[Jetcaster] Implement 'Your Library' (#1279)

![Screenshot_20240304_155503](https://github.com/android/compose-samples/assets/463186/83f8a2c2-c3e3-45e4-bef0-da776203e396)

Jetcaster/app/src/main/java/com/example/jetcaster/data/EpisodeStore.kt

@@ -39,7 +39,7 @@ class EpisodeStore(
     fun episodesInPodcast(
         podcastUri: String,
         limit: Int = Integer.MAX_VALUE
-    ): Flow<List<Episode>> {
+    ): Flow<List<EpisodeToPodcast>> {
         return episodesDao.episodesForPodcastUri(podcastUri, limit)
     }
 

Jetcaster/app/src/main/java/com/example/jetcaster/data/room/EpisodesDao.kt

@@ -46,7 +46,7 @@ abstract class EpisodesDao : BaseDao<Episode> {
     abstract fun episodesForPodcastUri(
         podcastUri: String,
         limit: Int
-    ): Flow<List<Episode>>
+    ): Flow<List<EpisodeToPodcast>>
 
     @Transaction
     @Query(

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

@@ -76,10 +76,12 @@ import androidx.lifecycle.viewmodel.compose.viewModel
 import coil.compose.AsyncImage
 import com.example.jetcaster.R
 import com.example.jetcaster.data.Category
+import com.example.jetcaster.data.EpisodeToPodcast
 import com.example.jetcaster.data.PodcastWithExtraInfo
 import com.example.jetcaster.ui.home.category.PodcastCategoryViewState
 import com.example.jetcaster.ui.home.discover.DiscoverViewState
 import com.example.jetcaster.ui.home.discover.discoverItems
+import com.example.jetcaster.ui.home.library.libraryItems
 import com.example.jetcaster.ui.theme.JetcasterTheme
 import com.example.jetcaster.ui.theme.Keyline1
 import com.example.jetcaster.ui.theme.MinContrastOfPrimaryVsSurface
@@ -108,6 +110,7 @@ fun Home(
             selectedHomeCategory = viewState.selectedHomeCategory,
             discoverViewState = viewState.discoverViewState,
             podcastCategoryViewState = viewState.podcastCategoryViewState,
+            libraryEpisodes = viewState.libraryEpisodes,
             onHomeCategorySelected = viewModel::onHomeCategorySelected,
             onCategorySelected = viewModel::onCategorySelected,
             onPodcastUnfollowed = viewModel::onPodcastUnfollowed,
@@ -173,6 +176,7 @@ fun Home(
     homeCategories: List<HomeCategory>,
     discoverViewState: DiscoverViewState,
     podcastCategoryViewState: PodcastCategoryViewState,
+    libraryEpisodes: List<EpisodeToPodcast>,
     modifier: Modifier = Modifier,
     onPodcastUnfollowed: (String) -> Unit,
     onHomeCategorySelected: (HomeCategory) -> Unit,
@@ -239,6 +243,7 @@ fun Home(
                 homeCategories = homeCategories,
                 discoverViewState = discoverViewState,
                 podcastCategoryViewState = podcastCategoryViewState,
+                libraryEpisodes = libraryEpisodes,
                 scrimColor = scrimColor,
                 pagerState = pagerState,
                 onPodcastUnfollowed = onPodcastUnfollowed,
@@ -260,6 +265,7 @@ private fun HomeContent(
     homeCategories: List<HomeCategory>,
     discoverViewState: DiscoverViewState,
     podcastCategoryViewState: PodcastCategoryViewState,
+    libraryEpisodes: List<EpisodeToPodcast>,
     scrimColor: Color,
     pagerState: PagerState,
     modifier: Modifier = Modifier,
@@ -303,7 +309,10 @@ private fun HomeContent(
 
         when (selectedHomeCategory) {
             HomeCategory.Library -> {
-                // TODO
+                libraryItems(
+                    episodes = libraryEpisodes,
+                    navigateToPlayer = navigateToPlayer
+                )
             }
 
             HomeCategory.Discover -> {
@@ -504,6 +513,7 @@ fun PreviewHomeContent() {
                 topPodcasts = PreviewPodcastsWithExtraInfo,
                 episodes = PreviewEpisodeToPodcasts,
             ),
+            libraryEpisodes = emptyList(),
             onCategorySelected = {},
             onPodcastUnfollowed = {},
             navigateToPlayer = {},

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

@@ -21,6 +21,8 @@ import androidx.lifecycle.viewModelScope
 import com.example.jetcaster.Graph
 import com.example.jetcaster.data.Category
 import com.example.jetcaster.data.CategoryStore
+import com.example.jetcaster.data.EpisodeStore
+import com.example.jetcaster.data.EpisodeToPodcast
 import com.example.jetcaster.data.PodcastStore
 import com.example.jetcaster.data.PodcastWithExtraInfo
 import com.example.jetcaster.data.PodcastsRepository
@@ -43,7 +45,8 @@ import kotlinx.coroutines.launch
 class HomeViewModel(
     private val podcastsRepository: PodcastsRepository = Graph.podcastRepository,
     private val categoryStore: CategoryStore = Graph.categoryStore,
-    private val podcastStore: PodcastStore = Graph.podcastStore
+    private val podcastStore: PodcastStore = Graph.podcastStore,
+    private val episodeStore: EpisodeStore = Graph.episodeStore
 ) : ViewModel() {
     // Holds our currently selected home category
     private val selectedHomeCategory = MutableStateFlow(HomeCategory.Discover)
@@ -56,6 +59,18 @@ class HomeViewModel(
     // Holds the view state if the UI is refreshing for new data
     private val refreshing = MutableStateFlow(false)
 
+    @OptIn(ExperimentalCoroutinesApi::class)
+    private val libraryEpisodes = podcastStore.followedPodcastsSortedByLastEpisode()
+        .flatMapLatest { followedPodcasts ->
+            combine(
+                followedPodcasts.map { p ->
+                    episodeStore.episodesInPodcast(p.podcast.uri, 5)
+                }
+            ) { allEpisodes ->
+                allEpisodes.toList().flatten().sortedByDescending { it.episode.published }
+            }
+        }
+
     private val discover = combine(
         categoryStore.categoriesSortedByPodcastCount()
             .onEach { categories ->
@@ -110,20 +125,23 @@ class HomeViewModel(
                 podcastStore.followedPodcastsSortedByLastEpisode(limit = 20),
                 refreshing,
                 discover,
-                podcastCategory
+                podcastCategory,
+                libraryEpisodes
             ) { homeCategories,
                 selectedHomeCategory,
                 podcasts,
                 refreshing,
                 discoverViewState,
-                podcastCategoryViewState ->
+                podcastCategoryViewState,
+                libraryEpisodes ->
                 HomeViewState(
                     homeCategories = homeCategories,
                     selectedHomeCategory = selectedHomeCategory,
                     featuredPodcasts = podcasts.toPersistentList(),
                     refreshing = refreshing,
                     discoverViewState = discoverViewState,
                     podcastCategoryViewState = podcastCategoryViewState,
+                    libraryEpisodes = libraryEpisodes,
                     errorMessage = null, /* TODO */
                 )
             }.catch { throwable ->
@@ -181,5 +199,6 @@ data class HomeViewState(
     val homeCategories: List<HomeCategory> = emptyList(),
     val discoverViewState: DiscoverViewState = DiscoverViewState(),
     val podcastCategoryViewState: PodcastCategoryViewState = PodcastCategoryViewState(),
+    val libraryEpisodes: List<EpisodeToPodcast> = emptyList(),
     val errorMessage: String? = null
 )

Jetcaster/app/src/main/java/com/example/jetcaster/ui/home/category/PodcastCategory.kt

@@ -80,6 +80,10 @@ import com.example.jetcaster.util.ToggleFollowPodcastIconButton
 import java.time.format.DateTimeFormatter
 import java.time.format.FormatStyle
 
+data class PodcastCategoryViewState(
+    val topPodcasts: List<PodcastWithExtraInfo> = emptyList(),
+    val episodes: List<EpisodeToPodcast> = emptyList()
+)
 fun LazyListScope.podcastCategory(
     topPodcasts: List<PodcastWithExtraInfo>,
     episodes: List<EpisodeToPodcast>,

Jetcaster/app/src/main/java/com/example/jetcaster/ui/home/library/Library.kt

@@ -0,0 +1,42 @@
+/*
+ * Copyright 2024 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.example.jetcaster.ui.home.library
+
+import androidx.compose.foundation.lazy.LazyListScope
+import androidx.compose.foundation.lazy.items
+import androidx.compose.ui.Modifier
+import com.example.jetcaster.data.EpisodeToPodcast
+import com.example.jetcaster.ui.home.category.EpisodeListItem
+
+fun LazyListScope.libraryItems(
+    episodes: List<EpisodeToPodcast>,
+    navigateToPlayer: (String) -> Unit
+) {
+    if (episodes.isEmpty()) {
+        // TODO: Empty state
+        return
+    }
+
+    items(episodes, key = { it.episode.uri }) { item ->
+        EpisodeListItem(
+            episode = item.episode,
+            podcast = item.podcast,
+            onClick = navigateToPlayer,
+            modifier = Modifier.fillParentMaxWidth()
+        )
+    }
+}

Jetcaster/app/src/main/java/com/example/jetcaster/util/Flows.kt

@@ -49,3 +49,46 @@ fun <T1, T2, T3, T4, T5, T6, R> combine(
             args[5] as T6,
         )
     }
+
+/**
+ * Combines seven flows into a single flow by combining their latest values using the provided transform function.
+ *
+ * @param flow The first flow.
+ * @param flow2 The second flow.
+ * @param flow3 The third flow.
+ * @param flow4 The fourth flow.
+ * @param flow5 The fifth flow.
+ * @param flow6 The sixth flow.
+ * @param flow7 The seventh flow.
+ * @param transform The transform function to combine the latest values of the seven flows.
+ * @return A flow that emits the results of the transform function applied to the latest values of the seven flows.
+ */
+fun <T1, T2, T3, T4, T5, T6, T7, R> combine(
+    flow: Flow<T1>,
+    flow2: Flow<T2>,
+    flow3: Flow<T3>,
+    flow4: Flow<T4>,
+    flow5: Flow<T5>,
+    flow6: Flow<T6>,
+    flow7: Flow<T7>,
+    transform: suspend (T1, T2, T3, T4, T5, T6, T7) -> R
+): Flow<R> =
+    kotlinx.coroutines.flow.combine(
+        flow,
+        flow2,
+        flow3,
+        flow4,
+        flow5,
+        flow6,
+        flow7
+    ) { args: Array<*> ->
+        transform(
+            args[0] as T1,
+            args[1] as T2,
+            args[2] as T3,
+            args[3] as T4,
+            args[4] as T5,
+            args[5] as T6,
+            args[6] as T7,
+        )
+    }