feat(theme): persist ThemeMode preference + reactive PyrycodeMobileTheme wiring (#86)

app/src/main/java/de/pyryco/mobile/MainActivity.kt

@@ -6,6 +6,7 @@ import android.os.Bundle
 import androidx.activity.ComponentActivity
 import androidx.activity.compose.setContent
 import androidx.activity.enableEdgeToEdge
+import androidx.compose.foundation.isSystemInDarkTheme
 import androidx.compose.foundation.layout.fillMaxSize
 import androidx.compose.foundation.layout.padding
 import androidx.compose.material3.Scaffold
@@ -25,6 +26,7 @@ import androidx.navigation.compose.composable
 import androidx.navigation.compose.rememberNavController
 import androidx.navigation.navArgument
 import de.pyryco.mobile.data.preferences.AppPreferences
+import de.pyryco.mobile.data.preferences.ThemeMode
 import de.pyryco.mobile.ui.conversations.list.ChannelListEvent
 import de.pyryco.mobile.ui.conversations.list.ChannelListNavigation
 import de.pyryco.mobile.ui.conversations.list.ChannelListScreen
@@ -48,9 +50,17 @@ class MainActivity : ComponentActivity() {
         super.onCreate(savedInstanceState)
         enableEdgeToEdge()
         setContent {
-            PyrycodeMobileTheme {
+            val appPreferences = koinInject<AppPreferences>()
+            val themeMode by appPreferences.themeMode
+                .collectAsStateWithLifecycle(initialValue = ThemeMode.SYSTEM)
+            val darkTheme =
+                when (themeMode) {
+                    ThemeMode.SYSTEM -> isSystemInDarkTheme()
+                    ThemeMode.LIGHT -> false
+                    ThemeMode.DARK -> true
+                }
+            PyrycodeMobileTheme(darkTheme = darkTheme) {
                 Scaffold(modifier = Modifier.fillMaxSize()) { innerPadding ->
-                    val appPreferences = koinInject<AppPreferences>()
                     val paired: Boolean? by produceState<Boolean?>(
                         initialValue = null,
                         appPreferences,
@@ -180,9 +190,13 @@ private fun PyryNavHost(
             Text("Conversation thread placeholder: $conversationId")
         }
         composable(Routes.SETTINGS) {
+            val appPreferences = koinInject<AppPreferences>()
+            val themeMode by appPreferences.themeMode
+                .collectAsStateWithLifecycle(initialValue = ThemeMode.SYSTEM)
             SettingsScreen(
                 onBack = { navController.popBackStack() },
                 onOpenLicense = { navController.navigate(Routes.LICENSE) },
+                themeMode = themeMode,
             )
         }
         composable(Routes.LICENSE) {

app/src/main/java/de/pyryco/mobile/data/preferences/AppPreferences.kt

@@ -4,6 +4,7 @@ import androidx.datastore.core.DataStore
 import androidx.datastore.preferences.core.Preferences
 import androidx.datastore.preferences.core.booleanPreferencesKey
 import androidx.datastore.preferences.core.edit
+import androidx.datastore.preferences.core.stringPreferencesKey
 import kotlinx.coroutines.flow.Flow
 import kotlinx.coroutines.flow.map
 
@@ -17,7 +18,18 @@ class AppPreferences(
         dataStore.edit { prefs -> prefs[PAIRED_SERVER_EXISTS] = value }
     }
 
+    val themeMode: Flow<ThemeMode> =
+        dataStore.data.map { prefs ->
+            val stored = prefs[THEME_MODE]
+            ThemeMode.entries.firstOrNull { it.name == stored } ?: ThemeMode.SYSTEM
+        }
+
+    suspend fun setThemeMode(mode: ThemeMode) {
+        dataStore.edit { prefs -> prefs[THEME_MODE] = mode.name }
+    }
+
     private companion object {
         val PAIRED_SERVER_EXISTS = booleanPreferencesKey("paired_server_exists")
+        val THEME_MODE = stringPreferencesKey("theme_mode")
     }
 }

app/src/main/java/de/pyryco/mobile/data/preferences/ThemeMode.kt

@@ -0,0 +1,3 @@
+package de.pyryco.mobile.data.preferences
+
+enum class ThemeMode { SYSTEM, LIGHT, DARK }

app/src/main/java/de/pyryco/mobile/ui/settings/SettingsScreen.kt

@@ -40,6 +40,7 @@ import androidx.compose.ui.tooling.preview.Preview
 import androidx.compose.ui.unit.dp
 import de.pyryco.mobile.BuildConfig
 import de.pyryco.mobile.R
+import de.pyryco.mobile.data.preferences.ThemeMode
 import de.pyryco.mobile.ui.theme.PyrycodeMobileTheme
 
 @OptIn(ExperimentalMaterial3Api::class)
@@ -48,6 +49,7 @@ fun SettingsScreen(
     onBack: () -> Unit,
     onOpenLicense: () -> Unit,
     modifier: Modifier = Modifier,
+    themeMode: ThemeMode = ThemeMode.SYSTEM,
 ) {
     Scaffold(
         modifier = modifier,
@@ -94,7 +96,7 @@ fun SettingsScreen(
             SettingsSectionHeader("Appearance")
             SettingsRow(
                 headline = "Theme",
-                supporting = "System",
+                supporting = themeMode.label(),
                 trailing = { ChevronIcon() },
                 onClick = {},
             )
@@ -261,6 +263,13 @@ private fun AddPill(onClick: () -> Unit) {
     }
 }
 
+private fun ThemeMode.label(): String =
+    when (this) {
+        ThemeMode.SYSTEM -> "System default"
+        ThemeMode.LIGHT -> "Light"
+        ThemeMode.DARK -> "Dark"
+    }
+
 private const val SOURCE_REPO_URL = "https://github.com/pyrycode/pyrycode-mobile"
 
 @Preview(name = "Settings — Light", showBackground = true, widthDp = 412)

app/src/test/java/de/pyryco/mobile/data/preferences/AppPreferencesTest.kt

@@ -3,6 +3,8 @@ package de.pyryco.mobile.data.preferences
 import androidx.datastore.core.DataStore
 import androidx.datastore.preferences.core.PreferenceDataStoreFactory
 import androidx.datastore.preferences.core.Preferences
+import androidx.datastore.preferences.core.edit
+import androidx.datastore.preferences.core.stringPreferencesKey
 import kotlinx.coroutines.CoroutineScope
 import kotlinx.coroutines.Dispatchers
 import kotlinx.coroutines.Job
@@ -52,4 +54,26 @@ class AppPreferencesTest {
             prefs.setPairedServerExists(true)
             assertEquals(true, prefs.pairedServerExists.first())
         }
+
+    @Test
+    fun themeMode_defaultsToSystem() =
+        runBlocking {
+            assertEquals(ThemeMode.SYSTEM, prefs.themeMode.first())
+        }
+
+    @Test
+    fun setThemeMode_roundTripsAllValues() =
+        runBlocking {
+            for (mode in ThemeMode.entries) {
+                prefs.setThemeMode(mode)
+                assertEquals(mode, prefs.themeMode.first())
+            }
+        }
+
+    @Test
+    fun themeMode_unparseableStoredValue_fallsBackToSystem() =
+        runBlocking {
+            dataStore.edit { it[stringPreferencesKey("theme_mode")] = "PURPLE" }
+            assertEquals(ThemeMode.SYSTEM, prefs.themeMode.first())
+        }
 }