[Jetcaster]: Display latest episodes for all subscribed podcasts in l…

…ibrary. (#1365)

<img width="703" alt="image"
src="https://github.com/android/compose-samples/assets/463186/8e2dade3-a0ee-4071-a069-e19733c8c98c">

Jetcaster/core/model/src/main/java/com/example/jetcaster/core/model/LibraryInfo.kt

@@ -17,6 +17,5 @@
 package com.example.jetcaster.core.model
 
 data class LibraryInfo(
-    val podcast: PodcastInfo? = null,
-    val episodes: List<EpisodeInfo> = emptyList()
-)
+    val episodes: List<PodcastToEpisodeInfo> = emptyList()
+) : List<PodcastToEpisodeInfo> by episodes

Jetcaster/core/model/src/main/java/com/example/jetcaster/core/model/PodcastCategoryFilterResult.kt

@@ -21,10 +21,5 @@ package com.example.jetcaster.core.model
  */
 data class PodcastCategoryFilterResult(
     val topPodcasts: List<PodcastInfo> = emptyList(),
-    val episodes: List<PodcastCategoryEpisode> = emptyList()
-)
-
-data class PodcastCategoryEpisode(
-    val episode: EpisodeInfo,
-    val podcast: PodcastInfo,
+    val episodes: List<PodcastToEpisodeInfo> = emptyList()
 )

Jetcaster/core/model/src/main/java/com/example/jetcaster/core/model/PodcastToEpisodeInfo.kt

@@ -0,0 +1,22 @@
+/*
+ * 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.core.model
+
+data class PodcastToEpisodeInfo(
+    val episode: EpisodeInfo,
+    val podcast: PodcastInfo,
+)

Jetcaster/core/src/main/java/com/example/jetcaster/core/data/database/model/EpisodeToPodcast.kt

@@ -20,7 +20,7 @@ import androidx.room.Embedded
 import androidx.room.Ignore
 import androidx.room.Relation
 import com.example.jetcaster.core.model.PlayerEpisode
-import com.example.jetcaster.core.model.PodcastCategoryEpisode
+import com.example.jetcaster.core.model.PodcastToEpisodeInfo
 import java.util.Objects
 
 class EpisodeToPodcast {
@@ -62,8 +62,8 @@ fun EpisodeToPodcast.toPlayerEpisode(): PlayerEpisode =
         podcastImageUrl = podcast.imageUrl ?: "",
     )
 
-fun EpisodeToPodcast.asPodcastCategoryEpisode(): PodcastCategoryEpisode =
-    PodcastCategoryEpisode(
+fun EpisodeToPodcast.asPodcastToEpisodeInfo(): PodcastToEpisodeInfo =
+    PodcastToEpisodeInfo(
         episode = episode.asExternalModel(),
         podcast = podcast.asExternalModel(),
     )

Jetcaster/core/src/main/java/com/example/jetcaster/core/data/domain/PodcastCategoryFilterUseCase.kt

@@ -18,7 +18,7 @@ package com.example.jetcaster.core.data.domain
 
 import com.example.jetcaster.core.data.database.model.Category
 import com.example.jetcaster.core.data.database.model.asExternalModel
-import com.example.jetcaster.core.data.database.model.asPodcastCategoryEpisode
+import com.example.jetcaster.core.data.database.model.asPodcastToEpisodeInfo
 import com.example.jetcaster.core.data.repository.CategoryStore
 import com.example.jetcaster.core.model.CategoryInfo
 import com.example.jetcaster.core.model.PodcastCategoryFilterResult
@@ -52,7 +52,7 @@ class PodcastCategoryFilterUseCase @Inject constructor(
         return combine(recentPodcastsFlow, episodesFlow) { topPodcasts, episodes ->
             PodcastCategoryFilterResult(
                 topPodcasts = topPodcasts.map { it.asExternalModel() },
-                episodes = episodes.map { it.asPodcastCategoryEpisode() }
+                episodes = episodes.map { it.asPodcastToEpisodeInfo() }
             )
         }
     }

Jetcaster/core/src/test/kotlin/com/example/jetcaster/core/data/domain/PodcastCategoryFilterUseCaseTest.kt

@@ -22,7 +22,7 @@ import com.example.jetcaster.core.data.database.model.EpisodeToPodcast
 import com.example.jetcaster.core.data.database.model.Podcast
 import com.example.jetcaster.core.data.database.model.PodcastWithExtraInfo
 import com.example.jetcaster.core.data.database.model.asExternalModel
-import com.example.jetcaster.core.data.database.model.asPodcastCategoryEpisode
+import com.example.jetcaster.core.data.database.model.asPodcastToEpisodeInfo
 import com.example.jetcaster.core.data.repository.TestCategoryStore
 import java.time.OffsetDateTime
 import kotlinx.coroutines.flow.first
@@ -109,7 +109,7 @@ class PodcastCategoryFilterUseCaseTest {
             result.topPodcasts
         )
         assertEquals(
-            testEpisodeToPodcast.map { it.asPodcastCategoryEpisode() },
+            testEpisodeToPodcast.map { it.asPodcastToEpisodeInfo() },
             result.episodes
         )
     }

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

@@ -921,7 +921,7 @@ private fun PreviewHomeContent() {
             ),
             podcastCategoryFilterResult = PodcastCategoryFilterResult(
                 topPodcasts = PreviewPodcasts,
-                episodes = PreviewPodcastCategoryEpisodes
+                episodes = PreviewPodcastEpisodes
             ),
             library = LibraryInfo(),
             onCategorySelected = {},
@@ -957,7 +957,7 @@ private fun PreviewHomeContentExpanded() {
             ),
             podcastCategoryFilterResult = PodcastCategoryFilterResult(
                 topPodcasts = PreviewPodcasts,
-                episodes = PreviewPodcastCategoryEpisodes
+                episodes = PreviewPodcastEpisodes
             ),
             library = LibraryInfo(),
             onCategorySelected = {},

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

@@ -21,6 +21,7 @@ import androidx.lifecycle.ViewModel
 import androidx.lifecycle.viewModelScope
 import com.example.jetcaster.core.data.database.model.EpisodeToPodcast
 import com.example.jetcaster.core.data.database.model.asExternalModel
+import com.example.jetcaster.core.data.database.model.asPodcastToEpisodeInfo
 import com.example.jetcaster.core.data.domain.FilterableCategoriesUseCase
 import com.example.jetcaster.core.data.domain.PodcastCategoryFilterUseCase
 import com.example.jetcaster.core.data.repository.EpisodeStore
@@ -41,9 +42,11 @@ import kotlinx.collections.immutable.persistentListOf
 import kotlinx.collections.immutable.toPersistentList
 import kotlinx.coroutines.ExperimentalCoroutinesApi
 import kotlinx.coroutines.flow.MutableStateFlow
+import kotlinx.coroutines.flow.SharingStarted
 import kotlinx.coroutines.flow.StateFlow
 import kotlinx.coroutines.flow.catch
 import kotlinx.coroutines.flow.flatMapLatest
+import kotlinx.coroutines.flow.shareIn
 import kotlinx.coroutines.launch
 
 @OptIn(ExperimentalCoroutinesApi::class)
@@ -70,6 +73,9 @@ class HomeViewModel @Inject constructor(
     // Holds the view state if the UI is refreshing for new data
     private val refreshing = MutableStateFlow(false)
 
+    private val subscribedPodcasts = podcastStore.followedPodcastsSortedByLastEpisode(limit = 10)
+        .shareIn(viewModelScope, SharingStarted.WhileSubscribed())
+
     val state: StateFlow<HomeScreenUiState>
         get() = _state
 
@@ -80,17 +86,17 @@ class HomeViewModel @Inject constructor(
             combine(
                 homeCategories,
                 selectedHomeCategory,
-                podcastStore.followedPodcastsSortedByLastEpisode(limit = 10),
+                subscribedPodcasts,
                 refreshing,
                 _selectedCategory.flatMapLatest { selectedCategory ->
                     filterableCategoriesUseCase(selectedCategory)
                 },
                 _selectedCategory.flatMapLatest {
                     podcastCategoryFilterUseCase(it)
                 },
-                selectedLibraryPodcast.flatMapLatest {
-                    episodeStore.episodesInPodcast(
-                        podcastUri = it?.uri ?: "",
+                subscribedPodcasts.flatMapLatest { podcasts ->
+                    episodeStore.episodesInPodcasts(
+                        podcastUris = podcasts.map { it.podcast.uri },
                         limit = 20
                     )
                 }
@@ -175,8 +181,7 @@ class HomeViewModel @Inject constructor(
 
 private fun List<EpisodeToPodcast>.asLibrary(): LibraryInfo =
     LibraryInfo(
-        podcast = this.firstOrNull()?.podcast?.asExternalModel(),
-        episodes = this.map { it.episode.asExternalModel() }
+        episodes = this.map { it.asPodcastToEpisodeInfo() }
     )
 
 enum class HomeCategory {

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

@@ -18,8 +18,8 @@ package com.example.jetcaster.ui.home
 
 import com.example.jetcaster.core.model.CategoryInfo
 import com.example.jetcaster.core.model.EpisodeInfo
-import com.example.jetcaster.core.model.PodcastCategoryEpisode
 import com.example.jetcaster.core.model.PodcastInfo
+import com.example.jetcaster.core.model.PodcastToEpisodeInfo
 import java.time.OffsetDateTime
 import java.time.ZoneOffset
 
@@ -58,8 +58,8 @@ val PreviewEpisodes = listOf(
     )
 )
 
-val PreviewPodcastCategoryEpisodes = listOf(
-    PodcastCategoryEpisode(
+val PreviewPodcastEpisodes = listOf(
+    PodcastToEpisodeInfo(
         podcast = PreviewPodcasts[0],
         episode = PreviewEpisodes[0],
     )

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

@@ -40,12 +40,6 @@ fun LazyListScope.libraryItems(
     navigateToPlayer: (EpisodeInfo) -> Unit,
     onQueueEpisode: (PlayerEpisode) -> Unit
 ) {
-    val podcast = library.podcast
-    if (podcast == null || library.episodes.isEmpty()) {
-        // TODO: Empty state
-        return
-    }
-
     item {
         Text(
             text = stringResource(id = R.string.latest_episodes),
@@ -58,12 +52,12 @@ fun LazyListScope.libraryItems(
     }
 
     items(
-        library.episodes,
-        key = { it.uri }
+        library,
+        key = { it.episode.uri }
     ) { item ->
         EpisodeListItem(
-            episode = item,
-            podcast = podcast,
+            episode = item.episode,
+            podcast = item.podcast,
             onClick = navigateToPlayer,
             onQueueEpisode = onQueueEpisode,
             modifier = Modifier.fillParentMaxWidth(),
@@ -76,12 +70,6 @@ fun LazyGridScope.libraryItems(
     navigateToPlayer: (EpisodeInfo) -> Unit,
     onQueueEpisode: (PlayerEpisode) -> Unit
 ) {
-    val podcast = library.podcast
-    if (podcast == null || library.episodes.isEmpty()) {
-        // TODO: Empty state
-        return
-    }
-
     fullWidthItem {
         Text(
             text = stringResource(id = R.string.latest_episodes),
@@ -94,12 +82,12 @@ fun LazyGridScope.libraryItems(
     }
 
     items(
-        library.episodes,
-        key = { it.uri }
+        library,
+        key = { it.episode.uri }
     ) { item ->
         EpisodeListItem(
-            episode = item,
-            podcast = podcast,
+            episode = item.episode,
+            podcast = item.podcast,
             onClick = navigateToPlayer,
             onQueueEpisode = onQueueEpisode,
             modifier = Modifier.fillMaxWidth()