[Jetcaster] Refactor home state and fix loading progress (#1499)

[Merge after #1498]

- This PR merges the home UI state into one data class to be able to
show loading state and content state at the same time.
- It also fixes the progress to wait for the loading to finish.
- Instead of circular progress, I switched to linear progress at the top
of the content, which can indicate the work while showing content

**After**


https://github.com/user-attachments/assets/ec3e9220-addc-4b96-9b6a-477294b6cf85




**Before**


https://github.com/user-attachments/assets/c795afc3-01f6-407b-b0b6-505da33652ec

Jetcaster/core/data/src/main/java/com/example/jetcaster/core/data/repository/PodcastsRepository.kt

@@ -49,8 +49,7 @@ class PodcastsRepository @Inject constructor(
         if (refreshingJob?.isActive == true) {
             refreshingJob?.join()
         } else if (force || podcastStore.isEmpty()) {
-
-            refreshingJob = scope.launch {
+            val job = scope.launch {
                 // Now fetch the podcasts, and add each to each store
                 podcastsFetcher(SampleFeeds)
                     .filter { it is PodcastRssResponse.Success }
@@ -72,6 +71,9 @@ class PodcastsRepository @Inject constructor(
                         }
                     }
             }
+            refreshingJob = job
+            // We need to wait here for the job to finish, otherwise the coroutine completes ~immediatelly
+            job.join()
         }
     }
 }

Jetcaster/mobile/src/main/java/com/example/jetcaster/ui/home/Home.kt

@@ -50,10 +50,10 @@ import androidx.compose.material.icons.Icons
 import androidx.compose.material.icons.filled.AccountCircle
 import androidx.compose.material.icons.filled.Search
 import androidx.compose.material3.Button
-import androidx.compose.material3.CircularProgressIndicator
 import androidx.compose.material3.ExperimentalMaterial3Api
 import androidx.compose.material3.HorizontalDivider
 import androidx.compose.material3.Icon
+import androidx.compose.material3.LinearProgressIndicator
 import androidx.compose.material3.MaterialTheme
 import androidx.compose.material3.Scaffold
 import androidx.compose.material3.SearchBar
@@ -134,6 +134,7 @@ import kotlinx.coroutines.launch
 
 data class HomeState(
     val windowSizeClass: WindowSizeClass,
+    val isLoading: Boolean,
     val featuredPodcasts: PersistentList<PodcastInfo>,
     val selectedHomeCategory: HomeCategory,
     val homeCategories: List<HomeCategory>,
@@ -180,10 +181,12 @@ fun calculateScaffoldDirective(
                 maxHorizontalPartitions = 1
                 verticalSpacerSize = 0.dp
             }
+
             WindowWidthSizeClass.MEDIUM -> {
                 maxHorizontalPartitions = 1
                 verticalSpacerSize = 0.dp
             }
+
             else -> {
                 maxHorizontalPartitions = 2
                 verticalSpacerSize = 24.dp
@@ -233,27 +236,17 @@ fun MainScreen(
     viewModel: HomeViewModel = hiltViewModel()
 ) {
     val homeScreenUiState by viewModel.state.collectAsStateWithLifecycle()
-    when (val uiState = homeScreenUiState) {
-        is HomeScreenUiState.Loading -> HomeScreenLoading()
-        is HomeScreenUiState.Error -> HomeScreenError(onRetry = viewModel::refresh)
-        is HomeScreenUiState.Ready -> {
-            HomeScreenReady(
-                uiState = uiState,
-                windowSizeClass = windowSizeClass,
-                navigateToPlayer = navigateToPlayer,
-                viewModel = viewModel,
-            )
-        }
-    }
-}
+    val uiState = homeScreenUiState
+    Box {
+        HomeScreenReady(
+            uiState = uiState,
+            windowSizeClass = windowSizeClass,
+            navigateToPlayer = navigateToPlayer,
+            viewModel = viewModel,
+        )
 
-@Composable
-private fun HomeScreenLoading(modifier: Modifier = Modifier) {
-    Surface(modifier.fillMaxSize()) {
-        Box {
-            CircularProgressIndicator(
-                modifier = Modifier.align(Alignment.Center)
-            )
+        if (uiState.errorMessage != null) {
+            HomeScreenError(onRetry = viewModel::refresh)
         }
     }
 }
@@ -288,7 +281,7 @@ fun HomeScreenErrorPreview() {
 @OptIn(ExperimentalMaterial3AdaptiveApi::class)
 @Composable
 private fun HomeScreenReady(
-    uiState: HomeScreenUiState.Ready,
+    uiState: HomeScreenUiState,
     windowSizeClass: WindowSizeClass,
     navigateToPlayer: (EpisodeInfo) -> Unit,
     viewModel: HomeViewModel = hiltViewModel()
@@ -302,6 +295,7 @@ private fun HomeScreenReady(
 
     val homeState = HomeState(
         windowSizeClass = windowSizeClass,
+        isLoading = uiState.isLoading,
         featuredPodcasts = uiState.featuredPodcasts,
         homeCategories = uiState.homeCategories,
         selectedHomeCategory = uiState.selectedHomeCategory,
@@ -443,10 +437,19 @@ private fun HomeScreen(
     ) {
         Scaffold(
             topBar = {
-                HomeAppBar(
-                    isExpanded = homeState.windowSizeClass.isCompact,
-                    modifier = Modifier.fillMaxWidth(),
-                )
+                Column {
+                    HomeAppBar(
+                        isExpanded = homeState.windowSizeClass.isCompact,
+                        modifier = Modifier.fillMaxWidth(),
+                    )
+                    if (homeState.isLoading) {
+                        LinearProgressIndicator(
+                            Modifier
+                                .fillMaxWidth()
+                                .padding(horizontal = 16.dp)
+                        )
+                    }
+                }
             },
             snackbarHost = {
                 SnackbarHost(hostState = snackbarHostState)
@@ -811,6 +814,7 @@ private fun PreviewHome() {
     JetcasterTheme {
         val homeState = HomeState(
             windowSizeClass = CompactWindowSizeClass,
+            isLoading = true,
             featuredPodcasts = PreviewPodcasts.toPersistentList(),
             homeCategories = HomeCategory.entries,
             selectedHomeCategory = HomeCategory.Discover,

Jetcaster/mobile/src/main/java/com/example/jetcaster/ui/home/HomeViewModel.kt

@@ -16,7 +16,7 @@
 
 package com.example.jetcaster.ui.home
 
-import android.util.Log
+import androidx.compose.runtime.Immutable
 import androidx.lifecycle.ViewModel
 import androidx.lifecycle.viewModelScope
 import com.example.jetcaster.core.data.database.model.EpisodeToPodcast
@@ -49,7 +49,6 @@ import kotlinx.coroutines.flow.shareIn
 import kotlinx.coroutines.launch
 
 @OptIn(ExperimentalCoroutinesApi::class)
-
 @HiltViewModel
 class HomeViewModel @Inject constructor(
     private val podcastsRepository: PodcastsRepository,
@@ -61,14 +60,19 @@ class HomeViewModel @Inject constructor(
 ) : ViewModel() {
     // Holds our currently selected podcast in the library
     private val selectedLibraryPodcast = MutableStateFlow<PodcastInfo?>(null)
+
     // Holds our currently selected home category
     private val selectedHomeCategory = MutableStateFlow(HomeCategory.Discover)
+
     // Holds the currently available home categories
     private val homeCategories = MutableStateFlow(HomeCategory.entries)
+
     // Holds our currently selected category
     private val _selectedCategory = MutableStateFlow<CategoryInfo?>(null)
+
     // Holds our view state which the UI collects via [state]
-    private val _state = MutableStateFlow<HomeScreenUiState>(HomeScreenUiState.Loading)
+    private val _state = MutableStateFlow(HomeScreenUiState())
+
     // Holds the view state if the UI is refreshing for new data
     private val refreshing = MutableStateFlow(false)
 
@@ -107,19 +111,15 @@ class HomeViewModel @Inject constructor(
                 podcastCategoryFilterResult,
                 libraryEpisodes ->
 
-                if (refreshing) {
-                    Log.d("Jetcaster", "refreshing: $refreshing, podcasts $podcasts")
-                    return@combine HomeScreenUiState.Loading
-                }
-
                 _selectedCategory.value = filterableCategories.selectedCategory
 
                 // Override selected home category to show 'DISCOVER' if there are no
                 // featured podcasts
                 selectedHomeCategory.value =
                     if (podcasts.isEmpty()) HomeCategory.Discover else homeCategory
 
-                HomeScreenUiState.Ready(
+                HomeScreenUiState(
+                    isLoading = refreshing,
                     homeCategories = homeCategories,
                     selectedHomeCategory = homeCategory,
                     featuredPodcasts = podcasts.map { it.asExternalModel() }.toPersistentList(),
@@ -128,7 +128,12 @@ class HomeViewModel @Inject constructor(
                     library = libraryEpisodes.asLibrary()
                 )
             }.catch { throwable ->
-                _state.value = HomeScreenUiState.Error(throwable.message)
+                emit(
+                    HomeScreenUiState(
+                        isLoading = false,
+                        errorMessage = throwable.message
+                    )
+                )
             }.collect {
                 _state.value = it
             }
@@ -187,21 +192,14 @@ enum class HomeCategory {
     Library, Discover
 }
 
-sealed interface HomeScreenUiState {
-    data object Loading : HomeScreenUiState
-
-    data class Error(
-        val errorMessage: String? = null
-    ) : HomeScreenUiState
-
-    data class Ready(
-        val featuredPodcasts: PersistentList<PodcastInfo> = persistentListOf(),
-        val selectedHomeCategory: HomeCategory = HomeCategory.Discover,
-        val homeCategories: List<HomeCategory> = emptyList(),
-        val filterableCategoriesModel: FilterableCategoriesModel =
-            FilterableCategoriesModel(),
-        val podcastCategoryFilterResult: PodcastCategoryFilterResult =
-            PodcastCategoryFilterResult(),
-        val library: LibraryInfo = LibraryInfo(),
-    ) : HomeScreenUiState
-}
+@Immutable
+data class HomeScreenUiState(
+    val isLoading: Boolean = true,
+    val errorMessage: String? = null,
+    val featuredPodcasts: PersistentList<PodcastInfo> = persistentListOf(),
+    val selectedHomeCategory: HomeCategory = HomeCategory.Discover,
+    val homeCategories: List<HomeCategory> = emptyList(),
+    val filterableCategoriesModel: FilterableCategoriesModel = FilterableCategoriesModel(),
+    val podcastCategoryFilterResult: PodcastCategoryFilterResult = PodcastCategoryFilterResult(),
+    val library: LibraryInfo = LibraryInfo(),
+)