Use splitConflated

app/src/main/java/io/timelimit/android/ui/model/MainModel.kt

@@ -24,12 +24,11 @@ import io.timelimit.android.data.model.UserType
 import io.timelimit.android.logic.DefaultAppLogic
 import io.timelimit.android.ui.main.ActivityViewModel
 import io.timelimit.android.ui.model.diagnose.DeviceOwnerHandling
+import io.timelimit.android.ui.model.flow.Case
+import io.timelimit.android.ui.model.flow.splitConflated
 import io.timelimit.android.ui.model.launch.LaunchHandling
 import io.timelimit.android.ui.model.main.OverviewHandling
 import io.timelimit.android.ui.model.managechild.ManageChildHandling
-import kotlinx.coroutines.CoroutineScope
-import kotlinx.coroutines.Job
-import kotlinx.coroutines.cancel
 import kotlinx.coroutines.channels.Channel
 import kotlinx.coroutines.channels.ReceiveChannel
 import kotlinx.coroutines.flow.*
@@ -106,39 +105,28 @@ class MainModel(application: Application): AndroidViewModel(application) {
     val state = MutableStateFlow(State.LaunchState as State)
     var fragmentIds = mutableSetOf<Int>()
 
-    val screen: Flow<Screen> = flow {
+    val screen: Flow<Screen> = state.splitConflated(
-        while (true) {
+        Case.simple<_, _, State.LaunchState> { LaunchHandling.processLaunchState(state, logic) },
-            val scope = CoroutineScope(viewModelScope.coroutineContext + Job())
+        Case.simple<_, _, State.Overview> { OverviewHandling.processState(logic, scope, activityCommandInternal, authenticationModelApi, state) },
+        Case.simple<_, _, State.ManageChild.Main> { state -> ManageChildHandling.processState(logic, state, updateMethod(::updateState)) },
+        Case.simple<_, _, State.ManageChild.Apps> { state -> ManageChildHandling.processState(logic, state, updateMethod(::updateState)) },
+        Case.simple<_, _, State.DiagnoseScreen.DeviceOwner> { DeviceOwnerHandling.processState(logic, scope, authenticationModelApi, state) },
+        Case.simple<_, _, FragmentState> { state ->
+            state.transform {
+                val containerId = it.containerId ?: run {
+                    (viewIdPool - fragmentIds).firstOrNull()?.also { id ->
+                        it.containerId = id
+                    }
+                }
 
-            when (val initialState = state.value) {
+                if (containerId != null) {
-                is State.LaunchState -> LaunchHandling.processLaunchState(state, logic)
+                    fragmentIds.add(containerId)
-                is State.Overview -> emitAll(OverviewHandling.processState(logic, scope, activityCommandInternal, authenticationModelApi, state))
-                is State.ManageChild.Main -> emitAll(ManageChildHandling.processState(logic, state))
-                is State.ManageChild.Apps -> emitAll(ManageChildHandling.processState(logic, state))
-                is State.DiagnoseScreen.DeviceOwner -> emitAll(DeviceOwnerHandling.processState(logic, scope, authenticationModelApi, state))
-                is FragmentState -> emitAll(state.transformWhile {
-                    if (it is FragmentState && it::class.java === initialState::class.java) {
-                        val containerId = it.containerId ?: run {
-                            (viewIdPool - fragmentIds).firstOrNull()?.also { id ->
-                                it.containerId = id
-                            }
-                        }
 
-                        if (containerId != null) {
+                    emit(Screen.FragmentScreen(it as State, it.toolbarIcons, it.toolbarOptions, it, containerId))
-                            fragmentIds.add(containerId)
+                }
-
-                            emit(Screen.FragmentScreen(it, it.toolbarIcons, it.toolbarOptions, it, containerId))
-                        }
-
-                        true
-                    } else false
-                })
-                else -> throw IllegalStateException()
             }
-
-            scope.cancel()
         }
-    }
+    ).shareIn(viewModelScope, SharingStarted.WhileSubscribed(1000), 1)
 
     fun execute(command: UpdateStateCommand) {
         command.applyTo(state)
@@ -147,4 +135,6 @@ class MainModel(application: Application): AndroidViewModel(application) {
     fun reportAuthenticationScreenClosed() {
         authenticationScreenClosed.tryEmit(Unit)
     }
+
+    private fun updateState(method: (State) -> State): Unit = state.update(method)
 }

app/src/main/java/io/timelimit/android/ui/model/flow/SplitFlow.kt

@@ -0,0 +1,104 @@
+/*
+ * TimeLimit Copyright <C> 2019 - 2023 Jonas Lochmann
+ *
+ * This program 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 version 3 of the License.
+ *
+ * This program 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 this program. If not, see <https://www.gnu.org/licenses/>.
+ */
+package io.timelimit.android.ui.model.flow
+
+import kotlinx.coroutines.CoroutineScope
+import kotlinx.coroutines.channels.Channel
+import kotlinx.coroutines.channels.consumeEach
+import kotlinx.coroutines.flow.*
+import kotlinx.coroutines.isActive
+import kotlinx.coroutines.launch
+
+class CaseScope<LocalStateType>(
+    val scope: CoroutineScope,
+    val className: Class<LocalStateType>
+) {
+    inline fun <SuperStateType, LocalStateType : SuperStateType> updateMethod(
+        crossinline parent: ((SuperStateType) -> SuperStateType) -> Unit
+    ): ((LocalStateType) -> SuperStateType) -> Unit = { request ->
+        parent { oldState ->
+            if (scope.isActive && className.isInstance(oldState)) request(oldState as LocalStateType)
+            else oldState
+        }
+    }
+}
+
+class Case<T, R>(
+    val className: Class<out Any>,
+    val key: (T) -> Any?,
+    val producer: CaseScope<T>.(Flow<T>, Any?) -> Flow<R>
+) {
+    companion object {
+        inline fun <T, R, reified C : Any> simple(
+            crossinline producer: CaseScope<C>.(Flow<C>) -> Flow<R>
+        ) = Case<T, R>(
+            className = C::class.java,
+            key = {}
+        ) { flow, _ -> producer(this as CaseScope<C>, flow as Flow<C>) }
+
+        inline fun <T, R, reified C : Any, K> withKey(
+            crossinline withKey: (C) -> K,
+            crossinline producer: CaseScope<C>.(K, Flow<C>) -> Flow<R>
+        ) = Case<T, R>(
+            className = C::class.java,
+            key = { withKey(it as C) }
+        ) { flow, key -> producer(this as CaseScope<C>, key as K, flow as Flow<C>) }
+    }
+
+    internal fun doesMatch(value: Any?): Boolean = className.isInstance(value)
+}
+
+fun <T, R> Flow<T>.splitConflated(vararg cases: Case<T, R>): Flow<R> {
+    val input = this
+
+    return channelFlow<R> {
+        val inputChannel = Channel<T>()
+
+        launch { input.collect { inputChannel.send(it) }; inputChannel.close() }
+
+        var value = inputChannel.receive()
+
+        while (true) {
+            val case = cases.first { it.doesMatch(value) }
+            val key = case.key(value)
+            val relayChannel = Channel<T>(Channel.CONFLATED)
+            val job = launch {
+                val scope = CaseScope<T>(this, case.className as Class<T>)
+                val inputFlow = flow { relayChannel.consumeEach { emit(it) } }
+
+                case.producer(scope, inputFlow, key).collect { send(it) }
+            }
+
+            try {
+                relayChannel.send(value)
+
+                while (true) {
+                    value = inputChannel.receive()
+
+                    val newCase = cases.first { it.doesMatch(value) }
+
+                    if (case !== newCase) break
+                    if (case.key(value) != key) break
+
+                    relayChannel.send(value)
+                }
+            } finally {
+                relayChannel.cancel()
+                job.cancel()
+            }
+        }
+    }
+}

app/src/main/java/io/timelimit/android/ui/model/launch/LaunchHandling.kt

@@ -1,3 +1,18 @@
+/*
+ * TimeLimit Copyright <C> 2019 - 2023 Jonas Lochmann
+ *
+ * This program 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 version 3 of the License.
+ *
+ * This program 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 this program. If not, see <https://www.gnu.org/licenses/>.
+ */
 package io.timelimit.android.ui.model.launch
 
 import io.timelimit.android.async.Threads
@@ -5,14 +20,17 @@ import io.timelimit.android.coroutines.executeAndWait
 import io.timelimit.android.data.model.UserType
 import io.timelimit.android.livedata.waitUntilValueMatches
 import io.timelimit.android.logic.AppLogic
+import io.timelimit.android.ui.model.Screen
 import io.timelimit.android.ui.model.State
+import kotlinx.coroutines.flow.Flow
 import kotlinx.coroutines.flow.MutableStateFlow
+import kotlinx.coroutines.flow.flow
 
 object LaunchHandling {
-    suspend fun processLaunchState(
+    fun processLaunchState(
         state: MutableStateFlow<State>,
         logic: AppLogic
-    ) {
+    ): Flow<Screen> = flow {
         val oldValue = state.value
 
         if (oldValue is State.LaunchState) {

app/src/main/java/io/timelimit/android/ui/model/managechild/ManageChildHandling.kt

@@ -17,38 +17,35 @@ package io.timelimit.android.ui.model.managechild
 
 import io.timelimit.android.R
 import io.timelimit.android.data.model.UserType
-import io.timelimit.android.extensions.whileTrue
 import io.timelimit.android.logic.AppLogic
 import io.timelimit.android.ui.model.BackStackItem
 import io.timelimit.android.ui.model.Screen
 import io.timelimit.android.ui.model.State
 import io.timelimit.android.ui.model.Title
+import io.timelimit.android.ui.model.flow.Case
+import io.timelimit.android.ui.model.flow.splitConflated
 import kotlinx.coroutines.flow.*
 
 object ManageChildHandling {
     fun processState(
         logic: AppLogic,
-        stateLive: MutableStateFlow<State>
+        state: Flow<State.ManageChild>,
-    ) = flow {
+        updateState: ((State.ManageChild) -> State) -> Unit
-        while (true) when (stateLive.value) {
+    ) = state.splitConflated(
-            is State.ManageChild.Main -> emitAll(processMainState(logic, stateLive))
+        Case.simple<_, _, State.ManageChild.Main> { processMainState(logic, it, updateMethod(updateState)) },
-            is State.ManageChild.Apps -> emitAll(processAppsState(logic, stateLive))
+        Case.simple<_, _, State.ManageChild.Apps> { processAppsState(logic, it, updateMethod(updateState)) }
-            else -> break
+    )
-        }
-    }
 
     private fun processMainState(
         logic: AppLogic,
-        stateLive: MutableStateFlow<State>
+        stateLive: Flow<State.ManageChild.Main>,
+        updateState: ((State.ManageChild.Main) -> State) -> Unit
     ): Flow<Screen> {
-        val hasMatchingStateLive = stateLive.map { it is State.ManageChild.Main }
+        return stateLive.transformLatest { state ->
-        val matchingState = stateLive.filterIsInstance<State.ManageChild.Main>()
-
-        val screenLive = matchingState.transformLatest { state ->
             val userLive = logic.database.user().getUserByIdFlow(state.childId)
 
             emitAll(userLive.transform {user ->
-                if (user?.type != UserType.Child) stateLive.compareAndSet(state, state.previousOverview)
+                if (user?.type != UserType.Child) updateState { state.previousOverview }
                 else emit(Screen.ManageChildScreen(
                     state,
                     state.toolbarIcons,
@@ -59,27 +56,23 @@ object ManageChildHandling {
                     listOf(
                         BackStackItem(
                             Title.StringResource(R.string.main_tab_overview)
-                        ) { stateLive.compareAndSet(state, state.previousOverview) }
+                        ) { updateState { state.previousOverview } }
                     )
                 ))
             })
         }
-
-        return hasMatchingStateLive.whileTrue { screenLive }
     }
 
     private fun processAppsState(
         logic: AppLogic,
-        stateLive: MutableStateFlow<State>
+        stateLive: Flow<State.ManageChild.Apps>,
+        updateState: ((State.ManageChild.Apps) -> State) -> Unit
     ): Flow<Screen> {
-        val hasMatchingStateLive = stateLive.map { it is State.ManageChild.Apps }
+        return stateLive.transformLatest { state ->
-        val matchingState = stateLive.filterIsInstance<State.ManageChild.Apps>()
-
-        val screenLive = matchingState.transformLatest { state ->
             val userLive = logic.database.user().getUserByIdFlow(state.childId)
 
             emitAll(userLive.transform {user ->
-                if (user?.type != UserType.Child) stateLive.compareAndSet(state, state.previousChild.previousOverview)
+                if (user?.type != UserType.Child) updateState { state.previousChild.previousOverview }
                 else emit(Screen.ManageChildAppsScreen(
                     state,
                     state.toolbarIcons,
@@ -89,15 +82,13 @@ object ManageChildHandling {
                     listOf(
                         BackStackItem(
                             Title.StringResource(R.string.main_tab_overview)
-                        ) { stateLive.compareAndSet(state, state.previousChild.previousOverview) },
+                        ) { updateState { state.previousChild.previousOverview } },
                         BackStackItem(
                             Title.Plain(user.name)
-                        ) { stateLive.compareAndSet(state, state.previousChild) }
+                        ) { updateState { state.previousChild } }
                     )
                 ))
             })
         }
-
-        return hasMatchingStateLive.whileTrue { screenLive }
     }
 }