Wait for switched user's home settings before fetching data (#1981)

## Description
There is a race condition when switching users between
`HomeViewModel.init` and `HomeSetttingsService.loadCurrentSettings`.
This happens more often if the new user doesn't have a customized home
page. The result is that the previous user's home page settings are used
for the initial load of the home page.

This PR fixes this by collecting the flows for current user & home
settings, waiting until both are valid and refer to the same user, then
fetch the data.

### Related issues
Fixes #1976
Maybe related (and fixes) #1980, but need to investigate more

### Testing
Emulator. It's easy to reproduce by adding a manual `delay(2.seconds)`
at the start of `HomeSetttingsService.loadCurrentSettings`.

## Screenshots
N/A

## AI or LLM usage
None

app/src/main/java/com/github/damontecres/wholphin/services/HomeSettingsService.kt

@@ -245,7 +245,7 @@ class HomeSettingsService
                         settings.rows.mapIndexed { index, config ->
                             resolve(index, config)
                         }
-                    HomePageResolvedSettings(resolvedRows)
+                    HomePageResolvedSettings(userId, resolvedRows)
                 } else {
                     createDefault(userId)
                 }
@@ -256,12 +256,15 @@ class HomeSettingsService
         /**
          * Resolve the settings and set them to be the current settings
          */
-        suspend fun updateCurrent(settings: HomePageSettings) {
+        suspend fun updateCurrent(
+            userId: UUID,
+            settings: HomePageSettings,
+        ) {
             val resolvedRows =
                 settings.rows.mapIndexed { index, config ->
                     resolve(index, config)
                 }
-            val resolvedSettings = HomePageResolvedSettings(resolvedRows)
+            val resolvedSettings = HomePageResolvedSettings(userId, resolvedRows)
             currentSettings.update { resolvedSettings }
         }
 
@@ -312,7 +315,7 @@ class HomeSettingsService
                     ),
                 )
             val rowConfig = continueWatchingRow + includedIds
-            return HomePageResolvedSettings(rowConfig)
+            return HomePageResolvedSettings(userId, rowConfig)
         }
 
         /**
@@ -428,7 +431,7 @@ class HomeSettingsService
                                 null
                             }
                         }.flatten()
-                HomePageResolvedSettings(rowConfigs)
+                HomePageResolvedSettings(userId, rowConfigs)
             } else {
                 null
             }
@@ -1224,10 +1227,11 @@ data class HomeRowConfigDisplay(
  * @see HomePageSettings
  */
 data class HomePageResolvedSettings(
+    val userId: UUID,
     val rows: List<HomeRowConfigDisplay>,
 ) {
     companion object {
-        val EMPTY = HomePageResolvedSettings(listOf())
+        val EMPTY = HomePageResolvedSettings(UUID.randomUUID(), emptyList())
     }
 }
 

app/src/main/java/com/github/damontecres/wholphin/services/SetupNavigationManager.kt

@@ -27,9 +27,6 @@ class SetupNavigationManager
         fun navigateTo(destination: SetupDestination) {
             backStack[0] = destination
             log()
-            if (destination !is SetupDestination.AppContent) {
-                navigationManager.reloadHome()
-            }
         }
 
         private fun log() {

app/src/main/java/com/github/damontecres/wholphin/ui/main/HomeViewModel.kt

@@ -20,6 +20,8 @@ import com.github.damontecres.wholphin.services.ServerReportService
 import com.github.damontecres.wholphin.services.UserPreferencesService
 import com.github.damontecres.wholphin.services.deleteItem
 import com.github.damontecres.wholphin.services.tvAccess
+import com.github.damontecres.wholphin.ui.collectLatestIn
+import com.github.damontecres.wholphin.ui.combinePair
 import com.github.damontecres.wholphin.ui.data.RowColumn
 import com.github.damontecres.wholphin.ui.launchDefault
 import com.github.damontecres.wholphin.ui.launchIO
@@ -31,6 +33,8 @@ import com.github.damontecres.wholphin.util.LoadingState
 import com.github.damontecres.wholphin.util.WholphinDispatchers
 import dagger.hilt.android.lifecycle.HiltViewModel
 import dagger.hilt.android.qualifiers.ApplicationContext
+import kotlinx.coroutines.CancellationException
+import kotlinx.coroutines.Job
 import kotlinx.coroutines.async
 import kotlinx.coroutines.awaitAll
 import kotlinx.coroutines.flow.MutableStateFlow
@@ -44,6 +48,7 @@ import kotlinx.coroutines.sync.withPermit
 import kotlinx.coroutines.withContext
 import org.jellyfin.sdk.api.client.exception.InvalidStatusException
 import org.jellyfin.sdk.model.api.BaseItemKind
+import org.jellyfin.sdk.model.api.UserDto
 import timber.log.Timber
 import java.util.UUID
 import javax.inject.Inject
@@ -68,23 +73,77 @@ class HomeViewModel
         private val _state = MutableStateFlow(HomeState.EMPTY)
         val state: StateFlow<HomeState> = _state
 
+        private var dataLoadingJob: Job? = null
+
         init {
             datePlayedService.invalidateAll()
-//            init()
+            serverRepository.currentUserDtoFlow
+                .combinePair(homeSettingsService.currentSettings)
+                .collectLatestIn(viewModelScope) { (userDto, settings) ->
+                    Timber.v(
+                        "Got new userDto & settings, userId=%s, settings?=%s",
+                        userDto?.id,
+                        settings != HomePageResolvedSettings.EMPTY,
+                    )
+                    _state.update { HomeState.EMPTY }
+                    dataLoadingJob?.cancel()
+                    if (userDto == null) {
+                        Timber.d("UserDto is null")
+                        return@collectLatestIn
+                    }
+                    if (settings == HomePageResolvedSettings.EMPTY) {
+                        Timber.d("Home settings are empty")
+                        return@collectLatestIn
+                    }
+                    if (userDto.id != settings.userId) {
+                        Timber.d("User IDs don't match: %s vs %s", userDto?.id, settings.userId)
+                        return@collectLatestIn
+                    }
+                    dataLoadingJob =
+                        viewModelScope.launchIO {
+                            loadHomeRows(userDto, settings)
+                        }
+                }
         }
 
         fun init() {
             viewModelScope.launchIO {
                 Timber.d("init HomeViewModel")
+                serverRepository.currentUserDto?.let { userDto ->
+                    if (dataLoadingJob?.isActive == false) {
+                        val settings =
+                            homeSettingsService.currentSettings.first { it != HomePageResolvedSettings.EMPTY }
+                        if (userDto.id == settings.userId) {
+                            dataLoadingJob =
+                                viewModelScope.launchIO {
+                                    loadHomeRows(userDto, settings)
+                                }
+                        } else {
+                            Timber.d(
+                                "Init user IDs don't match: %s vs %s",
+                                userDto.id,
+                                settings.userId,
+                            )
+                        }
+                    } else {
+                        Timber.v("Data loading job is active")
+                    }
+                }
+            }
+        }
+
+        suspend fun loadHomeRows(
+            userDto: UserDto,
+            settings: HomePageResolvedSettings,
+        ) {
+            Timber.i("Starting loadHomeRows")
             try {
                 val preferences = userPreferencesService.getCurrent()
                 val prefs = preferences.appPreferences.homePagePreferences
 
-                    serverRepository.currentUserDto?.let { userDto ->
                 val libraries =
                     navDrawerService.getAllUserLibraries(userDto.id, userDto.tvAccess)
-                        val settings =
+
-                            homeSettingsService.currentSettings.first { it != HomePageResolvedSettings.EMPTY }
                 val state = state.value
 
                 // Refreshing if a load has already occurred and the rows haven't significantly changed
@@ -202,7 +261,8 @@ class HomeViewModel
                     }
                 }
                 Timber.d("Home page load complete")
-                    }
+            } catch (ex: CancellationException) {
+                throw ex
             } catch (ex: Exception) {
                 Timber.e(ex, "Exception during home page loading")
                 if (state.value.loadingState == LoadingState.Success) {
@@ -215,7 +275,6 @@ class HomeViewModel
                 }
             }
         }
-        }
 
         fun setWatched(
             itemId: UUID,
@@ -298,7 +357,7 @@ data class HomeState(
             HomeState(
                 LoadingState.Pending,
                 LoadingState.Pending,
-                listOf(),
+                emptyList(),
                 HomePageResolvedSettings.EMPTY,
             )
     }

app/src/main/java/com/github/damontecres/wholphin/ui/main/settings/HomeSettingsViewModel.kt

@@ -595,7 +595,7 @@ class HomeSettingsViewModel
                             }
                         if (shouldSave) {
                             homeSettingsService.saveToLocal(user.id, settings)
-                            homeSettingsService.updateCurrent(settings)
+                            homeSettingsService.updateCurrent(user.id, settings)
                             showSaveToast()
                         } else {
                             Timber.d("No changes")
@@ -616,7 +616,11 @@ class HomeSettingsViewModel
             _state.update {
                 update.invoke(it)
             }
-            homeSettingsService.currentSettings.update { HomePageResolvedSettings(state.value.rows) }
+            serverRepository.currentUser?.id?.let { userId ->
+                homeSettingsService.currentSettings.update {
+                    HomePageResolvedSettings(userId, state.value.rows)
+                }
+            }
         }
 
         fun resizeCards(relative: Int) {

app/src/main/java/com/github/damontecres/wholphin/ui/setup/SwitchUserViewModel.kt

@@ -132,6 +132,7 @@ class SwitchUserViewModel
             viewModelScope.async(WholphinDispatchers.IO) {
                 try {
                     val current = serverRepository.changeUser(server, user)
+                    navigationManager.reloadHome()
                     setupNavigationManager.navigateTo(SetupDestination.AppContent(current))
                     SwitchUserResult.Success
                 } catch (ex: InvalidStatusException) {