposed to be little or big endian?
+                stream.write(size and 0xFF)
+                stream.write((size ushr 8) and 0xFF)
+            }
+            else -> throw Error("payload too big")
+        }
+    }
+
+    private fun apduSelectFile(): ByteArray {
+        return hexStringToByteArray("00A4040007A0000002471001")
+    }
+
+    private fun apduPutData(payload: ByteArray): ByteArray {
+        val stream = ByteArrayOutputStream()
+
+        // Class
+        stream.write(0x00)
+
+        // Instruction 0xDA = put data
+        stream.write(0xDA)
+
+        // Instruction parameters
+        // (proprietary encoding)
+        stream.write(0x01)
+        stream.write(0x00)
+
+        writeApduLength(stream, payload.size)
+
+        stream.write(payload)
+
+        return stream.toByteArray()
+    }
+
+    private fun apduPutTalerData(talerInst: Int, payload: ByteArray): ByteArray {
+        val realPayload = ByteArrayOutputStream()
+        realPayload.write(talerInst)
+        realPayload.write(payload)
+        return apduPutData(realPayload.toByteArray())
+    }
+
+    private fun apduGetData(): ByteArray {
+        val stream = ByteArrayOutputStream()
+
+        // Class
+        stream.write(0x00)
+
+        // Instruction 0xCA = get data
+        stream.write(0xCA)
+
+        // Instruction parameters
+        // (proprietary encoding)
+        stream.write(0x01)
+        stream.write(0x00)
+
+        // Max expected response size, two
+        // zero bytes denotes 65536
+        stream.write(0x0)
+        stream.write(0x0)
+
+        return stream.toByteArray()
+    }
+
+}
diff --git a/merchant-terminal/src/main/java/net/taler/merchantpos/QrCodeManager.kt b/merchant-terminal/src/main/java/net/taler/merchantpos/QrCodeManager.kt
new file mode 100644
index 0000000..595e7ac
--- /dev/null
+++ b/merchant-terminal/src/main/java/net/taler/merchantpos/QrCodeManager.kt
@@ -0,0 +1,42 @@
+/*
+ * This file is part of GNU Taler
+ * (C) 2020 Taler Systems S.A.
+ *
+ * GNU Taler is free software; you can redistribute it and/or modify it under the
+ * terms of the GNU General Public License as published by the Free Software
+ * Foundation; either version 3, or (at your option) any later version.
+ *
+ * GNU Taler is distributed in the hope that it will be useful, but WITHOUT ANY
+ * WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
+ * A PARTICULAR PURPOSE.  See the GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along with
+ * GNU Taler; see the file COPYING.  If not, see <http://www.gnu.org/licenses/>
+ */
+
+package net.taler.merchantpos
+
+import android.graphics.Bitmap
+import android.graphics.Bitmap.Config.RGB_565
+import android.graphics.Color.BLACK
+import android.graphics.Color.WHITE
+import com.google.zxing.BarcodeFormat.QR_CODE
+import com.google.zxing.qrcode.QRCodeWriter
+
+object QrCodeManager {
+
+    fun makeQrCode(text: String, size: Int = 256): Bitmap {
+        val qrCodeWriter = QRCodeWriter()
+        val bitMatrix = qrCodeWriter.encode(text, QR_CODE, size, size)
+        val height = bitMatrix.height
+        val width = bitMatrix.width
+        val bmp = Bitmap.createBitmap(width, height, RGB_565)
+        for (x in 0 until width) {
+            for (y in 0 until height) {
+                bmp.setPixel(x, y, if (bitMatrix.get(x, y)) BLACK else WHITE)
+            }
+        }
+        return bmp
+    }
+
+}
diff --git a/merchant-terminal/src/main/java/net/taler/merchantpos/Utils.kt b/merchant-terminal/src/main/java/net/taler/merchantpos/Utils.kt
new file mode 100644
index 0000000..a0c30d6
--- /dev/null
+++ b/merchant-terminal/src/main/java/net/taler/merchantpos/Utils.kt
@@ -0,0 +1,155 @@
+/*
+ * This file is part of GNU Taler
+ * (C) 2020 Taler Systems S.A.
+ *
+ * GNU Taler is free software; you can redistribute it and/or modify it under the
+ * terms of the GNU General Public License as published by the Free Software
+ * Foundation; either version 3, or (at your option) any later version.
+ *
+ * GNU Taler is distributed in the hope that it will be useful, but WITHOUT ANY
+ * WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
+ * A PARTICULAR PURPOSE.  See the GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along with
+ * GNU Taler; see the file COPYING.  If not, see <http://www.gnu.org/licenses/>
+ */
+
+package net.taler.merchantpos
+
+import android.content.Context
+import android.text.format.DateUtils.DAY_IN_MILLIS
+import android.text.format.DateUtils.FORMAT_ABBREV_MONTH
+import android.text.format.DateUtils.FORMAT_ABBREV_RELATIVE
+import android.text.format.DateUtils.FORMAT_NO_YEAR
+import android.text.format.DateUtils.FORMAT_SHOW_DATE
+import android.text.format.DateUtils.FORMAT_SHOW_TIME
+import android.text.format.DateUtils.MINUTE_IN_MILLIS
+import android.text.format.DateUtils.formatDateTime
+import android.text.format.DateUtils.getRelativeTimeSpanString
+import android.view.View
+import android.view.View.INVISIBLE
+import android.view.View.VISIBLE
+import androidx.annotation.StringRes
+import androidx.fragment.app.Fragment
+import androidx.lifecycle.LiveData
+import androidx.lifecycle.MediatorLiveData
+import androidx.lifecycle.Observer
+import androidx.navigation.NavController
+import androidx.navigation.NavDirections
+import androidx.navigation.fragment.findNavController
+import com.google.android.material.snackbar.BaseTransientBottomBar.ANIMATION_MODE_FADE
+import com.google.android.material.snackbar.BaseTransientBottomBar.Duration
+import com.google.android.material.snackbar.Snackbar.make
+
+object Utils {
+
+    private const val HEX_CHARS = "0123456789ABCDEF"
+
+    fun hexStringToByteArray(data: String): ByteArray {
+        val result = ByteArray(data.length / 2)
+
+        for (i in data.indices step 2) {
+            val firstIndex = HEX_CHARS.indexOf(data[i])
+            val secondIndex = HEX_CHARS.indexOf(data[i + 1])
+
+            val octet = firstIndex.shl(4).or(secondIndex)
+            result[i.shr(1)] = octet.toByte()
+        }
+        return result
+    }
+
+
+    private val HEX_CHARS_ARRAY = HEX_CHARS.toCharArray()
+
+    @Suppress("unused")
+    fun toHex(byteArray: ByteArray): String {
+        val result = StringBuffer()
+
+        byteArray.forEach {
+            val octet = it.toInt()
+            val firstIndex = (octet and 0xF0).ushr(4)
+            val secondIndex = octet and 0x0F
+            result.append(HEX_CHARS_ARRAY[firstIndex])
+            result.append(HEX_CHARS_ARRAY[secondIndex])
+        }
+        return result.toString()
+    }
+
+}
+
+fun View.fadeIn(endAction: () -> Unit = {}) {
+    if (visibility == VISIBLE) return
+    alpha = 0f
+    visibility = VISIBLE
+    animate().alpha(1f).withEndAction {
+        if (context != null) endAction.invoke()
+    }.start()
+}
+
+fun View.fadeOut(endAction: () -> Unit = {}) {
+    if (visibility == INVISIBLE) return
+    animate().alpha(0f).withEndAction {
+        if (context == null) return@withEndAction
+        visibility = INVISIBLE
+        alpha = 1f
+        endAction.invoke()
+    }.start()
+}
+
+fun topSnackbar(view: View, text: CharSequence, @Duration duration: Int) {
+    make(view, text, duration)
+        .setAnimationMode(ANIMATION_MODE_FADE)
+        .setAnchorView(R.id.navHostFragment)
+        .show()
+}
+
+fun topSnackbar(view: View, @StringRes resId: Int, @Duration duration: Int) {
+    topSnackbar(view, view.resources.getText(resId), duration)
+}
+
+fun NavDirections.navigate(nav: NavController) = nav.navigate(this)
+
+fun Fragment.navigate(directions: NavDirections) = findNavController().navigate(directions)
+
+fun Long.toRelativeTime(context: Context): CharSequence {
+    val now = System.currentTimeMillis()
+    return if (now - this > DAY_IN_MILLIS * 2) {
+        val flags = FORMAT_SHOW_TIME or FORMAT_SHOW_DATE or FORMAT_ABBREV_MONTH or FORMAT_NO_YEAR
+        formatDateTime(context, this, flags)
+    } else getRelativeTimeSpanString(this, now, MINUTE_IN_MILLIS, FORMAT_ABBREV_RELATIVE)
+}
+
+class CombinedLiveData<T, K, S>(
+    source1: LiveData<T>,
+    source2: LiveData<K>,
+    private val combine: (data1: T?, data2: K?) -> S
+) : MediatorLiveData<S>() {
+
+    private var data1: T? = null
+    private var data2: K? = null
+
+    init {
+        super.addSource(source1) { t ->
+            data1 = t
+            value = combine(data1, data2)
+        }
+        super.addSource(source2) { k ->
+            data2 = k
+            value = combine(data1, data2)
+        }
+    }
+
+    override fun <S : Any?> addSource(source: LiveData<S>, onChanged: Observer<in S>) {
+        throw UnsupportedOperationException()
+    }
+
+    override fun <T : Any?> removeSource(toRemote: LiveData<T>) {
+        throw UnsupportedOperationException()
+    }
+}
+
+/**
+ * Use this with 'when' expressions when you need it to handle all possibilities/branches.
+ */
+val <T> T.exhaustive: T
+    get() = this
diff --git a/merchant-terminal/src/main/java/net/taler/merchantpos/config/ConfigFetcherFragment.kt b/merchant-terminal/src/main/java/net/taler/merchantpos/config/ConfigFetcherFragment.kt
new file mode 100644
index 0000000..c370e33
--- /dev/null
+++ b/merchant-terminal/src/main/java/net/taler/merchantpos/config/ConfigFetcherFragment.kt
@@ -0,0 +1,66 @@
+/*
+ * This file is part of GNU Taler
+ * (C) 2020 Taler Systems S.A.
+ *
+ * GNU Taler is free software; you can redistribute it and/or modify it under the
+ * terms of the GNU General Public License as published by the Free Software
+ * Foundation; either version 3, or (at your option) any later version.
+ *
+ * GNU Taler is distributed in the hope that it will be useful, but WITHOUT ANY
+ * WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
+ * A PARTICULAR PURPOSE.  See the GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along with
+ * GNU Taler; see the file COPYING.  If not, see <http://www.gnu.org/licenses/>
+ */
+
+package net.taler.merchantpos.config
+
+import android.os.Bundle
+import android.view.LayoutInflater
+import android.view.View
+import android.view.ViewGroup
+import androidx.fragment.app.Fragment
+import androidx.fragment.app.activityViewModels
+import androidx.lifecycle.Observer
+import androidx.navigation.fragment.findNavController
+import com.google.android.material.snackbar.Snackbar
+import com.google.android.material.snackbar.Snackbar.LENGTH_SHORT
+import net.taler.merchantpos.MainViewModel
+import net.taler.merchantpos.R
+import net.taler.merchantpos.config.ConfigFetcherFragmentDirections.Companion.actionConfigFetcherToMerchantSettings
+import net.taler.merchantpos.config.ConfigFetcherFragmentDirections.Companion.actionConfigFetcherToOrder
+import net.taler.merchantpos.navigate
+
+class ConfigFetcherFragment : Fragment() {
+
+    private val model: MainViewModel by activityViewModels()
+    private val configManager by lazy { model.configManager }
+
+    override fun onCreateView(
+        inflater: LayoutInflater, container: ViewGroup?,
+        savedInstanceState: Bundle?
+    ): View? {
+        return inflater.inflate(R.layout.fragment_config_fetcher, container, false)
+    }
+
+    override fun onActivityCreated(savedInstanceState: Bundle?) {
+        super.onActivityCreated(savedInstanceState)
+        configManager.fetchConfig(configManager.config, false)
+        configManager.configUpdateResult.observe(viewLifecycleOwner, Observer { result ->
+            when (result) {
+                null -> return@Observer
+                is ConfigUpdateResult.Error -> onNetworkError(result.msg)
+                is ConfigUpdateResult.Success -> {
+                    actionConfigFetcherToOrder().navigate(findNavController())
+                }
+            }
+        })
+    }
+
+    private fun onNetworkError(msg: String) {
+        Snackbar.make(view!!, msg, LENGTH_SHORT).show()
+        actionConfigFetcherToMerchantSettings().navigate(findNavController())
+    }
+
+}
diff --git a/merchant-terminal/src/main/java/net/taler/merchantpos/config/ConfigManager.kt b/merchant-terminal/src/main/java/net/taler/merchantpos/config/ConfigManager.kt
new file mode 100644
index 0000000..edb8059
--- /dev/null
+++ b/merchant-terminal/src/main/java/net/taler/merchantpos/config/ConfigManager.kt
@@ -0,0 +1,181 @@
+/*
+ * This file is part of GNU Taler
+ * (C) 2020 Taler Systems S.A.
+ *
+ * GNU Taler is free software; you can redistribute it and/or modify it under the
+ * terms of the GNU General Public License as published by the Free Software
+ * Foundation; either version 3, or (at your option) any later version.
+ *
+ * GNU Taler is distributed in the hope that it will be useful, but WITHOUT ANY
+ * WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
+ * A PARTICULAR PURPOSE.  See the GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along with
+ * GNU Taler; see the file COPYING.  If not, see <http://www.gnu.org/licenses/>
+ */
+
+package net.taler.merchantpos.config
+
+import android.content.Context
+import android.content.Context.MODE_PRIVATE
+import android.util.Base64.NO_WRAP
+import android.util.Base64.encodeToString
+import android.util.Log
+import androidx.annotation.UiThread
+import androidx.lifecycle.LiveData
+import androidx.lifecycle.MutableLiveData
+import com.android.volley.Request.Method.GET
+import com.android.volley.RequestQueue
+import com.android.volley.Response.ErrorListener
+import com.android.volley.Response.Listener
+import com.android.volley.VolleyError
+import com.android.volley.toolbox.JsonObjectRequest
+import com.fasterxml.jackson.databind.ObjectMapper
+import com.fasterxml.jackson.module.kotlin.readValue
+import kotlinx.coroutines.CoroutineScope
+import kotlinx.coroutines.Dispatchers
+import kotlinx.coroutines.launch
+import net.taler.merchantpos.R
+import org.json.JSONObject
+
+private const val SETTINGS_NAME = "taler-merchant-terminal"
+
+private const val SETTINGS_CONFIG_URL = "configUrl"
+private const val SETTINGS_USERNAME = "username"
+private const val SETTINGS_PASSWORD = "password"
+
+internal const val CONFIG_URL_DEMO = "https://docs.taler.net/_static/sample-pos-config.json"
+internal const val CONFIG_USERNAME_DEMO = ""
+internal const val CONFIG_PASSWORD_DEMO = ""
+
+private val TAG = ConfigManager::class.java.simpleName
+
+interface ConfigurationReceiver {
+    /**
+     * Returns null if the configuration was valid, or a error string for user display otherwise.
+     */
+    suspend fun onConfigurationReceived(json: JSONObject, currency: String): String?
+}
+
+class ConfigManager(
+    private val context: Context,
+    private val scope: CoroutineScope,
+    private val mapper: ObjectMapper,
+    private val queue: RequestQueue
+) {
+
+    private val prefs = context.getSharedPreferences(SETTINGS_NAME, MODE_PRIVATE)
+    private val configurationReceivers = ArrayList<ConfigurationReceiver>()
+
+    var config = Config(
+        configUrl = prefs.getString(SETTINGS_CONFIG_URL, CONFIG_URL_DEMO)!!,
+        username = prefs.getString(SETTINGS_USERNAME, CONFIG_USERNAME_DEMO)!!,
+        password = prefs.getString(SETTINGS_PASSWORD, CONFIG_PASSWORD_DEMO)!!
+    )
+    var merchantConfig: MerchantConfig? = null
+        private set
+
+    private val mConfigUpdateResult = MutableLiveData<ConfigUpdateResult>()
+    val configUpdateResult: LiveData<ConfigUpdateResult> = mConfigUpdateResult
+
+    fun addConfigurationReceiver(receiver: ConfigurationReceiver) {
+        configurationReceivers.add(receiver)
+    }
+
+    @UiThread
+    fun fetchConfig(config: Config, save: Boolean, savePassword: Boolean = false) {
+        mConfigUpdateResult.value = null
+        val configToSave = if (save) {
+            if (savePassword) config else config.copy(password = "")
+        } else null
+
+        val stringRequest = object : JsonObjectRequest(GET, config.configUrl, null,
+            Listener { onConfigReceived(it, configToSave) },
+            ErrorListener { onNetworkError(it) }
+        ) {
+            // send basic auth header
+            override fun getHeaders(): MutableMap<String, String> {
+                val credentials = "${config.username}:${config.password}"
+                val auth = ("Basic ${encodeToString(credentials.toByteArray(), NO_WRAP)}")
+                return mutableMapOf("Authorization" to auth)
+            }
+        }
+        queue.add(stringRequest)
+    }
+
+    @UiThread
+    private fun onConfigReceived(json: JSONObject, config: Config?) {
+        val merchantConfig: MerchantConfig = try {
+            mapper.readValue(json.getString("config"))
+        } catch (e: Exception) {
+            Log.e(TAG, "Error parsing merchant config", e)
+            val msg = context.getString(R.string.config_error_malformed)
+            mConfigUpdateResult.value = ConfigUpdateResult.Error(msg)
+            return
+        }
+
+        val params = mapOf("instance" to merchantConfig.instance)
+        val req = MerchantRequest(GET, merchantConfig, "config", params, null,
+            Listener { onMerchantConfigReceived(config, json, merchantConfig, it) },
+            ErrorListener { onNetworkError(it) }
+        )
+        queue.add(req)
+    }
+
+    private fun onMerchantConfigReceived(
+        newConfig: Config?,
+        configJson: JSONObject,
+        merchantConfig: MerchantConfig,
+        json: JSONObject
+    ) = scope.launch(Dispatchers.Default) {
+        val currency = json.getString("currency")
+
+        for (receiver in configurationReceivers) {
+            val result = try {
+                receiver.onConfigurationReceived(configJson, currency)
+            } catch (e: Exception) {
+                Log.e(TAG, "Error handling configuration by ${receiver::class.java.simpleName}", e)
+                context.getString(R.string.config_error_unknown)
+            }
+            if (result != null) {  // error
+                mConfigUpdateResult.postValue(ConfigUpdateResult.Error(result))
+                return@launch
+            }
+        }
+        newConfig?.let {
+            config = it
+            saveConfig(it)
+        }
+        this@ConfigManager.merchantConfig = merchantConfig.copy(currency = currency)
+        mConfigUpdateResult.postValue(ConfigUpdateResult.Success(currency))
+    }
+
+    fun forgetPassword() {
+        config = config.copy(password = "")
+        saveConfig(config)
+        merchantConfig = null
+    }
+
+    private fun saveConfig(config: Config) {
+        prefs.edit()
+            .putString(SETTINGS_CONFIG_URL, config.configUrl)
+            .putString(SETTINGS_USERNAME, config.username)
+            .putString(SETTINGS_PASSWORD, config.password)
+            .apply()
+    }
+
+    @UiThread
+    private fun onNetworkError(it: VolleyError?) {
+        val msg = context.getString(
+            if (it?.networkResponse?.statusCode == 401) R.string.config_auth_error
+            else R.string.config_error_network
+        )
+        mConfigUpdateResult.value = ConfigUpdateResult.Error(msg)
+    }
+
+}
+
+sealed class ConfigUpdateResult {
+    data class Error(val msg: String) : ConfigUpdateResult()
+    data class Success(val currency: String) : ConfigUpdateResult()
+}
diff --git a/merchant-terminal/src/main/java/net/taler/merchantpos/config/MerchantConfig.kt b/merchant-terminal/src/main/java/net/taler/merchantpos/config/MerchantConfig.kt
new file mode 100644
index 0000000..2050e28
--- /dev/null
+++ b/merchant-terminal/src/main/java/net/taler/merchantpos/config/MerchantConfig.kt
@@ -0,0 +1,47 @@
+/*
+ * This file is part of GNU Taler
+ * (C) 2020 Taler Systems S.A.
+ *
+ * GNU Taler is free software; you can redistribute it and/or modify it under the
+ * terms of the GNU General Public License as published by the Free Software
+ * Foundation; either version 3, or (at your option) any later version.
+ *
+ * GNU Taler is distributed in the hope that it will be useful, but WITHOUT ANY
+ * WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
+ * A PARTICULAR PURPOSE.  See the GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along with
+ * GNU Taler; see the file COPYING.  If not, see <http://www.gnu.org/licenses/>
+ */
+
+package net.taler.merchantpos.config
+
+import android.net.Uri
+import com.fasterxml.jackson.annotation.JsonProperty
+
+data class Config(
+    val configUrl: String,
+    val username: String,
+    val password: String
+) {
+    fun isValid() = !configUrl.isBlank()
+    fun hasPassword() = !password.isBlank()
+}
+
+data class MerchantConfig(
+    @JsonProperty("base_url")
+    val baseUrl: String,
+    val instance: String,
+    @JsonProperty("api_key")
+    val apiKey: String,
+    val currency: String?
+) {
+    fun urlFor(endpoint: String, params: Map<String, String>?): String {
+        val uriBuilder = Uri.parse(baseUrl).buildUpon()
+        uriBuilder.appendPath(endpoint)
+        params?.forEach {
+            uriBuilder.appendQueryParameter(it.key, it.value)
+        }
+        return uriBuilder.toString()
+    }
+}
diff --git a/merchant-terminal/src/main/java/net/taler/merchantpos/config/MerchantConfigFragment.kt b/merchant-terminal/src/main/java/net/taler/merchantpos/config/MerchantConfigFragment.kt
new file mode 100644
index 0000000..aad1c93
--- /dev/null
+++ b/merchant-terminal/src/main/java/net/taler/merchantpos/config/MerchantConfigFragment.kt
@@ -0,0 +1,165 @@
+/*
+ * This file is part of GNU Taler
+ * (C) 2020 Taler Systems S.A.
+ *
+ * GNU Taler is free software; you can redistribute it and/or modify it under the
+ * terms of the GNU General Public License as published by the Free Software
+ * Foundation; either version 3, or (at your option) any later version.
+ *
+ * GNU Taler is distributed in the hope that it will be useful, but WITHOUT ANY
+ * WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
+ * A PARTICULAR PURPOSE.  See the GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along with
+ * GNU Taler; see the file COPYING.  If not, see <http://www.gnu.org/licenses/>
+ */
+
+package net.taler.merchantpos.config
+
+import android.net.Uri
+import android.os.Bundle
+import android.text.method.LinkMovementMethod
+import android.view.LayoutInflater
+import android.view.View
+import android.view.View.GONE
+import android.view.View.INVISIBLE
+import android.view.View.VISIBLE
+import android.view.ViewGroup
+import androidx.fragment.app.Fragment
+import androidx.fragment.app.activityViewModels
+import androidx.lifecycle.Observer
+import androidx.navigation.fragment.findNavController
+import com.google.android.material.snackbar.BaseTransientBottomBar.LENGTH_LONG
+import com.google.android.material.snackbar.Snackbar
+import kotlinx.android.synthetic.main.fragment_merchant_config.*
+import net.taler.merchantpos.MainViewModel
+import net.taler.merchantpos.R
+import net.taler.merchantpos.config.MerchantConfigFragmentDirections.Companion.actionSettingsToOrder
+import net.taler.merchantpos.navigate
+import net.taler.merchantpos.topSnackbar
+
+/**
+ * Fragment that displays merchant settings.
+ */
+class MerchantConfigFragment : Fragment() {
+
+    private val model: MainViewModel by activityViewModels()
+    private val configManager by lazy { model.configManager }
+
+    override fun onCreateView(
+        inflater: LayoutInflater,
+        container: ViewGroup?,
+        savedInstanceState: Bundle?
+    ): View? {
+        return inflater.inflate(R.layout.fragment_merchant_config, container, false)
+    }
+
+    override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
+        configUrlView.editText!!.setOnFocusChangeListener { _, hasFocus ->
+            if (!hasFocus) checkForUrlCredentials()
+        }
+        okButton.setOnClickListener {
+            checkForUrlCredentials()
+            val inputUrl = configUrlView.editText!!.text
+            val url = if (inputUrl.startsWith("http")) {
+                inputUrl.toString()
+            } else {
+                "https://$inputUrl".also { configUrlView.editText!!.setText(it) }
+            }
+            progressBar.visibility = VISIBLE
+            okButton.visibility = INVISIBLE
+            val config = Config(
+                configUrl = url,
+                username = usernameView.editText!!.text.toString(),
+                password = passwordView.editText!!.text.toString()
+            )
+            configManager.fetchConfig(config, true, savePasswordCheckBox.isChecked)
+            configManager.configUpdateResult.observe(viewLifecycleOwner, Observer { result ->
+                if (onConfigUpdate(result)) {
+                    configManager.configUpdateResult.removeObservers(viewLifecycleOwner)
+                }
+            })
+        }
+        forgetPasswordButton.setOnClickListener {
+            configManager.forgetPassword()
+            passwordView.editText!!.text = null
+            forgetPasswordButton.visibility = GONE
+        }
+        configDocsView.movementMethod = LinkMovementMethod.getInstance()
+        updateView(savedInstanceState == null)
+    }
+
+    override fun onStart() {
+        super.onStart()
+        // focus password if this is the only empty field
+        if (passwordView.editText!!.text.isBlank()
+            && !configUrlView.editText!!.text.isBlank()
+            && !usernameView.editText!!.text.isBlank()
+        ) {
+            passwordView.requestFocus()
+        }
+    }
+
+    private fun updateView(isInitialization: Boolean = false) {
+        val config = configManager.config
+        configUrlView.editText!!.setText(
+            if (isInitialization && config.configUrl.isBlank()) CONFIG_URL_DEMO
+            else config.configUrl
+        )
+        usernameView.editText!!.setText(
+            if (isInitialization && config.username.isBlank()) CONFIG_USERNAME_DEMO
+            else config.username
+        )
+        passwordView.editText!!.setText(
+            if (isInitialization && config.password.isBlank()) CONFIG_PASSWORD_DEMO
+            else config.password
+        )
+        forgetPasswordButton.visibility = if (config.hasPassword()) VISIBLE else GONE
+    }
+
+    private fun checkForUrlCredentials() {
+        val text = configUrlView.editText!!.text.toString()
+        Uri.parse(text)?.userInfo?.let { userInfo ->
+            if (userInfo.contains(':')) {
+                val (user, pass) = userInfo.split(':')
+                val strippedUrl = text.replace("${userInfo}@", "")
+                configUrlView.editText!!.setText(strippedUrl)
+                usernameView.editText!!.setText(user)
+                passwordView.editText!!.setText(pass)
+            }
+        }
+    }
+
+    /**
+     * Processes updated config and returns true, if observer can be removed.
+     */
+    private fun onConfigUpdate(result: ConfigUpdateResult?) = when (result) {
+        null -> false
+        is ConfigUpdateResult.Error -> {
+            onError(result.msg)
+            true
+        }
+        is ConfigUpdateResult.Success -> {
+            onConfigReceived(result.currency)
+            true
+        }
+    }
+
+    private fun onConfigReceived(currency: String) {
+        onResultReceived()
+        updateView()
+        topSnackbar(view!!, getString(R.string.config_changed, currency), LENGTH_LONG)
+        actionSettingsToOrder().navigate(findNavController())
+    }
+
+    private fun onError(msg: String) {
+        onResultReceived()
+        Snackbar.make(view!!, msg, LENGTH_LONG).show()
+    }
+
+    private fun onResultReceived() {
+        progressBar.visibility = INVISIBLE
+        okButton.visibility = VISIBLE
+    }
+
+}
diff --git a/merchant-terminal/src/main/java/net/taler/merchantpos/config/MerchantRequest.kt b/merchant-terminal/src/main/java/net/taler/merchantpos/config/MerchantRequest.kt
new file mode 100644
index 0000000..8d95378
--- /dev/null
+++ b/merchant-terminal/src/main/java/net/taler/merchantpos/config/MerchantRequest.kt
@@ -0,0 +1,41 @@
+/*
+ * This file is part of GNU Taler
+ * (C) 2020 Taler Systems S.A.
+ *
+ * GNU Taler is free software; you can redistribute it and/or modify it under the
+ * terms of the GNU General Public License as published by the Free Software
+ * Foundation; either version 3, or (at your option) any later version.
+ *
+ * GNU Taler is distributed in the hope that it will be useful, but WITHOUT ANY
+ * WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
+ * A PARTICULAR PURPOSE.  See the GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along with
+ * GNU Taler; see the file COPYING.  If not, see <http://www.gnu.org/licenses/>
+ */
+
+package net.taler.merchantpos.config
+
+
+import android.util.ArrayMap
+import com.android.volley.Response
+import com.android.volley.toolbox.JsonObjectRequest
+import org.json.JSONObject
+
+class MerchantRequest(
+    method: Int,
+    private val merchantConfig: MerchantConfig,
+    endpoint: String,
+    params: Map<String, String>?,
+    jsonRequest: JSONObject?,
+    listener: Response.Listener<JSONObject>,
+    errorListener: Response.ErrorListener
+) :
+    JsonObjectRequest(method, merchantConfig.urlFor(endpoint, params), jsonRequest, listener, errorListener) {
+
+    override fun getHeaders(): MutableMap<String, String> {
+        val headerMap = ArrayMap<String, String>()
+        headerMap["Authorization"] = "ApiKey " + merchantConfig.apiKey
+        return headerMap
+    }
+}
diff --git a/merchant-terminal/src/main/java/net/taler/merchantpos/history/HistoryManager.kt b/merchant-terminal/src/main/java/net/taler/merchantpos/history/HistoryManager.kt
new file mode 100644
index 0000000..594e7cc
--- /dev/null
+++ b/merchant-terminal/src/main/java/net/taler/merchantpos/history/HistoryManager.kt
@@ -0,0 +1,106 @@
+/*
+ * This file is part of GNU Taler
+ * (C) 2020 Taler Systems S.A.
+ *
+ * GNU Taler is free software; you can redistribute it and/or modify it under the
+ * terms of the GNU General Public License as published by the Free Software
+ * Foundation; either version 3, or (at your option) any later version.
+ *
+ * GNU Taler is distributed in the hope that it will be useful, but WITHOUT ANY
+ * WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
+ * A PARTICULAR PURPOSE.  See the GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along with
+ * GNU Taler; see the file COPYING.  If not, see <http://www.gnu.org/licenses/>
+ */
+
+package net.taler.merchantpos.history
+
+import android.util.Log
+import androidx.annotation.UiThread
+import androidx.lifecycle.LiveData
+import androidx.lifecycle.MutableLiveData
+import com.android.volley.Request.Method.GET
+import com.android.volley.Request.Method.POST
+import com.android.volley.RequestQueue
+import com.android.volley.Response.ErrorListener
+import com.android.volley.Response.Listener
+import com.fasterxml.jackson.annotation.JsonIgnore
+import com.fasterxml.jackson.annotation.JsonInclude
+import com.fasterxml.jackson.annotation.JsonInclude.Include.NON_EMPTY
+import com.fasterxml.jackson.annotation.JsonProperty
+import com.fasterxml.jackson.databind.ObjectMapper
+import com.fasterxml.jackson.module.kotlin.readValue
+import net.taler.merchantpos.Amount
+import net.taler.merchantpos.config.ConfigManager
+import net.taler.merchantpos.config.MerchantRequest
+import org.json.JSONObject
+
+@JsonInclude(NON_EMPTY)
+class Timestamp(
+    @JsonProperty("t_ms")
+    val ms: Long
+)
+
+data class HistoryItem(
+    @JsonProperty("order_id")
+    val orderId: String,
+    @JsonProperty("amount")
+    val amountStr: String,
+    val summary: String,
+    val timestamp: Timestamp
+) {
+    @get:JsonIgnore
+    val amount: Amount by lazy { Amount.fromString(amountStr) }
+
+    @get:JsonIgnore
+    val time = timestamp.ms
+}
+
+sealed class HistoryResult {
+    object Error : HistoryResult()
+    class Success(val items: List<HistoryItem>) : HistoryResult()
+}
+
+class HistoryManager(
+    private val configManager: ConfigManager,
+    private val queue: RequestQueue,
+    private val mapper: ObjectMapper
+) {
+
+    private val mIsLoading = MutableLiveData(false)
+    val isLoading: LiveData<Boolean> = mIsLoading
+
+    private val mItems = MutableLiveData<HistoryResult>()
+    val items: LiveData<HistoryResult> = mItems
+
+    @UiThread
+    internal fun fetchHistory() {
+        mIsLoading.value = true
+        val merchantConfig = configManager.merchantConfig!!
+        val params = mapOf("instance" to merchantConfig.instance)
+        val req = MerchantRequest(GET, merchantConfig, "history", params, null,
+            Listener { onHistoryResponse(it) },
+            ErrorListener { onHistoryError() })
+        queue.add(req)
+    }
+
+    @UiThread
+    private fun onHistoryResponse(body: JSONObject) {
+        mIsLoading.value = false
+        val items = arrayListOf<HistoryItem>()
+        val historyJson = body.getJSONArray("history")
+        for (i in 0 until historyJson.length()) {
+            val historyItem: HistoryItem = mapper.readValue(historyJson.getString(i))
+            items.add(historyItem)
+        }
+        mItems.value = HistoryResult.Success(items)
+    }
+
+    @UiThread
+    private fun onHistoryError() {
+        mIsLoading.value = false
+        mItems.value = HistoryResult.Error
+    }
+
+}
diff --git a/merchant-terminal/src/main/java/net/taler/merchantpos/history/MerchantHistoryFragment.kt b/merchant-terminal/src/main/java/net/taler/merchantpos/history/MerchantHistoryFragment.kt
new file mode 100644
index 0000000..0c53f71
--- /dev/null
+++ b/merchant-terminal/src/main/java/net/taler/merchantpos/history/MerchantHistoryFragment.kt
@@ -0,0 +1,160 @@
+/*
+ * This file is part of GNU Taler
+ * (C) 2020 Taler Systems S.A.
+ *
+ * GNU Taler is free software; you can redistribute it and/or modify it under the
+ * terms of the GNU General Public License as published by the Free Software
+ * Foundation; either version 3, or (at your option) any later version.
+ *
+ * GNU Taler is distributed in the hope that it will be useful, but WITHOUT ANY
+ * WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
+ * A PARTICULAR PURPOSE.  See the GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along with
+ * GNU Taler; see the file COPYING.  If not, see <http://www.gnu.org/licenses/>
+ */
+
+package net.taler.merchantpos.history
+
+import android.annotation.SuppressLint
+import android.os.Bundle
+import android.util.Log
+import android.view.LayoutInflater
+import android.view.View
+import android.view.ViewGroup
+import android.widget.ImageButton
+import android.widget.TextView
+import androidx.fragment.app.Fragment
+import androidx.fragment.app.activityViewModels
+import androidx.lifecycle.Observer
+import androidx.recyclerview.widget.DividerItemDecoration
+import androidx.recyclerview.widget.DividerItemDecoration.VERTICAL
+import androidx.recyclerview.widget.LinearLayoutManager
+import androidx.recyclerview.widget.RecyclerView.Adapter
+import androidx.recyclerview.widget.RecyclerView.ViewHolder
+import com.google.android.material.snackbar.Snackbar
+import com.google.android.material.snackbar.Snackbar.LENGTH_SHORT
+import kotlinx.android.synthetic.main.fragment_merchant_history.*
+import net.taler.merchantpos.MainViewModel
+import net.taler.merchantpos.R
+import net.taler.merchantpos.exhaustive
+import net.taler.merchantpos.history.HistoryItemAdapter.HistoryItemViewHolder
+import net.taler.merchantpos.history.MerchantHistoryFragmentDirections.Companion.actionGlobalMerchantSettings
+import net.taler.merchantpos.history.MerchantHistoryFragmentDirections.Companion.actionNavHistoryToRefundFragment
+import net.taler.merchantpos.navigate
+import net.taler.merchantpos.toRelativeTime
+import java.util.*
+
+private interface RefundClickListener {
+    fun onRefundClicked(item: HistoryItem)
+}
+
+/**
+ * Fragment to display the merchant's payment history, received from the backend.
+ */
+class MerchantHistoryFragment : Fragment(), RefundClickListener {
+
+    companion object {
+        const val TAG = "taler-merchant"
+    }
+
+    private val model: MainViewModel by activityViewModels()
+    private val historyManager by lazy { model.historyManager }
+    private val refundManager by lazy { model.refundManager }
+
+    private val historyListAdapter = HistoryItemAdapter(this)
+
+    override fun onCreateView(
+        inflater: LayoutInflater, container: ViewGroup?,
+        savedInstanceState: Bundle?
+    ): View? {
+        return inflater.inflate(R.layout.fragment_merchant_history, container, false)
+    }
+
+    override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
+        list_history.apply {
+            layoutManager = LinearLayoutManager(requireContext())
+            addItemDecoration(DividerItemDecoration(context, VERTICAL))
+            adapter = historyListAdapter
+        }
+
+        swipeRefresh.setOnRefreshListener {
+            Log.v(TAG, "refreshing!")
+            historyManager.fetchHistory()
+        }
+        historyManager.isLoading.observe(viewLifecycleOwner, Observer { loading ->
+            Log.v(TAG, "setting refreshing to $loading")
+            swipeRefresh.isRefreshing = loading
+        })
+        historyManager.items.observe(viewLifecycleOwner, Observer { result ->
+            when (result) {
+                is HistoryResult.Error -> onError()
+                is HistoryResult.Success -> historyListAdapter.setData(result.items)
+            }.exhaustive
+        })
+    }
+
+    override fun onStart() {
+        super.onStart()
+        if (model.configManager.merchantConfig?.instance == null) {
+            navigate(actionGlobalMerchantSettings())
+        } else {
+            historyManager.fetchHistory()
+        }
+    }
+
+    private fun onError() {
+        Snackbar.make(view!!, R.string.error_network, LENGTH_SHORT).show()
+    }
+
+    override fun onRefundClicked(item: HistoryItem) {
+        refundManager.startRefund(item)
+        navigate(actionNavHistoryToRefundFragment())
+    }
+
+}
+
+private class HistoryItemAdapter(private val listener: RefundClickListener) :
+    Adapter<HistoryItemViewHolder>() {
+
+    private val items = ArrayList<HistoryItem>()
+
+    override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): HistoryItemViewHolder {
+        val v =
+            LayoutInflater.from(parent.context).inflate(R.layout.list_item_history, parent, false)
+        return HistoryItemViewHolder(v)
+    }
+
+    override fun getItemCount() = items.size
+
+    override fun onBindViewHolder(holder: HistoryItemViewHolder, position: Int) {
+        holder.bind(items[position])
+    }
+
+    fun setData(items: List<HistoryItem>) {
+        this.items.clear()
+        this.items.addAll(items)
+        this.notifyDataSetChanged()
+    }
+
+    private inner class HistoryItemViewHolder(private val v: View) : ViewHolder(v) {
+
+        private val orderSummaryView: TextView = v.findViewById(R.id.orderSummaryView)
+        private val orderAmountView: TextView = v.findViewById(R.id.orderAmountView)
+        private val orderTimeView: TextView = v.findViewById(R.id.orderTimeView)
+        private val orderIdView: TextView = v.findViewById(R.id.orderIdView)
+        private val refundButton: ImageButton = v.findViewById(R.id.refundButton)
+
+        fun bind(item: HistoryItem) {
+            orderSummaryView.text = item.summary
+            val amount = item.amount
+            @SuppressLint("SetTextI18n")
+            orderAmountView.text = "${amount.amount} ${amount.currency}"
+            orderIdView.text = v.context.getString(R.string.history_ref_no, item.orderId)
+            orderTimeView.text = item.time.toRelativeTime(v.context)
+            refundButton.setOnClickListener { listener.onRefundClicked(item) }
+        }
+
+    }
+
+}
diff --git a/merchant-terminal/src/main/java/net/taler/merchantpos/history/RefundFragment.kt b/merchant-terminal/src/main/java/net/taler/merchantpos/history/RefundFragment.kt
new file mode 100644
index 0000000..1797cea
--- /dev/null
+++ b/merchant-terminal/src/main/java/net/taler/merchantpos/history/RefundFragment.kt
@@ -0,0 +1,99 @@
+/*
+ * This file is part of GNU Taler
+ * (C) 2020 Taler Systems S.A.
+ *
+ * GNU Taler is free software; you can redistribute it and/or modify it under the
+ * terms of the GNU General Public License as published by the Free Software
+ * Foundation; either version 3, or (at your option) any later version.
+ *
+ * GNU Taler is distributed in the hope that it will be useful, but WITHOUT ANY
+ * WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
+ * A PARTICULAR PURPOSE.  See the GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along with
+ * GNU Taler; see the file COPYING.  If not, see <http://www.gnu.org/licenses/>
+ */
+
+package net.taler.merchantpos.history
+
+import android.os.Bundle
+import android.view.LayoutInflater
+import android.view.View
+import android.view.ViewGroup
+import androidx.annotation.StringRes
+import androidx.fragment.app.Fragment
+import androidx.fragment.app.activityViewModels
+import androidx.lifecycle.Observer
+import androidx.navigation.fragment.findNavController
+import com.google.android.material.snackbar.BaseTransientBottomBar.LENGTH_LONG
+import com.google.android.material.snackbar.Snackbar
+import kotlinx.android.synthetic.main.fragment_refund.*
+import net.taler.merchantpos.MainViewModel
+import net.taler.merchantpos.R
+import net.taler.merchantpos.fadeIn
+import net.taler.merchantpos.fadeOut
+import net.taler.merchantpos.history.RefundFragmentDirections.Companion.actionRefundFragmentToRefundUriFragment
+import net.taler.merchantpos.history.RefundResult.Error
+import net.taler.merchantpos.history.RefundResult.PastDeadline
+import net.taler.merchantpos.history.RefundResult.Success
+import net.taler.merchantpos.navigate
+
+class RefundFragment : Fragment() {
+
+    private val model: MainViewModel by activityViewModels()
+    private val refundManager by lazy { model.refundManager }
+
+    override fun onCreateView(
+        inflater: LayoutInflater, container: ViewGroup?,
+        savedInstanceState: Bundle?
+    ): View? {
+        return inflater.inflate(R.layout.fragment_refund, container, false)
+    }
+
+    override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
+        val item = refundManager.toBeRefunded ?: throw IllegalStateException()
+        amountInputView.setText(item.amount.amount)
+        currencyView.text = item.amount.currency
+        abortButton.setOnClickListener { findNavController().navigateUp() }
+        refundButton.setOnClickListener { onRefundButtonClicked(item) }
+
+        refundManager.refundResult.observe(viewLifecycleOwner, Observer { result ->
+            onRefundResultChanged(result)
+        })
+    }
+
+    private fun onRefundButtonClicked(item: HistoryItem) {
+        val inputAmount = amountInputView.text.toString().toDouble()
+        if (inputAmount > item.amount.amount.toDouble()) {
+            amountView.error = getString(R.string.refund_error_max_amount, item.amount.amount)
+            return
+        }
+        if (inputAmount <= 0.0) {
+            amountView.error = getString(R.string.refund_error_zero)
+            return
+        }
+        amountView.error = null
+        refundButton.fadeOut()
+        progressBar.fadeIn()
+        refundManager.refund(item, inputAmount, reasonInputView.text.toString())
+    }
+
+    private fun onRefundResultChanged(result: RefundResult?): Any = when (result) {
+        Error -> onError(R.string.refund_error_backend)
+        PastDeadline -> onError(R.string.refund_error_deadline)
+        is Success -> {
+            progressBar.fadeOut()
+            refundButton.fadeIn()
+            navigate(actionRefundFragmentToRefundUriFragment())
+        }
+        null -> { // no-op
+        }
+    }
+
+    private fun onError(@StringRes res: Int) {
+        Snackbar.make(view!!, res, LENGTH_LONG).show()
+        progressBar.fadeOut()
+        refundButton.fadeIn()
+    }
+
+}
diff --git a/merchant-terminal/src/main/java/net/taler/merchantpos/history/RefundManager.kt b/merchant-terminal/src/main/java/net/taler/merchantpos/history/RefundManager.kt
new file mode 100644
index 0000000..270b3b8
--- /dev/null
+++ b/merchant-terminal/src/main/java/net/taler/merchantpos/history/RefundManager.kt
@@ -0,0 +1,111 @@
+/*
+ * This file is part of GNU Taler
+ * (C) 2020 Taler Systems S.A.
+ *
+ * GNU Taler is free software; you can redistribute it and/or modify it under the
+ * terms of the GNU General Public License as published by the Free Software
+ * Foundation; either version 3, or (at your option) any later version.
+ *
+ * GNU Taler is distributed in the hope that it will be useful, but WITHOUT ANY
+ * WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
+ * A PARTICULAR PURPOSE.  See the GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along with
+ * GNU Taler; see the file COPYING.  If not, see <http://www.gnu.org/licenses/>
+ */
+
+package net.taler.merchantpos.history
+
+import android.util.Log
+import androidx.annotation.UiThread
+import androidx.lifecycle.LiveData
+import androidx.lifecycle.MutableLiveData
+import com.android.volley.Request.Method.POST
+import com.android.volley.RequestQueue
+import com.android.volley.Response.ErrorListener
+import com.android.volley.Response.Listener
+import net.taler.merchantpos.config.ConfigManager
+import net.taler.merchantpos.config.MerchantRequest
+import org.json.JSONObject
+
+sealed class RefundResult {
+    object Error : RefundResult()
+    object PastDeadline : RefundResult()
+    class Success(
+        val refundUri: String,
+        val item: HistoryItem,
+        val amount: Double,
+        val reason: String
+    ) : RefundResult()
+}
+
+class RefundManager(
+    private val configManager: ConfigManager,
+    private val queue: RequestQueue
+) {
+
+    var toBeRefunded: HistoryItem? = null
+        private set
+
+    private val mRefundResult = MutableLiveData<RefundResult>()
+    internal val refundResult: LiveData<RefundResult> = mRefundResult
+
+    @UiThread
+    internal fun startRefund(item: HistoryItem) {
+        toBeRefunded = item
+        mRefundResult.value = null
+    }
+
+    @UiThread
+    internal fun refund(item: HistoryItem, amount: Double, reason: String) {
+        val merchantConfig = configManager.merchantConfig!!
+        val refundRequest = mapOf(
+            "order_id" to item.orderId,
+            "refund" to "${item.amount.currency}:$amount",
+            "reason" to reason
+        )
+        val body = JSONObject(refundRequest)
+        val req = MerchantRequest(POST, merchantConfig, "refund", null, body,
+            Listener { onRefundResponse(it, item, amount, reason) },
+            ErrorListener { onRefundError() }
+        )
+        queue.add(req)
+    }
+
+    @UiThread
+    private fun onRefundResponse(
+        json: JSONObject,
+        item: HistoryItem,
+        amount: Double,
+        reason: String
+    ) {
+        if (!json.has("contract_terms")) {
+            Log.e("TEST", "json: $json")
+            onRefundError()
+            return
+        }
+
+        val contractTerms = json.getJSONObject("contract_terms")
+        val refundDeadline = if (contractTerms.has("refund_deadline")) {
+            contractTerms.getJSONObject("refund_deadline").getLong("t_ms")
+        } else null
+        val autoRefund = contractTerms.has("auto_refund")
+        val refundUri = json.getString("taler_refund_uri")
+
+        Log.e("TEST", "refundDeadline: $refundDeadline")
+        if (refundDeadline != null) Log.e(
+            "TEST",
+            "refundDeadline passed: ${System.currentTimeMillis() > refundDeadline}"
+        )
+        Log.e("TEST", "autoRefund: $autoRefund")
+        Log.e("TEST", "refundUri: $refundUri")
+
+        mRefundResult.value = RefundResult.Success(refundUri, item, amount, reason)
+    }
+
+    @UiThread
+    private fun onRefundError() {
+        mRefundResult.value = RefundResult.Error
+    }
+
+}
diff --git a/merchant-terminal/src/main/java/net/taler/merchantpos/history/RefundUriFragment.kt b/merchant-terminal/src/main/java/net/taler/merchantpos/history/RefundUriFragment.kt
new file mode 100644
index 0000000..f2bd569
--- /dev/null
+++ b/merchant-terminal/src/main/java/net/taler/merchantpos/history/RefundUriFragment.kt
@@ -0,0 +1,65 @@
+/*
+ * This file is part of GNU Taler
+ * (C) 2020 Taler Systems S.A.
+ *
+ * GNU Taler is free software; you can redistribute it and/or modify it under the
+ * terms of the GNU General Public License as published by the Free Software
+ * Foundation; either version 3, or (at your option) any later version.
+ *
+ * GNU Taler is distributed in the hope that it will be useful, but WITHOUT ANY
+ * WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
+ * A PARTICULAR PURPOSE.  See the GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along with
+ * GNU Taler; see the file COPYING.  If not, see <http://www.gnu.org/licenses/>
+ */
+
+package net.taler.merchantpos.history
+
+import android.annotation.SuppressLint
+import android.os.Bundle
+import android.view.LayoutInflater
+import android.view.View
+import android.view.ViewGroup
+import androidx.fragment.app.Fragment
+import androidx.fragment.app.activityViewModels
+import androidx.navigation.fragment.findNavController
+import kotlinx.android.synthetic.main.fragment_refund_uri.*
+import net.taler.merchantpos.MainViewModel
+import net.taler.merchantpos.NfcManager.Companion.hasNfc
+import net.taler.merchantpos.QrCodeManager.makeQrCode
+import net.taler.merchantpos.R
+
+class RefundUriFragment : Fragment() {
+
+    private val model: MainViewModel by activityViewModels()
+    private val refundManager by lazy { model.refundManager }
+
+    override fun onCreateView(
+        inflater: LayoutInflater, container: ViewGroup?,
+        savedInstanceState: Bundle?
+    ): View? {
+        return inflater.inflate(R.layout.fragment_refund_uri, container, false)
+    }
+
+    override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
+        super.onViewCreated(view, savedInstanceState)
+        val result = refundManager.refundResult.value
+        if (result !is RefundResult.Success) throw IllegalStateException()
+
+        refundQrcodeView.setImageBitmap(makeQrCode(result.refundUri))
+
+        val introRes =
+            if (hasNfc(requireContext())) R.string.refund_intro_nfc else R.string.refund_intro
+        refundIntroView.setText(introRes)
+
+        @SuppressLint("SetTextI18n")
+        refundAmountView.text = "${result.amount} ${result.item.amount.currency}"
+
+        refundRefView.text =
+            getString(R.string.refund_order_ref, result.item.orderId, result.reason)
+
+        cancelRefundButton.setOnClickListener { findNavController().navigateUp() }
+    }
+
+}
diff --git a/merchant-terminal/src/main/java/net/taler/merchantpos/order/CategoriesFragment.kt b/merchant-terminal/src/main/java/net/taler/merchantpos/order/CategoriesFragment.kt
new file mode 100644
index 0000000..34b97c0
--- /dev/null
+++ b/merchant-terminal/src/main/java/net/taler/merchantpos/order/CategoriesFragment.kt
@@ -0,0 +1,106 @@
+/*
+ * This file is part of GNU Taler
+ * (C) 2020 Taler Systems S.A.
+ *
+ * GNU Taler is free software; you can redistribute it and/or modify it under the
+ * terms of the GNU General Public License as published by the Free Software
+ * Foundation; either version 3, or (at your option) any later version.
+ *
+ * GNU Taler is distributed in the hope that it will be useful, but WITHOUT ANY
+ * WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
+ * A PARTICULAR PURPOSE.  See the GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along with
+ * GNU Taler; see the file COPYING.  If not, see <http://www.gnu.org/licenses/>
+ */
+
+package net.taler.merchantpos.order
+
+import android.os.Bundle
+import android.view.LayoutInflater
+import android.view.View
+import android.view.View.INVISIBLE
+import android.view.ViewGroup
+import android.widget.Button
+import androidx.fragment.app.Fragment
+import androidx.fragment.app.activityViewModels
+import androidx.lifecycle.Observer
+import androidx.recyclerview.widget.LinearLayoutManager
+import androidx.recyclerview.widget.RecyclerView
+import androidx.recyclerview.widget.RecyclerView.Adapter
+import kotlinx.android.synthetic.main.fragment_categories.*
+import net.taler.merchantpos.MainViewModel
+import net.taler.merchantpos.R
+import net.taler.merchantpos.order.CategoryAdapter.CategoryViewHolder
+
+interface CategorySelectionListener {
+    fun onCategorySelected(category: Category)
+}
+
+class CategoriesFragment : Fragment(), CategorySelectionListener {
+
+    private val viewModel: MainViewModel by activityViewModels()
+    private val orderManager by lazy { viewModel.orderManager }
+    private val adapter = CategoryAdapter(this)
+
+    override fun onCreateView(
+        inflater: LayoutInflater,
+        container: ViewGroup?,
+        savedInstanceState: Bundle?
+    ): View? {
+        return inflater.inflate(R.layout.fragment_categories, container, false)
+    }
+
+    override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
+        categoriesList.apply {
+            adapter = this@CategoriesFragment.adapter
+            layoutManager = LinearLayoutManager(requireContext())
+        }
+
+        orderManager.categories.observe(viewLifecycleOwner, Observer { categories ->
+            adapter.setItems(categories)
+            progressBar.visibility = INVISIBLE
+        })
+    }
+
+    override fun onCategorySelected(category: Category) {
+        orderManager.setCurrentCategory(category)
+    }
+
+}
+
+private class CategoryAdapter(
+    private val listener: CategorySelectionListener
+) : Adapter<CategoryViewHolder>() {
+
+    private val categories = ArrayList<Category>()
+
+    override fun getItemCount() = categories.size
+
+    override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): CategoryViewHolder {
+        val view =
+            LayoutInflater.from(parent.context).inflate(R.layout.list_item_category, parent, false)
+        return CategoryViewHolder(view)
+    }
+
+    override fun onBindViewHolder(holder: CategoryViewHolder, position: Int) {
+        holder.bind(categories[position])
+    }
+
+    fun setItems(items: List<Category>) {
+        categories.clear()
+        categories.addAll(items)
+        notifyDataSetChanged()
+    }
+
+    private inner class CategoryViewHolder(v: View) : RecyclerView.ViewHolder(v) {
+        private val button: Button = v.findViewById(R.id.button)
+
+        fun bind(category: Category) {
+            button.text = category.localizedName
+            button.isPressed = category.selected
+            button.setOnClickListener { listener.onCategorySelected(category) }
+        }
+    }
+
+}
diff --git a/merchant-terminal/src/main/java/net/taler/merchantpos/order/Definitions.kt b/merchant-terminal/src/main/java/net/taler/merchantpos/order/Definitions.kt
new file mode 100644
index 0000000..63eda17
--- /dev/null
+++ b/merchant-terminal/src/main/java/net/taler/merchantpos/order/Definitions.kt
@@ -0,0 +1,205 @@
+/*
+ * This file is part of GNU Taler
+ * (C) 2020 Taler Systems S.A.
+ *
+ * GNU Taler is free software; you can redistribute it and/or modify it under the
+ * terms of the GNU General Public License as published by the Free Software
+ * Foundation; either version 3, or (at your option) any later version.
+ *
+ * GNU Taler is distributed in the hope that it will be useful, but WITHOUT ANY
+ * WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
+ * A PARTICULAR PURPOSE.  See the GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along with
+ * GNU Taler; see the file COPYING.  If not, see <http://www.gnu.org/licenses/>
+ */
+
+package net.taler.merchantpos.order
+
+import androidx.core.os.LocaleListCompat
+import com.fasterxml.jackson.annotation.JsonIgnore
+import com.fasterxml.jackson.annotation.JsonInclude
+import com.fasterxml.jackson.annotation.JsonInclude.Include.NON_NULL
+import com.fasterxml.jackson.annotation.JsonProperty
+import net.taler.merchantpos.Amount
+import java.util.*
+import java.util.Locale.LanguageRange
+import kotlin.collections.ArrayList
+import kotlin.collections.HashMap
+
+data class Category(
+    val id: Int,
+    val name: String,
+    @JsonProperty("name_i18n")
+    val nameI18n: Map<String, String>?
+) {
+    var selected: Boolean = false
+    val localizedName: String get() = getLocalizedString(nameI18n, name)
+}
+
+@JsonInclude(NON_NULL)
+abstract class Product {
+    @get:JsonProperty("product_id")
+    abstract val productId: String?
+    abstract val description: String
+    @get:JsonProperty("description_i18n")
+    abstract val descriptionI18n: Map<String, String>?
+    abstract val price: String
+    @get:JsonProperty("delivery_location")
+    abstract val location: String?
+    abstract val image: String?
+    @get:JsonIgnore
+    val localizedDescription: String
+        get() = getLocalizedString(descriptionI18n, description)
+}
+
+data class ConfigProduct(
+    @JsonIgnore
+    val id: String = UUID.randomUUID().toString(),
+    override val productId: String?,
+    override val description: String,
+    override val descriptionI18n: Map<String, String>?,
+    override val price: String,
+    override val location: String?,
+    override val image: String?,
+    val categories: List<Int>,
+    @JsonIgnore
+    val quantity: Int = 0
+) : Product() {
+    val priceAsDouble by lazy { Amount.fromString(price).amount.toDouble() }
+
+    override fun equals(other: Any?) = other is ConfigProduct && id == other.id
+    override fun hashCode() = id.hashCode()
+}
+
+data class ContractProduct(
+    override val productId: String?,
+    override val description: String,
+    override val descriptionI18n: Map<String, String>?,
+    override val price: String,
+    override val location: String?,
+    override val image: String?,
+    val quantity: Int
+) : Product() {
+    constructor(product: ConfigProduct) : this(
+        product.productId,
+        product.description,
+        product.descriptionI18n,
+        product.price,
+        product.location,
+        product.image,
+        product.quantity
+    )
+}
+
+private fun getLocalizedString(map: Map<String, String>?, default: String): String {
+    // just return the default, if it is the only element
+    if (map == null) return default
+    // create a priority list of language ranges from system locales
+    val locales = LocaleListCompat.getDefault()
+    val priorityList = ArrayList<LanguageRange>(locales.size())
+    for (i in 0 until locales.size()) {
+        priorityList.add(LanguageRange(locales[i].toLanguageTag()))
+    }
+    // create a list of locales available in the given map
+    val availableLocales = map.keys.mapNotNull {
+        if (it == "_") return@mapNotNull null
+        val list = it.split("_")
+        when (list.size) {
+            1 -> Locale(list[0])
+            2 -> Locale(list[0], list[1])
+            3 -> Locale(list[0], list[1], list[2])
+            else -> null
+        }
+    }
+    val match = Locale.lookup(priorityList, availableLocales)
+    return match?.toString()?.let { map[it] } ?: default
+}
+
+data class Order(val id: Int, val availableCategories: Map<Int, Category>) {
+    val products = ArrayList<ConfigProduct>()
+    val title: String = id.toString()
+    val summary: String
+        get() {
+            if (products.size == 1) return products[0].description
+            return getCategoryQuantities().map { (category: Category, quantity: Int) ->
+                "$quantity x ${category.localizedName}"
+            }.joinToString()
+        }
+    val total: Double
+        get() {
+            var total = 0.0
+            products.forEach { product ->
+                val price = product.priceAsDouble
+                total += price * product.quantity
+            }
+            return total
+        }
+    val totalAsString: String
+        get() = String.format("%.2f", total)
+
+    operator fun plus(product: ConfigProduct): Order {
+        val i = products.indexOf(product)
+        if (i == -1) {
+            products.add(product.copy(quantity = 1))
+        } else {
+            val quantity = products[i].quantity
+            products[i] = products[i].copy(quantity = quantity + 1)
+        }
+        return this
+    }
+
+    operator fun minus(product: ConfigProduct): Order {
+        val i = products.indexOf(product)
+        if (i == -1) return this
+        val quantity = products[i].quantity
+        if (quantity <= 1) {
+            products.remove(product)
+        } else {
+            products[i] = products[i].copy(quantity = quantity - 1)
+        }
+        return this
+    }
+
+    private fun getCategoryQuantities(): HashMap<Category, Int> {
+        val categories = HashMap<Category, Int>()
+        products.forEach { product ->
+            val categoryId = product.categories[0]
+            val category = availableCategories.getValue(categoryId)
+            val oldQuantity = categories[category] ?: 0
+            categories[category] = oldQuantity + product.quantity
+        }
+        return categories
+    }
+
+    /**
+     * Returns a map of i18n summaries for each locale present in *all* given [Category]s
+     * or null if there's no locale that fulfills this criteria.
+     */
+    val summaryI18n: Map<String, String>?
+        get() {
+            if (products.size == 1) return products[0].descriptionI18n
+            val categoryQuantities = getCategoryQuantities()
+            // get all available locales
+            val availableLocales = categoryQuantities.mapNotNull { (category, _) ->
+                val nameI18n = category.nameI18n
+                // if one category doesn't have locales, we can return null here already
+                nameI18n?.keys ?: return null
+            }.flatten().toHashSet()
+            // remove all locales not supported by all categories
+            categoryQuantities.forEach { (category, _) ->
+                // category.nameI18n should be non-null now
+                availableLocales.retainAll(category.nameI18n!!.keys)
+                if (availableLocales.isEmpty()) return null
+            }
+            return availableLocales.map { locale ->
+                Pair(
+                    locale, categoryQuantities.map { (category, quantity) ->
+                        // category.nameI18n should be non-null now
+                        "$quantity x ${category.nameI18n!![locale]}"
+                    }.joinToString()
+                )
+            }.toMap()
+        }
+
+}
diff --git a/merchant-terminal/src/main/java/net/taler/merchantpos/order/LiveOrder.kt b/merchant-terminal/src/main/java/net/taler/merchantpos/order/LiveOrder.kt
new file mode 100644
index 0000000..ff6061a
--- /dev/null
+++ b/merchant-terminal/src/main/java/net/taler/merchantpos/order/LiveOrder.kt
@@ -0,0 +1,109 @@
+/*
+ * This file is part of GNU Taler
+ * (C) 2020 Taler Systems S.A.
+ *
+ * GNU Taler is free software; you can redistribute it and/or modify it under the
+ * terms of the GNU General Public License as published by the Free Software
+ * Foundation; either version 3, or (at your option) any later version.
+ *
+ * GNU Taler is distributed in the hope that it will be useful, but WITHOUT ANY
+ * WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
+ * A PARTICULAR PURPOSE.  See the GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along with
+ * GNU Taler; see the file COPYING.  If not, see <http://www.gnu.org/licenses/>
+ */
+
+package net.taler.merchantpos.order
+
+import androidx.annotation.UiThread
+import androidx.lifecycle.LiveData
+import androidx.lifecycle.MutableLiveData
+import androidx.lifecycle.Transformations
+import net.taler.merchantpos.CombinedLiveData
+import net.taler.merchantpos.order.RestartState.DISABLED
+import net.taler.merchantpos.order.RestartState.ENABLED
+import net.taler.merchantpos.order.RestartState.UNDO
+
+internal enum class RestartState { ENABLED, DISABLED, UNDO }
+
+internal interface LiveOrder {
+    val order: LiveData<Order>
+    val orderTotal: LiveData<Double>
+    val restartState: LiveData<RestartState>
+    val modifyOrderAllowed: LiveData<Boolean>
+    val lastAddedProduct: ConfigProduct?
+    val selectedProductKey: String?
+    fun restartOrUndo()
+    fun selectOrderLine(product: ConfigProduct?)
+    fun increaseSelectedOrderLine()
+    fun decreaseSelectedOrderLine()
+}
+
+internal class MutableLiveOrder(
+    val id: Int,
+    private val productsByCategory: HashMap<Category, ArrayList<ConfigProduct>>
+) : LiveOrder {
+    private val availableCategories: Map<Int, Category>
+        get() = productsByCategory.keys.map { it.id to it }.toMap()
+    override val order: MutableLiveData<Order> = MutableLiveData(Order(id, availableCategories))
+    override val orderTotal: LiveData<Double> = Transformations.map(order) { it.total }
+    override val restartState = MutableLiveData(DISABLED)
+    private val selectedOrderLine = MutableLiveData<ConfigProduct>()
+    override val selectedProductKey: String?
+        get() = selectedOrderLine.value?.id
+    override val modifyOrderAllowed =
+        CombinedLiveData(restartState, selectedOrderLine) { restartState, selectedOrderLine ->
+            restartState != DISABLED && selectedOrderLine != null
+        }
+    override var lastAddedProduct: ConfigProduct? = null
+    private var undoOrder: Order? = null
+
+    @UiThread
+    internal fun addProduct(product: ConfigProduct) {
+        lastAddedProduct = product
+        order.value = order.value!! + product
+        restartState.value = ENABLED
+    }
+
+    @UiThread
+    internal fun removeProduct(product: ConfigProduct) {
+        val modifiedOrder = order.value!! - product
+        order.value = modifiedOrder
+        restartState.value = if (modifiedOrder.products.isEmpty()) DISABLED else ENABLED
+    }
+
+    @UiThread
+    internal fun isEmpty() = order.value!!.products.isEmpty()
+
+    @UiThread
+    override fun restartOrUndo() {
+        if (restartState.value == UNDO) {
+            order.value = undoOrder
+            restartState.value = ENABLED
+            undoOrder = null
+        } else {
+            undoOrder = order.value
+            order.value = Order(id, availableCategories)
+            restartState.value = UNDO
+        }
+    }
+
+    @UiThread
+    override fun selectOrderLine(product: ConfigProduct?) {
+        selectedOrderLine.value = product
+    }
+
+    @UiThread
+    override fun increaseSelectedOrderLine() {
+        val orderLine = selectedOrderLine.value ?: throw IllegalStateException()
+        addProduct(orderLine)
+    }
+
+    @UiThread
+    override fun decreaseSelectedOrderLine() {
+        val orderLine = selectedOrderLine.value ?: throw IllegalStateException()
+        removeProduct(orderLine)
+    }
+
+}
diff --git a/merchant-terminal/src/main/java/net/taler/merchantpos/order/OrderFragment.kt b/merchant-terminal/src/main/java/net/taler/merchantpos/order/OrderFragment.kt
new file mode 100644
index 0000000..49f7cf2
--- /dev/null
+++ b/merchant-terminal/src/main/java/net/taler/merchantpos/order/OrderFragment.kt
@@ -0,0 +1,115 @@
+/*
+ * This file is part of GNU Taler
+ * (C) 2020 Taler Systems S.A.
+ *
+ * GNU Taler is free software; you can redistribute it and/or modify it under the
+ * terms of the GNU General Public License as published by the Free Software
+ * Foundation; either version 3, or (at your option) any later version.
+ *
+ * GNU Taler is distributed in the hope that it will be useful, but WITHOUT ANY
+ * WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
+ * A PARTICULAR PURPOSE.  See the GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along with
+ * GNU Taler; see the file COPYING.  If not, see <http://www.gnu.org/licenses/>
+ */
+
+package net.taler.merchantpos.order
+
+import android.os.Bundle
+import android.view.LayoutInflater
+import android.view.View
+import android.view.ViewGroup
+import androidx.fragment.app.Fragment
+import androidx.fragment.app.activityViewModels
+import androidx.lifecycle.Observer
+import androidx.navigation.fragment.findNavController
+import androidx.transition.TransitionManager.beginDelayedTransition
+import kotlinx.android.synthetic.main.fragment_order.*
+import net.taler.merchantpos.MainViewModel
+import net.taler.merchantpos.R
+import net.taler.merchantpos.navigate
+import net.taler.merchantpos.order.OrderFragmentDirections.Companion.actionGlobalConfigFetcher
+import net.taler.merchantpos.order.OrderFragmentDirections.Companion.actionOrderToMerchantSettings
+import net.taler.merchantpos.order.OrderFragmentDirections.Companion.actionOrderToProcessPayment
+import net.taler.merchantpos.order.RestartState.ENABLED
+import net.taler.merchantpos.order.RestartState.UNDO
+
+class OrderFragment : Fragment() {
+
+    private val viewModel: MainViewModel by activityViewModels()
+    private val orderManager by lazy { viewModel.orderManager }
+    private val paymentManager by lazy { viewModel.paymentManager }
+
+    override fun onCreateView(
+        inflater: LayoutInflater,
+        container: ViewGroup?,
+        savedInstanceState: Bundle?
+    ): View? {
+        return inflater.inflate(R.layout.fragment_order, container, false)
+    }
+
+    override fun onActivityCreated(savedInstanceState: Bundle?) {
+        super.onActivityCreated(savedInstanceState)
+        orderManager.currentOrderId.observe(viewLifecycleOwner, Observer { orderId ->
+            val liveOrder = orderManager.getOrder(orderId)
+            onOrderSwitched(orderId, liveOrder)
+            // add a new OrderStateFragment for each order
+            // as switching its internals (like we do here) would be too messy
+            childFragmentManager.beginTransaction()
+                .replace(R.id.fragment1, OrderStateFragment())
+                .commit()
+        })
+    }
+
+    override fun onStart() {
+        super.onStart()
+        if (!viewModel.configManager.config.isValid()) {
+            actionOrderToMerchantSettings().navigate(findNavController())
+        } else if (viewModel.configManager.merchantConfig?.currency == null) {
+            actionGlobalConfigFetcher().navigate(findNavController())
+        }
+    }
+
+    private fun onOrderSwitched(orderId: Int, liveOrder: LiveOrder) {
+        // order title
+        liveOrder.order.observe(viewLifecycleOwner, Observer { order ->
+            activity?.title = getString(R.string.order_label_title, order.title)
+        })
+        // restart button
+        restartButton.setOnClickListener { liveOrder.restartOrUndo() }
+        liveOrder.restartState.observe(viewLifecycleOwner, Observer { state ->
+            beginDelayedTransition(view as ViewGroup)
+            if (state == UNDO) {
+                restartButton.setText(R.string.order_undo)
+                restartButton.isEnabled = true
+                completeButton.isEnabled = false
+            } else {
+                restartButton.setText(R.string.order_restart)
+                restartButton.isEnabled = state == ENABLED
+                completeButton.isEnabled = state == ENABLED
+            }
+        })
+        // -1 and +1 buttons
+        liveOrder.modifyOrderAllowed.observe(viewLifecycleOwner, Observer { allowed ->
+            minusButton.isEnabled = allowed
+            plusButton.isEnabled = allowed
+        })
+        minusButton.setOnClickListener { liveOrder.decreaseSelectedOrderLine() }
+        plusButton.setOnClickListener { liveOrder.increaseSelectedOrderLine() }
+        // previous and next button
+        prevButton.isEnabled = orderManager.hasPreviousOrder(orderId)
+        orderManager.hasNextOrder(orderId).observe(viewLifecycleOwner, Observer { hasNextOrder ->
+            nextButton.isEnabled = hasNextOrder
+        })
+        prevButton.setOnClickListener { orderManager.previousOrder() }
+        nextButton.setOnClickListener { orderManager.nextOrder() }
+        // complete button
+        completeButton.setOnClickListener {
+            val order = liveOrder.order.value ?: return@setOnClickListener
+            paymentManager.createPayment(order)
+            actionOrderToProcessPayment().navigate(findNavController())
+        }
+    }
+
+}
diff --git a/merchant-terminal/src/main/java/net/taler/merchantpos/order/OrderManager.kt b/merchant-terminal/src/main/java/net/taler/merchantpos/order/OrderManager.kt
new file mode 100644
index 0000000..48ddc57
--- /dev/null
+++ b/merchant-terminal/src/main/java/net/taler/merchantpos/order/OrderManager.kt
@@ -0,0 +1,196 @@
+/*
+ * This file is part of GNU Taler
+ * (C) 2020 Taler Systems S.A.
+ *
+ * GNU Taler is free software; you can redistribute it and/or modify it under the
+ * terms of the GNU General Public License as published by the Free Software
+ * Foundation; either version 3, or (at your option) any later version.
+ *
+ * GNU Taler is distributed in the hope that it will be useful, but WITHOUT ANY
+ * WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
+ * A PARTICULAR PURPOSE.  See the GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along with
+ * GNU Taler; see the file COPYING.  If not, see <http://www.gnu.org/licenses/>
+ */
+
+package net.taler.merchantpos.order
+
+import android.content.Context
+import android.util.Log
+import androidx.annotation.UiThread
+import androidx.lifecycle.LiveData
+import androidx.lifecycle.MutableLiveData
+import androidx.lifecycle.Transformations.map
+import com.fasterxml.jackson.core.type.TypeReference
+import com.fasterxml.jackson.databind.ObjectMapper
+import net.taler.merchantpos.Amount.Companion.fromString
+import net.taler.merchantpos.R
+import net.taler.merchantpos.config.ConfigurationReceiver
+import net.taler.merchantpos.order.RestartState.ENABLED
+import org.json.JSONObject
+
+class OrderManager(
+    private val context: Context,
+    private val mapper: ObjectMapper
+) : ConfigurationReceiver {
+
+    companion object {
+        val TAG = OrderManager::class.java.simpleName
+    }
+
+    private var orderCounter: Int = 0
+    private val mCurrentOrderId = MutableLiveData<Int>()
+    internal val currentOrderId: LiveData<Int> = mCurrentOrderId
+
+    private val productsByCategory = HashMap<Category, ArrayList<ConfigProduct>>()
+
+    private val orders = LinkedHashMap<Int, MutableLiveOrder>()
+
+    private val mProducts = MutableLiveData<List<ConfigProduct>>()
+    internal val products: LiveData<List<ConfigProduct>> = mProducts
+
+    private val mCategories = MutableLiveData<List<Category>>()
+    internal val categories: LiveData<List<Category>> = mCategories
+
+    override suspend fun onConfigurationReceived(json: JSONObject, currency: String): String? {
+        // parse categories
+        val categoriesStr = json.getJSONArray("categories").toString()
+        val categoriesType = object : TypeReference<List<Category>>() {}
+        val categories: List<Category> = mapper.readValue(categoriesStr, categoriesType)
+        if (categories.isEmpty()) {
+            Log.e(TAG, "No valid category found.")
+            return context.getString(R.string.config_error_category)
+        }
+        // pre-select the first category
+        categories[0].selected = true
+
+        // parse products (live data gets updated in setCurrentCategory())
+        val productsStr = json.getJSONArray("products").toString()
+        val productsType = object : TypeReference<List<ConfigProduct>>() {}
+        val products: List<ConfigProduct> = mapper.readValue(productsStr, productsType)
+
+        // group products by categories
+        productsByCategory.clear()
+        products.forEach { product ->
+            val productCurrency = fromString(product.price).currency
+            if (productCurrency != currency) {
+                Log.e(TAG, "Product $product has currency $productCurrency, $currency expected")
+                return context.getString(
+                    R.string.config_error_currency, product.description, productCurrency, currency
+                )
+            }
+            product.categories.forEach { categoryId ->
+                val category = categories.find { it.id == categoryId }
+                if (category == null) {
+                    Log.e(TAG, "Product $product has unknown category $categoryId")
+                    return context.getString(
+                        R.string.config_error_product_category_id, product.description, categoryId
+                    )
+                }
+                if (productsByCategory.containsKey(category)) {
+                    productsByCategory[category]?.add(product)
+                } else {
+                    productsByCategory[category] = ArrayList<ConfigProduct>().apply { add(product) }
+                }
+            }
+        }
+        return if (productsByCategory.size > 0) {
+            mCategories.postValue(categories)
+            mProducts.postValue(productsByCategory[categories[0]])
+            // Initialize first empty order, note this won't work when updating config mid-flight
+            if (orders.isEmpty()) {
+                val id = orderCounter++
+                orders[id] = MutableLiveOrder(id, productsByCategory)
+                mCurrentOrderId.postValue(id)
+            }
+            null // success, no error string
+        } else context.getString(R.string.config_error_product_zero)
+    }
+
+    @UiThread
+    internal fun getOrder(orderId: Int): LiveOrder {
+        return orders[orderId] ?: throw IllegalArgumentException()
+    }
+
+    @UiThread
+    internal fun nextOrder() {
+        val currentId = currentOrderId.value!!
+        var foundCurrentOrder = false
+        var nextId: Int? = null
+        for (orderId in orders.keys) {
+            if (foundCurrentOrder) {
+                nextId = orderId
+                break
+            }
+            if (orderId == currentId) foundCurrentOrder = true
+        }
+        if (nextId == null) {
+            nextId = orderCounter++
+            orders[nextId] = MutableLiveOrder(nextId, productsByCategory)
+        }
+        val currentOrder = order(currentId)
+        if (currentOrder.isEmpty()) orders.remove(currentId)
+        else currentOrder.lastAddedProduct = null  // not needed anymore and it would get selected
+        mCurrentOrderId.value = nextId
+    }
+
+    @UiThread
+    internal fun previousOrder() {
+        val currentId = currentOrderId.value!!
+        var previousId: Int? = null
+        var foundCurrentOrder = false
+        for (orderId in orders.keys) {
+            if (orderId == currentId) {
+                foundCurrentOrder = true
+                break
+            }
+            previousId = orderId
+        }
+        if (previousId == null || !foundCurrentOrder) {
+            throw AssertionError("Could not find previous order for $currentId")
+        }
+        val currentOrder = order(currentId)
+        // remove current order if empty, or lastAddedProduct as it is not needed anymore
+        // and would get selected when navigating back instead of last selection
+        if (currentOrder.isEmpty()) orders.remove(currentId)
+        else currentOrder.lastAddedProduct = null
+        mCurrentOrderId.value = previousId
+    }
+
+    fun hasPreviousOrder(currentOrderId: Int): Boolean {
+        return currentOrderId != orders.keys.first()
+    }
+
+    fun hasNextOrder(currentOrderId: Int) = map(order(currentOrderId).restartState) { state ->
+        state == ENABLED || currentOrderId != orders.keys.last()
+    }
+
+    internal fun setCurrentCategory(category: Category) {
+        val newCategories = categories.value?.apply {
+            forEach { if (it.selected) it.selected = false }
+            category.selected = true
+        }
+        mCategories.postValue(newCategories)
+        mProducts.postValue(productsByCategory[category])
+    }
+
+    @UiThread
+    internal fun addProduct(orderId: Int, product: ConfigProduct) {
+        order(orderId).addProduct(product)
+    }
+
+    @UiThread
+    internal fun onOrderPaid(orderId: Int) {
+        if (currentOrderId.value == orderId) {
+            if (hasPreviousOrder(orderId)) previousOrder()
+            else nextOrder()
+        }
+        orders.remove(orderId)
+    }
+
+    private fun order(orderId: Int): MutableLiveOrder {
+        return orders[orderId] ?: throw IllegalStateException()
+    }
+
+}
diff --git a/merchant-terminal/src/main/java/net/taler/merchantpos/order/OrderStateFragment.kt b/merchant-terminal/src/main/java/net/taler/merchantpos/order/OrderStateFragment.kt
new file mode 100644
index 0000000..1b70016
--- /dev/null
+++ b/merchant-terminal/src/main/java/net/taler/merchantpos/order/OrderStateFragment.kt
@@ -0,0 +1,213 @@
+/*
+ * This file is part of GNU Taler
+ * (C) 2020 Taler Systems S.A.
+ *
+ * GNU Taler is free software; you can redistribute it and/or modify it under the
+ * terms of the GNU General Public License as published by the Free Software
+ * Foundation; either version 3, or (at your option) any later version.
+ *
+ * GNU Taler is distributed in the hope that it will be useful, but WITHOUT ANY
+ * WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
+ * A PARTICULAR PURPOSE.  See the GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along with
+ * GNU Taler; see the file COPYING.  If not, see <http://www.gnu.org/licenses/>
+ */
+
+package net.taler.merchantpos.order
+
+import android.os.Bundle
+import android.view.LayoutInflater
+import android.view.MotionEvent
+import android.view.View
+import android.view.ViewGroup
+import android.widget.TextView
+import androidx.fragment.app.Fragment
+import androidx.fragment.app.activityViewModels
+import androidx.lifecycle.Observer
+import androidx.recyclerview.selection.ItemDetailsLookup
+import androidx.recyclerview.selection.ItemKeyProvider
+import androidx.recyclerview.selection.SelectionPredicates
+import androidx.recyclerview.selection.SelectionTracker
+import androidx.recyclerview.selection.StorageStrategy
+import androidx.recyclerview.widget.AsyncListDiffer
+import androidx.recyclerview.widget.DiffUtil
+import androidx.recyclerview.widget.LinearLayoutManager
+import androidx.recyclerview.widget.RecyclerView
+import androidx.recyclerview.widget.RecyclerView.Adapter
+import androidx.recyclerview.widget.RecyclerView.ViewHolder
+import kotlinx.android.synthetic.main.fragment_order_state.*
+import net.taler.merchantpos.MainViewModel
+import net.taler.merchantpos.R
+import net.taler.merchantpos.fadeIn
+import net.taler.merchantpos.fadeOut
+import net.taler.merchantpos.order.OrderAdapter.OrderLineLookup
+import net.taler.merchantpos.order.OrderAdapter.OrderViewHolder
+
+class OrderStateFragment : Fragment() {
+
+    private val viewModel: MainViewModel by activityViewModels()
+    private val orderManager by lazy { viewModel.orderManager }
+    private val liveOrder by lazy { orderManager.getOrder(orderManager.currentOrderId.value!!) }
+    private val adapter = OrderAdapter()
+    private var tracker: SelectionTracker<String>? = null
+
+    override fun onCreateView(
+        inflater: LayoutInflater,
+        container: ViewGroup?,
+        savedInstanceState: Bundle?
+    ): View? {
+        return inflater.inflate(R.layout.fragment_order_state, container, false)
+    }
+
+    override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
+        orderList.apply {
+            adapter = this@OrderStateFragment.adapter
+            layoutManager = LinearLayoutManager(requireContext())
+        }
+        val detailsLookup = OrderLineLookup(orderList)
+        val tracker = SelectionTracker.Builder(
+            "order-selection-id",
+            orderList,
+            adapter.keyProvider,
+            detailsLookup,
+            StorageStrategy.createStringStorage()
+        ).withSelectionPredicate(
+            SelectionPredicates.createSelectSingleAnything()
+        ).build()
+        savedInstanceState?.let { tracker.onRestoreInstanceState(it) }
+        adapter.tracker = tracker
+        this.tracker = tracker
+        if (savedInstanceState == null) {
+            // select last selected order line when re-creating this fragment
+            // do it before attaching the tracker observer
+            liveOrder.selectedProductKey?.let { tracker.select(it) }
+        }
+        tracker.addObserver(object : SelectionTracker.SelectionObserver<String>() {
+            override fun onItemStateChanged(key: String, selected: Boolean) {
+                super.onItemStateChanged(key, selected)
+                val item = if (selected) adapter.getItemByKey(key) else null
+                liveOrder.selectOrderLine(item)
+            }
+        })
+        liveOrder.order.observe(viewLifecycleOwner, Observer { order ->
+            onOrderChanged(order, tracker)
+        })
+        liveOrder.orderTotal.observe(viewLifecycleOwner, Observer { orderTotal ->
+            if (orderTotal == 0.0) {
+                totalView.fadeOut()
+                totalView.text = null
+            } else {
+                val currency = viewModel.configManager.merchantConfig?.currency
+                totalView.text = getString(R.string.order_total, orderTotal, currency)
+                totalView.fadeIn()
+            }
+        })
+    }
+
+    override fun onSaveInstanceState(outState: Bundle) {
+        super.onSaveInstanceState(outState)
+        tracker?.onSaveInstanceState(outState)
+    }
+
+    private fun onOrderChanged(order: Order, tracker: SelectionTracker<String>) {
+        adapter.setItems(order.products) {
+            liveOrder.lastAddedProduct?.let {
+                val position = adapter.findPosition(it)
+                if (position >= 0) {
+                    // orderList can be null m(
+                    orderList?.scrollToPosition(position)
+                    orderList?.post { this.tracker?.select(it.id) }
+                }
+            }
+            // workaround for bug: SelectionObserver doesn't update when removing selected item
+            if (tracker.hasSelection()) {
+                val key = tracker.selection.first()
+                val product = order.products.find { it.id == key }
+                if (product == null) tracker.clearSelection()
+            }
+        }
+    }
+
+}
+
+private class OrderAdapter : Adapter<OrderViewHolder>() {
+
+    lateinit var tracker: SelectionTracker<String>
+    val keyProvider = OrderKeyProvider()
+    private val itemCallback = object : DiffUtil.ItemCallback<ConfigProduct>() {
+        override fun areItemsTheSame(oldItem: ConfigProduct, newItem: ConfigProduct): Boolean {
+            return oldItem == newItem
+        }
+
+        override fun areContentsTheSame(oldItem: ConfigProduct, newItem: ConfigProduct): Boolean {
+            return oldItem.quantity == newItem.quantity
+        }
+    }
+    private val differ = AsyncListDiffer(this, itemCallback)
+
+    override fun getItemCount() = differ.currentList.size
+
+    override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): OrderViewHolder {
+        val view =
+            LayoutInflater.from(parent.context).inflate(R.layout.list_item_order, parent, false)
+        return OrderViewHolder(view)
+    }
+
+    override fun onBindViewHolder(holder: OrderViewHolder, position: Int) {
+        val item = getItem(position)!!
+        holder.bind(item, tracker.isSelected(item.id))
+    }
+
+    fun setItems(items: List<ConfigProduct>, commitCallback: () -> Unit) {
+        // toMutableList() is needed for some reason, otherwise doesn't update adapter
+        differ.submitList(items.toMutableList(), commitCallback)
+    }
+
+    fun getItem(position: Int): ConfigProduct? = differ.currentList[position]
+
+    fun getItemByKey(key: String): ConfigProduct? {
+        return differ.currentList.find { it.id == key }
+    }
+
+    fun findPosition(product: ConfigProduct): Int {
+        return differ.currentList.indexOf(product)
+    }
+
+    private inner class OrderViewHolder(private val v: View) : ViewHolder(v) {
+        private val quantity: TextView = v.findViewById(R.id.quantity)
+        private val name: TextView = v.findViewById(R.id.name)
+        private val price: TextView = v.findViewById(R.id.price)
+
+        fun bind(product: ConfigProduct, selected: Boolean) {
+            v.isActivated = selected
+            quantity.text = product.quantity.toString()
+            name.text = product.localizedDescription
+            price.text = String.format("%.2f", product.priceAsDouble * product.quantity)
+        }
+    }
+
+    private inner class OrderKeyProvider : ItemKeyProvider<String>(SCOPE_MAPPED) {
+        override fun getKey(position: Int) = getItem(position)!!.id
+        override fun getPosition(key: String): Int {
+            return differ.currentList.indexOfFirst { it.id == key }
+        }
+    }
+
+    internal class OrderLineLookup(private val list: RecyclerView) : ItemDetailsLookup<String>() {
+        override fun getItemDetails(e: MotionEvent): ItemDetails<String>? {
+            list.findChildViewUnder(e.x, e.y)?.let { view ->
+                val holder = list.getChildViewHolder(view)
+                val adapter = list.adapter as OrderAdapter
+                val position = holder.adapterPosition
+                return object : ItemDetails<String>() {
+                    override fun getPosition(): Int = position
+                    override fun getSelectionKey(): String = adapter.keyProvider.getKey(position)
+                    override fun inSelectionHotspot(e: MotionEvent) = true
+                }
+            }
+            return null
+        }
+    }
+
+}
diff --git a/merchant-terminal/src/main/java/net/taler/merchantpos/order/ProductsFragment.kt b/merchant-terminal/src/main/java/net/taler/merchantpos/order/ProductsFragment.kt
new file mode 100644
index 0000000..4704ad0
--- /dev/null
+++ b/merchant-terminal/src/main/java/net/taler/merchantpos/order/ProductsFragment.kt
@@ -0,0 +1,111 @@
+/*
+ * This file is part of GNU Taler
+ * (C) 2020 Taler Systems S.A.
+ *
+ * GNU Taler is free software; you can redistribute it and/or modify it under the
+ * terms of the GNU General Public License as published by the Free Software
+ * Foundation; either version 3, or (at your option) any later version.
+ *
+ * GNU Taler is distributed in the hope that it will be useful, but WITHOUT ANY
+ * WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
+ * A PARTICULAR PURPOSE.  See the GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along with
+ * GNU Taler; see the file COPYING.  If not, see <http://www.gnu.org/licenses/>
+ */
+
+package net.taler.merchantpos.order
+
+import android.os.Bundle
+import android.view.LayoutInflater
+import android.view.View
+import android.view.View.INVISIBLE
+import android.view.ViewGroup
+import android.widget.TextView
+import androidx.fragment.app.Fragment
+import androidx.fragment.app.activityViewModels
+import androidx.lifecycle.Observer
+import androidx.recyclerview.widget.GridLayoutManager
+import androidx.recyclerview.widget.RecyclerView.Adapter
+import androidx.recyclerview.widget.RecyclerView.ViewHolder
+import kotlinx.android.synthetic.main.fragment_products.*
+import net.taler.merchantpos.MainViewModel
+import net.taler.merchantpos.R
+import net.taler.merchantpos.order.ProductAdapter.ProductViewHolder
+
+interface ProductSelectionListener {
+    fun onProductSelected(product: ConfigProduct)
+}
+
+class ProductsFragment : Fragment(), ProductSelectionListener {
+
+    private val viewModel: MainViewModel by activityViewModels()
+    private val orderManager by lazy { viewModel.orderManager }
+    private val adapter = ProductAdapter(this)
+
+    override fun onCreateView(
+        inflater: LayoutInflater,
+        container: ViewGroup?,
+        savedInstanceState: Bundle?
+    ): View? {
+        return inflater.inflate(R.layout.fragment_products, container, false)
+    }
+
+    override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
+        productsList.apply {
+            adapter = this@ProductsFragment.adapter
+            layoutManager = GridLayoutManager(requireContext(), 3)
+        }
+
+        orderManager.products.observe(viewLifecycleOwner, Observer { products ->
+            if (products == null) {
+                adapter.setItems(emptyList())
+            } else {
+                adapter.setItems(products)
+            }
+            progressBar.visibility = INVISIBLE
+        })
+    }
+
+    override fun onProductSelected(product: ConfigProduct) {
+        orderManager.addProduct(orderManager.currentOrderId.value!!, product)
+    }
+
+}
+
+private class ProductAdapter(
+    private val listener: ProductSelectionListener
+) : Adapter<ProductViewHolder>() {
+
+    private val products = ArrayList<ConfigProduct>()
+
+    override fun getItemCount() = products.size
+
+    override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): ProductViewHolder {
+        val view =
+            LayoutInflater.from(parent.context).inflate(R.layout.list_item_product, parent, false)
+        return ProductViewHolder(view)
+    }
+
+    override fun onBindViewHolder(holder: ProductViewHolder, position: Int) {
+        holder.bind(products[position])
+    }
+
+    fun setItems(items: List<ConfigProduct>) {
+        products.clear()
+        products.addAll(items)
+        notifyDataSetChanged()
+    }
+
+    private inner class ProductViewHolder(private val v: View) : ViewHolder(v) {
+        private val name: TextView = v.findViewById(R.id.name)
+        private val price: TextView = v.findViewById(R.id.price)
+
+        fun bind(product: ConfigProduct) {
+            name.text = product.localizedDescription
+            price.text = product.priceAsDouble.toString()
+            v.setOnClickListener { listener.onProductSelected(product) }
+        }
+    }
+
+}
diff --git a/merchant-terminal/src/main/java/net/taler/merchantpos/payment/Payment.kt b/merchant-terminal/src/main/java/net/taler/merchantpos/payment/Payment.kt
new file mode 100644
index 0000000..b7e4a4b
--- /dev/null
+++ b/merchant-terminal/src/main/java/net/taler/merchantpos/payment/Payment.kt
@@ -0,0 +1,29 @@
+/*
+ * This file is part of GNU Taler
+ * (C) 2020 Taler Systems S.A.
+ *
+ * GNU Taler is free software; you can redistribute it and/or modify it under the
+ * terms of the GNU General Public License as published by the Free Software
+ * Foundation; either version 3, or (at your option) any later version.
+ *
+ * GNU Taler is distributed in the hope that it will be useful, but WITHOUT ANY
+ * WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
+ * A PARTICULAR PURPOSE.  See the GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along with
+ * GNU Taler; see the file COPYING.  If not, see <http://www.gnu.org/licenses/>
+ */
+
+package net.taler.merchantpos.payment
+
+import net.taler.merchantpos.order.Order
+
+data class Payment(
+    val order: Order,
+    val summary: String,
+    val currency: String,
+    val orderId: String? = null,
+    val talerPayUri: String? = null,
+    val paid: Boolean = false,
+    val error: Boolean = false
+)
diff --git a/merchant-terminal/src/main/java/net/taler/merchantpos/payment/PaymentManager.kt b/merchant-terminal/src/main/java/net/taler/merchantpos/payment/PaymentManager.kt
new file mode 100644
index 0000000..7f15816
--- /dev/null
+++ b/merchant-terminal/src/main/java/net/taler/merchantpos/payment/PaymentManager.kt
@@ -0,0 +1,154 @@
+/*
+ * This file is part of GNU Taler
+ * (C) 2020 Taler Systems S.A.
+ *
+ * GNU Taler is free software; you can redistribute it and/or modify it under the
+ * terms of the GNU General Public License as published by the Free Software
+ * Foundation; either version 3, or (at your option) any later version.
+ *
+ * GNU Taler is distributed in the hope that it will be useful, but WITHOUT ANY
+ * WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
+ * A PARTICULAR PURPOSE.  See the GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along with
+ * GNU Taler; see the file COPYING.  If not, see <http://www.gnu.org/licenses/>
+ */
+
+package net.taler.merchantpos.payment
+
+import android.os.CountDownTimer
+import android.util.Log
+import androidx.annotation.UiThread
+import androidx.lifecycle.LiveData
+import androidx.lifecycle.MutableLiveData
+import com.android.volley.Request.Method.GET
+import com.android.volley.Request.Method.POST
+import com.android.volley.RequestQueue
+import com.android.volley.Response.ErrorListener
+import com.android.volley.Response.Listener
+import com.android.volley.VolleyError
+import com.fasterxml.jackson.databind.ObjectMapper
+import net.taler.merchantpos.config.ConfigManager
+import net.taler.merchantpos.config.MerchantRequest
+import net.taler.merchantpos.order.ContractProduct
+import net.taler.merchantpos.order.Order
+import org.json.JSONArray
+import org.json.JSONObject
+import java.net.URLEncoder
+import java.util.concurrent.TimeUnit.MINUTES
+import java.util.concurrent.TimeUnit.SECONDS
+
+private val TIMEOUT = MINUTES.toMillis(2)
+private val CHECK_INTERVAL = SECONDS.toMillis(1)
+private const val FULFILLMENT_PREFIX = "taler://fulfillment-success/"
+
+class PaymentManager(
+    private val configManager: ConfigManager,
+    private val queue: RequestQueue,
+    private val mapper: ObjectMapper
+) {
+
+    companion object {
+        val TAG = PaymentManager::class.java.simpleName
+    }
+
+    private val mPayment = MutableLiveData<Payment>()
+    val payment: LiveData<Payment> = mPayment
+
+    private val checkTimer = object : CountDownTimer(TIMEOUT, CHECK_INTERVAL) {
+        override fun onTick(millisUntilFinished: Long) {
+            val orderId = payment.value?.orderId
+            if (orderId == null) cancel()
+            else checkPayment(orderId)
+        }
+
+        override fun onFinish() {
+            payment.value?.copy(error = true)?.let { mPayment.value = it }
+        }
+    }
+
+    @UiThread
+    fun createPayment(order: Order) {
+        val merchantConfig = configManager.merchantConfig!!
+
+        val currency = merchantConfig.currency!!
+        val amount = "$currency:${order.totalAsString}"
+        val summary = order.summary
+        val summaryI18n = order.summaryI18n
+
+        mPayment.value = Payment(order, summary, currency)
+
+        val fulfillmentId = "${System.currentTimeMillis()}-${order.hashCode()}"
+        val fulfillmentUrl =
+            "${FULFILLMENT_PREFIX}${URLEncoder.encode(summary, "UTF-8")}#$fulfillmentId"
+        val body = JSONObject().apply {
+            put("order", JSONObject().apply {
+                put("amount", amount)
+                put("summary", summary)
+                if (summaryI18n != null) put("summary_i18n", order.summaryI18n)
+                // fulfillment_url needs to be unique per order
+                put("fulfillment_url", fulfillmentUrl)
+                put("instance", "default")
+                put("products", order.getProductsJson())
+            })
+        }
+
+        Log.d(TAG, body.toString(4))
+
+        val req = MerchantRequest(POST, merchantConfig, "order", null, body,
+            Listener { onOrderCreated(it) },
+            ErrorListener { onNetworkError(it) }
+        )
+        queue.add(req)
+    }
+
+    private fun Order.getProductsJson(): JSONArray {
+        val contractProducts = products.map { ContractProduct(it) }
+        val productsStr = mapper.writeValueAsString(contractProducts)
+        return JSONArray(productsStr)
+    }
+
+    private fun onOrderCreated(orderResponse: JSONObject) {
+        val orderId = orderResponse.getString("order_id")
+        mPayment.value = mPayment.value!!.copy(orderId = orderId)
+        checkTimer.start()
+    }
+
+    private fun checkPayment(orderId: String) {
+        val merchantConfig = configManager.merchantConfig!!
+        val params = mapOf(
+            "order_id" to orderId,
+            "instance" to merchantConfig.instance
+        )
+
+        val req = MerchantRequest(GET, merchantConfig, "check-payment", params, null,
+            Listener { onPaymentChecked(it) },
+            ErrorListener { onNetworkError(it) })
+        queue.add(req)
+    }
+
+    /**
+     * Called when the /check-payment response gave a result.
+     */
+    private fun onPaymentChecked(checkPaymentResponse: JSONObject) {
+        val currentValue = requireNotNull(mPayment.value)
+        if (checkPaymentResponse.getBoolean("paid")) {
+            mPayment.value = currentValue.copy(paid = true)
+            checkTimer.cancel()
+        } else if (currentValue.talerPayUri == null) {
+            val talerPayUri = checkPaymentResponse.getString("taler_pay_uri")
+            mPayment.value = currentValue.copy(talerPayUri = talerPayUri)
+        }
+    }
+
+    private fun onNetworkError(volleyError: VolleyError) {
+        Log.e(PaymentManager::class.java.simpleName, volleyError.toString())
+        cancelPayment()
+    }
+
+    fun cancelPayment() {
+        mPayment.value = mPayment.value!!.copy(error = true)
+        checkTimer.cancel()
+    }
+
+}
diff --git a/merchant-terminal/src/main/java/net/taler/merchantpos/payment/PaymentSuccessFragment.kt b/merchant-terminal/src/main/java/net/taler/merchantpos/payment/PaymentSuccessFragment.kt
new file mode 100644
index 0000000..10d538d
--- /dev/null
+++ b/merchant-terminal/src/main/java/net/taler/merchantpos/payment/PaymentSuccessFragment.kt
@@ -0,0 +1,44 @@
+/*
+ * This file is part of GNU Taler
+ * (C) 2020 Taler Systems S.A.
+ *
+ * GNU Taler is free software; you can redistribute it and/or modify it under the
+ * terms of the GNU General Public License as published by the Free Software
+ * Foundation; either version 3, or (at your option) any later version.
+ *
+ * GNU Taler is distributed in the hope that it will be useful, but WITHOUT ANY
+ * WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
+ * A PARTICULAR PURPOSE.  See the GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along with
+ * GNU Taler; see the file COPYING.  If not, see <http://www.gnu.org/licenses/>
+ */
+
+package net.taler.merchantpos.payment
+
+import android.os.Bundle
+import android.view.LayoutInflater
+import android.view.View
+import android.view.ViewGroup
+import androidx.fragment.app.Fragment
+import androidx.navigation.fragment.findNavController
+import kotlinx.android.synthetic.main.fragment_payment_success.*
+import net.taler.merchantpos.R
+
+class PaymentSuccessFragment : Fragment() {
+
+    override fun onCreateView(
+        inflater: LayoutInflater, container: ViewGroup?,
+        savedInstanceState: Bundle?
+    ): View? {
+        return inflater.inflate(R.layout.fragment_payment_success, container, false)
+    }
+
+    override fun onActivityCreated(savedInstanceState: Bundle?) {
+        super.onActivityCreated(savedInstanceState)
+        paymentButton.setOnClickListener {
+            findNavController().navigateUp()
+        }
+    }
+
+}
diff --git a/merchant-terminal/src/main/java/net/taler/merchantpos/payment/ProcessPaymentFragment.kt b/merchant-terminal/src/main/java/net/taler/merchantpos/payment/ProcessPaymentFragment.kt
new file mode 100644
index 0000000..24f67f1
--- /dev/null
+++ b/merchant-terminal/src/main/java/net/taler/merchantpos/payment/ProcessPaymentFragment.kt
@@ -0,0 +1,96 @@
+/*
+ * This file is part of GNU Taler
+ * (C) 2020 Taler Systems S.A.
+ *
+ * GNU Taler is free software; you can redistribute it and/or modify it under the
+ * terms of the GNU General Public License as published by the Free Software
+ * Foundation; either version 3, or (at your option) any later version.
+ *
+ * GNU Taler is distributed in the hope that it will be useful, but WITHOUT ANY
+ * WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
+ * A PARTICULAR PURPOSE.  See the GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along with
+ * GNU Taler; see the file COPYING.  If not, see <http://www.gnu.org/licenses/>
+ */
+
+package net.taler.merchantpos.payment
+
+import android.annotation.SuppressLint
+import android.os.Bundle
+import android.view.LayoutInflater
+import android.view.View
+import android.view.ViewGroup
+import androidx.fragment.app.Fragment
+import androidx.fragment.app.activityViewModels
+import androidx.lifecycle.Observer
+import androidx.navigation.fragment.findNavController
+import com.google.android.material.snackbar.BaseTransientBottomBar.LENGTH_LONG
+import kotlinx.android.synthetic.main.fragment_process_payment.*
+import net.taler.merchantpos.MainViewModel
+import net.taler.merchantpos.NfcManager.Companion.hasNfc
+import net.taler.merchantpos.QrCodeManager.makeQrCode
+import net.taler.merchantpos.R
+import net.taler.merchantpos.fadeIn
+import net.taler.merchantpos.fadeOut
+import net.taler.merchantpos.navigate
+import net.taler.merchantpos.payment.ProcessPaymentFragmentDirections.Companion.actionProcessPaymentToPaymentSuccess
+import net.taler.merchantpos.topSnackbar
+
+class ProcessPaymentFragment : Fragment() {
+
+    private val model: MainViewModel by activityViewModels()
+    private val paymentManager by lazy { model.paymentManager }
+
+    override fun onCreateView(
+        inflater: LayoutInflater, container: ViewGroup?,
+        savedInstanceState: Bundle?
+    ): View? {
+        return inflater.inflate(R.layout.fragment_process_payment, container, false)
+    }
+
+    override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
+        val introRes =
+            if (hasNfc(requireContext())) R.string.payment_intro_nfc else R.string.payment_intro
+        payIntroView.setText(introRes)
+        paymentManager.payment.observe(viewLifecycleOwner, Observer { payment ->
+            onPaymentStateChanged(payment)
+        })
+        cancelPaymentButton.setOnClickListener {
+            onPaymentCancel()
+        }
+    }
+
+    private fun onPaymentStateChanged(payment: Payment) {
+        if (payment.error) {
+            topSnackbar(view!!, R.string.error_network, LENGTH_LONG)
+            findNavController().navigateUp()
+            return
+        }
+        if (payment.paid) {
+            model.orderManager.onOrderPaid(payment.order.id)
+            actionProcessPaymentToPaymentSuccess().navigate(findNavController())
+            return
+        }
+        payIntroView.fadeIn()
+        @SuppressLint("SetTextI18n")
+        amountView.text = "${payment.order.totalAsString} ${payment.currency}"
+        payment.orderId?.let {
+            orderRefView.text = getString(R.string.payment_order_ref, it)
+            orderRefView.fadeIn()
+        }
+        payment.talerPayUri?.let {
+            val qrcodeBitmap = makeQrCode(it)
+            qrcodeView.setImageBitmap(qrcodeBitmap)
+            qrcodeView.fadeIn()
+            progressBar.fadeOut()
+        }
+    }
+
+    private fun onPaymentCancel() {
+        paymentManager.cancelPayment()
+        findNavController().navigateUp()
+        topSnackbar(view!!, R.string.payment_canceled, LENGTH_LONG)
+    }
+
+}
diff --git a/merchant-terminal/src/main/res/color/button_bottom.xml b/merchant-terminal/src/main/res/color/button_bottom.xml
new file mode 100644
index 0000000..83363e9
--- /dev/null
+++ b/merchant-terminal/src/main/res/color/button_bottom.xml
@@ -0,0 +1,5 @@
+<?xml version="1.0" encoding="utf-8"?>
+<selector xmlns:android="http://schemas.android.com/apk/res/android">
+    <item android:color="@color/bottomButtons" android:state_enabled="true" />
+    <item android:alpha="0.12" android:color="?attr/colorOnSurface" />
+</selector>
diff --git a/merchant-terminal/src/main/res/drawable/ic_cash_refund.xml b/merchant-terminal/src/main/res/drawable/ic_cash_refund.xml
new file mode 100644
index 0000000..7359ca3
--- /dev/null
+++ b/merchant-terminal/src/main/res/drawable/ic_cash_refund.xml
@@ -0,0 +1,9 @@
+<vector xmlns:android="http://schemas.android.com/apk/res/android"
+        android:width="24dp"
+        android:height="24dp"
+        android:viewportWidth="24"
+        android:viewportHeight="24">
+    <path
+            android:fillColor="#000000"
+            android:pathData="M3,11H21V23H3V11M12,15A2,2 0 0,1 14,17A2,2 0 0,1 12,19A2,2 0 0,1 10,17A2,2 0 0,1 12,15M7,13A2,2 0 0,1 5,15V19A2,2 0 0,1 7,21H17A2,2 0 0,1 19,19V15A2,2 0 0,1 17,13H7M17,5V10H15.5V6.5H9.88L12.3,8.93L11.24,10L7,5.75L11.24,1.5L12.3,2.57L9.88,5H17Z" />
+</vector>
diff --git a/merchant-terminal/src/main/res/drawable/ic_check_circle.xml b/merchant-terminal/src/main/res/drawable/ic_check_circle.xml
new file mode 100644
index 0000000..61e1b5a
--- /dev/null
+++ b/merchant-terminal/src/main/res/drawable/ic_check_circle.xml
@@ -0,0 +1,10 @@
+<vector xmlns:android="http://schemas.android.com/apk/res/android"
+        android:width="24dp"
+        android:height="24dp"
+        android:alpha="0.56"
+        android:viewportWidth="24.0"
+        android:viewportHeight="24.0">
+    <path
+            android:fillColor="@color/green"
+            android:pathData="M12,2C6.48,2 2,6.48 2,12s4.48,10 10,10 10,-4.48 10,-10S17.52,2 12,2zM10,17l-5,-5 1.41,-1.41L10,14.17l7.59,-7.59L19,8l-9,9z" />
+</vector>
diff --git a/merchant-terminal/src/main/res/drawable/ic_history_black_24dp.xml b/merchant-terminal/src/main/res/drawable/ic_history_black_24dp.xml
new file mode 100644
index 0000000..a61de1b
--- /dev/null
+++ b/merchant-terminal/src/main/res/drawable/ic_history_black_24dp.xml
@@ -0,0 +1,9 @@
+<vector xmlns:android="http://schemas.android.com/apk/res/android"
+        android:width="24dp"
+        android:height="24dp"
+        android:viewportWidth="24.0"
+        android:viewportHeight="24.0">
+    <path
+        android:fillColor="#FF000000"
+        android:pathData="M13,3c-4.97,0 -9,4.03 -9,9L1,12l3.89,3.89 0.07,0.14L9,12L6,12c0,-3.87 3.13,-7 7,-7s7,3.13 7,7 -3.13,7 -7,7c-1.93,0 -3.68,-0.79 -4.94,-2.06l-1.42,1.42C8.27,19.99 10.51,21 13,21c4.97,0 9,-4.03 9,-9s-4.03,-9 -9,-9zM12,8v5l4.28,2.54 0.72,-1.21 -3.5,-2.08L13.5,8L12,8z"/>
+</vector>
diff --git a/merchant-terminal/src/main/res/drawable/ic_launcher_background.xml b/merchant-terminal/src/main/res/drawable/ic_launcher_background.xml
new file mode 100644
index 0000000..2408e30
--- /dev/null
+++ b/merchant-terminal/src/main/res/drawable/ic_launcher_background.xml
@@ -0,0 +1,74 @@
+<?xml version="1.0" encoding="utf-8"?>
+<vector
+    android:height="108dp"
+    android:width="108dp"
+    android:viewportHeight="108"
+    android:viewportWidth="108"
+    xmlns:android="http://schemas.android.com/apk/res/android">
+    <path android:fillColor="#008577"
+          android:pathData="M0,0h108v108h-108z"/>
+    <path android:fillColor="#00000000" android:pathData="M9,0L9,108"
+          android:strokeColor="#33FFFFFF" android:strokeWidth="0.8"/>
+    <path android:fillColor="#00000000" android:pathData="M19,0L19,108"
+          android:strokeColor="#33FFFFFF" android:strokeWidth="0.8"/>
+    <path android:fillColor="#00000000" android:pathData="M29,0L29,108"
+          android:strokeColor="#33FFFFFF" android:strokeWidth="0.8"/>
+    <path android:fillColor="#00000000" android:pathData="M39,0L39,108"
+          android:strokeColor="#33FFFFFF" android:strokeWidth="0.8"/>
+    <path android:fillColor="#00000000" android:pathData="M49,0L49,108"
+          android:strokeColor="#33FFFFFF" android:strokeWidth="0.8"/>
+    <path android:fillColor="#00000000" android:pathData="M59,0L59,108"
+          android:strokeColor="#33FFFFFF" android:strokeWidth="0.8"/>
+    <path android:fillColor="#00000000" android:pathData="M69,0L69,108"
+          android:strokeColor="#33FFFFFF" android:strokeWidth="0.8"/>
+    <path android:fillColor="#00000000" android:pathData="M79,0L79,108"
+          android:strokeColor="#33FFFFFF" android:strokeWidth="0.8"/>
+    <path android:fillColor="#00000000" android:pathData="M89,0L89,108"
+          android:strokeColor="#33FFFFFF" android:strokeWidth="0.8"/>
+    <path android:fillColor="#00000000" android:pathData="M99,0L99,108"
+          android:strokeColor="#33FFFFFF" android:strokeWidth="0.8"/>
+    <path android:fillColor="#00000000" android:pathData="M0,9L108,9"
+          android:strokeColor="#33FFFFFF" android:strokeWidth="0.8"/>
+    <path android:fillColor="#00000000" android:pathData="M0,19L108,19"
+          android:strokeColor="#33FFFFFF" android:strokeWidth="0.8"/>
+    <path android:fillColor="#00000000" android:pathData="M0,29L108,29"
+          android:strokeColor="#33FFFFFF" android:strokeWidth="0.8"/>
+    <path android:fillColor="#00000000" android:pathData="M0,39L108,39"
+          android:strokeColor="#33FFFFFF" android:strokeWidth="0.8"/>
+    <path android:fillColor="#00000000" android:pathData="M0,49L108,49"
+          android:strokeColor="#33FFFFFF" android:strokeWidth="0.8"/>
+    <path android:fillColor="#00000000" android:pathData="M0,59L108,59"
+          android:strokeColor="#33FFFFFF" android:strokeWidth="0.8"/>
+    <path android:fillColor="#00000000" android:pathData="M0,69L108,69"
+          android:strokeColor="#33FFFFFF" android:strokeWidth="0.8"/>
+    <path android:fillColor="#00000000" android:pathData="M0,79L108,79"
+          android:strokeColor="#33FFFFFF" android:strokeWidth="0.8"/>
+    <path android:fillColor="#00000000" android:pathData="M0,89L108,89"
+          android:strokeColor="#33FFFFFF" android:strokeWidth="0.8"/>
+    <path android:fillColor="#00000000" android:pathData="M0,99L108,99"
+          android:strokeColor="#33FFFFFF" android:strokeWidth="0.8"/>
+    <path android:fillColor="#00000000" android:pathData="M19,29L89,29"
+          android:strokeColor="#33FFFFFF" android:strokeWidth="0.8"/>
+    <path android:fillColor="#00000000" android:pathData="M19,39L89,39"
+          android:strokeColor="#33FFFFFF" android:strokeWidth="0.8"/>
+    <path android:fillColor="#00000000" android:pathData="M19,49L89,49"
+          android:strokeColor="#33FFFFFF" android:strokeWidth="0.8"/>
+    <path android:fillColor="#00000000" android:pathData="M19,59L89,59"
+          android:strokeColor="#33FFFFFF" android:strokeWidth="0.8"/>
+    <path android:fillColor="#00000000" android:pathData="M19,69L89,69"
+          android:strokeColor="#33FFFFFF" android:strokeWidth="0.8"/>
+    <path android:fillColor="#00000000" android:pathData="M19,79L89,79"
+          android:strokeColor="#33FFFFFF" android:strokeWidth="0.8"/>
+    <path android:fillColor="#00000000" android:pathData="M29,19L29,89"
+          android:strokeColor="#33FFFFFF" android:strokeWidth="0.8"/>
+    <path android:fillColor="#00000000" android:pathData="M39,19L39,89"
+          android:strokeColor="#33FFFFFF" android:strokeWidth="0.8"/>
+    <path android:fillColor="#00000000" android:pathData="M49,19L49,89"
+          android:strokeColor="#33FFFFFF" android:strokeWidth="0.8"/>
+    <path android:fillColor="#00000000" android:pathData="M59,19L59,89"
+          android:strokeColor="#33FFFFFF" android:strokeWidth="0.8"/>
+    <path android:fillColor="#00000000" android:pathData="M69,19L69,89"
+          android:strokeColor="#33FFFFFF" android:strokeWidth="0.8"/>
+    <path android:fillColor="#00000000" android:pathData="M79,19L79,89"
+          android:strokeColor="#33FFFFFF" android:strokeWidth="0.8"/>
+</vector>
diff --git a/merchant-terminal/src/main/res/drawable/ic_menu_manage.xml b/merchant-terminal/src/main/res/drawable/ic_menu_manage.xml
new file mode 100644
index 0000000..a0e423c
--- /dev/null
+++ b/merchant-terminal/src/main/res/drawable/ic_menu_manage.xml
@@ -0,0 +1,9 @@
+<vector xmlns:android="http://schemas.android.com/apk/res/android"
+        android:width="24dp"
+        android:height="24dp"
+        android:viewportWidth="24.0"
+        android:viewportHeight="24.0">
+    <path
+            android:fillColor="#FF000000"
+            android:pathData="M22.7,19l-9.1,-9.1c0.9,-2.3 0.4,-5 -1.5,-6.9 -2,-2 -5,-2.4 -7.4,-1.3L9,6 6,9 1.6,4.7C0.4,7.1 0.9,10.1 2.9,12.1c1.9,1.9 4.6,2.4 6.9,1.5l9.1,9.1c0.4,0.4 1,0.4 1.4,0l2.3,-2.3c0.5,-0.4 0.5,-1.1 0.1,-1.4z"/>
+</vector>
\ No newline at end of file
diff --git a/merchant-terminal/src/main/res/drawable/ic_move_money_24dp.xml b/merchant-terminal/src/main/res/drawable/ic_move_money_24dp.xml
new file mode 100644
index 0000000..349f48f
--- /dev/null
+++ b/merchant-terminal/src/main/res/drawable/ic_move_money_24dp.xml
@@ -0,0 +1,9 @@
+<vector xmlns:android="http://schemas.android.com/apk/res/android"
+        android:width="24dp"
+        android:height="24dp"
+        android:viewportWidth="24.0"
+        android:viewportHeight="24.0">
+    <path
+        android:fillColor="#FF000000"
+        android:pathData="M19,3L4.99,3c-1.11,0 -1.98,0.9 -1.98,2L3,19c0,1.1 0.88,2 1.99,2L19,21c1.1,0 2,-0.9 2,-2L21,5c0,-1.1 -0.9,-2 -2,-2zM19,15h-4c0,1.66 -1.35,3 -3,3s-3,-1.34 -3,-3L4.99,15L4.99,5L19,5v10zM16,10h-2L14,7h-4v3L8,10l4,4 4,-4z"/>
+</vector>
diff --git a/merchant-terminal/src/main/res/drawable/selectable_background.xml b/merchant-terminal/src/main/res/drawable/selectable_background.xml
new file mode 100644
index 0000000..b82de92
--- /dev/null
+++ b/merchant-terminal/src/main/res/drawable/selectable_background.xml
@@ -0,0 +1,5 @@
+<?xml version="1.0" encoding="utf-8"?>
+<selector xmlns:android="http://schemas.android.com/apk/res/android">
+    <item android:drawable="@color/selectedBackground" android:state_activated="true" />
+    <item android:drawable="@android:color/transparent" />
+</selector>
\ No newline at end of file
diff --git a/merchant-terminal/src/main/res/drawable/side_nav_bar.xml b/merchant-terminal/src/main/res/drawable/side_nav_bar.xml
new file mode 100644
index 0000000..50dc048
--- /dev/null
+++ b/merchant-terminal/src/main/res/drawable/side_nav_bar.xml
@@ -0,0 +1,9 @@
+<shape xmlns:android="http://schemas.android.com/apk/res/android"
+       android:shape="rectangle">
+    <gradient
+            android:angle="135"
+            android:centerColor="@color/colorPrimaryDark"
+            android:endColor="@color/colorPrimaryDark"
+            android:startColor="@color/colorPrimary"
+            android:type="linear"/>
+</shape>
\ No newline at end of file
diff --git a/merchant-terminal/src/main/res/layout/activity_main.xml b/merchant-terminal/src/main/res/layout/activity_main.xml
new file mode 100644
index 0000000..6523caa
--- /dev/null
+++ b/merchant-terminal/src/main/res/layout/activity_main.xml
@@ -0,0 +1,42 @@
+<?xml version="1.0" encoding="utf-8"?>
+<!--
+  ~ This file is part of GNU Taler
+  ~ (C) 2020 Taler Systems S.A.
+  ~
+  ~ GNU Taler is free software; you can redistribute it and/or modify it under the
+  ~ terms of the GNU General Public License as published by the Free Software
+  ~ Foundation; either version 3, or (at your option) any later version.
+  ~
+  ~ GNU Taler is distributed in the hope that it will be useful, but WITHOUT ANY
+  ~ WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
+  ~ A PARTICULAR PURPOSE.  See the GNU General Public License for more details.
+  ~
+  ~ You should have received a copy of the GNU General Public License along with
+  ~ GNU Taler; see the file COPYING.  If not, see <http://www.gnu.org/licenses/>
+  -->
+
+<androidx.drawerlayout.widget.DrawerLayout
+        xmlns:android="http://schemas.android.com/apk/res/android"
+        xmlns:app="http://schemas.android.com/apk/res-auto"
+        xmlns:tools="http://schemas.android.com/tools"
+        android:id="@+id/drawer_layout"
+        android:layout_width="match_parent"
+        android:layout_height="match_parent"
+        android:fitsSystemWindows="true"
+        tools:openDrawer="start">
+
+    <include
+            layout="@layout/app_bar_main"
+            android:layout_width="match_parent"
+            android:layout_height="match_parent"/>
+
+    <com.google.android.material.navigation.NavigationView
+            android:id="@+id/nav_view"
+            android:layout_width="wrap_content"
+            android:layout_height="match_parent"
+            android:layout_gravity="start"
+            android:fitsSystemWindows="true"
+            app:menu="@menu/activity_main_drawer"
+            app:headerLayout="@layout/nav_header_main" />
+
+</androidx.drawerlayout.widget.DrawerLayout>
diff --git a/merchant-terminal/src/main/res/layout/app_bar_main.xml b/merchant-terminal/src/main/res/layout/app_bar_main.xml
new file mode 100644
index 0000000..0254c71
--- /dev/null
+++ b/merchant-terminal/src/main/res/layout/app_bar_main.xml
@@ -0,0 +1,53 @@
+<?xml version="1.0" encoding="utf-8"?>
+<!--
+  ~ This file is part of GNU Taler
+  ~ (C) 2020 Taler Systems S.A.
+  ~
+  ~ GNU Taler is free software; you can redistribute it and/or modify it under the
+  ~ terms of the GNU General Public License as published by the Free Software
+  ~ Foundation; either version 3, or (at your option) any later version.
+  ~
+  ~ GNU Taler is distributed in the hope that it will be useful, but WITHOUT ANY
+  ~ WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
+  ~ A PARTICULAR PURPOSE.  See the GNU General Public License for more details.
+  ~
+  ~ You should have received a copy of the GNU General Public License along with
+  ~ GNU Taler; see the file COPYING.  If not, see <http://www.gnu.org/licenses/>
+  -->
+
+<androidx.coordinatorlayout.widget.CoordinatorLayout xmlns:android="http://schemas.android.com/apk/res/android"
+        xmlns:app="http://schemas.android.com/apk/res-auto"
+        xmlns:tools="http://schemas.android.com/tools"
+        android:layout_width="match_parent"
+        android:layout_height="match_parent"
+        tools:context=".MainActivity">
+
+    <com.google.android.material.appbar.AppBarLayout
+            android:layout_width="match_parent"
+            android:layout_height="wrap_content"
+            android:theme="@style/AppTheme.AppBarOverlay">
+
+        <androidx.appcompat.widget.Toolbar
+                android:id="@+id/toolbar"
+                android:layout_width="match_parent"
+                android:layout_height="?attr/actionBarSize"
+                android:background="?attr/colorPrimary"
+                app:popupTheme="@style/AppTheme.PopupOverlay" />
+
+    </com.google.android.material.appbar.AppBarLayout>
+
+    <androidx.fragment.app.FragmentContainerView
+            android:id="@+id/navHostFragment"
+            android:name="androidx.navigation.fragment.NavHostFragment"
+            android:layout_width="match_parent"
+            android:layout_height="match_parent"
+            app:defaultNavHost="true"
+            app:layout_insetEdge="top"
+            app:layout_behavior="@string/appbar_scrolling_view_behavior"
+            app:layout_constraintBottom_toBottomOf="parent"
+            app:layout_constraintLeft_toLeftOf="parent"
+            app:layout_constraintRight_toRightOf="parent"
+            app:layout_constraintTop_toTopOf="parent"
+            app:navGraph="@navigation/nav_graph" />
+
+</androidx.coordinatorlayout.widget.CoordinatorLayout>
diff --git a/merchant-terminal/src/main/res/layout/fragment_categories.xml b/merchant-terminal/src/main/res/layout/fragment_categories.xml
new file mode 100644
index 0000000..a90585f
--- /dev/null
+++ b/merchant-terminal/src/main/res/layout/fragment_categories.xml
@@ -0,0 +1,46 @@
+<?xml version="1.0" encoding="utf-8"?>
+<!--
+  ~ This file is part of GNU Taler
+  ~ (C) 2020 Taler Systems S.A.
+  ~
+  ~ GNU Taler is free software; you can redistribute it and/or modify it under the
+  ~ terms of the GNU General Public License as published by the Free Software
+  ~ Foundation; either version 3, or (at your option) any later version.
+  ~
+  ~ GNU Taler is distributed in the hope that it will be useful, but WITHOUT ANY
+  ~ WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
+  ~ A PARTICULAR PURPOSE.  See the GNU General Public License for more details.
+  ~
+  ~ You should have received a copy of the GNU General Public License along with
+  ~ GNU Taler; see the file COPYING.  If not, see <http://www.gnu.org/licenses/>
+  -->
+
+<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
+        xmlns:app="http://schemas.android.com/apk/res-auto"
+        android:layout_width="match_parent"
+        xmlns:tools="http://schemas.android.com/tools"
+        android:layout_marginStart="8dp"
+        android:layout_marginEnd="8dp"
+        android:layout_height="match_parent">
+
+    <androidx.recyclerview.widget.RecyclerView
+            android:id="@+id/categoriesList"
+            android:layout_width="0dp"
+            tools:listitem="@layout/list_item_category"
+            android:layout_height="0dp"
+            app:layout_constraintBottom_toBottomOf="parent"
+            app:layout_constraintEnd_toEndOf="parent"
+            app:layout_constraintStart_toStartOf="parent"
+            app:layout_constraintTop_toTopOf="parent" />
+
+    <ProgressBar
+            android:id="@+id/progressBar"
+            style="?android:attr/progressBarStyleLarge"
+            android:layout_width="wrap_content"
+            android:layout_height="wrap_content"
+            app:layout_constraintBottom_toBottomOf="parent"
+            app:layout_constraintEnd_toEndOf="parent"
+            app:layout_constraintStart_toStartOf="parent"
+            app:layout_constraintTop_toTopOf="parent" />
+
+</androidx.constraintlayout.widget.ConstraintLayout>
diff --git a/merchant-terminal/src/main/res/layout/fragment_config_fetcher.xml b/merchant-terminal/src/main/res/layout/fragment_config_fetcher.xml
new file mode 100644
index 0000000..af7dcaf
--- /dev/null
+++ b/merchant-terminal/src/main/res/layout/fragment_config_fetcher.xml
@@ -0,0 +1,45 @@
+<?xml version="1.0" encoding="utf-8"?>
+<!--
+  ~ This file is part of GNU Taler
+  ~ (C) 2020 Taler Systems S.A.
+  ~
+  ~ GNU Taler is free software; you can redistribute it and/or modify it under the
+  ~ terms of the GNU General Public License as published by the Free Software
+  ~ Foundation; either version 3, or (at your option) any later version.
+  ~
+  ~ GNU Taler is distributed in the hope that it will be useful, but WITHOUT ANY
+  ~ WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
+  ~ A PARTICULAR PURPOSE.  See the GNU General Public License for more details.
+  ~
+  ~ You should have received a copy of the GNU General Public License along with
+  ~ GNU Taler; see the file COPYING.  If not, see <http://www.gnu.org/licenses/>
+  -->
+
+<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
+        xmlns:app="http://schemas.android.com/apk/res-auto"
+        android:layout_width="match_parent"
+        android:layout_height="match_parent"
+        android:layout_margin="16dp">
+
+    <TextView
+            android:id="@+id/titleView"
+            android:layout_width="wrap_content"
+            android:layout_height="wrap_content"
+            android:layout_margin="16dp"
+            android:text="@string/config_fetching"
+            android:textAppearance="@style/TextAppearance.AppCompat.Headline"
+            app:layout_constraintEnd_toEndOf="parent"
+            app:layout_constraintStart_toStartOf="parent"
+            app:layout_constraintTop_toTopOf="parent" />
+
+    <ProgressBar
+            android:id="@+id/progressBar"
+            style="?android:attr/progressBarStyleLarge"
+            android:layout_width="wrap_content"
+            android:layout_height="wrap_content"
+            android:layout_margin="16dp"
+            app:layout_constraintEnd_toEndOf="parent"
+            app:layout_constraintStart_toStartOf="parent"
+            app:layout_constraintTop_toBottomOf="@+id/titleView" />
+
+</androidx.constraintlayout.widget.ConstraintLayout>
diff --git a/merchant-terminal/src/main/res/layout/fragment_merchant_config.xml b/merchant-terminal/src/main/res/layout/fragment_merchant_config.xml
new file mode 100644
index 0000000..2541887
--- /dev/null
+++ b/merchant-terminal/src/main/res/layout/fragment_merchant_config.xml
@@ -0,0 +1,152 @@
+<?xml version="1.0" encoding="utf-8"?>
+<!--
+  ~ This file is part of GNU Taler
+  ~ (C) 2020 Taler Systems S.A.
+  ~
+  ~ GNU Taler is free software; you can redistribute it and/or modify it under the
+  ~ terms of the GNU General Public License as published by the Free Software
+  ~ Foundation; either version 3, or (at your option) any later version.
+  ~
+  ~ GNU Taler is distributed in the hope that it will be useful, but WITHOUT ANY
+  ~ WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
+  ~ A PARTICULAR PURPOSE.  See the GNU General Public License for more details.
+  ~
+  ~ You should have received a copy of the GNU General Public License along with
+  ~ GNU Taler; see the file COPYING.  If not, see <http://www.gnu.org/licenses/>
+  -->
+
+<ScrollView xmlns:android="http://schemas.android.com/apk/res/android"
+        xmlns:app="http://schemas.android.com/apk/res-auto"
+        xmlns:tools="http://schemas.android.com/tools"
+        android:layout_width="match_parent"
+        android:layout_height="match_parent"
+        android:fillViewport="true">
+
+    <androidx.constraintlayout.widget.ConstraintLayout
+            android:layout_width="match_parent"
+            android:layout_height="wrap_content"
+            tools:context=".config.MerchantConfigFragment">
+
+        <com.google.android.material.textfield.TextInputLayout
+                android:id="@+id/configUrlView"
+                android:layout_width="0dp"
+                android:layout_height="wrap_content"
+                android:layout_margin="16dp"
+                android:hint="@string/config_url"
+                app:boxBackgroundColor="@android:color/transparent"
+                app:boxBackgroundMode="outline"
+                app:layout_constraintEnd_toEndOf="parent"
+                app:layout_constraintStart_toStartOf="parent"
+                app:layout_constraintTop_toTopOf="parent">
+
+            <com.google.android.material.textfield.TextInputEditText
+                    android:layout_width="match_parent"
+                    android:layout_height="wrap_content"
+                    android:inputType="textUri" />
+
+        </com.google.android.material.textfield.TextInputLayout>
+
+        <com.google.android.material.textfield.TextInputLayout
+                android:id="@+id/usernameView"
+                android:layout_width="0dp"
+                android:layout_height="wrap_content"
+                android:layout_margin="16dp"
+                android:hint="@string/config_username"
+                app:boxBackgroundColor="@android:color/transparent"
+                app:boxBackgroundMode="outline"
+                app:layout_constraintEnd_toEndOf="parent"
+                app:layout_constraintStart_toStartOf="parent"
+                app:layout_constraintTop_toBottomOf="@+id/configUrlView">
+
+            <com.google.android.material.textfield.TextInputEditText
+                    android:layout_width="match_parent"
+                    android:layout_height="wrap_content"
+                    android:inputType="text" />
+
+        </com.google.android.material.textfield.TextInputLayout>
+
+        <com.google.android.material.textfield.TextInputLayout
+                android:id="@+id/passwordView"
+                android:layout_width="0dp"
+                android:layout_height="wrap_content"
+                android:layout_margin="16dp"
+                android:hint="@string/config_password"
+                app:boxBackgroundColor="@android:color/transparent"
+                app:boxBackgroundMode="outline"
+                app:endIconMode="password_toggle"
+                app:layout_constraintEnd_toStartOf="@+id/forgetPasswordButton"
+                app:layout_constraintStart_toStartOf="parent"
+                app:layout_constraintTop_toBottomOf="@+id/usernameView">
+
+            <com.google.android.material.textfield.TextInputEditText
+                    android:layout_width="match_parent"
+                    android:layout_height="wrap_content"
+                    android:inputType="textWebPassword" />
+
+        </com.google.android.material.textfield.TextInputLayout>
+
+        <Button
+                android:id="@+id/forgetPasswordButton"
+                android:layout_width="wrap_content"
+                android:layout_height="wrap_content"
+                android:layout_margin="16dp"
+                android:text="@string/config_forget_password"
+                android:visibility="gone"
+                app:layout_constraintBottom_toBottomOf="@+id/passwordView"
+                app:layout_constraintEnd_toEndOf="parent"
+                app:layout_constraintTop_toTopOf="@+id/passwordView"
+                tools:visibility="visible" />
+
+        <CheckBox
+                android:id="@+id/savePasswordCheckBox"
+                android:layout_width="0dp"
+                android:layout_height="wrap_content"
+                android:layout_marginStart="16dp"
+                android:layout_marginTop="16dp"
+                android:layout_marginBottom="16dp"
+                android:checked="true"
+                android:text="@string/config_save_password"
+                app:layout_constraintBottom_toBottomOf="parent"
+                app:layout_constraintEnd_toStartOf="@+id/okButton"
+                app:layout_constraintHorizontal_chainStyle="spread_inside"
+                app:layout_constraintStart_toStartOf="parent"
+                app:layout_constraintTop_toBottomOf="@+id/passwordView"
+                app:layout_constraintVertical_bias="0.0" />
+
+        <com.google.android.material.button.MaterialButton
+                android:id="@+id/okButton"
+                android:layout_width="wrap_content"
+                android:layout_height="wrap_content"
+                android:layout_margin="16dp"
+                android:text="@string/config_ok"
+                app:layout_constraintBottom_toBottomOf="parent"
+                app:layout_constraintEnd_toEndOf="parent"
+                app:layout_constraintStart_toEndOf="@+id/savePasswordCheckBox"
+                app:layout_constraintTop_toBottomOf="@+id/passwordView"
+                app:layout_constraintVertical_bias="0.0" />
+
+        <ProgressBar
+                android:id="@+id/progressBar"
+                style="?android:attr/progressBarStyle"
+                android:layout_width="wrap_content"
+                android:layout_height="wrap_content"
+                android:visibility="invisible"
+                app:layout_constraintBottom_toBottomOf="@+id/okButton"
+                app:layout_constraintEnd_toEndOf="@+id/okButton"
+                app:layout_constraintStart_toStartOf="@+id/okButton"
+                app:layout_constraintTop_toTopOf="@+id/okButton"
+                tools:visibility="visible" />
+
+        <TextView
+                android:id="@+id/configDocsView"
+                android:layout_width="0dp"
+                android:layout_height="wrap_content"
+                android:layout_margin="16dp"
+                android:text="@string/config_docs"
+                app:layout_constraintEnd_toEndOf="parent"
+                app:layout_constraintStart_toStartOf="parent"
+                app:layout_constraintTop_toBottomOf="@+id/okButton" />
+
+    </androidx.constraintlayout.widget.ConstraintLayout>
+
+</ScrollView>
diff --git a/merchant-terminal/src/main/res/layout/fragment_merchant_history.xml b/merchant-terminal/src/main/res/layout/fragment_merchant_history.xml
new file mode 100644
index 0000000..21e6f08
--- /dev/null
+++ b/merchant-terminal/src/main/res/layout/fragment_merchant_history.xml
@@ -0,0 +1,29 @@
+<?xml version="1.0" encoding="utf-8"?>
+<!--
+  ~ This file is part of GNU Taler
+  ~ (C) 2020 Taler Systems S.A.
+  ~
+  ~ GNU Taler is free software; you can redistribute it and/or modify it under the
+  ~ terms of the GNU General Public License as published by the Free Software
+  ~ Foundation; either version 3, or (at your option) any later version.
+  ~
+  ~ GNU Taler is distributed in the hope that it will be useful, but WITHOUT ANY
+  ~ WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
+  ~ A PARTICULAR PURPOSE.  See the GNU General Public License for more details.
+  ~
+  ~ You should have received a copy of the GNU General Public License along with
+  ~ GNU Taler; see the file COPYING.  If not, see <http://www.gnu.org/licenses/>
+  -->
+
+<androidx.swiperefreshlayout.widget.SwipeRefreshLayout xmlns:android="http://schemas.android.com/apk/res/android"
+        android:id="@+id/swipeRefresh"
+        android:layout_width="match_parent"
+        android:layout_height="match_parent">
+
+    <androidx.recyclerview.widget.RecyclerView
+            android:id="@+id/list_history"
+            android:layout_width="match_parent"
+            android:layout_height="match_parent"
+            android:scrollbars="vertical" />
+
+</androidx.swiperefreshlayout.widget.SwipeRefreshLayout>
diff --git a/merchant-terminal/src/main/res/layout/fragment_order.xml b/merchant-terminal/src/main/res/layout/fragment_order.xml
new file mode 100644
index 0000000..4af9c77
--- /dev/null
+++ b/merchant-terminal/src/main/res/layout/fragment_order.xml
@@ -0,0 +1,138 @@
+<?xml version="1.0" encoding="utf-8"?>
+<!--
+  ~ This file is part of GNU Taler
+  ~ (C) 2020 Taler Systems S.A.
+  ~
+  ~ GNU Taler is free software; you can redistribute it and/or modify it under the
+  ~ terms of the GNU General Public License as published by the Free Software
+  ~ Foundation; either version 3, or (at your option) any later version.
+  ~
+  ~ GNU Taler is distributed in the hope that it will be useful, but WITHOUT ANY
+  ~ WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
+  ~ A PARTICULAR PURPOSE.  See the GNU General Public License for more details.
+  ~
+  ~ You should have received a copy of the GNU General Public License along with
+  ~ GNU Taler; see the file COPYING.  If not, see <http://www.gnu.org/licenses/>
+  -->
+
+<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
+        xmlns:app="http://schemas.android.com/apk/res-auto"
+        xmlns:tools="http://schemas.android.com/tools"
+        android:layout_width="match_parent"
+        android:layout_height="match_parent">
+
+    <androidx.fragment.app.FragmentContainerView
+            android:id="@+id/fragment1"
+            android:layout_width="0dp"
+            android:layout_height="0dp"
+            android:layout_marginBottom="8dp"
+            app:layout_constraintBottom_toTopOf="@+id/restartButton"
+            app:layout_constraintEnd_toStartOf="@+id/guideline1"
+            app:layout_constraintStart_toStartOf="parent"
+            app:layout_constraintTop_toTopOf="parent"
+            tools:layout="@layout/fragment_order_state" />
+
+    <androidx.constraintlayout.widget.Guideline
+            android:id="@+id/guideline1"
+            android:layout_width="wrap_content"
+            android:layout_height="wrap_content"
+            android:orientation="vertical"
+            app:layout_constraintGuide_percent="0.25" />
+
+    <androidx.fragment.app.FragmentContainerView
+            android:id="@+id/fragment2"
+            android:name="net.taler.merchantpos.order.ProductsFragment"
+            android:layout_width="0dp"
+            android:layout_height="0dp"
+            android:layout_marginBottom="8dp"
+            app:layout_constraintBottom_toTopOf="@+id/restartButton"
+            app:layout_constraintEnd_toStartOf="@+id/guideline2"
+            app:layout_constraintStart_toStartOf="@+id/guideline1"
+            app:layout_constraintTop_toTopOf="parent"
+            tools:layout="@layout/fragment_products" />
+
+    <androidx.constraintlayout.widget.Guideline
+            android:id="@+id/guideline2"
+            android:layout_width="wrap_content"
+            android:layout_height="wrap_content"
+            android:orientation="vertical"
+            app:layout_constraintGuide_percent="0.75" />
+
+    <androidx.fragment.app.FragmentContainerView
+            android:id="@+id/fragment3"
+            android:name="net.taler.merchantpos.order.CategoriesFragment"
+            android:layout_width="0dp"
+            android:layout_height="0dp"
+            android:layout_marginBottom="8dp"
+            app:layout_constraintBottom_toTopOf="@+id/restartButton"
+            app:layout_constraintEnd_toEndOf="parent"
+            app:layout_constraintStart_toStartOf="@+id/guideline2"
+            app:layout_constraintTop_toTopOf="parent"
+            tools:layout="@layout/fragment_categories" />
+
+    <Button
+            android:id="@+id/restartButton"
+            android:layout_width="wrap_content"
+            android:layout_height="wrap_content"
+            android:layout_marginStart="8dp"
+            android:backgroundTint="@color/button_bottom"
+            android:text="@string/order_restart"
+            app:layout_constraintBottom_toBottomOf="parent"
+            app:layout_constraintStart_toStartOf="parent" />
+
+    <Button
+            android:id="@+id/plusButton"
+            android:layout_width="wrap_content"
+            android:layout_height="wrap_content"
+            android:layout_marginStart="16dp"
+            android:minWidth="48dp"
+            android:text="+1"
+            app:layout_constraintBottom_toBottomOf="parent"
+            app:layout_constraintStart_toEndOf="@+id/minusButton"
+            tools:ignore="HardcodedText" />
+
+    <Button
+            android:id="@+id/minusButton"
+            android:layout_width="wrap_content"
+            android:layout_height="wrap_content"
+            android:layout_marginStart="32dp"
+            android:minWidth="48dp"
+            android:text="-1"
+            app:layout_constraintBottom_toBottomOf="parent"
+            app:layout_constraintStart_toEndOf="@+id/restartButton"
+            tools:ignore="HardcodedText" />
+
+    <Button
+            android:id="@+id/prevButton"
+            android:layout_width="wrap_content"
+            android:layout_height="wrap_content"
+            android:layout_marginStart="32dp"
+            android:backgroundTint="@color/button_bottom"
+            android:text="@string/order_previous"
+            app:layout_constraintBottom_toBottomOf="parent"
+            app:layout_constraintStart_toEndOf="@+id/plusButton" />
+
+    <Button
+            android:id="@+id/nextButton"
+            android:layout_width="wrap_content"
+            android:layout_height="wrap_content"
+            android:layout_marginStart="16dp"
+            android:backgroundTint="@color/button_bottom"
+            android:text="@string/order_next"
+            app:layout_constraintBottom_toBottomOf="parent"
+            app:layout_constraintStart_toEndOf="@+id/prevButton" />
+
+    <Button
+            android:id="@+id/completeButton"
+            android:layout_width="wrap_content"
+            android:layout_height="wrap_content"
+            android:layout_marginStart="32dp"
+            android:layout_marginEnd="8dp"
+            android:backgroundTint="@color/button_bottom"
+            android:text="@string/order_complete"
+            app:layout_constraintBottom_toBottomOf="parent"
+            app:layout_constraintEnd_toEndOf="parent"
+            app:layout_constraintHorizontal_bias="1.0"
+            app:layout_constraintStart_toEndOf="@+id/nextButton" />
+
+</androidx.constraintlayout.widget.ConstraintLayout>
diff --git a/merchant-terminal/src/main/res/layout/fragment_order_state.xml b/merchant-terminal/src/main/res/layout/fragment_order_state.xml
new file mode 100644
index 0000000..7d6b258
--- /dev/null
+++ b/merchant-terminal/src/main/res/layout/fragment_order_state.xml
@@ -0,0 +1,52 @@
+<?xml version="1.0" encoding="utf-8"?>
+<!--
+  ~ This file is part of GNU Taler
+  ~ (C) 2020 Taler Systems S.A.
+  ~
+  ~ GNU Taler is free software; you can redistribute it and/or modify it under the
+  ~ terms of the GNU General Public License as published by the Free Software
+  ~ Foundation; either version 3, or (at your option) any later version.
+  ~
+  ~ GNU Taler is distributed in the hope that it will be useful, but WITHOUT ANY
+  ~ WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
+  ~ A PARTICULAR PURPOSE.  See the GNU General Public License for more details.
+  ~
+  ~ You should have received a copy of the GNU General Public License along with
+  ~ GNU Taler; see the file COPYING.  If not, see <http://www.gnu.org/licenses/>
+  -->
+
+<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
+        xmlns:app="http://schemas.android.com/apk/res-auto"
+        xmlns:tools="http://schemas.android.com/tools"
+        android:layout_width="match_parent"
+        android:layout_height="match_parent">
+
+    <androidx.recyclerview.widget.RecyclerView
+            android:id="@+id/orderList"
+            android:layout_width="0dp"
+            android:layout_height="0dp"
+            app:layout_constraintBottom_toTopOf="@+id/totalView"
+            app:layout_constraintEnd_toEndOf="parent"
+            app:layout_constraintStart_toStartOf="parent"
+            app:layout_constraintTop_toTopOf="parent"
+            tools:listitem="@layout/list_item_order" />
+
+    <TextView
+            android:id="@+id/totalView"
+            android:layout_width="0dp"
+            android:layout_height="wrap_content"
+            android:background="@color/highlightedBackground"
+            android:elevation="2dp"
+            android:gravity="center_vertical|end"
+            android:padding="8dp"
+            android:textColor="?android:textColorPrimary"
+            android:textSize="16sp"
+            android:visibility="invisible"
+            app:layout_constraintBottom_toBottomOf="parent"
+            app:layout_constraintEnd_toEndOf="parent"
+            app:layout_constraintStart_toStartOf="parent"
+            app:layout_constraintTop_toBottomOf="@+id/orderList"
+            tools:text="Total: 23.75 TESTKUDOS"
+            tools:visibility="visible" />
+
+</androidx.constraintlayout.widget.ConstraintLayout>
diff --git a/merchant-terminal/src/main/res/layout/fragment_payment_success.xml b/merchant-terminal/src/main/res/layout/fragment_payment_success.xml
new file mode 100644
index 0000000..1bc9be7
--- /dev/null
+++ b/merchant-terminal/src/main/res/layout/fragment_payment_success.xml
@@ -0,0 +1,78 @@
+<?xml version="1.0" encoding="utf-8"?>
+<!--
+  ~ This file is part of GNU Taler
+  ~ (C) 2020 Taler Systems S.A.
+  ~
+  ~ GNU Taler is free software; you can redistribute it and/or modify it under the
+  ~ terms of the GNU General Public License as published by the Free Software
+  ~ Foundation; either version 3, or (at your option) any later version.
+  ~
+  ~ GNU Taler is distributed in the hope that it will be useful, but WITHOUT ANY
+  ~ WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
+  ~ A PARTICULAR PURPOSE.  See the GNU General Public License for more details.
+  ~
+  ~ You should have received a copy of the GNU General Public License along with
+  ~ GNU Taler; see the file COPYING.  If not, see <http://www.gnu.org/licenses/>
+  -->
+
+<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
+        xmlns:app="http://schemas.android.com/apk/res-auto"
+        xmlns:tools="http://schemas.android.com/tools"
+        android:layout_width="match_parent"
+        android:layout_height="match_parent"
+        tools:context=".payment.PaymentSuccessFragment">
+
+    <ImageView
+            android:id="@+id/paymentIcon"
+            android:layout_width="0dp"
+            android:layout_height="0dp"
+            android:layout_margin="16dp"
+            android:src="@drawable/ic_check_circle"
+            app:layout_constraintBottom_toTopOf="@+id/paymentLabel"
+            app:layout_constraintEnd_toEndOf="parent"
+            app:layout_constraintHorizontal_bias="0.5"
+            app:layout_constraintStart_toStartOf="parent"
+            app:layout_constraintTop_toTopOf="parent"
+            app:layout_constraintVertical_chainStyle="spread_inside"
+            tools:ignore="ContentDescription" />
+
+    <TextView
+            android:id="@+id/paymentLabel"
+            android:layout_width="0dp"
+            android:layout_height="0dp"
+            android:layout_margin="16dp"
+            android:gravity="center_horizontal|top"
+            android:text="@string/payment_received"
+            android:textColor="@color/green"
+            app:autoSizeMaxTextSize="42sp"
+            app:autoSizeTextType="uniform"
+            app:layout_constraintBottom_toTopOf="@+id/paymentButton"
+            app:layout_constraintEnd_toEndOf="parent"
+            app:layout_constraintStart_toStartOf="parent"
+            app:layout_constraintTop_toBottomOf="@+id/paymentIcon" />
+
+    <androidx.constraintlayout.widget.Guideline
+            android:id="@+id/guidelineLeft"
+            android:layout_width="wrap_content"
+            android:layout_height="wrap_content"
+            android:orientation="vertical"
+            app:layout_constraintGuide_percent="0.25" />
+
+    <androidx.constraintlayout.widget.Guideline
+            android:id="@+id/guidelineRight"
+            android:layout_width="wrap_content"
+            android:layout_height="wrap_content"
+            android:orientation="vertical"
+            app:layout_constraintGuide_percent="0.75" />
+
+    <Button
+            android:id="@+id/paymentButton"
+            android:layout_width="0dp"
+            android:layout_height="wrap_content"
+            android:layout_margin="16dp"
+            android:text="@string/payment_back_button"
+            app:layout_constraintBottom_toBottomOf="parent"
+            app:layout_constraintEnd_toStartOf="@+id/guidelineRight"
+            app:layout_constraintStart_toStartOf="@+id/guidelineLeft" />
+
+</androidx.constraintlayout.widget.ConstraintLayout>
diff --git a/merchant-terminal/src/main/res/layout/fragment_process_payment.xml b/merchant-terminal/src/main/res/layout/fragment_process_payment.xml
new file mode 100644
index 0000000..6cd8ea1
--- /dev/null
+++ b/merchant-terminal/src/main/res/layout/fragment_process_payment.xml
@@ -0,0 +1,110 @@
+<?xml version="1.0" encoding="utf-8"?>
+<!--
+  ~ This file is part of GNU Taler
+  ~ (C) 2020 Taler Systems S.A.
+  ~
+  ~ GNU Taler is free software; you can redistribute it and/or modify it under the
+  ~ terms of the GNU General Public License as published by the Free Software
+  ~ Foundation; either version 3, or (at your option) any later version.
+  ~
+  ~ GNU Taler is distributed in the hope that it will be useful, but WITHOUT ANY
+  ~ WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
+  ~ A PARTICULAR PURPOSE.  See the GNU General Public License for more details.
+  ~
+  ~ You should have received a copy of the GNU General Public License along with
+  ~ GNU Taler; see the file COPYING.  If not, see <http://www.gnu.org/licenses/>
+  -->
+
+<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
+        xmlns:app="http://schemas.android.com/apk/res-auto"
+        xmlns:tools="http://schemas.android.com/tools"
+        android:layout_width="match_parent"
+        android:layout_height="match_parent"
+        tools:context=".payment.ProcessPaymentFragment">
+
+    <ImageView
+            android:id="@+id/qrcodeView"
+            android:layout_width="0dp"
+            android:layout_height="0dp"
+            android:layout_margin="32dp"
+            android:visibility="invisible"
+            app:layout_constraintBottom_toBottomOf="parent"
+            app:layout_constraintEnd_toStartOf="@+id/guideline"
+            app:layout_constraintStart_toStartOf="parent"
+            app:layout_constraintTop_toTopOf="parent"
+            tools:ignore="ContentDescription"
+            tools:src="@tools:sample/avatars"
+            tools:visibility="visible" />
+
+    <ProgressBar
+            android:id="@+id/progressBar"
+            style="?android:attr/progressBarStyleLarge"
+            android:layout_width="wrap_content"
+            android:layout_height="wrap_content"
+            app:layout_constraintBottom_toBottomOf="@+id/qrcodeView"
+            app:layout_constraintEnd_toEndOf="@+id/qrcodeView"
+            app:layout_constraintStart_toStartOf="@+id/qrcodeView"
+            app:layout_constraintTop_toTopOf="@+id/qrcodeView" />
+
+    <androidx.constraintlayout.widget.Guideline
+            android:id="@+id/guideline"
+            android:layout_width="wrap_content"
+            android:layout_height="wrap_content"
+            android:orientation="vertical"
+            app:layout_constraintGuide_percent="0.54" />
+
+    <TextView
+            android:id="@+id/payIntroView"
+            android:layout_width="0dp"
+            android:layout_height="wrap_content"
+            android:layout_margin="16dp"
+            android:text="@string/payment_intro_nfc"
+            android:textAlignment="center"
+            android:textSize="24sp"
+            android:visibility="invisible"
+            app:layout_constraintBottom_toTopOf="@+id/amountView"
+            app:layout_constraintEnd_toEndOf="parent"
+            app:layout_constraintStart_toStartOf="@+id/guideline"
+            app:layout_constraintTop_toTopOf="parent"
+            app:layout_constraintVertical_chainStyle="spread"
+            tools:visibility="visible" />
+
+    <TextView
+            android:id="@+id/amountView"
+            android:layout_width="wrap_content"
+            android:layout_height="wrap_content"
+            android:layout_margin="16dp"
+            android:textAppearance="@style/TextAppearance.AppCompat.Headline"
+            app:layout_constraintBottom_toTopOf="@+id/orderRefView"
+            app:layout_constraintEnd_toEndOf="parent"
+            app:layout_constraintStart_toStartOf="@+id/guideline"
+            app:layout_constraintTop_toBottomOf="@+id/payIntroView"
+            tools:text="10.49 TESTKUDOS" />
+
+    <TextView
+            android:id="@+id/orderRefView"
+            android:layout_width="0dp"
+            android:layout_height="wrap_content"
+            android:layout_margin="16dp"
+            android:textAlignment="center"
+            android:visibility="invisible"
+            app:layout_constraintBottom_toTopOf="@id/cancelPaymentButton"
+            app:layout_constraintEnd_toEndOf="parent"
+            app:layout_constraintStart_toStartOf="@+id/guideline"
+            app:layout_constraintTop_toBottomOf="@+id/amountView"
+            tools:text="@string/payment_order_ref"
+            tools:visibility="visible" />
+
+    <Button
+            android:id="@+id/cancelPaymentButton"
+            android:layout_width="wrap_content"
+            android:layout_height="wrap_content"
+            android:layout_margin="16dp"
+            android:backgroundTint="@color/red"
+            android:text="@string/payment_cancel"
+            app:layout_constraintBottom_toBottomOf="parent"
+            app:layout_constraintEnd_toEndOf="parent"
+            app:layout_constraintHorizontal_bias="0.0"
+            app:layout_constraintStart_toStartOf="@+id/guideline" />
+
+</androidx.constraintlayout.widget.ConstraintLayout>
diff --git a/merchant-terminal/src/main/res/layout/fragment_products.xml b/merchant-terminal/src/main/res/layout/fragment_products.xml
new file mode 100644
index 0000000..f0e86e7
--- /dev/null
+++ b/merchant-terminal/src/main/res/layout/fragment_products.xml
@@ -0,0 +1,44 @@
+<?xml version="1.0" encoding="utf-8"?>
+<!--
+  ~ This file is part of GNU Taler
+  ~ (C) 2020 Taler Systems S.A.
+  ~
+  ~ GNU Taler is free software; you can redistribute it and/or modify it under the
+  ~ terms of the GNU General Public License as published by the Free Software
+  ~ Foundation; either version 3, or (at your option) any later version.
+  ~
+  ~ GNU Taler is distributed in the hope that it will be useful, but WITHOUT ANY
+  ~ WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
+  ~ A PARTICULAR PURPOSE.  See the GNU General Public License for more details.
+  ~
+  ~ You should have received a copy of the GNU General Public License along with
+  ~ GNU Taler; see the file COPYING.  If not, see <http://www.gnu.org/licenses/>
+  -->
+
+<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
+        xmlns:app="http://schemas.android.com/apk/res-auto"
+        android:layout_width="match_parent"
+        xmlns:tools="http://schemas.android.com/tools"
+        android:layout_height="match_parent">
+
+    <androidx.recyclerview.widget.RecyclerView
+            android:id="@+id/productsList"
+            android:layout_width="0dp"
+            android:layout_height="0dp"
+            app:layout_constraintTop_toTopOf="parent"
+            app:layout_constraintBottom_toBottomOf="parent"
+            app:layout_constraintEnd_toEndOf="parent"
+            app:layout_constraintStart_toStartOf="parent"
+            tools:listitem="@layout/list_item_product" />
+
+    <ProgressBar
+            android:id="@+id/progressBar"
+            style="?android:attr/progressBarStyleLarge"
+            android:layout_width="wrap_content"
+            android:layout_height="wrap_content"
+            app:layout_constraintBottom_toBottomOf="parent"
+            app:layout_constraintEnd_toEndOf="parent"
+            app:layout_constraintStart_toStartOf="parent"
+            app:layout_constraintTop_toTopOf="parent" />
+
+</androidx.constraintlayout.widget.ConstraintLayout>
diff --git a/merchant-terminal/src/main/res/layout/fragment_refund.xml b/merchant-terminal/src/main/res/layout/fragment_refund.xml
new file mode 100644
index 0000000..5a78cdd
--- /dev/null
+++ b/merchant-terminal/src/main/res/layout/fragment_refund.xml
@@ -0,0 +1,122 @@
+<?xml version="1.0" encoding="utf-8"?><!--
+  ~ This file is part of GNU Taler
+  ~ (C) 2020 Taler Systems S.A.
+  ~
+  ~ GNU Taler is free software; you can redistribute it and/or modify it under the
+  ~ terms of the GNU General Public License as published by the Free Software
+  ~ Foundation; either version 3, or (at your option) any later version.
+  ~
+  ~ GNU Taler is distributed in the hope that it will be useful, but WITHOUT ANY
+  ~ WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
+  ~ A PARTICULAR PURPOSE.  See the GNU General Public License for more details.
+  ~
+  ~ You should have received a copy of the GNU General Public License along with
+  ~ GNU Taler; see the file COPYING.  If not, see <http://www.gnu.org/licenses/>
+  -->
+
+<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
+        xmlns:app="http://schemas.android.com/apk/res-auto"
+        xmlns:tools="http://schemas.android.com/tools"
+        android:layout_width="match_parent"
+        android:layout_height="match_parent"
+        tools:context=".history.RefundFragment">
+
+    <com.google.android.material.textfield.TextInputLayout
+            android:id="@+id/amountView"
+            style="@style/Widget.MaterialComponents.TextInputLayout.OutlinedBox.Dense"
+            android:layout_width="wrap_content"
+            android:layout_height="wrap_content"
+            android:layout_margin="16dp"
+            android:hint="@string/refund_amount"
+            app:boxBackgroundMode="outline"
+            app:endIconMode="clear_text"
+            app:endIconTint="?attr/colorControlNormal"
+            app:layout_constraintBottom_toTopOf="@+id/reasonView"
+            app:layout_constraintEnd_toStartOf="@+id/currencyView"
+            app:layout_constraintHorizontal_chainStyle="packed"
+            app:layout_constraintStart_toStartOf="parent"
+            app:layout_constraintTop_toTopOf="parent"
+            app:layout_constraintVertical_chainStyle="spread">
+
+        <com.google.android.material.textfield.TextInputEditText
+                android:id="@+id/amountInputView"
+                android:layout_width="match_parent"
+                android:layout_height="wrap_content"
+                android:ems="6"
+                android:inputType="numberDecimal"
+                tools:text="23.42" />
+
+    </com.google.android.material.textfield.TextInputLayout>
+
+    <TextView
+            android:id="@+id/currencyView"
+            android:layout_width="wrap_content"
+            android:layout_height="0dp"
+            android:layout_marginStart="8dp"
+            android:gravity="start|center_vertical"
+            app:layout_constraintBottom_toBottomOf="@+id/amountView"
+            app:layout_constraintEnd_toEndOf="parent"
+            app:layout_constraintStart_toEndOf="@+id/amountView"
+            app:layout_constraintTop_toTopOf="@+id/amountView"
+            tools:text="TESTKUDOS" />
+
+    <com.google.android.material.textfield.TextInputLayout
+            android:id="@+id/reasonView"
+            style="@style/Widget.MaterialComponents.TextInputLayout.OutlinedBox.Dense"
+            android:layout_width="0dp"
+            android:layout_height="wrap_content"
+            android:layout_margin="16dp"
+            android:hint="@string/refund_reason"
+            app:endIconMode="clear_text"
+            app:layout_constraintBottom_toTopOf="@+id/abortButton"
+            app:layout_constraintEnd_toEndOf="parent"
+            app:layout_constraintHorizontal_bias="0.5"
+            app:layout_constraintStart_toStartOf="parent"
+            app:layout_constraintTop_toBottomOf="@+id/amountView">
+
+        <com.google.android.material.textfield.TextInputEditText
+                android:id="@+id/reasonInputView"
+                android:layout_width="match_parent"
+                android:layout_height="wrap_content"
+                android:inputType="textAutoComplete|textAutoCorrect|textMultiLine" />
+
+    </com.google.android.material.textfield.TextInputLayout>
+
+    <Button
+            android:id="@+id/abortButton"
+            android:layout_width="wrap_content"
+            android:layout_height="wrap_content"
+            android:layout_margin="16dp"
+            android:backgroundTint="@color/red"
+            android:text="@string/refund_abort"
+            app:layout_constraintBottom_toBottomOf="parent"
+            app:layout_constraintEnd_toStartOf="@+id/refundButton"
+            app:layout_constraintHorizontal_bias="0.76"
+            app:layout_constraintHorizontal_chainStyle="spread_inside"
+            app:layout_constraintStart_toStartOf="parent" />
+
+    <Button
+            android:id="@+id/refundButton"
+            android:layout_width="wrap_content"
+            android:layout_height="wrap_content"
+            android:layout_margin="16dp"
+            android:backgroundTint="@color/green"
+            android:text="@string/refund_confirm"
+            app:layout_constraintBottom_toBottomOf="parent"
+            app:layout_constraintEnd_toEndOf="parent"
+            app:layout_constraintHorizontal_bias="0.5"
+            app:layout_constraintStart_toEndOf="@+id/abortButton" />
+
+    <ProgressBar
+            android:id="@+id/progressBar"
+            style="?android:attr/progressBarStyle"
+            android:layout_width="wrap_content"
+            android:layout_height="wrap_content"
+            android:visibility="invisible"
+            app:layout_constraintBottom_toBottomOf="@+id/refundButton"
+            app:layout_constraintEnd_toEndOf="@+id/refundButton"
+            app:layout_constraintStart_toStartOf="@+id/refundButton"
+            app:layout_constraintTop_toTopOf="@+id/refundButton"
+            tools:visibility="visible" />
+
+</androidx.constraintlayout.widget.ConstraintLayout>
diff --git a/merchant-terminal/src/main/res/layout/fragment_refund_uri.xml b/merchant-terminal/src/main/res/layout/fragment_refund_uri.xml
new file mode 100644
index 0000000..8447d28
--- /dev/null
+++ b/merchant-terminal/src/main/res/layout/fragment_refund_uri.xml
@@ -0,0 +1,93 @@
+<?xml version="1.0" encoding="utf-8"?><!--
+  ~ This file is part of GNU Taler
+  ~ (C) 2020 Taler Systems S.A.
+  ~
+  ~ GNU Taler is free software; you can redistribute it and/or modify it under the
+  ~ terms of the GNU General Public License as published by the Free Software
+  ~ Foundation; either version 3, or (at your option) any later version.
+  ~
+  ~ GNU Taler is distributed in the hope that it will be useful, but WITHOUT ANY
+  ~ WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
+  ~ A PARTICULAR PURPOSE.  See the GNU General Public License for more details.
+  ~
+  ~ You should have received a copy of the GNU General Public License along with
+  ~ GNU Taler; see the file COPYING.  If not, see <http://www.gnu.org/licenses/>
+  -->
+
+<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
+        xmlns:app="http://schemas.android.com/apk/res-auto"
+        xmlns:tools="http://schemas.android.com/tools"
+        android:layout_width="match_parent"
+        android:layout_height="match_parent"
+        tools:context=".payment.ProcessPaymentFragment">
+
+    <ImageView
+            android:id="@+id/refundQrcodeView"
+            android:layout_width="0dp"
+            android:layout_height="0dp"
+            android:layout_margin="32dp"
+            app:layout_constraintBottom_toBottomOf="parent"
+            app:layout_constraintEnd_toStartOf="@+id/guideline"
+            app:layout_constraintStart_toStartOf="parent"
+            app:layout_constraintTop_toTopOf="parent"
+            tools:ignore="ContentDescription"
+            tools:src="@tools:sample/avatars" />
+
+    <androidx.constraintlayout.widget.Guideline
+            android:id="@+id/guideline"
+            android:layout_width="wrap_content"
+            android:layout_height="wrap_content"
+            android:orientation="vertical"
+            app:layout_constraintGuide_percent="0.54" />
+
+    <TextView
+            android:id="@+id/refundIntroView"
+            android:layout_width="0dp"
+            android:layout_height="wrap_content"
+            android:layout_margin="16dp"
+            android:text="@string/refund_intro_nfc"
+            android:textAlignment="center"
+            android:textSize="24sp"
+            app:layout_constraintBottom_toTopOf="@+id/refundAmountView"
+            app:layout_constraintEnd_toEndOf="parent"
+            app:layout_constraintStart_toStartOf="@+id/guideline"
+            app:layout_constraintTop_toTopOf="parent"
+            app:layout_constraintVertical_chainStyle="spread" />
+
+    <TextView
+            android:id="@+id/refundAmountView"
+            android:layout_width="wrap_content"
+            android:layout_height="wrap_content"
+            android:layout_margin="16dp"
+            android:textAppearance="@style/TextAppearance.AppCompat.Headline"
+            app:layout_constraintBottom_toTopOf="@+id/refundRefView"
+            app:layout_constraintEnd_toEndOf="parent"
+            app:layout_constraintStart_toStartOf="@+id/guideline"
+            app:layout_constraintTop_toBottomOf="@+id/refundIntroView"
+            tools:text="10.49 TESTKUDOS" />
+
+    <TextView
+            android:id="@+id/refundRefView"
+            android:layout_width="0dp"
+            android:layout_height="wrap_content"
+            android:layout_margin="16dp"
+            android:textAlignment="center"
+            app:layout_constraintBottom_toTopOf="@id/cancelRefundButton"
+            app:layout_constraintEnd_toEndOf="parent"
+            app:layout_constraintStart_toStartOf="@+id/guideline"
+            app:layout_constraintTop_toBottomOf="@+id/refundAmountView"
+            tools:text="@string/refund_order_ref" />
+
+    <Button
+            android:id="@+id/cancelRefundButton"
+            android:layout_width="wrap_content"
+            android:layout_height="wrap_content"
+            android:layout_margin="16dp"
+            android:backgroundTint="@color/red"
+            android:text="@string/refund_abort"
+            app:layout_constraintBottom_toBottomOf="parent"
+            app:layout_constraintEnd_toEndOf="parent"
+            app:layout_constraintHorizontal_bias="0.0"
+            app:layout_constraintStart_toStartOf="@+id/guideline" />
+
+</androidx.constraintlayout.widget.ConstraintLayout>
diff --git a/merchant-terminal/src/main/res/layout/list_item_category.xml b/merchant-terminal/src/main/res/layout/list_item_category.xml
new file mode 100644
index 0000000..cbdbd34
--- /dev/null
+++ b/merchant-terminal/src/main/res/layout/list_item_category.xml
@@ -0,0 +1,33 @@
+<?xml version="1.0" encoding="utf-8"?>
+<!--
+  ~ This file is part of GNU Taler
+  ~ (C) 2020 Taler Systems S.A.
+  ~
+  ~ GNU Taler is free software; you can redistribute it and/or modify it under the
+  ~ terms of the GNU General Public License as published by the Free Software
+  ~ Foundation; either version 3, or (at your option) any later version.
+  ~
+  ~ GNU Taler is distributed in the hope that it will be useful, but WITHOUT ANY
+  ~ WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
+  ~ A PARTICULAR PURPOSE.  See the GNU General Public License for more details.
+  ~
+  ~ You should have received a copy of the GNU General Public License along with
+  ~ GNU Taler; see the file COPYING.  If not, see <http://www.gnu.org/licenses/>
+  -->
+
+<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
+        xmlns:app="http://schemas.android.com/apk/res-auto"
+        xmlns:tools="http://schemas.android.com/tools"
+        android:layout_width="match_parent"
+        android:layout_height="wrap_content">
+
+    <Button
+            android:id="@+id/button"
+            android:layout_width="0dp"
+            android:layout_height="wrap_content"
+            app:layout_constraintEnd_toEndOf="parent"
+            app:layout_constraintStart_toStartOf="parent"
+            app:layout_constraintTop_toTopOf="parent"
+            tools:text="Snacks" />
+
+</androidx.constraintlayout.widget.ConstraintLayout>
diff --git a/merchant-terminal/src/main/res/layout/list_item_history.xml b/merchant-terminal/src/main/res/layout/list_item_history.xml
new file mode 100644
index 0000000..fe485ba
--- /dev/null
+++ b/merchant-terminal/src/main/res/layout/list_item_history.xml
@@ -0,0 +1,97 @@
+<?xml version="1.0" encoding="utf-8"?><!--
+  ~ This file is part of GNU Taler
+  ~ (C) 2020 Taler Systems S.A.
+  ~
+  ~ GNU Taler is free software; you can redistribute it and/or modify it under the
+  ~ terms of the GNU General Public License as published by the Free Software
+  ~ Foundation; either version 3, or (at your option) any later version.
+  ~
+  ~ GNU Taler is distributed in the hope that it will be useful, but WITHOUT ANY
+  ~ WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
+  ~ A PARTICULAR PURPOSE.  See the GNU General Public License for more details.
+  ~
+  ~ You should have received a copy of the GNU General Public License along with
+  ~ GNU Taler; see the file COPYING.  If not, see <http://www.gnu.org/licenses/>
+  -->
+
+<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
+        xmlns:app="http://schemas.android.com/apk/res-auto"
+        xmlns:tools="http://schemas.android.com/tools"
+        android:layout_width="match_parent"
+        android:layout_height="wrap_content"
+        android:padding="16dp">
+
+    <TextView
+            android:id="@+id/orderSummaryView"
+            android:layout_width="0dp"
+            android:layout_height="wrap_content"
+            android:textColor="?android:attr/textColorPrimary"
+            android:textSize="20sp"
+            android:textStyle="bold"
+            app:layout_constraintEnd_toStartOf="@+id/orderAmountView"
+            app:layout_constraintHorizontal_bias="1.0"
+            app:layout_constraintHorizontal_chainStyle="spread_inside"
+            app:layout_constraintStart_toStartOf="parent"
+            app:layout_constraintTop_toTopOf="parent"
+            tools:text="One Cappuccino or another name that can be so long that it spans more than one line" />
+
+    <TextView
+            android:id="@+id/orderAmountView"
+            android:layout_width="wrap_content"
+            android:layout_height="wrap_content"
+            android:layout_marginStart="8dp"
+            android:layout_marginEnd="16dp"
+            android:textColor="?android:attr/textColorPrimary"
+            android:textSize="20sp"
+            android:textStyle="bold"
+            app:layout_constraintBottom_toBottomOf="@+id/orderSummaryView"
+            app:layout_constraintEnd_toStartOf="@+id/refundButton"
+            app:layout_constraintStart_toEndOf="@+id/orderSummaryView"
+            app:layout_constraintTop_toTopOf="parent"
+            app:layout_constraintVertical_bias="0.0"
+            tools:text="23.42 TESTKUDOS" />
+
+    <TextView
+            android:id="@+id/orderIdView"
+            android:layout_width="0dp"
+            android:layout_height="wrap_content"
+            android:layout_marginTop="8dp"
+            android:text="@string/history_ref_no"
+            android:textAllCaps="false"
+            android:textSize="20sp"
+            app:layout_constraintBottom_toBottomOf="parent"
+            app:layout_constraintEnd_toStartOf="@+id/orderTimeView"
+            app:layout_constraintHorizontal_bias="0.5"
+            app:layout_constraintHorizontal_chainStyle="spread_inside"
+            app:layout_constraintStart_toStartOf="parent"
+            app:layout_constraintTop_toBottomOf="@+id/orderSummaryView" />
+
+    <TextView
+            android:id="@+id/orderTimeView"
+            android:layout_width="wrap_content"
+            android:layout_height="wrap_content"
+            android:layout_marginStart="8dp"
+            android:layout_marginTop="8dp"
+            android:layout_marginEnd="16dp"
+            android:textSize="20sp"
+            app:layout_constraintBottom_toBottomOf="parent"
+            app:layout_constraintEnd_toStartOf="@+id/refundButton"
+            app:layout_constraintStart_toEndOf="@+id/orderIdView"
+            app:layout_constraintTop_toBottomOf="@+id/orderAmountView"
+            app:layout_constraintVertical_bias="1.0"
+            tools:text="3 hrs. ago" />
+
+    <ImageButton
+            android:id="@+id/refundButton"
+            android:layout_width="48dp"
+            android:layout_height="48dp"
+            android:backgroundTint="?colorPrimary"
+            android:contentDescription="@string/history_refund"
+            android:tint="?attr/colorOnPrimary"
+            android:visibility="gone"
+            app:layout_constraintBottom_toBottomOf="parent"
+            app:layout_constraintEnd_toEndOf="parent"
+            app:layout_constraintTop_toTopOf="parent"
+            app:srcCompat="@drawable/ic_cash_refund" />
+
+</androidx.constraintlayout.widget.ConstraintLayout>
diff --git a/merchant-terminal/src/main/res/layout/list_item_order.xml b/merchant-terminal/src/main/res/layout/list_item_order.xml
new file mode 100644
index 0000000..f88364d
--- /dev/null
+++ b/merchant-terminal/src/main/res/layout/list_item_order.xml
@@ -0,0 +1,61 @@
+<?xml version="1.0" encoding="utf-8"?>
+<!--
+  ~ This file is part of GNU Taler
+  ~ (C) 2020 Taler Systems S.A.
+  ~
+  ~ GNU Taler is free software; you can redistribute it and/or modify it under the
+  ~ terms of the GNU General Public License as published by the Free Software
+  ~ Foundation; either version 3, or (at your option) any later version.
+  ~
+  ~ GNU Taler is distributed in the hope that it will be useful, but WITHOUT ANY
+  ~ WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
+  ~ A PARTICULAR PURPOSE.  See the GNU General Public License for more details.
+  ~
+  ~ You should have received a copy of the GNU General Public License along with
+  ~ GNU Taler; see the file COPYING.  If not, see <http://www.gnu.org/licenses/>
+  -->
+
+<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
+        xmlns:app="http://schemas.android.com/apk/res-auto"
+        xmlns:tools="http://schemas.android.com/tools"
+        android:layout_width="match_parent"
+        android:layout_height="wrap_content"
+        android:background="@drawable/selectable_background"
+        android:minHeight="48dp"
+        android:padding="8dp">
+
+    <TextView
+            android:id="@+id/quantity"
+            android:layout_width="0dp"
+            android:layout_height="wrap_content"
+            android:gravity="end"
+            android:minWidth="24dp"
+            app:layout_constraintBottom_toBottomOf="parent"
+            app:layout_constraintStart_toStartOf="parent"
+            app:layout_constraintTop_toTopOf="@+id/name"
+            app:layout_constraintVertical_bias="0.0"
+            tools:text="31" />
+
+    <TextView
+            android:id="@+id/name"
+            android:layout_width="0dp"
+            android:layout_height="wrap_content"
+            android:layout_marginStart="8dp"
+            android:layout_marginEnd="8dp"
+            app:layout_constraintBottom_toBottomOf="parent"
+            app:layout_constraintEnd_toStartOf="@+id/price"
+            app:layout_constraintStart_toEndOf="@+id/quantity"
+            app:layout_constraintTop_toTopOf="parent"
+            tools:text="An order product item that in some cases could have a very long name" />
+
+    <TextView
+            android:id="@+id/price"
+            android:layout_width="wrap_content"
+            android:layout_height="wrap_content"
+            app:layout_constraintBottom_toBottomOf="parent"
+            app:layout_constraintEnd_toEndOf="parent"
+            app:layout_constraintTop_toTopOf="@+id/name"
+            app:layout_constraintVertical_bias="0.0"
+            tools:text="23.42" />
+
+</androidx.constraintlayout.widget.ConstraintLayout>
diff --git a/merchant-terminal/src/main/res/layout/list_item_product.xml b/merchant-terminal/src/main/res/layout/list_item_product.xml
new file mode 100644
index 0000000..1037bef
--- /dev/null
+++ b/merchant-terminal/src/main/res/layout/list_item_product.xml
@@ -0,0 +1,56 @@
+<?xml version="1.0" encoding="utf-8"?>
+<!--
+  ~ This file is part of GNU Taler
+  ~ (C) 2020 Taler Systems S.A.
+  ~
+  ~ GNU Taler is free software; you can redistribute it and/or modify it under the
+  ~ terms of the GNU General Public License as published by the Free Software
+  ~ Foundation; either version 3, or (at your option) any later version.
+  ~
+  ~ GNU Taler is distributed in the hope that it will be useful, but WITHOUT ANY
+  ~ WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
+  ~ A PARTICULAR PURPOSE.  See the GNU General Public License for more details.
+  ~
+  ~ You should have received a copy of the GNU General Public License along with
+  ~ GNU Taler; see the file COPYING.  If not, see <http://www.gnu.org/licenses/>
+  -->
+
+<com.google.android.material.card.MaterialCardView xmlns:android="http://schemas.android.com/apk/res/android"
+        xmlns:app="http://schemas.android.com/apk/res-auto"
+        xmlns:tools="http://schemas.android.com/tools"
+        android:layout_width="match_parent"
+        android:layout_height="wrap_content"
+        android:layout_margin="4dp"
+        android:clickable="true"
+        android:focusable="true"
+        app:cardUseCompatPadding="true">
+
+    <androidx.constraintlayout.widget.ConstraintLayout
+            android:layout_width="match_parent"
+            android:layout_height="wrap_content"
+            android:padding="8dp">
+
+        <TextView
+                android:id="@+id/name"
+                android:layout_width="0dp"
+                android:layout_height="wrap_content"
+                android:textColor="?android:textColorPrimary"
+                android:textStyle="bold"
+                app:layout_constraintEnd_toEndOf="parent"
+                app:layout_constraintStart_toStartOf="parent"
+                app:layout_constraintTop_toTopOf="parent"
+                tools:text="Steak and two Eggs" />
+
+        <TextView
+                android:id="@+id/price"
+                android:layout_width="0dp"
+                android:layout_height="wrap_content"
+                android:layout_marginTop="8dp"
+                android:textColor="?android:textColorSecondary"
+                app:layout_constraintEnd_toEndOf="parent"
+                app:layout_constraintTop_toBottomOf="@+id/name"
+                tools:text="7.95" />
+
+    </androidx.constraintlayout.widget.ConstraintLayout>
+
+</com.google.android.material.card.MaterialCardView>
\ No newline at end of file
diff --git a/merchant-terminal/src/main/res/layout/nav_header_main.xml b/merchant-terminal/src/main/res/layout/nav_header_main.xml
new file mode 100644
index 0000000..14bbd51
--- /dev/null
+++ b/merchant-terminal/src/main/res/layout/nav_header_main.xml
@@ -0,0 +1,55 @@
+<?xml version="1.0" encoding="utf-8"?>
+<!--
+  ~ This file is part of GNU Taler
+  ~ (C) 2020 Taler Systems S.A.
+  ~
+  ~ GNU Taler is free software; you can redistribute it and/or modify it under the
+  ~ terms of the GNU General Public License as published by the Free Software
+  ~ Foundation; either version 3, or (at your option) any later version.
+  ~
+  ~ GNU Taler is distributed in the hope that it will be useful, but WITHOUT ANY
+  ~ WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
+  ~ A PARTICULAR PURPOSE.  See the GNU General Public License for more details.
+  ~
+  ~ You should have received a copy of the GNU General Public License along with
+  ~ GNU Taler; see the file COPYING.  If not, see <http://www.gnu.org/licenses/>
+  -->
+
+<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
+        xmlns:app="http://schemas.android.com/apk/res-auto"
+        xmlns:tools="http://schemas.android.com/tools"
+        android:layout_width="match_parent"
+        android:layout_height="@dimen/nav_header_height"
+        android:background="@drawable/side_nav_bar"
+        android:gravity="bottom"
+        android:orientation="vertical"
+        android:paddingLeft="@dimen/activity_horizontal_margin"
+        android:paddingTop="@dimen/activity_vertical_margin"
+        android:paddingRight="@dimen/activity_horizontal_margin"
+        android:paddingBottom="@dimen/activity_vertical_margin"
+        android:theme="@style/AppTheme">
+
+    <ImageView
+            android:id="@+id/imageView"
+            android:layout_width="wrap_content"
+            android:layout_height="wrap_content"
+            android:paddingTop="@dimen/nav_header_vertical_spacing"
+            app:srcCompat="@mipmap/ic_taler_logo_round"
+            tools:ignore="ContentDescription" />
+
+    <TextView
+            android:layout_width="match_parent"
+            android:layout_height="wrap_content"
+            android:paddingTop="@dimen/nav_header_vertical_spacing"
+            android:text="@string/project_name"
+            android:textAppearance="@style/TextAppearance.AppCompat.Body1"
+            android:textColor="#FFF" />
+
+    <TextView
+            android:id="@+id/textView"
+            android:layout_width="wrap_content"
+            android:layout_height="wrap_content"
+            android:text="@string/app_name_short"
+            android:textColor="#FFF" />
+
+</LinearLayout>
diff --git a/merchant-terminal/src/main/res/menu/activity_main_drawer.xml b/merchant-terminal/src/main/res/menu/activity_main_drawer.xml
new file mode 100644
index 0000000..1303605
--- /dev/null
+++ b/merchant-terminal/src/main/res/menu/activity_main_drawer.xml
@@ -0,0 +1,36 @@
+<?xml version="1.0" encoding="utf-8"?>
+<!--
+  ~ This file is part of GNU Taler
+  ~ (C) 2020 Taler Systems S.A.
+  ~
+  ~ GNU Taler is free software; you can redistribute it and/or modify it under the
+  ~ terms of the GNU General Public License as published by the Free Software
+  ~ Foundation; either version 3, or (at your option) any later version.
+  ~
+  ~ GNU Taler is distributed in the hope that it will be useful, but WITHOUT ANY
+  ~ WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
+  ~ A PARTICULAR PURPOSE.  See the GNU General Public License for more details.
+  ~
+  ~ You should have received a copy of the GNU General Public License along with
+  ~ GNU Taler; see the file COPYING.  If not, see <http://www.gnu.org/licenses/>
+  -->
+
+<menu xmlns:android="http://schemas.android.com/apk/res/android"
+        xmlns:tools="http://schemas.android.com/tools"
+        tools:showIn="navigation_view">
+
+    <group android:checkableBehavior="single">
+        <item
+                android:id="@+id/nav_order"
+                android:icon="@drawable/ic_move_money_24dp"
+                android:title="@string/menu_order" />
+        <item
+                android:id="@+id/nav_history"
+                android:icon="@drawable/ic_history_black_24dp"
+                android:title="@string/menu_history" />
+        <item
+                android:id="@+id/nav_settings"
+                android:icon="@drawable/ic_menu_manage"
+                android:title="@string/menu_settings" />
+    </group>
+</menu>
diff --git a/merchant-terminal/src/main/res/mipmap-anydpi-v26/ic_taler_logo.xml b/merchant-terminal/src/main/res/mipmap-anydpi-v26/ic_taler_logo.xml
new file mode 100644
index 0000000..c4a603d
--- /dev/null
+++ b/merchant-terminal/src/main/res/mipmap-anydpi-v26/ic_taler_logo.xml
@@ -0,0 +1,5 @@
+<?xml version="1.0" encoding="utf-8"?>
+<adaptive-icon xmlns:android="http://schemas.android.com/apk/res/android">
+    <background android:drawable="@drawable/ic_launcher_background"/>
+    <foreground android:drawable="@mipmap/ic_launcher_foreground"/>
+</adaptive-icon>
\ No newline at end of file
diff --git a/merchant-terminal/src/main/res/mipmap-anydpi-v26/ic_taler_logo_round.xml b/merchant-terminal/src/main/res/mipmap-anydpi-v26/ic_taler_logo_round.xml
new file mode 100644
index 0000000..c4a603d
--- /dev/null
+++ b/merchant-terminal/src/main/res/mipmap-anydpi-v26/ic_taler_logo_round.xml
@@ -0,0 +1,5 @@
+<?xml version="1.0" encoding="utf-8"?>
+<adaptive-icon xmlns:android="http://schemas.android.com/apk/res/android">
+    <background android:drawable="@drawable/ic_launcher_background"/>
+    <foreground android:drawable="@mipmap/ic_launcher_foreground"/>
+</adaptive-icon>
\ No newline at end of file
diff --git a/merchant-terminal/src/main/res/mipmap-hdpi/ic_launcher_foreground.png b/merchant-terminal/src/main/res/mipmap-hdpi/ic_launcher_foreground.png
new file mode 100644
index 0000000..75273ec
--- /dev/null
+++ b/merchant-terminal/src/main/res/mipmap-hdpi/ic_launcher_foreground.png
diff --git a/merchant-terminal/src/main/res/mipmap-hdpi/ic_taler_logo.png b/merchant-terminal/src/main/res/mipmap-hdpi/ic_taler_logo.png
new file mode 100644
index 0000000..eaecede
--- /dev/null
+++ b/merchant-terminal/src/main/res/mipmap-hdpi/ic_taler_logo.png
diff --git a/merchant-terminal/src/main/res/mipmap-hdpi/ic_taler_logo_round.png b/merchant-terminal/src/main/res/mipmap-hdpi/ic_taler_logo_round.png
new file mode 100644
index 0000000..caa2a3e
--- /dev/null
+++ b/merchant-terminal/src/main/res/mipmap-hdpi/ic_taler_logo_round.png
diff --git a/merchant-terminal/src/main/res/mipmap-mdpi/ic_launcher_foreground.png b/merchant-terminal/src/main/res/mipmap-mdpi/ic_launcher_foreground.png
new file mode 100644
index 0000000..a450287
--- /dev/null
+++ b/merchant-terminal/src/main/res/mipmap-mdpi/ic_launcher_foreground.png
diff --git a/merchant-terminal/src/main/res/mipmap-mdpi/ic_taler_logo.png b/merchant-terminal/src/main/res/mipmap-mdpi/ic_taler_logo.png
new file mode 100644
index 0000000..e1f7374
--- /dev/null
+++ b/merchant-terminal/src/main/res/mipmap-mdpi/ic_taler_logo.png
diff --git a/merchant-terminal/src/main/res/mipmap-mdpi/ic_taler_logo_round.png b/merchant-terminal/src/main/res/mipmap-mdpi/ic_taler_logo_round.png
new file mode 100644
index 0000000..e92d2d3
--- /dev/null
+++ b/merchant-terminal/src/main/res/mipmap-mdpi/ic_taler_logo_round.png
diff --git a/merchant-terminal/src/main/res/mipmap-xhdpi/ic_launcher_foreground.png b/merchant-terminal/src/main/res/mipmap-xhdpi/ic_launcher_foreground.png
new file mode 100644
index 0000000..a5e875c
--- /dev/null
+++ b/merchant-terminal/src/main/res/mipmap-xhdpi/ic_launcher_foreground.png
diff --git a/merchant-terminal/src/main/res/mipmap-xhdpi/ic_taler_logo.png b/merchant-terminal/src/main/res/mipmap-xhdpi/ic_taler_logo.png
new file mode 100644
index 0000000..5ca4409
--- /dev/null
+++ b/merchant-terminal/src/main/res/mipmap-xhdpi/ic_taler_logo.png
diff --git a/merchant-terminal/src/main/res/mipmap-xhdpi/ic_taler_logo_round.png b/merchant-terminal/src/main/res/mipmap-xhdpi/ic_taler_logo_round.png
new file mode 100644
index 0000000..12b9056
--- /dev/null
+++ b/merchant-terminal/src/main/res/mipmap-xhdpi/ic_taler_logo_round.png
diff --git a/merchant-terminal/src/main/res/mipmap-xxhdpi/ic_launcher_foreground.png b/merchant-terminal/src/main/res/mipmap-xxhdpi/ic_launcher_foreground.png
new file mode 100644
index 0000000..e9d1fc9
--- /dev/null
+++ b/merchant-terminal/src/main/res/mipmap-xxhdpi/ic_launcher_foreground.png
diff --git a/merchant-terminal/src/main/res/mipmap-xxhdpi/ic_taler_logo.png b/merchant-terminal/src/main/res/mipmap-xxhdpi/ic_taler_logo.png
new file mode 100644
index 0000000..a786efa
--- /dev/null
+++ b/merchant-terminal/src/main/res/mipmap-xxhdpi/ic_taler_logo.png
diff --git a/merchant-terminal/src/main/res/mipmap-xxhdpi/ic_taler_logo_round.png b/merchant-terminal/src/main/res/mipmap-xxhdpi/ic_taler_logo_round.png
new file mode 100644
index 0000000..b22a84e
--- /dev/null
+++ b/merchant-terminal/src/main/res/mipmap-xxhdpi/ic_taler_logo_round.png
diff --git a/merchant-terminal/src/main/res/mipmap-xxxhdpi/ic_launcher_foreground.png b/merchant-terminal/src/main/res/mipmap-xxxhdpi/ic_launcher_foreground.png
new file mode 100644
index 0000000..f8037d1
--- /dev/null
+++ b/merchant-terminal/src/main/res/mipmap-xxxhdpi/ic_launcher_foreground.png
diff --git a/merchant-terminal/src/main/res/mipmap-xxxhdpi/ic_taler_logo.png b/merchant-terminal/src/main/res/mipmap-xxxhdpi/ic_taler_logo.png
new file mode 100644
index 0000000..0e9df6a
--- /dev/null
+++ b/merchant-terminal/src/main/res/mipmap-xxxhdpi/ic_taler_logo.png
diff --git a/merchant-terminal/src/main/res/mipmap-xxxhdpi/ic_taler_logo_round.png b/merchant-terminal/src/main/res/mipmap-xxxhdpi/ic_taler_logo_round.png
new file mode 100644
index 0000000..6bef9bd
--- /dev/null
+++ b/merchant-terminal/src/main/res/mipmap-xxxhdpi/ic_taler_logo_round.png
diff --git a/merchant-terminal/src/main/res/navigation/nav_graph.xml b/merchant-terminal/src/main/res/navigation/nav_graph.xml
new file mode 100644
index 0000000..2e337f2
--- /dev/null
+++ b/merchant-terminal/src/main/res/navigation/nav_graph.xml
@@ -0,0 +1,137 @@
+<?xml version="1.0" encoding="utf-8"?><!--
+  ~ This file is part of GNU Taler
+  ~ (C) 2020 Taler Systems S.A.
+  ~
+  ~ GNU Taler is free software; you can redistribute it and/or modify it under the
+  ~ terms of the GNU General Public License as published by the Free Software
+  ~ Foundation; either version 3, or (at your option) any later version.
+  ~
+  ~ GNU Taler is distributed in the hope that it will be useful, but WITHOUT ANY
+  ~ WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
+  ~ A PARTICULAR PURPOSE.  See the GNU General Public License for more details.
+  ~
+  ~ You should have received a copy of the GNU General Public License along with
+  ~ GNU Taler; see the file COPYING.  If not, see <http://www.gnu.org/licenses/>
+  -->
+
+<navigation xmlns:android="http://schemas.android.com/apk/res/android"
+        xmlns:app="http://schemas.android.com/apk/res-auto"
+        xmlns:tools="http://schemas.android.com/tools"
+        android:id="@+id/nav_graph"
+        app:startDestination="@+id/nav_order"
+        tools:ignore="UnusedNavigation">
+
+    <fragment
+            android:id="@+id/nav_order"
+            android:name="net.taler.merchantpos.order.OrderFragment"
+            android:label=""
+            tools:layout="@layout/fragment_order">
+        <action
+                android:id="@+id/action_order_to_merchantSettings"
+                app:destination="@+id/nav_settings"
+                app:launchSingleTop="true"
+                app:popUpTo="@+id/nav_graph"
+                app:popUpToInclusive="true" />
+        <action
+                android:id="@+id/action_order_self"
+                app:destination="@+id/nav_order"
+                app:popUpTo="@+id/nav_graph" />
+        <action
+                android:id="@+id/action_order_to_processPayment"
+                app:destination="@+id/processPayment" />
+    </fragment>
+
+    <fragment
+            android:id="@+id/processPayment"
+            android:name="net.taler.merchantpos.payment.ProcessPaymentFragment"
+            android:label="@string/payment_process_label"
+            tools:layout="@layout/fragment_process_payment">
+        <action
+                android:id="@+id/action_processPayment_to_paymentSuccess"
+                app:destination="@+id/paymentSuccess"
+                app:popUpTo="@id/nav_order" />
+    </fragment>
+
+    <fragment
+            android:id="@+id/nav_history"
+            android:name="net.taler.merchantpos.history.MerchantHistoryFragment"
+            android:label="@string/history_label"
+            tools:layout="@layout/fragment_merchant_history">
+        <action
+                android:id="@+id/action_nav_history_to_refundFragment"
+                app:destination="@id/refundFragment" />
+    </fragment>
+
+    <fragment
+            android:id="@+id/refundFragment"
+            android:name="net.taler.merchantpos.history.RefundFragment"
+            android:label="@string/history_refund"
+            tools:layout="@layout/fragment_refund">
+        <action
+                android:id="@+id/action_refundFragment_to_refundUriFragment"
+                app:destination="@id/refundUriFragment" />
+    </fragment>
+
+    <fragment
+            android:id="@+id/refundUriFragment"
+            android:name="net.taler.merchantpos.history.RefundUriFragment"
+            android:label="@string/history_refund"
+            tools:layout="@layout/fragment_refund_uri" />
+
+    <fragment
+            android:id="@+id/nav_settings"
+            android:name="net.taler.merchantpos.config.MerchantConfigFragment"
+            android:label="@string/config_label"
+            tools:layout="@layout/fragment_merchant_config">
+        <action
+                android:id="@+id/action_settings_to_order"
+                app:destination="@+id/nav_order"
+                app:launchSingleTop="true"
+                app:popUpTo="@+id/nav_graph"
+                app:popUpToInclusive="true" />
+    </fragment>
+
+    <fragment
+            android:id="@+id/configFetcher"
+            android:name="net.taler.merchantpos.config.ConfigFetcherFragment"
+            android:label="@string/config_fetching_label"
+            tools:layout="@layout/fragment_config_fetcher">
+        <action
+                android:id="@+id/action_configFetcher_to_merchantSettings"
+                app:destination="@+id/nav_settings"
+                app:launchSingleTop="true"
+                app:popUpTo="@+id/nav_graph"
+                app:popUpToInclusive="true" />
+        <action
+                android:id="@+id/action_configFetcher_to_order"
+                app:destination="@+id/nav_order"
+                app:launchSingleTop="true"
+                app:popUpTo="@+id/nav_graph"
+                app:popUpToInclusive="true" />
+    </fragment>
+
+    <fragment
+            android:id="@+id/paymentSuccess"
+            android:name="net.taler.merchantpos.payment.PaymentSuccessFragment"
+            android:label="@string/payment_received"
+            tools:layout="@layout/fragment_payment_success" />
+
+    <action
+            android:id="@+id/action_global_order"
+            app:destination="@+id/nav_order"
+            app:launchSingleTop="true"
+            app:popUpTo="@+id/nav_graph" />
+    <action
+            android:id="@+id/action_global_merchantHistory"
+            app:destination="@+id/nav_history"
+            app:launchSingleTop="true" />
+    <action
+            android:id="@+id/action_global_merchantSettings"
+            app:destination="@+id/nav_settings"
+            app:launchSingleTop="true" />
+    <action
+            android:id="@+id/action_global_configFetcher"
+            app:destination="@+id/configFetcher"
+            app:launchSingleTop="true" />
+
+</navigation>
diff --git a/merchant-terminal/src/main/res/values-night/colors.xml b/merchant-terminal/src/main/res/values-night/colors.xml
new file mode 100644
index 0000000..10bdbb9
--- /dev/null
+++ b/merchant-terminal/src/main/res/values-night/colors.xml
@@ -0,0 +1,5 @@
+<?xml version="1.0" encoding="utf-8"?>
+<resources>
+    <color name="highlightedBackground">#2E2E2E</color>
+    <color name="selectedBackground">#363636</color>
+</resources>
diff --git a/merchant-terminal/src/main/res/values/colors.xml b/merchant-terminal/src/main/res/values/colors.xml
new file mode 100644
index 0000000..bf0c849
--- /dev/null
+++ b/merchant-terminal/src/main/res/values/colors.xml
@@ -0,0 +1,14 @@
+<?xml version="1.0" encoding="utf-8"?>
+<resources>
+    <color name="colorPrimary">#795548</color>
+    <color name="colorPrimaryDark">#5D4037</color>
+    <color name="colorAccent">#FFEB3B</color>
+
+    <color name="highlightedBackground">#E4E4E4</color>
+    <color name="selectedBackground">#DADADA</color>
+    <color name="bottomButtons">#9E9D24</color>
+
+    <color name="green">#388E3C</color>
+    <color name="red">#C62828</color>
+
+</resources>
diff --git a/merchant-terminal/src/main/res/values/dimens.xml b/merchant-terminal/src/main/res/values/dimens.xml
new file mode 100644
index 0000000..eedc3c6
--- /dev/null
+++ b/merchant-terminal/src/main/res/values/dimens.xml
@@ -0,0 +1,6 @@
+<resources>
+    <dimen name="activity_horizontal_margin">16dp</dimen>
+    <dimen name="activity_vertical_margin">16dp</dimen>
+    <dimen name="nav_header_vertical_spacing">8dp</dimen>
+    <dimen name="nav_header_height">176dp</dimen>
+</resources>
\ No newline at end of file
diff --git a/merchant-terminal/src/main/res/values/strings.xml b/merchant-terminal/src/main/res/values/strings.xml
new file mode 100644
index 0000000..77c7e03
--- /dev/null
+++ b/merchant-terminal/src/main/res/values/strings.xml
@@ -0,0 +1,68 @@
+<resources>
+    <string name="app_name">Taler Merchant PoS Terminal</string>
+    <string name="app_name_short">Merchant Terminal</string>
+    <string name="project_name">GNU Taler</string>
+
+    <string name="menu_order">Orders</string>
+    <string name="menu_history">History</string>
+    <string name="menu_settings">Settings</string>
+
+    <string name="order_label_title">Order #%s</string>
+    <!-- The first placeholder is the amount and the second the currency -->
+    <string name="order_total">Total: %1$.2f %2$s</string>
+    <string name="order_restart">Restart</string>
+    <string name="order_undo">Undo</string>
+    <string name="order_previous">Prev</string>
+    <string name="order_next">Next</string>
+    <string name="order_complete">Complete</string>
+
+    <string name="config_label">Merchant Settings</string>
+    <string name="config_url">Configuration URL</string>
+    <string name="config_username">Username</string>
+    <string name="config_password">Password</string>
+    <string name="config_ok">Fetch Configuration</string>
+    <string name="config_auth_error">Error: Invalid username or password</string>
+    <string name="config_error_network">Error: Could not connect to configuration server</string>
+    <string name="config_error_category">Error: No valid product category found</string>
+    <string name="config_error_malformed">Error: The configuration JSON is malformed</string>
+    <string name="config_error_currency">Error: Product %1$s has currency %2$s, but %3$s expected</string>
+    <string name="config_error_product_category_id">Error: Product %1$s references unknown category ID %2$d</string>
+    <string name="config_error_product_zero">Error: No valid products found</string>
+    <string name="config_error_unknown">Error: Invalid Configuration</string>
+    <string name="config_fetching">Fetching Configuration…</string>
+    <string name="config_save_password">Remember Password</string>
+    <string name="config_forget_password">Forget</string>
+    <string name="config_changed">Changed to new merchant using %s</string>
+    <string name="config_fetching_label">Fetching Configuration</string>
+    <string name="config_docs">Please refer to <a href="https://docs.taler.net/taler-merchant-pos-terminal.html#apis-and-data-formats">the documentation</a> for the configuration format.</string>
+
+    <string name="payment_intro_nfc">Please scan QR Code or use NFC to pay</string>
+    <string name="payment_intro">Please scan QR Code to pay</string>
+    <string name="payment_cancel">Cancel Payment</string>
+    <string name="payment_received">Payment received</string>
+    <string name="payment_back_button">Continue</string>
+    <string name="payment_order_ref">Order Reference: %s</string>
+    <string name="payment_process_label">Customer Payment Required</string>
+    <string name="payment_canceled">Payment Canceled</string>
+
+    <string name="history_label">Payment History</string>
+    <string name="history_received_at">Received at</string>
+    <string name="history_ref_no">Ref. No: %s</string>
+    <string name="history_refund">Refund Order</string>
+    <string name="refund_amount">Amount</string>
+    <string name="refund_reason">Refund reason</string>
+    <string name="refund_abort">Abort</string>
+    <string name="refund_confirm">Give Refund</string>
+    <string name="refund_error_max_amount">Greater than order amount of %s</string>
+    <string name="refund_error_zero">Needs to be positive amount</string>
+    <string name="refund_error_backend">Error processing refund</string>
+    <string name="refund_error_deadline">Refund deadline has passed</string>
+    <string name="refund_intro_nfc">Please scan QR Code or use NFC to give refund</string>
+    <string name="refund_intro">Please scan QR Code to give refund</string>
+    <string name="refund_order_ref">Order Reference: %1$s\n\n%2$s</string>
+
+    <string name="error_network">Network Error</string>
+
+    <string name="toast_back_to_exit">Click BACK again to exit</string>
+
+</resources>
diff --git a/merchant-terminal/src/main/res/values/styles.xml b/merchant-terminal/src/main/res/values/styles.xml
new file mode 100644
index 0000000..4445a01
--- /dev/null
+++ b/merchant-terminal/src/main/res/values/styles.xml
@@ -0,0 +1,21 @@
+<resources>
+    <!-- Base application theme. -->
+    <style name="AppTheme" parent="Theme.MaterialComponents.DayNight.DarkActionBar">
+        <!-- Customize your theme here. -->
+        <item name="colorPrimary">@color/colorPrimary</item>
+        <item name="colorOnPrimary">@android:color/white</item>
+        <item name="colorPrimaryDark">@color/colorPrimaryDark</item>
+        <item name="colorAccent">@color/colorAccent</item>
+    </style>
+
+    <style name="AppTheme.NoActionBar">
+        <item name="windowActionBar">false</item>
+        <item name="windowNoTitle">true</item>
+        <item name="android:statusBarColor">@android:color/transparent</item>
+    </style>
+
+    <style name="AppTheme.AppBarOverlay" parent="ThemeOverlay.AppCompat.Dark.ActionBar" />
+
+    <style name="AppTheme.PopupOverlay" parent="ThemeOverlay.AppCompat.Light" />
+
+</resources>
diff --git a/merchant-terminal/src/main/res/xml/backup_descriptor.xml b/merchant-terminal/src/main/res/xml/backup_descriptor.xml
new file mode 100644
index 0000000..6fd6103
--- /dev/null
+++ b/merchant-terminal/src/main/res/xml/backup_descriptor.xml
@@ -0,0 +1,4 @@
+<?xml version="1.0" encoding="utf-8"?>
+<full-backup-content>
+    <!-- Exclude specific shared preferences that contain GCM registration Id -->
+</full-backup-content>
diff --git a/merchant-terminal/src/test/java/net/taler/merchantpos/order/OrderManagerTest.kt b/merchant-terminal/src/test/java/net/taler/merchantpos/order/OrderManagerTest.kt
new file mode 100644
index 0000000..cdb928a
--- /dev/null
+++ b/merchant-terminal/src/test/java/net/taler/merchantpos/order/OrderManagerTest.kt
@@ -0,0 +1,151 @@
+/*
+ * This file is part of GNU Taler
+ * (C) 2020 Taler Systems S.A.
+ *
+ * GNU Taler is free software; you can redistribute it and/or modify it under the
+ * terms of the GNU General Public License as published by the Free Software
+ * Foundation; either version 3, or (at your option) any later version.
+ *
+ * GNU Taler is distributed in the hope that it will be useful, but WITHOUT ANY
+ * WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
+ * A PARTICULAR PURPOSE.  See the GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along with
+ * GNU Taler; see the file COPYING.  If not, see <http://www.gnu.org/licenses/>
+ */
+
+package net.taler.merchantpos.order
+
+import android.app.Application
+import androidx.test.core.app.ApplicationProvider.getApplicationContext
+import androidx.test.ext.junit.runners.AndroidJUnit4
+import com.fasterxml.jackson.databind.DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES
+import com.fasterxml.jackson.databind.ObjectMapper
+import com.fasterxml.jackson.module.kotlin.KotlinModule
+import kotlinx.coroutines.runBlocking
+import net.taler.merchantpos.R
+import org.json.JSONObject
+import org.junit.Assert.assertEquals
+import org.junit.Assert.assertNull
+import org.junit.Test
+import org.junit.runner.RunWith
+
+@RunWith(AndroidJUnit4::class)
+class OrderManagerTest {
+
+    private val mapper = ObjectMapper()
+        .registerModule(KotlinModule())
+        .configure(FAIL_ON_UNKNOWN_PROPERTIES, false)
+
+    private val app: Application = getApplicationContext()
+    private val orderManager = OrderManager(app, mapper)
+
+    @Test
+    fun `config test missing categories`() = runBlocking {
+        val json = JSONObject(
+            """
+            { "categories": [] }
+        """.trimIndent()
+        )
+        val result = orderManager.onConfigurationReceived(json, "KUDOS")
+        assertEquals(app.getString(R.string.config_error_category), result)
+    }
+
+    @Test
+    fun `config test currency mismatch`() = runBlocking {
+        val json = JSONObject(
+            """{
+            "categories": [
+                {
+                    "id": 1,
+                    "name": "Snacks"
+                }
+            ],
+            "products": [
+                {
+                    "product_id": "631361561",
+                    "description": "Chips",
+                    "price": "WRONGCURRENCY:1.00",
+                    "categories": [ 1 ],
+                    "delivery_location": "cafeteria"
+                }
+            ]
+        }""".trimIndent()
+        )
+        val result = orderManager.onConfigurationReceived(json, "KUDOS")
+        val expectedStr = app.getString(
+            R.string.config_error_currency, "Chips", "WRONGCURRENCY", "KUDOS"
+        )
+        assertEquals(expectedStr, result)
+    }
+
+    @Test
+    fun `config test unknown category ID`() = runBlocking {
+        val json = JSONObject(
+            """{
+            "categories": [
+                {
+                    "id": 1,
+                    "name": "Snacks"
+                }
+            ],
+            "products": [
+                {
+                    "product_id": "631361561",
+                    "description": "Chips",
+                    "price": "KUDOS:1.00",
+                    "categories": [ 2 ]
+                }
+            ]
+        }""".trimIndent()
+        )
+        val result = orderManager.onConfigurationReceived(json, "KUDOS")
+        val expectedStr = app.getString(
+            R.string.config_error_product_category_id, "Chips", 2
+        )
+        assertEquals(expectedStr, result)
+    }
+
+    @Test
+    fun `config test no products`() = runBlocking {
+        val json = JSONObject(
+            """{
+            "categories": [
+                {
+                    "id": 1,
+                    "name": "Snacks"
+                }
+            ],
+            "products": []
+        }""".trimIndent()
+        )
+        val result = orderManager.onConfigurationReceived(json, "KUDOS")
+        val expectedStr = app.getString(R.string.config_error_product_zero)
+        assertEquals(expectedStr, result)
+    }
+
+    @Test
+    fun `config test valid config gets accepted`() = runBlocking {
+        val json = JSONObject(
+            """{
+            "categories": [
+                {
+                    "id": 1,
+                    "name": "Snacks"
+                }
+            ],
+            "products": [
+                {
+                    "product_id": "631361561",
+                    "description": "Chips",
+                    "price": "KUDOS:1.00",
+                    "categories": [ 1 ]
+                }
+            ]
+        }""".trimIndent()
+        )
+        val result = orderManager.onConfigurationReceived(json, "KUDOS")
+        assertNull(result)
+    }
+
+}