music: add playlist song sorting

Add the internal sort modes for playlist songs.

Theoretically this might be better as playlist-specific, but it's
harder to integrate that currently.

app/src/main/java/org/oxycblt/auxio/music/MusicSettings.kt

@@ -60,9 +60,11 @@ interface MusicSettings : Settings<MusicSettings.Listener> {
     var albumSongSort: Sort
     /** The [Sort] mode used in an [Artist]'s [Song] list. */
     var artistSongSort: Sort
-    /** The [Sort] mode used in an [Genre]'s [Song] list. */
+    /** The [Sort] mode used in a [Genre]'s [Song] list. */
     var genreSongSort: Sort
-    /** The [] */
+    /** The [Sort] mode used in a [Playlist]'s [Song] list, or null if sorting by original ordering. */
+    var playlistSongSort: Sort?
+
     interface Listener {
         /** Called when a setting controlling how music is loaded has changed. */
         fun onIndexingSettingChanged() {}
@@ -222,6 +224,16 @@ class MusicSettingsImpl @Inject constructor(@ApplicationContext context: Context
             }
         }
 
+    override var playlistSongSort: Sort?
+        get() = Sort.fromIntCode(sharedPreferences.getInt(
+                    getString(R.string.set_key_playlist_songs_sort), Int.MIN_VALUE))
+        set(value) {
+            sharedPreferences.edit {
+                putInt(getString(R.string.lbl_playlist), value?.intCode ?: -1)
+                apply()
+            }
+        }
+
     override fun onSettingChanged(key: String, listener: MusicSettings.Listener) {
         // TODO: Differentiate "hard reloads" (Need the cache) and "Soft reloads"
         //  (just need to manipulate data)

app/src/main/java/org/oxycblt/auxio/playback/PlaybackViewModel.kt

@@ -20,6 +20,7 @@ package org.oxycblt.auxio.playback
 
 import androidx.lifecycle.ViewModel
 import androidx.lifecycle.viewModelScope
+import androidx.room.util.query
 import dagger.hilt.android.lifecycle.HiltViewModel
 import javax.inject.Inject
 import kotlinx.coroutines.Job
@@ -288,10 +289,11 @@ constructor(
                 is Genre -> musicSettings.genreSongSort
                 is Artist -> musicSettings.artistSongSort
                 is Album -> musicSettings.albumSongSort
-                is Playlist -> TODO("handle this")
+                is Playlist -> musicSettings.playlistSongSort
                 null -> musicSettings.songSort
             }
-        val queue = sort.songs(parent?.songs ?: deviceLibrary.songs)
+        val songs = parent?.songs ?: deviceLibrary.songs
+        val queue = sort?.songs(songs) ?: songs
         playbackManager.play(song, parent, queue, shuffled)
     }
 
@@ -489,11 +491,11 @@ constructor(
     private fun selectionToSongs(selection: List<Music>): List<Song> {
         return selection.flatMap {
             when (it) {
+                is Song -> listOf(it)
                 is Album -> musicSettings.albumSongSort.songs(it.songs)
                 is Artist -> musicSettings.artistSongSort.songs(it.songs)
                 is Genre -> musicSettings.genreSongSort.songs(it.songs)
-                is Song -> listOf(it)
-                is Playlist -> TODO("handle this")
+                is Playlist -> musicSettings.playlistSongSort?.songs(it.songs) ?: it.songs
             }
         }
     }

app/src/main/res/values/settings.xml

@@ -52,6 +52,7 @@
     <string name="set_key_album_songs_sort" translatable="false">auxio_album_sort</string>
     <string name="set_key_artist_songs_sort" translatable="false">auxio_artist_sort</string>
     <string name="set_key_genre_songs_sort" translatable="false">auxio_genre_sort</string>
+    <string name="set_key_playlist_songs_sort" translatable="false">auxio_playlist_sort</string>
 
     <string-array name="entries_theme">
         <item>@string/set_theme_auto</item>