feat(wallee app): navigation and state handling using view model

16 files changed, 402 insertions, 385 deletions

diff --git a/wallee-c2ec/app/build.gradle.kts b/wallee-c2ec/app/build.gradle.kts
index 44d0084..bc8cb03 100644
--- a/wallee-c2ec/app/build.gradle.kts
+++ b/wallee-c2ec/app/build.gradle.kts
@@ -64,6 +64,7 @@ dependencies {
     implementation(libs.androidx.ui.graphics)
     implementation(libs.androidx.ui.tooling.preview)
     implementation(libs.androidx.material3)
+    implementation(libs.androidx.navigation.compose)
     testImplementation(libs.junit)
     androidTestImplementation(libs.androidx.junit)
     androidTestImplementation(libs.androidx.espresso.core)
diff --git a/wallee-c2ec/app/src/main/AndroidManifest.xml b/wallee-c2ec/app/src/main/AndroidManifest.xml
index 86771a7..f276936 100644
--- a/wallee-c2ec/app/src/main/AndroidManifest.xml
+++ b/wallee-c2ec/app/src/main/AndroidManifest.xml
@@ -13,21 +13,6 @@
         android:theme="@style/Theme.Walleec2ec"
         tools:targetApi="31">
         <activity
-            android:name=".PaymentActivity"
-            android:exported="false"
-            android:label="@string/title_activity_payment"
-            android:theme="@style/Theme.Walleec2ec" />
-        <activity
-            android:name=".WithdrawalCreationActivity"
-            android:exported="false"
-            android:label="@string/title_activity_withdrawal_creation"
-            android:theme="@style/Theme.Walleec2ec" />
-        <activity
-            android:name=".ExchangeActivity"
-            android:exported="false"
-            android:label="@string/title_activity_exchange"
-            android:theme="@style/Theme.Walleec2ec" />
-        <activity
             android:name=".MainActivity"
             android:exported="true"
             android:label="@string/app_name"
@@ -38,6 +23,12 @@
                 <category android:name="android.intent.category.LAUNCHER" />
             </intent-filter>
         </activity>
+        <activity
+            android:name=".withdrawal.WithdrawalActivity"
+            android:exported="true"
+            android:label="@string/app_name"
+            android:theme="@style/Theme.Walleec2ec">
+        </activity>
     </application>
 
 </manifest>
\ No newline at end of file
diff --git a/wallee-c2ec/app/src/main/java/ch/bfh/habej2/wallee_c2ec/ExchangeActivity.kt b/wallee-c2ec/app/src/main/java/ch/bfh/habej2/wallee_c2ec/ExchangeActivity.kt
deleted file mode 100644
index 8bdc310..0000000
--- a/wallee-c2ec/app/src/main/java/ch/bfh/habej2/wallee_c2ec/ExchangeActivity.kt
+++ /dev/null
@@ -1,56 +0,0 @@
-package ch.bfh.habej2.wallee_c2ec
-
-import android.content.Intent
-import android.os.Bundle
-import androidx.activity.ComponentActivity
-import androidx.activity.compose.setContent
-import androidx.appcompat.app.AppCompatActivity
-import androidx.compose.foundation.layout.Column
-import androidx.compose.foundation.layout.fillMaxSize
-import androidx.compose.material3.Button
-import androidx.compose.material3.MaterialTheme
-import androidx.compose.material3.Surface
-import androidx.compose.material3.Text
-import androidx.compose.ui.Alignment
-import androidx.compose.ui.Modifier
-import androidx.compose.ui.platform.LocalContext
-import ch.bfh.habej2.wallee_c2ec.config.EXCHANGES
-import ch.bfh.habej2.wallee_c2ec.ui.theme.Walleec2ecTheme
-
-class ExchangeActivity : AppCompatActivity() {
-
-    override fun onCreate(savedInstanceState: Bundle?) {
-        super.onCreate(savedInstanceState)
-        setContent {
-            Walleec2ecTheme {
-                // A surface container using the 'background' color from the theme
-                Surface(
-                    modifier = Modifier.fillMaxSize(),
-                    color = MaterialTheme.colorScheme.background
-                ) {
-
-                    Column(
-                        horizontalAlignment = Alignment.CenterHorizontally
-                    ) {
-
-                        Text(text = "Choose the exchange to withdraw from")
-
-                        // TODO let user select exchanges from config here
-                        //  config must contain display name, credentials (generated by cli)
-                        //  and the base url of the c2ec bank-integration api
-                        EXCHANGES.forEach { Text(text = it.displayName) }
-
-                        val ctx = LocalContext.current
-                        Button(onClick = { ctx.startActivity(Intent(this@ExchangeActivity.parent, WithdrawalCreationActivity::class.java)) }) {
-                            Text(text = "withdraw")
-                        }
-
-                        Button(onClick = { finish() }) {
-                            Text(text = "back")
-                        }
-                    }
-                }
-            }
-        }
-    }
-}
\ No newline at end of file
diff --git a/wallee-c2ec/app/src/main/java/ch/bfh/habej2/wallee_c2ec/MainActivity.kt b/wallee-c2ec/app/src/main/java/ch/bfh/habej2/wallee_c2ec/MainActivity.kt
index 13d84fc..be02bd8 100644
--- a/wallee-c2ec/app/src/main/java/ch/bfh/habej2/wallee_c2ec/MainActivity.kt
+++ b/wallee-c2ec/app/src/main/java/ch/bfh/habej2/wallee_c2ec/MainActivity.kt
@@ -4,9 +4,7 @@ import android.content.Intent
 import android.os.Bundle
 import androidx.activity.ComponentActivity
 import androidx.activity.compose.setContent
-import androidx.appcompat.app.AppCompatActivity
 import androidx.compose.foundation.layout.Column
-import androidx.compose.foundation.layout.Row
 import androidx.compose.foundation.layout.fillMaxSize
 import androidx.compose.material3.Button
 import androidx.compose.material3.MaterialTheme
@@ -16,11 +14,10 @@ import androidx.compose.runtime.Composable
 import androidx.compose.ui.Alignment
 import androidx.compose.ui.Modifier
 import androidx.compose.ui.platform.LocalContext
-import androidx.compose.ui.tooling.preview.Preview
-import ch.bfh.habej2.wallee_c2ec.config.loadConfiguredExchanges
 import ch.bfh.habej2.wallee_c2ec.ui.theme.Walleec2ecTheme
+import ch.bfh.habej2.wallee_c2ec.withdrawal.WithdrawalActivity
 
-class MainActivity : AppCompatActivity() {
+class MainActivity : ComponentActivity() {
 
     override fun onCreate(savedInstanceState: Bundle?) {
         super.onCreate(savedInstanceState)
@@ -36,15 +33,17 @@ class MainActivity : AppCompatActivity() {
                         horizontalAlignment = Alignment.CenterHorizontally
                     ) {
                         Text(text = "Withdraw Taler using Wallee")
-                        Button(onClick = { ctx.startActivity(Intent(this@MainActivity, WithdrawalCreationActivity::class.java)) }) {
+                        Button(onClick = { ctx.startActivity(Intent(this@MainActivity, WithdrawalActivity::class.java)) }) {
                             Text(text = "Start Withdrawal")
                         }
-                        Button(onClick = { ctx.startActivity(Intent(this@MainActivity, ExchangeActivity::class.java)) }) {
-                            Text(text = "Choose Exchange")
-                        }
                     }
                 }
             }
         }
     }
+
+    @Composable
+    fun SelectExchangeScreen() {
+
+    }
 }
diff --git a/wallee-c2ec/app/src/main/java/ch/bfh/habej2/wallee_c2ec/PaymentActivity.kt b/wallee-c2ec/app/src/main/java/ch/bfh/habej2/wallee_c2ec/PaymentActivity.kt
deleted file mode 100644
index e63552b..0000000
--- a/wallee-c2ec/app/src/main/java/ch/bfh/habej2/wallee_c2ec/PaymentActivity.kt
+++ /dev/null
@@ -1,127 +0,0 @@
-package ch.bfh.habej2.wallee_c2ec
-
-import android.os.Bundle
-import androidx.activity.compose.setContent
-import androidx.appcompat.app.AppCompatActivity
-import androidx.compose.foundation.layout.Column
-import androidx.compose.foundation.layout.fillMaxSize
-import androidx.compose.material3.Button
-import androidx.compose.material3.MaterialTheme
-import androidx.compose.material3.Surface
-import androidx.compose.material3.Text
-import androidx.compose.material3.TextField
-import androidx.compose.ui.Alignment
-import androidx.compose.ui.Modifier
-import ch.bfh.habej2.wallee_c2ec.client.taler.BankIntegrationClient
-import ch.bfh.habej2.wallee_c2ec.client.wallee.WalleeResponseHandler
-import ch.bfh.habej2.wallee_c2ec.config.TalerBankIntegrationConfig
-import ch.bfh.habej2.wallee_c2ec.ui.theme.Walleec2ecTheme
-import com.wallee.android.till.sdk.ApiClient
-import com.wallee.android.till.sdk.data.LineItem
-import com.wallee.android.till.sdk.data.Transaction
-import com.wallee.android.till.sdk.data.TransactionProcessingBehavior
-import java.math.BigDecimal
-import java.util.Currency
-import java.util.Optional
-
-class PaymentActivity : AppCompatActivity() {
-    override fun onCreate(savedInstanceState: Bundle?) {
-        super.onCreate(savedInstanceState)
-
-        // TODO retrieve WithdrawalViewModel here
-        //  maybe something like savedStateRegistry.getSavedStateProvider("current-withdrawal")
-        val model = WithdrawalViewModel(BankIntegrationClient(
-            TalerBankIntegrationConfig("TestExchange", "http://localhost:8082/c2ec", "Wallee-1", "secret")))
-        val client = ApiClient(WalleeResponseHandler())
-
-        setContent {
-            Walleec2ecTheme {
-                // A surface container using the 'background' color from the theme
-                Surface(
-                    modifier = Modifier.fillMaxSize(),
-                    color = MaterialTheme.colorScheme.background
-                ) {
-                    Column(
-                        horizontalAlignment = Alignment.CenterHorizontally
-                    ) {
-
-                        Text(text = "present card, trigger payment")
-
-                        TextField(
-                            value = "",
-                            onValueChange = {
-                                val optAmount = parseAmount(it)
-                                if (optAmount.isPresent) {
-                                    model.updateAmount(optAmount.get())
-                                }
-                            },
-                            label = { Text(text = "Enter amount") },
-                            placeholder = { Text(text = "amount") }
-                        )
-
-                        Button(enabled = false, onClick = {
-                            val withdrawalAmount = LineItem
-                                .ListBuilder(
-                                    model.uiState.encodedWopid,
-                                    BigDecimal("${model.uiState.amount.value}.${model.uiState.amount.frac}")
-                                )
-                                .build()
-
-                            val transaction = Transaction.Builder(withdrawalAmount)
-                                .setCurrency(Currency.getInstance(model.uiState.currency))
-                                .setInvoiceReference(model.uiState.encodedWopid)
-                                .setMerchantReference(model.uiState.encodedWopid)
-                                .setTransactionProcessingBehavior(TransactionProcessingBehavior.COMPLETE_IMMEDIATELY)
-                                .build()
-
-                            try {
-                                client.authorizeTransaction(transaction)
-                            } catch (e: Exception) {
-                                e.printStackTrace()
-                            }
-                        }) {
-                            Text(text = "")
-                        }
-
-                        Button(onClick = {
-                            model.withdrawalOperationFailed(applicationContext)
-                            finish()
-                        }) {
-                            Text(text = "abort")
-                        }
-                    }
-                }
-            }
-        }
-    }
-
-    /**
-     * Format expected X[.X], X an integer
-     */
-    private fun parseAmount(inp: String): Optional<Amount> {
-
-        val points = inp.count { it == '.' }
-        if (points > 1) {
-            return Optional.empty()
-        }
-
-        if (points == 1) {
-            val valueStr = inp.split(".")[0]
-            val fracStr = inp.split(".")[1]
-            return try {
-                val value = valueStr.toInt()
-                val frac = fracStr.toInt()
-                Optional.of(Amount(value, frac))
-            } catch (ex: NumberFormatException) {
-                Optional.empty()
-            }
-        }
-
-        return try {
-            val value = inp.toInt()
-            Optional.of(Amount(value, 0))
-        } catch (ex: NumberFormatException) {
-            Optional.empty()
-        }
-    }
-}
diff --git a/wallee-c2ec/app/src/main/java/ch/bfh/habej2/wallee_c2ec/WithdrawalCreationActivity.kt b/wallee-c2ec/app/src/main/java/ch/bfh/habej2/wallee_c2ec/WithdrawalCreationActivity.kt
deleted file mode 100644
index 229f911..0000000
--- a/wallee-c2ec/app/src/main/java/ch/bfh/habej2/wallee_c2ec/WithdrawalCreationActivity.kt
+++ /dev/null
@@ -1,65 +0,0 @@
-package ch.bfh.habej2.wallee_c2ec
-
-import android.os.Bundle
-import androidx.activity.compose.setContent
-import androidx.appcompat.app.AppCompatActivity
-import androidx.compose.foundation.layout.Column
-import androidx.compose.foundation.layout.fillMaxSize
-import androidx.compose.material3.Button
-import androidx.compose.material3.MaterialTheme
-import androidx.compose.material3.Surface
-import androidx.compose.material3.Text
-import androidx.compose.ui.Alignment
-import androidx.compose.ui.Modifier
-import androidx.compose.ui.platform.LocalContext
-import ch.bfh.habej2.wallee_c2ec.client.taler.BankIntegrationClient
-import ch.bfh.habej2.wallee_c2ec.config.TalerBankIntegrationConfig
-import ch.bfh.habej2.wallee_c2ec.ui.theme.Walleec2ecTheme
-import java.util.concurrent.Executors
-
-class WithdrawalCreationActivity : AppCompatActivity() {
-
-    override fun onCreate(savedInstanceState: Bundle?) {
-        super.onCreate(savedInstanceState)
-
-        // TODO Initialize model properly and put in location where everyone involved has access
-        val model = WithdrawalViewModel(BankIntegrationClient(TalerBankIntegrationConfig(
-            "TestExchange", "http://localhost:8082/c2ec", "Wallee-1", "secret"
-        )))
-        model.initialize()
-
-        setContent {
-
-            // start long polling activity for the created wopid and start authorization
-            model.startAuthorizationWhenReadyOrAbort(LocalContext.current)
-
-            Walleec2ecTheme {
-                Surface(
-                    modifier = Modifier.fillMaxSize(),
-                    color = MaterialTheme.colorScheme.background
-                ) {
-
-                    Column(
-                        horizontalAlignment = Alignment.CenterHorizontally
-                    ) {
-
-                        Text(text = "Generated Random WOPID=${model.uiState.encodedWopid}")
-
-                        Text(text = "QR-Code content: ${formatTalerUri(model.uiState.encodedWopid)}")
-
-                        QRCode(model.uiState.encodedWopid)
-
-                        Button(onClick = {
-                            Executors.newSingleThreadExecutor().submit { model.withdrawalOperationFailed(applicationContext) }
-                            finish()
-                        }) {
-                           Text(text = "abort")
-                        }
-                    }
-                }
-            }
-        }
-    }
-
-    private fun formatTalerUri(encodedWopid: String) = "taler://withdraw/$encodedWopid"
-}
diff --git a/wallee-c2ec/app/src/main/java/ch/bfh/habej2/wallee_c2ec/WithdrawalViewModel.kt b/wallee-c2ec/app/src/main/java/ch/bfh/habej2/wallee_c2ec/WithdrawalViewModel.kt
deleted file mode 100644
index f23fa7d..0000000
--- a/wallee-c2ec/app/src/main/java/ch/bfh/habej2/wallee_c2ec/WithdrawalViewModel.kt
+++ /dev/null
@@ -1,102 +0,0 @@
-package ch.bfh.habej2.wallee_c2ec
-
-import android.content.Context
-import android.content.Intent
-import androidx.compose.runtime.Stable
-import androidx.compose.runtime.getValue
-import androidx.compose.runtime.mutableStateOf
-import androidx.compose.runtime.setValue
-import androidx.lifecycle.ViewModel
-import androidx.lifecycle.viewModelScope
-import ch.bfh.habej2.wallee_c2ec.client.taler.BankIntegrationClient
-import ch.bfh.habej2.wallee_c2ec.client.taler.model.PaymentNotification
-import ch.bfh.habej2.wallee_c2ec.client.wallee.WalleeResponseHandler
-import ch.bfh.habej2.wallee_c2ec.encoding.Base32Encode
-import com.wallee.android.till.sdk.ApiClient
-import com.wallee.android.till.sdk.data.Transaction
-import kotlinx.coroutines.launch
-import java.io.Closeable
-import java.math.BigDecimal
-import java.security.SecureRandom
-
-data class Amount(
-    val value: Int,
-    val frac: Int
-) {
-    fun toBigDecimal(): BigDecimal = BigDecimal("$value.$frac")
-}
-
-@Stable
-interface WithdrawalOperationState{
-    val exchangeBankIntegrationApiUrl: String
-    val encodedWopid: String
-    val amount: Amount
-    val currency: String
-    val payed: Boolean
-    val transaction: Transaction?
-}
-
-private class MutableWithdrawalOperationState: WithdrawalOperationState {
-    override var exchangeBankIntegrationApiUrl: String by mutableStateOf("")
-    override var encodedWopid: String by mutableStateOf("")
-    override var amount: Amount by mutableStateOf(Amount(0,0))
-    override var currency: String by mutableStateOf("")
-    override var payed: Boolean by mutableStateOf(false)
-    override var transaction: Transaction? by mutableStateOf(null)
-}
-
-class WithdrawalViewModel(
-    private val bankIntegrationClient: BankIntegrationClient,
-    vararg closeables: Closeable
-) : ViewModel(*closeables) {
-
-    private val _uiState = MutableWithdrawalOperationState()
-    val uiState: WithdrawalOperationState = _uiState
-
-    fun initialize() {
-        _uiState.encodedWopid = Base32Encode(wopid())
-    }
-
-    fun updateAmount(amount: Amount) {
-        _uiState.amount = amount
-    }
-
-    fun updateCurrency(currency: String) {
-        _uiState.currency = currency
-    }
-
-    fun updateWalleeTransaction(transaction: Transaction) {
-        _uiState.transaction = transaction
-    }
-
-    fun startAuthorizationWhenReadyOrAbort(ctx: Context) {
-        viewModelScope.launch {
-            val result = bankIntegrationClient.retrieveWithdrawalStatus(uiState.encodedWopid, 30000)
-            if (result.isPresent) {
-                ctx.startActivity(Intent(ctx, PaymentActivity::class.java))
-            } else {
-                withdrawalOperationFailed(ctx)
-            }
-        }
-    }
-
-    fun withdrawalOperationFailed(ctx: Context? = null) {
-        viewModelScope.launch {
-            bankIntegrationClient.abortWithdrawal(uiState.encodedWopid)
-            ctx?.startActivity(Intent(ctx, MainActivity::class.java))
-        }
-    }
-
-    fun confirmPayment() {
-        viewModelScope.launch{
-            bankIntegrationClient.sendPaymentNotification(PaymentNotification())
-        }
-    }
-
-    private fun wopid(): ByteArray {
-        val wopid = ByteArray(32)
-        val rand = SecureRandom()
-        rand.nextBytes(wopid) // will seed automatically
-        return wopid
-    }
-}
\ No newline at end of file
diff --git a/wallee-c2ec/app/src/main/java/ch/bfh/habej2/wallee_c2ec/client/taler/BankIntegrationClient.kt b/wallee-c2ec/app/src/main/java/ch/bfh/habej2/wallee_c2ec/client/taler/BankIntegrationClient.kt
index 55b9b8d..28b3914 100644
--- a/wallee-c2ec/app/src/main/java/ch/bfh/habej2/wallee_c2ec/client/taler/BankIntegrationClient.kt
+++ b/wallee-c2ec/app/src/main/java/ch/bfh/habej2/wallee_c2ec/client/taler/BankIntegrationClient.kt
@@ -1,10 +1,10 @@
 package ch.bfh.habej2.wallee_c2ec.client.taler
 
+import ch.bfh.habej2.wallee_c2ec.client.taler.config.TalerBankIntegrationConfig
 import ch.bfh.habej2.wallee_c2ec.client.taler.model.BankIntegrationConfig
 import ch.bfh.habej2.wallee_c2ec.client.taler.model.PaymentNotification
 import ch.bfh.habej2.wallee_c2ec.client.taler.model.WithdrawalOperation
 import ch.bfh.habej2.wallee_c2ec.client.taler.model.WithdrawalOperationStatus
-import ch.bfh.habej2.wallee_c2ec.config.TalerBankIntegrationConfig
 import com.squareup.moshi.Moshi
 import okhttp3.HttpUrl
 import okhttp3.Interceptor
diff --git a/wallee-c2ec/app/src/main/java/ch/bfh/habej2/wallee_c2ec/config/TalerBankIntegrationConfig.kt b/wallee-c2ec/app/src/main/java/ch/bfh/habej2/wallee_c2ec/client/taler/config/TalerBankIntegrationConfig.kt
index a5dcab9..8ca70f3 100644
--- a/wallee-c2ec/app/src/main/java/ch/bfh/habej2/wallee_c2ec/config/TalerBankIntegrationConfig.kt
+++ b/wallee-c2ec/app/src/main/java/ch/bfh/habej2/wallee_c2ec/client/taler/config/TalerBankIntegrationConfig.kt
@@ -1,4 +1,4 @@
-package ch.bfh.habej2.wallee_c2ec.config
+package ch.bfh.habej2.wallee_c2ec.client.taler.config
 
 // TODO how to configure ?? -> implement ativity allowing to choose one of the configured exchanges
 
diff --git a/wallee-c2ec/app/src/main/java/ch/bfh/habej2/wallee_c2ec/config/TerminalConfig.kt b/wallee-c2ec/app/src/main/java/ch/bfh/habej2/wallee_c2ec/client/taler/config/TerminalConfig.kt
index e69c74b..0ef0ae6 100644
--- a/wallee-c2ec/app/src/main/java/ch/bfh/habej2/wallee_c2ec/config/TerminalConfig.kt
+++ b/wallee-c2ec/app/src/main/java/ch/bfh/habej2/wallee_c2ec/client/taler/config/TerminalConfig.kt
@@ -1,4 +1,4 @@
-package ch.bfh.habej2.wallee_c2ec.config
+package ch.bfh.habej2.wallee_c2ec.client.taler.config
 
 // TODO how to configure ??
 
diff --git a/wallee-c2ec/app/src/main/java/ch/bfh/habej2/wallee_c2ec/client/taler/encoding/TalerBase32Codec.kt b/wallee-c2ec/app/src/main/java/ch/bfh/habej2/wallee_c2ec/client/taler/encoding/TalerBase32Codec.kt
new file mode 100644
index 0000000..5464858
--- /dev/null
+++ b/wallee-c2ec/app/src/main/java/ch/bfh/habej2/wallee_c2ec/client/taler/encoding/TalerBase32Codec.kt
@@ -0,0 +1,8 @@
+package ch.bfh.habej2.wallee_c2ec.client.taler.encoding
+
+import android.util.Base64
+import org.apache.commons.codec.binary.Base32
+
+fun Base32Encode(byts: ByteArray): String = Base64.encodeToString(byts, 0) // Base32().encodeAsString(byts)
+
+fun Base32Decode(enc: String) = Base32().decode(enc)
\ No newline at end of file
diff --git a/wallee-c2ec/app/src/main/java/ch/bfh/habej2/wallee_c2ec/encoding/TalerBase32Codec.kt b/wallee-c2ec/app/src/main/java/ch/bfh/habej2/wallee_c2ec/encoding/TalerBase32Codec.kt
deleted file mode 100644
index 15c1805..0000000
--- a/wallee-c2ec/app/src/main/java/ch/bfh/habej2/wallee_c2ec/encoding/TalerBase32Codec.kt
+++ /dev/null
@@ -1,7 +0,0 @@
-package ch.bfh.habej2.wallee_c2ec.encoding
-
-import org.apache.commons.codec.binary.Base32
-
-fun Base32Encode(byts: ByteArray): String = Base32().encodeAsString(byts)
-
-fun Base32Decode(enc: String) = Base32().decode(enc)
\ No newline at end of file
diff --git a/wallee-c2ec/app/src/main/java/ch/bfh/habej2/wallee_c2ec/QRCodeComposable.kt b/wallee-c2ec/app/src/main/java/ch/bfh/habej2/wallee_c2ec/withdrawal/QRCodeComposable.kt
index 3fe6004..ed7cbc8 100644
--- a/wallee-c2ec/app/src/main/java/ch/bfh/habej2/wallee_c2ec/QRCodeComposable.kt
+++ b/wallee-c2ec/app/src/main/java/ch/bfh/habej2/wallee_c2ec/withdrawal/QRCodeComposable.kt
@@ -1,4 +1,25 @@
-package ch.bfh.habej2.wallee_c2ec
+/*
+ * This file is part of GNU Taler
+ * (C) 2022 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/>
+ */
+
+/*
+ * The code in this file was copied from the Taler Wallet App
+ * source:  https://git.taler.net/taler-android.git/wallet/src/main/java/net/taler/wallet/compose/QrCodeUriComposable.kt
+ */
+
+package ch.bfh.habej2.wallee_c2ec.withdrawal
 
 import android.graphics.Bitmap
 import android.graphics.Color
diff --git a/wallee-c2ec/app/src/main/java/ch/bfh/habej2/wallee_c2ec/withdrawal/WithdrawalActivity.kt b/wallee-c2ec/app/src/main/java/ch/bfh/habej2/wallee_c2ec/withdrawal/WithdrawalActivity.kt
new file mode 100644
index 0000000..94238e7
--- /dev/null
+++ b/wallee-c2ec/app/src/main/java/ch/bfh/habej2/wallee_c2ec/withdrawal/WithdrawalActivity.kt
@@ -0,0 +1,234 @@
+package ch.bfh.habej2.wallee_c2ec.withdrawal
+
+import android.app.Activity
+import android.os.Bundle
+import androidx.activity.ComponentActivity
+import androidx.activity.compose.setContent
+import androidx.compose.foundation.layout.Column
+import androidx.compose.material3.Button
+import androidx.compose.material3.Text
+import androidx.compose.material3.TextField
+import androidx.compose.runtime.Composable
+import androidx.compose.runtime.collectAsState
+import androidx.compose.runtime.getValue
+import androidx.compose.ui.Alignment
+import androidx.compose.ui.platform.LocalContext
+import androidx.navigation.compose.NavHost
+import androidx.navigation.compose.composable
+import androidx.navigation.compose.rememberNavController
+import ch.bfh.habej2.wallee_c2ec.client.taler.config.TalerBankIntegrationConfig
+import ch.bfh.habej2.wallee_c2ec.client.wallee.WalleeResponseHandler
+import com.wallee.android.till.sdk.ApiClient
+import com.wallee.android.till.sdk.data.LineItem
+import com.wallee.android.till.sdk.data.Transaction
+import com.wallee.android.till.sdk.data.TransactionProcessingBehavior
+import java.math.BigDecimal
+import java.util.Currency
+import java.util.Optional
+
+class WithdrawalActivity : ComponentActivity() {
+
+    override fun onCreate(savedInstanceState: Bundle?) {
+        super.onCreate(savedInstanceState)
+
+        setContent {
+
+            val model = WithdrawalViewModel()
+            val navController = rememberNavController()
+
+            NavHost(navController = navController, startDestination = "chooseExchangeScreen") {
+                composable("chooseExchangeScreen") {
+                    ExchangeSelectionScreen(model) {
+                        navController.navigate("registerWithdrawalScreen")
+                    }
+                }
+                composable("registerWithdrawalScreen") {
+                    RegisterWithdrawalScreen(model) {
+                        navController.navigate("paymentScreen")
+                    }
+                }
+                composable("paymentScreen") { PaymentScreen(model) }
+            }
+        }
+    }
+}
+
+@Composable
+fun RegisterWithdrawalScreen(
+    model: WithdrawalViewModel,
+    navigateToWhenRegistered: () -> Unit
+) {
+
+    val uiState by model.uiState.collectAsState()
+    val activity = (LocalContext.current as Activity)
+
+    model.startAuthorizationWhenReadyOrAbort(navigateToWhenRegistered) {
+        activity.finish()
+    }
+
+    Column(
+        horizontalAlignment = Alignment.CenterHorizontally
+    ) {
+
+        Text(text = "QR-Code content: ${formatTalerUri(uiState.encodedWopid)}")
+
+        QRCode(formatTalerUri(uiState.encodedWopid))
+
+        Button(onClick = {
+            model.withdrawalOperationFailed()
+            activity.finish()
+        }) {
+            Text(text = "abort")
+        }
+    }
+}
+
+@Composable
+fun PaymentScreen(model: WithdrawalViewModel) {
+
+    val activity = LocalContext.current as Activity
+
+    Column(
+        horizontalAlignment = Alignment.CenterHorizontally
+    ) {
+
+        Text(text = "present card, trigger payment")
+
+        TextField(
+            value = "",
+            onValueChange = {
+                val optAmount = parseAmount(it)
+                if (optAmount.isPresent) {
+                    model.updateAmount(optAmount.get())
+                }
+            },
+            label = { Text(text = "Enter amount") },
+            placeholder = { Text(text = "amount") }
+        )
+
+        AuthorizePaymentButton(model = model)
+
+        Button(onClick = {
+            model.withdrawalOperationFailed()
+            activity.finish()
+        }) {
+            Text(text = "abort")
+        }
+    }
+}
+
+@Composable
+fun AuthorizePaymentButton(model: WithdrawalViewModel) {
+
+    val uiState by model.uiState.collectAsState()
+    val activity = LocalContext.current as Activity
+    val client = ApiClient(WalleeResponseHandler())
+
+    client.bind(activity)
+
+    Button(enabled = false, onClick = {
+        val withdrawalAmount = LineItem
+            .ListBuilder(
+                uiState.encodedWopid,
+                BigDecimal("${uiState.amount.value}.${uiState.amount.frac}")
+            )
+            .build()
+
+        val transaction = Transaction.Builder(withdrawalAmount)
+            .setCurrency(Currency.getInstance(uiState.currency))
+            .setInvoiceReference(uiState.encodedWopid)
+            .setMerchantReference(uiState.encodedWopid)
+            .setTransactionProcessingBehavior(TransactionProcessingBehavior.COMPLETE_IMMEDIATELY)
+            .build()
+
+        try {
+            client.authorizeTransaction(transaction)
+        } catch (e: Exception) {
+            e.printStackTrace()
+        }
+    }) {
+        Text(text = "")
+    }
+}
+
+@Composable
+fun ExchangeSelectionScreen(
+    model: WithdrawalViewModel,
+    onNavigateToWithdrawal: () -> Unit
+) {
+
+    val activity = LocalContext.current as Activity
+
+    Column(
+        horizontalAlignment = Alignment.CenterHorizontally
+    ) {
+
+        Text(text = "Choose the exchange to withdraw from")
+
+        // TODO let user select exchanges from config here
+        //  config must contain display name, credentials (generated by cli)
+        //  and the base url of the c2ec bank-integration api
+
+        val ctx = LocalContext.current
+        Button(onClick = {
+            // TODO trigger model.exchangeUpdated(...)
+            model.exchangeUpdated(TalerBankIntegrationConfig("","","",""))
+            onNavigateToWithdrawal()
+        }) {
+            Text(text = "withdraw")
+        }
+
+        Button(onClick = { activity.finish() }) {
+            Text(text = "abort")
+        }
+    }
+}
+
+@Composable
+fun SummaryScreen(model: WithdrawalViewModel) {
+
+    val activity = LocalContext.current as Activity
+
+    Column(
+        horizontalAlignment = Alignment.CenterHorizontally
+    ) {
+
+        Text(text = "Transaction Executed")
+
+        Button(onClick = { activity.finish() }) {
+            Text(text = "finish")
+        }
+    }
+}
+
+/**
+ * Format expected X[.X], X an integer
+ */
+private fun parseAmount(inp: String): Optional<Amount> {
+
+    val points = inp.count { it == '.' }
+    if (points > 1) {
+        return Optional.empty()
+    }
+
+    if (points == 1) {
+        val valueStr = inp.split(".")[0]
+        val fracStr = inp.split(".")[1]
+        return try {
+            val value = valueStr.toInt()
+            val frac = fracStr.toInt()
+            Optional.of(Amount(value, frac))
+        } catch (ex: NumberFormatException) {
+            Optional.empty()
+        }
+    }
+
+    return try {
+        val value = inp.toInt()
+        Optional.of(Amount(value, 0))
+    } catch (ex: NumberFormatException) {
+        Optional.empty()
+    }
+}
+
+private fun formatTalerUri(encodedWopid: String) = "taler://withdraw/$encodedWopid"
diff --git a/wallee-c2ec/app/src/main/java/ch/bfh/habej2/wallee_c2ec/withdrawal/WithdrawalViewModel.kt b/wallee-c2ec/app/src/main/java/ch/bfh/habej2/wallee_c2ec/withdrawal/WithdrawalViewModel.kt
new file mode 100644
index 0000000..46490e0
--- /dev/null
+++ b/wallee-c2ec/app/src/main/java/ch/bfh/habej2/wallee_c2ec/withdrawal/WithdrawalViewModel.kt
@@ -0,0 +1,118 @@
+package ch.bfh.habej2.wallee_c2ec.withdrawal
+
+import androidx.compose.runtime.Stable
+import androidx.compose.runtime.getValue
+import androidx.compose.runtime.mutableStateOf
+import androidx.compose.runtime.setValue
+import androidx.lifecycle.ViewModel
+import androidx.lifecycle.viewModelScope
+import ch.bfh.habej2.wallee_c2ec.client.taler.BankIntegrationClient
+import ch.bfh.habej2.wallee_c2ec.client.taler.config.TalerBankIntegrationConfig
+import ch.bfh.habej2.wallee_c2ec.client.taler.model.PaymentNotification
+import ch.bfh.habej2.wallee_c2ec.client.taler.encoding.Base32Encode
+import com.wallee.android.till.sdk.data.TransactionCompletionResponse
+import kotlinx.coroutines.flow.MutableStateFlow
+import kotlinx.coroutines.flow.StateFlow
+import kotlinx.coroutines.launch
+import java.io.Closeable
+import java.math.BigDecimal
+import java.security.SecureRandom
+
+data class Amount(
+    val value: Int,
+    val frac: Int
+) {
+    fun toBigDecimal(): BigDecimal = BigDecimal("$value.$frac")
+}
+
+@Stable
+interface WithdrawalOperationState{
+    val exchangeBankIntegrationApiUrl: String
+    val encodedWopid: String
+    val amount: Amount
+    val currency: String
+    val payed: Boolean
+    val transaction: TransactionCompletionResponse?
+}
+
+private class MutableWithdrawalOperationState: WithdrawalOperationState {
+    override var exchangeBankIntegrationApiUrl: String by mutableStateOf("")
+    override var encodedWopid: String by mutableStateOf("")
+    override var amount: Amount by mutableStateOf(Amount(0,0))
+    override var currency: String by mutableStateOf("")
+    override var payed: Boolean by mutableStateOf(false)
+    override var transaction: TransactionCompletionResponse? by mutableStateOf(null)
+}
+
+class WithdrawalViewModel(
+    vararg closeables: Closeable
+) : ViewModel(*closeables) {
+
+    private var bankIntegrationClient: BankIntegrationClient? = null
+    private val _uiState = MutableStateFlow(MutableWithdrawalOperationState())
+    val uiState: StateFlow<WithdrawalOperationState> = _uiState
+
+    init {
+        initializeWopid()
+    }
+
+    fun exchangeUpdated(cfg: TalerBankIntegrationConfig) {
+        bankIntegrationClient = BankIntegrationClient(cfg)
+        _uiState.value = MutableWithdrawalOperationState() // reset withdrawal operation
+        initializeWopid() // initialize new withdrawal operation identifier
+    }
+
+    fun initializeWopid() {
+        _uiState.value.encodedWopid = Base32Encode(wopid())
+    }
+
+    fun updateAmount(amount: Amount) {
+        _uiState.value.amount = amount
+    }
+
+    fun updateCurrency(currency: String) {
+        _uiState.value.currency = currency
+    }
+
+    fun updateWalleeTransaction(completion: TransactionCompletionResponse) {
+        _uiState.value.transaction = completion
+    }
+
+    fun startAuthorizationWhenReadyOrAbort(
+        onSuccess: () -> Unit,
+        onFailure: () -> Unit
+    ) {
+
+        return
+
+        viewModelScope.launch {
+            onSuccess() // TODO
+//            val result = bankIntegrationClient!!.retrieveWithdrawalStatus(uiState.value.encodedWopid, 30000)
+//            if (result.isPresent) {
+//                onSuccess()
+//            } else {
+//                withdrawalOperationFailed()
+//                onFailure()
+//            }
+        }
+    }
+
+    fun withdrawalOperationFailed() {
+        viewModelScope.launch {
+            bankIntegrationClient!!.abortWithdrawal(uiState.value.encodedWopid)
+        }
+    }
+
+    fun confirmPayment() {
+        viewModelScope.launch{
+            bankIntegrationClient!!.sendPaymentNotification(PaymentNotification())
+        }
+    }
+
+    private fun wopid(): ByteArray {
+        val wopid = ByteArray(32)
+        val rand = SecureRandom()
+        rand.nextBytes(wopid) // will seed automatically
+        return wopid
+    }
+}
\ No newline at end of file
diff --git a/wallee-c2ec/gradle/libs.versions.toml b/wallee-c2ec/gradle/libs.versions.toml
index 16e0f1a..b14cea4 100644
--- a/wallee-c2ec/gradle/libs.versions.toml
+++ b/wallee-c2ec/gradle/libs.versions.toml
@@ -14,6 +14,7 @@ composeBom = "2023.08.00"
 moshiKotlin = "1.15.1"
 okhttp = "4.12.0"
 sdk = "0.9.12"
+navigationCompose = "2.7.7"
 
 [libraries]
 androidx-appcompat = { module = "androidx.appcompat:appcompat", version.ref = "appcompat" }
@@ -36,6 +37,7 @@ androidx-material3 = { group = "androidx.compose.material3", name = "material3"
 moshi-kotlin = { module = "com.squareup.moshi:moshi-kotlin", version.ref = "moshiKotlin" }
 okhttp = { module = "com.squareup.okhttp3:okhttp", version.ref = "okhttp" }
 wallee-sdk = { module = "com.wallee.android.till:sdk", version.ref = "sdk" }
+androidx-navigation-compose = { group = "androidx.navigation", name = "navigation-compose", version.ref = "navigationCompose" }
 
 [plugins]
 androidApplication = { id = "com.android.application", version.ref = "agp" }