home: replace list only when resorting

Leverage the new UpdateInstructions system to allow the home view to
diff the lists on music updates, and then replace the lists on
resorting events.

This just improves quality-of-life overall.

app/src/main/java/org/oxycblt/auxio/home/HomeFragment.kt

@@ -145,7 +145,7 @@ class HomeFragment :
         // --- VIEWMODEL SETUP ---
         collect(homeModel.shouldRecreate, ::handleRecreate)
         collectImmediately(homeModel.currentTabMode, ::updateCurrentTab)
-        collectImmediately(homeModel.songLists, homeModel.isFastScrolling, ::updateFab)
+        collectImmediately(homeModel.songsList, homeModel.isFastScrolling, ::updateFab)
         collectImmediately(musicModel.indexerState, ::updateIndexerState)
         collect(navModel.exploreNavigationItem, ::handleNavigation)
         collectImmediately(selectionModel.selected, ::updateSelection)

app/src/main/java/org/oxycblt/auxio/home/HomeViewModel.kt

@@ -22,6 +22,7 @@ import androidx.lifecycle.AndroidViewModel
 import kotlinx.coroutines.flow.MutableStateFlow
 import kotlinx.coroutines.flow.StateFlow
 import org.oxycblt.auxio.home.tabs.Tab
+import org.oxycblt.auxio.list.UpdateInstructions
 import org.oxycblt.auxio.music.*
 import org.oxycblt.auxio.music.MusicStore
 import org.oxycblt.auxio.music.library.Library
@@ -42,13 +43,19 @@ class HomeViewModel(application: Application) :
 
     private val _songsList = MutableStateFlow(listOf<Song>())
     /** A list of [Song]s, sorted by the preferred [Sort], to be shown in the home view. */
-    val songLists: StateFlow<List<Song>>
+    val songsList: StateFlow<List<Song>>
         get() = _songsList
+    /** Specifies how to update [songsList] when it changes. */
+    var songsListInstructions: UpdateInstructions? = null
+        private set
 
     private val _albumsLists = MutableStateFlow(listOf<Album>())
     /** A list of [Album]s, sorted by the preferred [Sort], to be shown in the home view. */
     val albumsList: StateFlow<List<Album>>
         get() = _albumsLists
+    /** Specifies how to update [albumsList] when it changes. */
+    var albumsListInstructions: UpdateInstructions? = null
+        private set
 
     private val _artistsList = MutableStateFlow(listOf<Artist>())
     /**
@@ -58,11 +65,17 @@ class HomeViewModel(application: Application) :
      */
     val artistsList: MutableStateFlow<List<Artist>>
         get() = _artistsList
+    /** Specifies how to update [artistsList] when it changes. */
+    var artistsListInstructions: UpdateInstructions? = null
+        private set
 
     private val _genresList = MutableStateFlow(listOf<Genre>())
     /** A list of [Genre]s, sorted by the preferred [Sort], to be shown in the home view. */
     val genresList: StateFlow<List<Genre>>
         get() = _genresList
+    /** Specifies how to update [genresList] when it changes. */
+    var genresListInstructions: UpdateInstructions? = null
+        private set
 
     /** The [MusicMode] to use when playing a [Song] from the UI. */
     val playbackMode: MusicMode
@@ -107,8 +120,11 @@ class HomeViewModel(application: Application) :
             logD("Library changed, refreshing library")
             // Get the each list of items in the library to use as our list data.
             // Applying the preferred sorting to them.
+            songsListInstructions = UpdateInstructions.DIFF
             _songsList.value = musicSettings.songSort.songs(library.songs)
+            albumsListInstructions = UpdateInstructions.DIFF
             _albumsLists.value = musicSettings.albumSort.albums(library.albums)
+            artistsListInstructions = UpdateInstructions.DIFF
             _artistsList.value =
                 musicSettings.artistSort.artists(
                     if (homeSettings.shouldHideCollaborators) {
@@ -117,6 +133,7 @@ class HomeViewModel(application: Application) :
                     } else {
                         library.artists
                     })
+            genresListInstructions = UpdateInstructions.DIFF
             _genresList.value = musicSettings.genreSort.genres(library.genres)
         }
     }
@@ -133,23 +150,6 @@ class HomeViewModel(application: Application) :
         onLibraryChanged(musicStore.library)
     }
 
-    /**
-     * Update [currentTabMode] to reflect a new ViewPager2 position
-     * @param pagerPos The new position of the ViewPager2 instance.
-     */
-    fun synchronizeTabPosition(pagerPos: Int) {
-        logD("Updating current tab to ${currentTabModes[pagerPos]}")
-        _currentTabMode.value = currentTabModes[pagerPos]
-    }
-
-    /**
-     * Mark the recreation process as complete.
-     * @see shouldRecreate
-     */
-    fun finishRecreate() {
-        _shouldRecreate.value = false
-    }
-
     /**
      * Get the preferred [Sort] for a given [Tab].
      * @param tabMode The [MusicMode] of the [Tab] desired.
@@ -173,23 +173,70 @@ class HomeViewModel(application: Application) :
         when (_currentTabMode.value) {
             MusicMode.SONGS -> {
                 musicSettings.songSort = sort
+                songsListInstructions = UpdateInstructions.REPLACE
                 _songsList.value = sort.songs(_songsList.value)
             }
             MusicMode.ALBUMS -> {
                 musicSettings.albumSort = sort
+                albumsListInstructions = UpdateInstructions.REPLACE
                 _albumsLists.value = sort.albums(_albumsLists.value)
             }
             MusicMode.ARTISTS -> {
                 musicSettings.artistSort = sort
+                artistsListInstructions = UpdateInstructions.REPLACE
                 _artistsList.value = sort.artists(_artistsList.value)
             }
             MusicMode.GENRES -> {
                 musicSettings.genreSort = sort
+                genresListInstructions = UpdateInstructions.REPLACE
                 _genresList.value = sort.genres(_genresList.value)
             }
         }
     }
 
+    /** Signal that the specified [UpdateInstructions] in [songsListInstructions] were performed. */
+    fun finishSongsListInstructions() {
+        songsListInstructions = null
+    }
+
+    /**
+     * Signal that the specified [UpdateInstructions] in [albumsListInstructions] were performed.
+     */
+    fun finishAlbumsListInstructions() {
+        albumsListInstructions = null
+    }
+
+    /**
+     * Signal that the specified [UpdateInstructions] in [artistsListInstructions] were performed.
+     */
+    fun finishArtistsListInstructions() {
+        artistsListInstructions = null
+    }
+
+    /**
+     * Signal that the specified [UpdateInstructions] in [genresListInstructions] were performed.
+     */
+    fun finishGenresListInstructions() {
+        genresListInstructions = null
+    }
+
+    /**
+     * Update [currentTabMode] to reflect a new ViewPager2 position
+     * @param pagerPos The new position of the ViewPager2 instance.
+     */
+    fun synchronizeTabPosition(pagerPos: Int) {
+        logD("Updating current tab to ${currentTabModes[pagerPos]}")
+        _currentTabMode.value = currentTabModes[pagerPos]
+    }
+
+    /**
+     * Mark the recreation process as complete.
+     * @see shouldRecreate
+     */
+    fun finishRecreate() {
+        _shouldRecreate.value = false
+    }
+
     /**
      * Update whether the user is fast scrolling or not in the home view.
      * @param isFastScrolling true if the user is currently fast scrolling, false otherwise.

app/src/main/java/org/oxycblt/auxio/home/list/AlbumListFragment.kt

@@ -66,7 +66,7 @@ class AlbumListFragment :
             listener = this@AlbumListFragment
         }
 
-        collectImmediately(homeModel.albumsList, albumAdapter::replaceList)
+        collectImmediately(homeModel.albumsList, ::updateList)
         collectImmediately(selectionModel.selected, ::updateSelection)
         collectImmediately(playbackModel.parent, playbackModel.isPlaying, ::updatePlayback)
     }
@@ -130,6 +130,11 @@ class AlbumListFragment :
         openMusicMenu(anchor, R.menu.menu_album_actions, item)
     }
 
+    private fun updateList(albums: List<Album>) {
+        albumAdapter.submitList(albums, homeModel.albumsListInstructions ?: UpdateInstructions.DIFF)
+        homeModel.finishAlbumsListInstructions()
+    }
+
     private fun updateSelection(selection: List<Music>) {
         albumAdapter.setSelected(selection.filterIsInstanceTo(mutableSetOf()))
     }

app/src/main/java/org/oxycblt/auxio/home/list/ArtistListFragment.kt

@@ -64,7 +64,7 @@ class ArtistListFragment :
             listener = this@ArtistListFragment
         }
 
-        collectImmediately(homeModel.artistsList, artistAdapter::replaceList)
+        collectImmediately(homeModel.artistsList, ::updateList)
         collectImmediately(selectionModel.selected, ::updateSelection)
         collectImmediately(playbackModel.parent, playbackModel.isPlaying, ::updatePlayback)
     }
@@ -108,6 +108,12 @@ class ArtistListFragment :
         openMusicMenu(anchor, R.menu.menu_artist_actions, item)
     }
 
+    private fun updateList(artists: List<Artist>) {
+        artistAdapter.submitList(
+            artists, homeModel.artistsListInstructions ?: UpdateInstructions.DIFF)
+        homeModel.finishArtistsListInstructions()
+    }
+
     private fun updateSelection(selection: List<Music>) {
         artistAdapter.setSelected(selection.filterIsInstanceTo(mutableSetOf()))
     }

app/src/main/java/org/oxycblt/auxio/home/list/GenreListFragment.kt

@@ -63,7 +63,7 @@ class GenreListFragment :
             listener = this@GenreListFragment
         }
 
-        collectImmediately(homeModel.genresList, genreAdapter::replaceList)
+        collectImmediately(homeModel.genresList, ::updateList)
         collectImmediately(selectionModel.selected, ::updateSelection)
         collectImmediately(playbackModel.parent, playbackModel.isPlaying, ::updatePlayback)
     }
@@ -107,6 +107,12 @@ class GenreListFragment :
         openMusicMenu(anchor, R.menu.menu_artist_actions, item)
     }
 
+    private fun updateList(artists: List<Genre>) {
+        genreAdapter.submitList(
+            artists, homeModel.genresListInstructions ?: UpdateInstructions.DIFF)
+        homeModel.finishGenresListInstructions()
+    }
+
     private fun updateSelection(selection: List<Music>) {
         genreAdapter.setSelected(selection.filterIsInstanceTo(mutableSetOf()))
     }

app/src/main/java/org/oxycblt/auxio/home/list/SongListFragment.kt

@@ -69,7 +69,7 @@ class SongListFragment :
             listener = this@SongListFragment
         }
 
-        collectImmediately(homeModel.songLists, songAdapter::replaceList)
+        collectImmediately(homeModel.songsList, ::updateList)
         collectImmediately(selectionModel.selected, ::updateSelection)
         collectImmediately(
             playbackModel.song, playbackModel.parent, playbackModel.isPlaying, ::updatePlayback)
@@ -85,7 +85,7 @@ class SongListFragment :
     }
 
     override fun getPopup(pos: Int): String? {
-        val song = homeModel.songLists.value[pos]
+        val song = homeModel.songsList.value[pos]
         // Change how we display the popup depending on the current sort mode.
         // Note: We don't use the more correct individual artist name here, as sorts are largely
         // based off the names of the parent objects and not the child objects.
@@ -137,6 +137,11 @@ class SongListFragment :
         openMusicMenu(anchor, R.menu.menu_song_actions, item)
     }
 
+    private fun updateList(songs: List<Song>) {
+        songAdapter.submitList(songs, homeModel.songsListInstructions ?: UpdateInstructions.DIFF)
+        homeModel.finishSongsListInstructions()
+    }
+
     private fun updateSelection(selection: List<Music>) {
         songAdapter.setSelected(selection.filterIsInstanceTo(mutableSetOf()))
     }

app/src/main/java/org/oxycblt/auxio/util/ContextUtil.kt

@@ -18,7 +18,6 @@
 package org.oxycblt.auxio.util
 
 import android.app.PendingIntent
-import android.content.ActivityNotFoundException
 import android.content.Context
 import android.content.Intent
 import android.content.res.ColorStateList
@@ -27,7 +26,6 @@ import android.os.Build
 import android.util.TypedValue
 import android.view.LayoutInflater
 import android.widget.Toast
-import androidx.activity.result.ActivityResultLauncher
 import androidx.annotation.AttrRes
 import androidx.annotation.ColorRes
 import androidx.annotation.DimenRes