music: modify model configuration

Do a couple things to the music models:
1. Make the genre field non-nullable. This is because I beleive I've
largely eliminated the genre bugs in previous versions and future ones
can be caught with a crash screen I plan to add.
2. Make the initial album grouping process use hashCode instead of a
pair of names. This just helps with loading speed in general, albeit I
am slightly worried that it may result in improper grouping if some
edge case appears.

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

@@ -65,17 +65,17 @@ data class Song(
     /** The track number of this song. */
     val track: Int,
     /** Internal field. Do not use. */
-    val _mediaStoreId: Long,
+    val internalMediaStoreId: Long,
     /** Internal field. Do not use. */
-    val _mediaStoreArtistName: String?,
+    val internalMediaStoreArtistName: String?,
     /** Internal field. Do not use. */
-    val _mediaStoreAlbumArtistName: String?,
+    val internalMediaStoreAlbumArtistName: String?,
     /** Internal field. Do not use. */
-    val _mediaStoreAlbumId: Long,
+    val internalMediaStoreAlbumId: Long,
     /** Internal field. Do not use. */
-    val _mediaStoreAlbumName: String,
+    val internalMediaStoreAlbumName: String,
     /** Internal field. Do not use. */
-    val _mediaStoreYear: Int
+    val internalMediaStoreYear: Int
 ) : Music() {
     override val id: Long get() {
         var result = name.hashCode().toLong()
@@ -88,7 +88,7 @@ data class Song(
 
     /** The URI for this song. */
     val uri: Uri get() = ContentUris.withAppendedId(
-        MediaStore.Audio.Media.EXTERNAL_CONTENT_URI, _mediaStoreId
+        MediaStore.Audio.Media.EXTERNAL_CONTENT_URI, internalMediaStoreId
     )
     /** The duration of this song, in seconds (rounded down) */
     val seconds: Long get() = duration / 1000
@@ -100,8 +100,8 @@ data class Song(
     val album: Album get() = requireNotNull(mAlbum)
 
     var mGenre: Genre? = null
-    /** The genre of this song. May be null due to MediaStore insanity. */
+    /** The genre of this song. Will be an "unknown genre" if the song does not have any. */
-    val genre: Genre? get() = mGenre
+    val genre: Genre get() = requireNotNull(mGenre)
 
     /** An album name resolved to this song in particular. */
     val resolvedAlbumName: String get() =
@@ -109,15 +109,29 @@ data class Song(
 
     /** An artist name resolved to this song in particular. */
     val resolvedArtistName: String get() =
-        _mediaStoreArtistName ?: album.artist.resolvedName
+        internalMediaStoreArtistName ?: album.artist.resolvedName
+
+    /** Internal field. Do not use. */
+    val internalGroupingId: Int get() {
+        var result = internalGroupingArtistName.lowercase().hashCode()
+        result = 31 * result + internalMediaStoreAlbumName.lowercase().hashCode()
+        return result
+    }
+
+    /** Internal field. Do not use. */
+    val internalGroupingArtistName: String get() = internalMediaStoreAlbumArtistName
+        ?: internalMediaStoreArtistName ?: MediaStore.UNKNOWN_STRING
+
+    /** Internal field. Do not use. **/
+    val internalMissingGenre: Boolean get() = mGenre == null
 
     /** Internal method. Do not use. */
-    fun mediaStoreLinkAlbum(album: Album) {
+    fun internalLinkAlbum(album: Album) {
         mAlbum = album
     }
 
     /** Internal method. Do not use. */
-    fun mediaStoreLinkGenre(genre: Genre) {
+    fun internalLinkGenre(genre: Genre) {
         mGenre = genre
     }
 }
@@ -134,11 +148,11 @@ data class Album(
     /** The songs of this album. */
     val songs: List<Song>,
     /** Internal field. Do not use. */
-    val _mediaStoreArtistName: String,
+    val internalGroupingArtistName: String,
 ) : MusicParent() {
     init {
         for (song in songs) {
-            song.mediaStoreLinkAlbum(this)
+            song.internalLinkAlbum(this)
         }
     }
 
@@ -165,7 +179,7 @@ data class Album(
         artist.resolvedName
 
     /** Internal method. Do not use. */
-    fun mediaStoreLinkArtist(artist: Artist) {
+    fun internalLinkArtist(artist: Artist) {
         mArtist = artist
     }
 }
@@ -182,7 +196,7 @@ data class Artist(
 ) : MusicParent() {
     init {
         for (album in albums) {
-            album.mediaStoreLinkArtist(this)
+            album.internalLinkArtist(this)
         }
     }
 
@@ -202,7 +216,7 @@ data class Genre(
 ) : MusicParent() {
     init {
         for (song in songs) {
-            song.mediaStoreLinkGenre(this)
+            song.internalLinkGenre(this)
         }
     }
 

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

@@ -92,6 +92,7 @@ class MusicLoader {
         for (song in songs) {
             try {
                 song.album.artist
+                song.genre
             } catch (e: Exception) {
                 logE("Found malformed song: ${song.name}")
                 throw e
@@ -187,18 +188,13 @@ class MusicLoader {
         }
 
         songs = songs.distinctBy {
-            it.name to it._mediaStoreAlbumName to it._mediaStoreArtistName to it._mediaStoreAlbumArtistName to it.track to it.duration
+            it.name to it.internalMediaStoreAlbumName to it.internalMediaStoreArtistName to it.internalMediaStoreAlbumArtistName to it.track to it.duration
         }.toMutableList()
 
         return songs
     }
 
     private fun buildAlbums(songs: List<Song>): List<Album> {
-        // When assigning an artist to an album, use the album artist first, then the
-        // normal artist, and then the internal representation of an unknown artist name.
-        fun Song.resolveAlbumArtistName() = _mediaStoreAlbumArtistName ?: _mediaStoreArtistName
-            ?: MediaStore.UNKNOWN_STRING
-
         // Group up songs by their lowercase artist and album name. This serves two purposes:
         // 1. Sometimes artist names can be styled differently, e.g "Rammstein" vs. "RAMMSTEIN".
         // This makes sure both of those are resolved into a single artist called "Rammstein"
@@ -209,9 +205,7 @@ class MusicLoader {
         // the template, but it seems to work pretty well.
         val albums = mutableListOf<Album>()
         val songsByAlbum = songs.groupBy { song ->
-            val albumName = song._mediaStoreAlbumName
+            song.internalGroupingId
-            val artistName = song.resolveAlbumArtistName()
-            Pair(albumName.lowercase(), artistName.lowercase())
         }
 
         for (entry in songsByAlbum) {
@@ -220,14 +214,14 @@ class MusicLoader {
             // Use the song with the latest year as our metadata song.
             // This allows us to replicate the LAST_YEAR field, which is useful as it means that
             // weird years like "0" wont show up if there are alternatives.
-            val templateSong = requireNotNull(albumSongs.maxByOrNull { it._mediaStoreYear })
+            val templateSong = requireNotNull(albumSongs.maxByOrNull { it.internalMediaStoreYear })
-            val albumName = templateSong._mediaStoreAlbumName
+            val albumName = templateSong.internalMediaStoreAlbumName
-            val albumYear = templateSong._mediaStoreYear
+            val albumYear = templateSong.internalMediaStoreYear
             val albumCoverUri = ContentUris.withAppendedId(
                 Uri.parse("content://media/external/audio/albumart"),
-                templateSong._mediaStoreAlbumId
+                templateSong.internalMediaStoreAlbumId
             )
-            val artistName = templateSong.resolveAlbumArtistName()
+            val artistName = templateSong.internalGroupingArtistName
 
             albums.add(
                 Album(
@@ -245,7 +239,7 @@ class MusicLoader {
 
     private fun buildArtists(context: Context, albums: List<Album>): List<Artist> {
         val artists = mutableListOf<Artist>()
-        val albumsByArtist = albums.groupBy { it._mediaStoreArtistName }
+        val albumsByArtist = albums.groupBy { it.internalGroupingArtistName }
 
         for (entry in albumsByArtist) {
             val artistName = entry.key
@@ -318,7 +312,7 @@ class MusicLoader {
             }
         }
 
-        val songsWithoutGenres = songs.filter { it.genre == null }
+        val songsWithoutGenres = songs.filter { it.internalMissingGenre }
 
         if (songsWithoutGenres.isNotEmpty()) {
             // Songs that don't have a genre will be thrown into an unknown genre.
@@ -350,7 +344,7 @@ class MusicLoader {
             while (cursor.moveToNext()) {
                 val id = cursor.getLong(idIndex)
 
-                songs.find { it._mediaStoreId == id }?.let { song ->
+                songs.find { it.internalMediaStoreId == id }?.let { song ->
                     genreSongs.add(song)
                 }
             }