Settings: Save server, username, password

app/build.gradle

@@ -61,6 +61,7 @@ dependencies {
 
     // Kordophone lib
     implementation project(':backend')
+    implementation 'androidx.security:security-crypto-ktx:1.1.0-alpha06'
 
     // Navigation
     def nav_version = "2.6.0"

app/src/main/java/net/buzzert/kordophonedroid/ui/settings/SettingsScreen.kt

@@ -98,8 +98,8 @@ fun SettingsFormView(
             })
         }
 
-        var usernameInput by remember { mutableStateOf(TextFieldValue()) }
-        var passwordInput by remember { mutableStateOf(TextFieldValue()) }
+        var usernameInput by remember { mutableStateOf(TextFieldValue(userName.value)) }
+        var passwordInput by remember { mutableStateOf(TextFieldValue(password.value)) }
         SettingsTextField(
             name = "Authentication",
             icon = R.drawable.account_circle,

app/src/main/java/net/buzzert/kordophonedroid/ui/settings/SettingsViewModel.kt

@@ -23,6 +23,15 @@ class SettingsViewModel @Inject constructor(
     private val _passwordPreference: MutableStateFlow<String> = MutableStateFlow("")
     var passwordPreference = _passwordPreference.asStateFlow()
 
+    init {
+        val serverConfig = serverConfigRepository.serverConfig.value
+        serverConfig.serverName?.let { _serverPreference.value = it }
+        serverConfig.authentication?.let {
+            _usernamePreference.value = it.username
+            _passwordPreference.value = it.password
+        }
+    }
+
     fun saveServerPreference(serverName: String) {
         _serverPreference.value = serverName
 
@@ -36,7 +45,7 @@ class SettingsViewModel @Inject constructor(
         _passwordPreference.value = password
 
         serverConfigRepository.applyConfig {
-            authentication = ServerAuthentication(username, password)
+            this.authentication = ServerAuthentication(username, password)
         }
     }
 }

app/src/main/java/net/buzzert/kordophonedroid/ui/shared/ServerConfigRepository.kt

@@ -1,28 +1,102 @@
 package net.buzzert.kordophonedroid.ui.shared
 
+import android.content.Context
+import android.content.SharedPreferences
+import androidx.core.content.edit
+import androidx.security.crypto.EncryptedSharedPreferences
+import androidx.security.crypto.MasterKey
+import dagger.hilt.android.qualifiers.ApplicationContext
 import kotlinx.coroutines.flow.MutableStateFlow
 import kotlinx.coroutines.flow.StateFlow
+import java.lang.reflect.Constructor
 import javax.inject.Inject
 import javax.inject.Singleton
 
+
 data class ServerConfig(
     var serverName: String? = null,
     var authentication: ServerAuthentication? = null,
+) {
+    companion object {
+        private const val SHARED_PREF_NAME = "KordophonePreferences"
+
+        fun loadFromSettings(context: Context): ServerConfig {
+            val prefs = getSharedPreferences(context)
+            return ServerConfig(
+                serverName = prefs.getString("serverName", null),
+                authentication = ServerAuthentication.loadFromEncryptedSettings(context)
             )
+        }
+
+        private fun getSharedPreferences(context: Context): SharedPreferences {
+            return context.getSharedPreferences(SHARED_PREF_NAME, Context.MODE_PRIVATE)
+        }
+    }
+
+    fun saveToSettings(context: Context) {
+        val prefs = getSharedPreferences(context)
+        prefs.edit {
+            putString("serverName", serverName)
+            apply()
+        }
+
+        authentication?.saveToEncryptedSettings(context)
+    }
+}
 
 data class ServerAuthentication(
     val username: String,
     val password: String,
+) {
+    companion object {
+        fun loadFromEncryptedSettings(context: Context): ServerAuthentication? {
+            val prefs = getEncryptedSharedPreferences(context)
+
+            val username = prefs.getString("username", null)
+            val password = prefs.getString("password", null)
+            if (username != null && password != null) {
+                return ServerAuthentication(username, password)
+            }
+
+            return null
+        }
+
+        private fun getEncryptedSharedPreferences(context: Context): SharedPreferences {
+            val masterKey = MasterKey.Builder(context)
+                .setKeyScheme(MasterKey.KeyScheme.AES256_GCM)
+                .build()
+
+            return EncryptedSharedPreferences(
+                context,
+                "secrets",
+                masterKey,
+                EncryptedSharedPreferences.PrefKeyEncryptionScheme.AES256_SIV,
+                EncryptedSharedPreferences.PrefValueEncryptionScheme.AES256_GCM
             )
+        }
+    }
+
+    fun saveToEncryptedSettings(context: Context) {
+        val prefs = getEncryptedSharedPreferences(context)
+        prefs.edit {
+            putString("username", username)
+            putString("password", password)
+            apply()
+        }
+    }
+}
 
 @Singleton
-class ServerConfigRepository @Inject constructor() {
+class ServerConfigRepository @Inject constructor(
+    @ApplicationContext val context: Context,
+) {
     // TODO: Initial config should be loaded from device settings.
-    private val _serverConfig = MutableStateFlow(ServerConfig()) // Initial config
+    private val _serverConfig = MutableStateFlow(ServerConfig.loadFromSettings(context)) // Initial config
     val serverConfig: StateFlow<ServerConfig> = _serverConfig
 
     fun applyConfig(applicator: ServerConfig.() -> Unit) {
         val config = _serverConfig.value.copy()
         _serverConfig.value = config.apply(applicator)
+        _serverConfig.value.saveToSettings(context)
     }
 }