1 files changed, 181 insertions, 0 deletions
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
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+++ 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()
+}