Introduce subscription-based state, remove DataStore stopgap

app/build.gradle.kts

@@ -66,7 +66,6 @@ dependencies {
 	implementation ( "androidx.compose.ui" , "ui" , "1.7.6" )
 	implementation ( "androidx.compose.ui" , "ui-graphics" , "1.7.6" )
 	debugImplementation ( "androidx.compose.ui" , "ui-tooling" , "1.7.6" )
-	implementation ( "androidx.datastore" , "datastore-preferences" , "1.1.1" )
 	implementation ( "androidx.lifecycle" , "lifecycle-runtime-ktx" , "2.8.7" )
 	implementation ( "org.jetbrains.kotlinx" , "kotlinx-coroutines-android" , "1.9.0" )
 	implementation ( "org.jetbrains.kotlinx" , "kotlinx-serialization-json" , "1.7.3" )

app/src/main/java/com/kernelmaft/zanbur/app-state.kt

@@ -1,26 +1,31 @@
 package com.kernelmaft.zanbur
 
-import androidx.compose.runtime.*
 
 
+enum class ChangeSource { Local , Remote }
+
+typealias CurrentSceneSubscriber = ( Group , Scene , ChangeSource ) -> Unit
+typealias GroupAddedSubscriber = ( Group , ChangeSource ) -> Unit
 
 object AppState {
-	// The index of a group in this list is always equal to its ID
-	val groups : State < List <Group> > get () = groupsAsMutable
-	private val groupsAsMutable : MutableState < List <Group> > = mutableStateOf ( emptyList () )
+	private val currentSceneSubscribers : MutableList <CurrentSceneSubscriber> = mutableListOf ()
+	private val groupAddedSubscribers : MutableList <GroupAddedSubscriber> = mutableListOf ()
 
-	fun setCurrentScene ( groupId : Int , scene : Scene ) {
-		groupsAsMutable . value = groupsAsMutable . value . mapIndexed { index , group ->
-			if ( index == groupId ) group . copy ( currentScene = scene )
-			else group
+	fun setCurrentScene ( group : Group , newScene : Scene , source : ChangeSource ) {
+		for ( subscriber in currentSceneSubscribers ) {
+			subscriber ( group , newScene , source )
 		}
 	}
+	fun subscribeToCurrentScene ( subscriber : CurrentSceneSubscriber ) {
+		currentSceneSubscribers . add (subscriber)
+	}
 
-	fun addGroup ( group : Group ) {
-		val newGroups = groupsAsMutable . value . toMutableList ()
-		// Wow this is sooo much better than Java
-		if ( newGroups . getOrNull ( group . id ) != null ) newGroups . removeAt ( group . id )
-		newGroups . add ( group . id , group )
-		groupsAsMutable . value = newGroups
+	fun addGroup ( newGroup : Group , source : ChangeSource ) {
+		for ( subscriber in groupAddedSubscribers ) {
+			subscriber ( newGroup , source )
+		}
+	}
+	fun subscribeToGroupAdded ( subscriber : GroupAddedSubscriber ) {
+		groupAddedSubscribers . add (subscriber)
 	}
 }

app/src/main/java/com/kernelmaft/zanbur/compose-state.kt

@@ -0,0 +1,21 @@
+package com.kernelmaft.zanbur
+
+import androidx.compose.runtime.*
+
+
+
+fun createGroupsComposeState () : MutableState < List <Group> > {
+	val groups : MutableState < List <Group> > = mutableStateOf ( emptyList () )
+
+	AppState . subscribeToGroupAdded { newGroup , _ ->
+		groups . value = groups . value . plus (newGroup)
+	}
+	AppState . subscribeToCurrentScene { group , newScene , source ->
+		groups . value = groups . value . map { when ( it . id ) {
+			group . id -> it . copy ( currentScene = newScene )
+			else -> it
+		} }
+	}
+
+	return groups
+}

app/src/main/java/com/kernelmaft/zanbur/main.kt

@@ -5,40 +5,31 @@ import androidx.activity.compose.*
 import androidx.compose.foundation.layout.*
 import androidx.compose.ui.*
 import androidx.compose.ui.unit.*
-import androidx.datastore.preferences.*
-import androidx.datastore.preferences.core.*
 import androidx.lifecycle.*
-import kotlinx.coroutines.*
-import kotlinx.coroutines.Dispatchers.IO
-import kotlinx.coroutines.flow.*
+import com.kernelmaft.zanbur.ChangeSource.*
 
 
 
 class MainActivity : EdgeToEdgeActivity () {
-	val dataStore = PreferenceDataStoreFactory . create { preferencesDataStoreFile ("state") }
-
 	override fun onCreate ( savedInstanceState : Bundle ? ) {
 		super . onCreate (savedInstanceState)
 
-		Config . groups . forEach { AppState . addGroup (it) }
+		val groups = createGroupsComposeState ()
 
-		lifecycleScope . launch (IO) {
-			val prefs = dataStore . data . firstOrNull ()
-			val savedSceneName = prefs ?. get ( stringPreferencesKey ("scene") )
-			if ( savedSceneName != null ) {
-				val savedScene = AppState . groups . value [0] . scenes
-					. find { it . name == savedSceneName }
-				savedScene ?. let { AppState . setCurrentScene ( 0 , it ) }
+		AppState . subscribeToCurrentScene { group , newScene , source ->
+			if ( source == Local ) {
+				publishSceneChange ( group , newScene )
 			}
 		}
 
+		Config . groups . forEach { AppState . addGroup ( it , Remote ) }
+
 		setContent {
 			AppFrame {
 				Column ( Modifier . width ( 300 . dp ) ) {
-					AppState . groups . value . forEach { group ->
+					groups . value . forEach { group ->
 						SceneSwitcher (group) { newScene ->
-							AppState . setCurrentScene ( group . id , newScene )
-							publishSceneChange ( group , newScene )
+							AppState . setCurrentScene ( group , newScene , Local )
 						}
 					}
 				}
@@ -47,15 +38,4 @@ class MainActivity : EdgeToEdgeActivity () {
 
 		MqttClient . run (lifecycleScope)
 	}
-
-	override fun onStop () {
-		super . onStop ()
-
-		val currentScene = AppState . groups . value [0] . currentScene
-		if ( currentScene != null ) lifecycleScope . launch (IO) {
-			dataStore . edit {
-				it [ stringPreferencesKey ("scene") ] = currentScene . name
-			}
-		}
-	}
 }