musikr: reformat

Had to remove some, but they were outdated anyway.

app/src/main/java/org/oxycblt/auxio/image/covers/CoverModule.kt

@@ -23,7 +23,7 @@ import dagger.Module
 import dagger.Provides
 import dagger.hilt.InstallIn
 import dagger.hilt.components.SingletonComponent
-import org.oxycblt.musikr.cover.CoverIdentifier
+import org.oxycblt.musikr.cover.fs.CoverIdentifier
 
 @Module
 @InstallIn(SingletonComponent::class)

app/src/main/java/org/oxycblt/auxio/image/covers/CoverSilo.kt

@@ -19,7 +19,7 @@
 package org.oxycblt.auxio.image.covers
 
 import java.util.UUID
-import org.oxycblt.musikr.cover.CoverParams
+import org.oxycblt.musikr.cover.fs.CoverParams
 
 data class CoverSilo(val revision: UUID, val params: CoverParams) {
     override fun toString() = "${revision}.${params.resolution}.${params.quality}"

app/src/main/java/org/oxycblt/auxio/image/covers/SettingCovers.kt

@@ -23,9 +23,9 @@ import java.util.UUID
 import javax.inject.Inject
 import org.oxycblt.auxio.image.CoverMode
 import org.oxycblt.auxio.image.ImageSettings
-import org.oxycblt.musikr.cover.CoverIdentifier
-import org.oxycblt.musikr.cover.CoverParams
 import org.oxycblt.musikr.cover.MutableCovers
+import org.oxycblt.musikr.cover.fs.CoverIdentifier
+import org.oxycblt.musikr.cover.fs.CoverParams
 
 interface SettingCovers {
     suspend fun create(context: Context, revision: UUID): MutableCovers

app/src/main/java/org/oxycblt/auxio/image/covers/SiloedCovers.kt

@@ -23,21 +23,21 @@ import java.io.File
 import kotlinx.coroutines.Dispatchers
 import kotlinx.coroutines.withContext
 import org.oxycblt.musikr.cover.Cover
-import org.oxycblt.musikr.cover.CoverFormat
-import org.oxycblt.musikr.cover.CoverIdentifier
 import org.oxycblt.musikr.cover.Covers
-import org.oxycblt.musikr.cover.FileCover
-import org.oxycblt.musikr.cover.FileCovers
 import org.oxycblt.musikr.cover.MutableCovers
-import org.oxycblt.musikr.cover.MutableFileCovers
 import org.oxycblt.musikr.cover.ObtainResult
-import org.oxycblt.musikr.fs.app.AppFiles
+import org.oxycblt.musikr.cover.fs.CoverFormat
+import org.oxycblt.musikr.cover.fs.CoverIdentifier
+import org.oxycblt.musikr.cover.fs.FSCovers
+import org.oxycblt.musikr.cover.fs.FileCover
+import org.oxycblt.musikr.cover.fs.MutableFSCovers
+import org.oxycblt.musikr.fs.app.AppFS
 
-open class SiloedCovers(private val silo: CoverSilo, private val fileCovers: FileCovers) : Covers {
+open class SiloedCovers(private val silo: CoverSilo, private val FSCovers: FSCovers) : Covers {
     override suspend fun obtain(id: String): ObtainResult<SiloedCover> {
         val coverId = SiloedCoverId.parse(id) ?: return ObtainResult.Miss()
         if (coverId.silo != silo) return ObtainResult.Miss()
-        return when (val result = fileCovers.obtain(coverId.id)) {
+        return when (val result = FSCovers.obtain(coverId.id)) {
             is ObtainResult.Hit -> ObtainResult.Hit(SiloedCover(silo, result.cover))
             is ObtainResult.Miss -> ObtainResult.Miss()
         }
@@ -46,7 +46,7 @@ open class SiloedCovers(private val silo: CoverSilo, private val fileCovers: Fil
     companion object {
         suspend fun from(context: Context, silo: CoverSilo): SiloedCovers {
             val core = SiloCore.from(context, silo)
-            return SiloedCovers(silo, FileCovers(core.files, core.format))
+            return SiloedCovers(silo, FSCovers(core.files, core.format))
         }
     }
 }
@@ -55,7 +55,7 @@ class MutableSiloedCovers
 private constructor(
     private val rootDir: File,
     private val silo: CoverSilo,
-    private val fileCovers: MutableFileCovers
+    private val fileCovers: MutableFSCovers
 ) : SiloedCovers(silo, fileCovers), MutableCovers {
     override suspend fun write(data: ByteArray) = SiloedCover(silo, fileCovers.write(data))
 
@@ -77,7 +77,7 @@ private constructor(
         ): MutableSiloedCovers {
             val core = SiloCore.from(context, silo)
             return MutableSiloedCovers(
-                core.rootDir, silo, MutableFileCovers(core.files, core.format, coverIdentifier))
+                core.rootDir, silo, MutableFSCovers(core.files, core.format, coverIdentifier))
         }
     }
 }
@@ -101,7 +101,7 @@ data class SiloedCoverId(val silo: CoverSilo, val id: String) {
     }
 }
 
-private data class SiloCore(val rootDir: File, val files: AppFiles, val format: CoverFormat) {
+private data class SiloCore(val rootDir: File, val files: AppFS, val format: CoverFormat) {
     companion object {
         suspend fun from(context: Context, silo: CoverSilo): SiloCore {
             val rootDir: File
@@ -110,7 +110,7 @@ private data class SiloCore(val rootDir: File, val files: AppFiles, val format:
                 rootDir = context.coversDir()
                 revisionDir = rootDir.resolve(silo.toString()).apply { mkdirs() }
             }
-            val files = AppFiles.at(revisionDir)
+            val files = AppFS.at(revisionDir)
             val format = CoverFormat.jpeg(silo.params)
             return SiloCore(rootDir, files, format)
         }

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

@@ -29,6 +29,7 @@ import kotlinx.coroutines.withContext
 import kotlinx.coroutines.yield
 import org.oxycblt.auxio.image.covers.SettingCovers
 import org.oxycblt.auxio.music.MusicRepository.IndexingWorker
+import org.oxycblt.auxio.music.shim.WriteOnlySongCache
 import org.oxycblt.musikr.IndexingProgress
 import org.oxycblt.musikr.Interpretation
 import org.oxycblt.musikr.Library
@@ -38,7 +39,8 @@ import org.oxycblt.musikr.MutableLibrary
 import org.oxycblt.musikr.Playlist
 import org.oxycblt.musikr.Song
 import org.oxycblt.musikr.Storage
-import org.oxycblt.musikr.cache.StoredCache
+import org.oxycblt.musikr.cache.MutableSongCache
+import org.oxycblt.musikr.log.Logger
 import org.oxycblt.musikr.playlist.db.StoredPlaylists
 import org.oxycblt.musikr.tag.interpret.Naming
 import org.oxycblt.musikr.tag.interpret.Separators
@@ -236,7 +238,7 @@ class MusicRepositoryImpl
 @Inject
 constructor(
     @ApplicationContext private val context: Context,
-    private val storedCache: StoredCache,
+    private val songCache: MutableSongCache,
     private val storedPlaylists: StoredPlaylists,
     private val settingCovers: SettingCovers,
     private val musicSettings: MusicSettings
@@ -387,13 +389,14 @@ constructor(
 
         val currentRevision = musicSettings.revision
         val newRevision = currentRevision?.takeIf { withCache } ?: UUID.randomUUID()
-        val cache = if (withCache) storedCache.visible() else storedCache.invisible()
+        val cache = if (withCache) WriteOnlySongCache(songCache) else songCache
         val covers = settingCovers.create(context, newRevision)
         val storage = Storage(cache, covers, storedPlaylists)
         val interpretation = Interpretation(nameFactory, separators)
 
         val result =
-            Musikr.new(context, storage, interpretation).run(locations, ::emitIndexingProgress)
+            Musikr.new(context, storage, interpretation, Logger.root())
+                .run(locations, ::emitIndexingProgress)
         // Music loading completed, update the revision right now so we re-use this work
         // later.
         musicSettings.revision = newRevision

app/src/main/java/org/oxycblt/auxio/music/shim/MusikrShimModule.kt

@@ -25,7 +25,8 @@ import dagger.hilt.InstallIn
 import dagger.hilt.android.qualifiers.ApplicationContext
 import dagger.hilt.components.SingletonComponent
 import javax.inject.Singleton
-import org.oxycblt.musikr.cache.StoredCache
+import org.oxycblt.musikr.cache.MutableSongCache
+import org.oxycblt.musikr.cache.db.DBSongCache
 import org.oxycblt.musikr.playlist.db.StoredPlaylists
 
 @Module
@@ -33,7 +34,8 @@ import org.oxycblt.musikr.playlist.db.StoredPlaylists
 class MusikrShimModule {
     @Singleton
     @Provides
-    fun storedCache(@ApplicationContext context: Context) = StoredCache.from(context)
+    fun songCache(@ApplicationContext context: Context): MutableSongCache =
+        DBSongCache.from(context)
 
     @Singleton
     @Provides

app/src/main/java/org/oxycblt/auxio/music/shim/WriteOnlyStoredCache.kt

@@ -0,0 +1,41 @@
+/*
+ * Copyright (c) 2025 Auxio Project
+ * WriteOnlyStoredCache.kt is part of Auxio.
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+ 
+package org.oxycblt.auxio.music.shim
+
+import org.oxycblt.musikr.Song
+import org.oxycblt.musikr.cache.CacheResult
+import org.oxycblt.musikr.cache.CachedSong
+import org.oxycblt.musikr.cache.MutableSongCache
+import org.oxycblt.musikr.fs.device.DeviceFile
+
+class WriteOnlySongCache(private val songCache: MutableSongCache) : MutableSongCache {
+    override suspend fun read(file: DeviceFile) =
+        when (val result = songCache.read(file)) {
+            is CacheResult.Hit -> CacheResult.Outdated(file, result.song.addedMs)
+            else -> result
+        }
+
+    override suspend fun write(song: CachedSong) {
+        songCache.write(song)
+    }
+
+    override suspend fun cleanup(exclude: Collection<Song>) {
+        songCache.cleanup(exclude)
+    }
+}

musikr/src/main/java/org/oxycblt/musikr/Config.kt

@@ -18,26 +18,25 @@
  
 package org.oxycblt.musikr
 
-import org.oxycblt.musikr.cache.Cache
+import org.oxycblt.musikr.cache.MutableSongCache
 import org.oxycblt.musikr.cover.MutableCovers
 import org.oxycblt.musikr.playlist.db.StoredPlaylists
 import org.oxycblt.musikr.tag.interpret.Naming
 import org.oxycblt.musikr.tag.interpret.Separators
 
-/** Side-effect laden [Storage] for use during music loading and [MutableLibrary] operation. */
+/** Side-effect repositories for use during music loading and [MutableLibrary] operation. */
 data class Storage(
     /**
-     * A factory producing a repository of cached metadata to read and write from over the course of
-     * music loading. This will only be used during music loading.
+     * A repository of cached metadata to read and write from over the course of music loading only.
      */
-    val cache: Cache.Factory,
+    val cache: MutableSongCache,
 
     /**
      * A repository of cover images to for re-use during music loading. Should be kept in lock-step
-     * with the cache for best performance. This will be used during music loading and when
+     * with the [cache] for best performance. This will be used during music loading and when
      * retrieving cover information from the library.
      */
-    val storedCovers: MutableCovers,
+    val covers: MutableCovers,
 
     /**
      * A repository of user-created playlists that should also be loaded into the library. This will

musikr/src/main/java/org/oxycblt/musikr/Musikr.kt

@@ -19,16 +19,24 @@
 package org.oxycblt.musikr
 
 import android.content.Context
+import android.os.Build
 import kotlinx.coroutines.channels.Channel
 import kotlinx.coroutines.coroutineScope
 import kotlinx.coroutines.flow.buffer
+import kotlinx.coroutines.flow.filterIsInstance
+import kotlinx.coroutines.flow.merge
 import kotlinx.coroutines.flow.onCompletion
 import kotlinx.coroutines.flow.onEach
 import kotlinx.coroutines.flow.onStart
 import org.oxycblt.musikr.fs.MusicLocation
+import org.oxycblt.musikr.log.Logger
+import org.oxycblt.musikr.pipeline.Divert
 import org.oxycblt.musikr.pipeline.EvaluateStep
 import org.oxycblt.musikr.pipeline.ExploreStep
+import org.oxycblt.musikr.pipeline.Explored
 import org.oxycblt.musikr.pipeline.ExtractStep
+import org.oxycblt.musikr.pipeline.Extracted
+import org.oxycblt.musikr.pipeline.divert
 
 /**
  * A highly opinionated, multi-threaded device music library.
@@ -62,18 +70,25 @@ interface Musikr {
          * Create a new instance from the given configuration.
          *
          * @param context The context to use for loading resources.
+         * @param logger The logger to use for logging events.
          * @param storage Side-effect laden storage for use within the music loader **and** when
          *   mutating [MutableLibrary]. You should take responsibility for managing their long-term
          *   state.
          * @param interpretation The configuration to use for interpreting certain vague tags. This
          *   should be configured by the user, if possible.
          */
-        fun new(context: Context, storage: Storage, interpretation: Interpretation): Musikr =
+        fun new(
+            context: Context,
+            storage: Storage,
+            interpretation: Interpretation,
+            logger: Logger
+        ): Musikr =
             MusikrImpl(
+                logger,
                 storage,
-                ExploreStep.from(context, storage),
-                ExtractStep.from(context, storage),
-                EvaluateStep.new(storage, interpretation))
+                ExploreStep.from(context, storage, logger),
+                ExtractStep.from(context, storage, logger),
+                EvaluateStep.new(storage, interpretation, logger))
     }
 }
 
@@ -110,6 +125,7 @@ sealed interface IndexingProgress {
 }
 
 private class MusikrImpl(
+    private val logger: Logger,
     private val storage: Storage,
     private val exploreStep: ExploreStep,
     private val extractStep: ExtractStep,
@@ -119,6 +135,16 @@ private class MusikrImpl(
         locations: List<MusicLocation>,
         onProgress: suspend (IndexingProgress) -> Unit
     ) = coroutineScope {
+        logger.d(
+            "musikr start.",
+            "hw:",
+            Build.MANUFACTURER,
+            Build.MODEL,
+            Build.SUPPORTED_ABIS.joinToString(" "),
+            "sw:",
+            Build.VERSION.SDK_INT,
+            Build.DISPLAY)
+
         var exploredCount = 0
         var extractedCount = 0
         val explored =
@@ -127,13 +153,28 @@ private class MusikrImpl(
                 .buffer(Channel.UNLIMITED)
                 .onStart { onProgress(IndexingProgress.Songs(0, 0)) }
                 .onEach { onProgress(IndexingProgress.Songs(extractedCount, ++exploredCount)) }
+
+        val typeDiversion =
+            explored.divert {
+                when (it) {
+                    is Explored.Known -> Divert.Right(it)
+                    is Explored.New -> Divert.Left(it)
+                }
+            }
+        val known = typeDiversion.right
+        val new = typeDiversion.left
+
         val extracted =
             extractStep
-                .extract(explored)
+                .extract(new)
                 .buffer(Channel.UNLIMITED)
                 .onEach { onProgress(IndexingProgress.Songs(++extractedCount, exploredCount)) }
                 .onCompletion { onProgress(IndexingProgress.Indeterminate) }
-        val library = evaluateStep.evaluate(extracted)
+
+        val complete =
+            merge(typeDiversion.manager, known, extracted.filterIsInstance<Extracted.Valid>())
+        val library = evaluateStep.evaluate(complete)
+
         LibraryResultImpl(storage, library)
     }
 }
@@ -143,6 +184,7 @@ private class LibraryResultImpl(
     override val library: MutableLibrary
 ) : LibraryResult {
     override suspend fun cleanup() {
-        storage.storedCovers.cleanup(library.songs.mapNotNull { it.cover })
+        storage.cache.cleanup(library.songs)
+        storage.covers.cleanup(library.songs.mapNotNull { it.cover })
     }
 }

musikr/src/main/java/org/oxycblt/musikr/cache/Cache.kt

@@ -1,41 +0,0 @@
-/*
- * Copyright (c) 2024 Auxio Project
- * Cache.kt is part of Auxio.
- *
- * This program is free software: you can redistribute it and/or modify
- * it under the terms of the GNU General Public License as published by
- * the Free Software Foundation, either version 3 of the License, or
- * (at your option) any later version.
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
- * GNU General Public License for more details.
- *
- * You should have received a copy of the GNU General Public License
- * along with this program.  If not, see <https://www.gnu.org/licenses/>.
- */
- 
-package org.oxycblt.musikr.cache
-
-import org.oxycblt.musikr.cover.Covers
-import org.oxycblt.musikr.fs.DeviceFile
-import org.oxycblt.musikr.pipeline.RawSong
-
-abstract class Cache {
-    internal abstract suspend fun read(file: DeviceFile, covers: Covers): CacheResult
-
-    internal abstract suspend fun write(song: RawSong)
-
-    internal abstract suspend fun finalize()
-
-    abstract class Factory {
-        internal abstract fun open(): Cache
-    }
-}
-
-internal sealed interface CacheResult {
-    data class Hit(val song: RawSong) : CacheResult
-
-    data class Miss(val file: DeviceFile, val addedMs: Long?) : CacheResult
-}

musikr/src/main/java/org/oxycblt/musikr/cache/CacheDatabase.kt

@@ -1,208 +0,0 @@
-/*
- * Copyright (c) 2023 Auxio Project
- * CacheDatabase.kt is part of Auxio.
- *
- * This program is free software: you can redistribute it and/or modify
- * it under the terms of the GNU General Public License as published by
- * the Free Software Foundation, either version 3 of the License, or
- * (at your option) any later version.
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
- * GNU General Public License for more details.
- *
- * You should have received a copy of the GNU General Public License
- * along with this program.  If not, see <https://www.gnu.org/licenses/>.
- */
- 
-package org.oxycblt.musikr.cache
-
-import android.content.Context
-import androidx.room.Dao
-import androidx.room.Database
-import androidx.room.Entity
-import androidx.room.Insert
-import androidx.room.OnConflictStrategy
-import androidx.room.PrimaryKey
-import androidx.room.Query
-import androidx.room.Room
-import androidx.room.RoomDatabase
-import androidx.room.Transaction
-import androidx.room.TypeConverter
-import androidx.room.TypeConverters
-import org.oxycblt.musikr.cover.Covers
-import org.oxycblt.musikr.cover.ObtainResult
-import org.oxycblt.musikr.fs.DeviceFile
-import org.oxycblt.musikr.metadata.Properties
-import org.oxycblt.musikr.pipeline.RawSong
-import org.oxycblt.musikr.tag.Date
-import org.oxycblt.musikr.tag.parse.ParsedTags
-import org.oxycblt.musikr.util.correctWhitespace
-import org.oxycblt.musikr.util.splitEscaped
-
-@Database(entities = [CachedSong::class], version = 57, exportSchema = false)
-internal abstract class CacheDatabase : RoomDatabase() {
-    abstract fun visibleDao(): VisibleCacheDao
-
-    abstract fun invisibleDao(): InvisibleCacheDao
-
-    abstract fun writeDao(): CacheWriteDao
-
-    companion object {
-        fun from(context: Context) =
-            Room.databaseBuilder(
-                    context.applicationContext, CacheDatabase::class.java, "music_cache.db")
-                .fallbackToDestructiveMigration()
-                .build()
-    }
-}
-
-@Dao
-internal interface VisibleCacheDao {
-    @Query("SELECT * FROM CachedSong WHERE uri = :uri")
-    suspend fun selectSong(uri: String): CachedSong?
-
-    @Query("SELECT addedMs FROM CachedSong WHERE uri = :uri")
-    suspend fun selectAddedMs(uri: String): Long?
-
-    @Transaction suspend fun touch(uri: String) = updateTouchedNs(uri, System.nanoTime())
-
-    @Query("UPDATE CachedSong SET touchedNs = :nowNs WHERE uri = :uri")
-    suspend fun updateTouchedNs(uri: String, nowNs: Long)
-}
-
-@Dao
-internal interface InvisibleCacheDao {
-    @Query("SELECT addedMs FROM CachedSong WHERE uri = :uri")
-    suspend fun selectAddedMs(uri: String): Long?
-}
-
-@Dao
-internal interface CacheWriteDao {
-    @Insert(onConflict = OnConflictStrategy.REPLACE) suspend fun updateSong(cachedSong: CachedSong)
-
-    @Query("DELETE FROM CachedSong WHERE touchedNs < :now") suspend fun pruneOlderThan(now: Long)
-}
-
-@Entity
-@TypeConverters(CachedSong.Converters::class)
-internal data class CachedSong(
-    @PrimaryKey val uri: String,
-    val modifiedMs: Long,
-    val addedMs: Long,
-    val touchedNs: Long,
-    val mimeType: String,
-    val durationMs: Long,
-    val bitrateHz: Int,
-    val sampleRateHz: Int,
-    val musicBrainzId: String?,
-    val name: String,
-    val sortName: String?,
-    val track: Int?,
-    val disc: Int?,
-    val subtitle: String?,
-    val date: Date?,
-    val albumMusicBrainzId: String?,
-    val albumName: String?,
-    val albumSortName: String?,
-    val releaseTypes: List<String>,
-    val artistMusicBrainzIds: List<String>,
-    val artistNames: List<String>,
-    val artistSortNames: List<String>,
-    val albumArtistMusicBrainzIds: List<String>,
-    val albumArtistNames: List<String>,
-    val albumArtistSortNames: List<String>,
-    val genreNames: List<String>,
-    val replayGainTrackAdjustment: Float?,
-    val replayGainAlbumAdjustment: Float?,
-    val coverId: String?,
-) {
-    suspend fun intoRawSong(file: DeviceFile, covers: Covers): RawSong? {
-        val cover =
-            when (val result = coverId?.let { covers.obtain(it) }) {
-                // We found the cover.
-                is ObtainResult.Hit -> result.cover
-                // We actually didn't find the cover, can't safely convert.
-                is ObtainResult.Miss -> return null
-                // No cover in the first place, can ignore.
-                null -> null
-            }
-        return RawSong(
-            file,
-            Properties(mimeType, durationMs, bitrateHz, sampleRateHz),
-            ParsedTags(
-                musicBrainzId = musicBrainzId,
-                name = name,
-                sortName = sortName,
-                durationMs = durationMs,
-                track = track,
-                disc = disc,
-                subtitle = subtitle,
-                date = date,
-                albumMusicBrainzId = albumMusicBrainzId,
-                albumName = albumName,
-                albumSortName = albumSortName,
-                releaseTypes = releaseTypes,
-                artistMusicBrainzIds = artistMusicBrainzIds,
-                artistNames = artistNames,
-                artistSortNames = artistSortNames,
-                albumArtistMusicBrainzIds = albumArtistMusicBrainzIds,
-                albumArtistNames = albumArtistNames,
-                albumArtistSortNames = albumArtistSortNames,
-                genreNames = genreNames,
-                replayGainTrackAdjustment = replayGainTrackAdjustment,
-                replayGainAlbumAdjustment = replayGainAlbumAdjustment),
-            cover = cover,
-            addedMs = addedMs)
-    }
-
-    object Converters {
-        @TypeConverter
-        fun fromMultiValue(values: List<String>) =
-            values.joinToString(";") { it.replace(";", "\\;") }
-
-        @TypeConverter
-        fun toMultiValue(string: String) = string.splitEscaped { it == ';' }.correctWhitespace()
-
-        @TypeConverter fun fromDate(date: Date?) = date?.toString()
-
-        @TypeConverter fun toDate(string: String?) = string?.let(Date::from)
-    }
-
-    companion object {
-        fun fromRawSong(rawSong: RawSong) =
-            CachedSong(
-                uri = rawSong.file.uri.toString(),
-                modifiedMs = rawSong.file.modifiedMs,
-                addedMs = rawSong.addedMs,
-                // Should be strictly monotonic so we don't prune this
-                // by accident later.
-                touchedNs = System.nanoTime(),
-                musicBrainzId = rawSong.tags.musicBrainzId,
-                name = rawSong.tags.name,
-                sortName = rawSong.tags.sortName,
-                durationMs = rawSong.tags.durationMs,
-                track = rawSong.tags.track,
-                disc = rawSong.tags.disc,
-                subtitle = rawSong.tags.subtitle,
-                date = rawSong.tags.date,
-                albumMusicBrainzId = rawSong.tags.albumMusicBrainzId,
-                albumName = rawSong.tags.albumName,
-                albumSortName = rawSong.tags.albumSortName,
-                releaseTypes = rawSong.tags.releaseTypes,
-                artistMusicBrainzIds = rawSong.tags.artistMusicBrainzIds,
-                artistNames = rawSong.tags.artistNames,
-                artistSortNames = rawSong.tags.artistSortNames,
-                albumArtistMusicBrainzIds = rawSong.tags.albumArtistMusicBrainzIds,
-                albumArtistNames = rawSong.tags.albumArtistNames,
-                albumArtistSortNames = rawSong.tags.albumArtistSortNames,
-                genreNames = rawSong.tags.genreNames,
-                replayGainTrackAdjustment = rawSong.tags.replayGainTrackAdjustment,
-                replayGainAlbumAdjustment = rawSong.tags.replayGainAlbumAdjustment,
-                coverId = rawSong.cover?.id,
-                mimeType = rawSong.properties.mimeType,
-                bitrateHz = rawSong.properties.bitrateKbps,
-                sampleRateHz = rawSong.properties.sampleRateHz)
-    }
-}

musikr/src/main/java/org/oxycblt/musikr/cache/SongCache.kt

@@ -0,0 +1,50 @@
+/*
+ * Copyright (c) 2024 Auxio Project
+ * SongCache.kt is part of Auxio.
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+ 
+package org.oxycblt.musikr.cache
+
+import org.oxycblt.musikr.Song
+import org.oxycblt.musikr.fs.device.DeviceFile
+import org.oxycblt.musikr.metadata.Properties
+import org.oxycblt.musikr.tag.parse.ParsedTags
+
+interface SongCache {
+    suspend fun read(file: DeviceFile): CacheResult
+}
+
+interface MutableSongCache : SongCache {
+    suspend fun write(song: CachedSong)
+
+    suspend fun cleanup(exclude: Collection<Song>)
+}
+
+data class CachedSong(
+    val file: DeviceFile,
+    val properties: Properties,
+    val tags: ParsedTags,
+    val coverId: String?,
+    val addedMs: Long
+)
+
+sealed interface CacheResult {
+    data class Hit(val song: CachedSong) : CacheResult
+
+    data class Outdated(val file: DeviceFile, val addedMs: Long) : CacheResult
+
+    data class Miss(val file: DeviceFile) : CacheResult
+}

musikr/src/main/java/org/oxycblt/musikr/cache/StoredCache.kt

@@ -1,87 +0,0 @@
-/*
- * Copyright (c) 2024 Auxio Project
- * StoredCache.kt is part of Auxio.
- *
- * This program is free software: you can redistribute it and/or modify
- * it under the terms of the GNU General Public License as published by
- * the Free Software Foundation, either version 3 of the License, or
- * (at your option) any later version.
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
- * GNU General Public License for more details.
- *
- * You should have received a copy of the GNU General Public License
- * along with this program.  If not, see <https://www.gnu.org/licenses/>.
- */
- 
-package org.oxycblt.musikr.cache
-
-import android.content.Context
-import org.oxycblt.musikr.cover.Covers
-import org.oxycblt.musikr.fs.DeviceFile
-import org.oxycblt.musikr.pipeline.RawSong
-
-interface StoredCache {
-    fun visible(): Cache.Factory
-
-    fun invisible(): Cache.Factory
-
-    companion object {
-        fun from(context: Context): StoredCache = StoredCacheImpl(CacheDatabase.from(context))
-    }
-}
-
-private class StoredCacheImpl(private val cacheDatabase: CacheDatabase) : StoredCache {
-    override fun visible(): Cache.Factory = VisibleStoredCache.Factory(cacheDatabase)
-
-    override fun invisible(): Cache.Factory = InvisibleStoredCache.Factory(cacheDatabase)
-}
-
-private abstract class BaseStoredCache(protected val writeDao: CacheWriteDao) : Cache() {
-    private val created = System.nanoTime()
-
-    override suspend fun write(song: RawSong) = writeDao.updateSong(CachedSong.fromRawSong(song))
-
-    override suspend fun finalize() {
-        // Anything not create during this cache's use implies that it has not been
-        // access during this run and should be pruned.
-        writeDao.pruneOlderThan(created)
-    }
-}
-
-private class VisibleStoredCache(private val visibleDao: VisibleCacheDao, writeDao: CacheWriteDao) :
-    BaseStoredCache(writeDao) {
-    override suspend fun read(file: DeviceFile, covers: Covers): CacheResult {
-        val song = visibleDao.selectSong(file.uri.toString()) ?: return CacheResult.Miss(file, null)
-        if (song.modifiedMs != file.modifiedMs) {
-            // We *found* this file earlier, but it's out of date.
-            // Send back it with the timestamp so it will be re-used.
-            // The touch timestamp will be updated on write.
-            return CacheResult.Miss(file, song.addedMs)
-        }
-        // Valid file, update the touch time.
-        visibleDao.touch(file.uri.toString())
-        val rawSong = song.intoRawSong(file, covers) ?: return CacheResult.Miss(file, song.addedMs)
-        return CacheResult.Hit(rawSong)
-    }
-
-    class Factory(private val cacheDatabase: CacheDatabase) : Cache.Factory() {
-        override fun open() =
-            VisibleStoredCache(cacheDatabase.visibleDao(), cacheDatabase.writeDao())
-    }
-}
-
-private class InvisibleStoredCache(
-    private val invisibleCacheDao: InvisibleCacheDao,
-    writeDao: CacheWriteDao
-) : BaseStoredCache(writeDao) {
-    override suspend fun read(file: DeviceFile, covers: Covers) =
-        CacheResult.Miss(file, invisibleCacheDao.selectAddedMs(file.uri.toString()))
-
-    class Factory(private val cacheDatabase: CacheDatabase) : Cache.Factory() {
-        override fun open() =
-            InvisibleStoredCache(cacheDatabase.invisibleDao(), cacheDatabase.writeDao())
-    }
-}

musikr/src/main/java/org/oxycblt/musikr/cache/db/DBSongCache.kt

@@ -0,0 +1,115 @@
+/*
+ * Copyright (c) 2024 Auxio Project
+ * DBSongCache.kt is part of Auxio.
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+ 
+package org.oxycblt.musikr.cache.db
+
+import android.content.Context
+import org.oxycblt.musikr.Song
+import org.oxycblt.musikr.cache.CacheResult
+import org.oxycblt.musikr.cache.CachedSong
+import org.oxycblt.musikr.cache.MutableSongCache
+import org.oxycblt.musikr.fs.device.DeviceFile
+import org.oxycblt.musikr.metadata.Properties
+import org.oxycblt.musikr.tag.parse.ParsedTags
+
+class DBSongCache
+private constructor(private val readDao: CacheReadDao, private val writeDao: CacheWriteDao) :
+    MutableSongCache {
+    override suspend fun read(file: DeviceFile): CacheResult {
+        val data = readDao.selectSong(file.uri.toString()) ?: return CacheResult.Miss(file)
+        if (data.modifiedMs != file.modifiedMs) {
+            // We *found* this file earlier, but it's out of date.
+            // Send back it with the timestamp so it will be re-used.
+            // The touch timestamp will be updated on write.
+            return CacheResult.Outdated(file, data.addedMs)
+        }
+        val cachedSong =
+            data.run {
+                CachedSong(
+                    file,
+                    Properties(mimeType, durationMs, bitrateHz, sampleRateHz),
+                    ParsedTags(
+                        musicBrainzId = musicBrainzId,
+                        name = name,
+                        sortName = sortName,
+                        durationMs = durationMs,
+                        track = track,
+                        disc = disc,
+                        subtitle = subtitle,
+                        date = date,
+                        albumMusicBrainzId = albumMusicBrainzId,
+                        albumName = albumName,
+                        albumSortName = albumSortName,
+                        releaseTypes = releaseTypes,
+                        artistMusicBrainzIds = artistMusicBrainzIds,
+                        artistNames = artistNames,
+                        artistSortNames = artistSortNames,
+                        albumArtistMusicBrainzIds = albumArtistMusicBrainzIds,
+                        albumArtistNames = albumArtistNames,
+                        albumArtistSortNames = albumArtistSortNames,
+                        genreNames = genreNames,
+                        replayGainTrackAdjustment = replayGainTrackAdjustment,
+                        replayGainAlbumAdjustment = replayGainAlbumAdjustment),
+                    coverId = coverId,
+                    addedMs = addedMs)
+            }
+        return CacheResult.Hit(cachedSong)
+    }
+
+    override suspend fun write(song: CachedSong) {
+        writeDao.updateSong(
+            CachedSongData(
+                uri = song.file.uri.toString(),
+                modifiedMs = song.file.modifiedMs,
+                addedMs = song.addedMs,
+                mimeType = song.properties.mimeType,
+                durationMs = song.properties.durationMs,
+                bitrateHz = song.properties.bitrateKbps,
+                sampleRateHz = song.properties.sampleRateHz,
+                musicBrainzId = song.tags.musicBrainzId,
+                name = song.tags.name,
+                sortName = song.tags.sortName,
+                track = song.tags.track,
+                disc = song.tags.disc,
+                subtitle = song.tags.subtitle,
+                date = song.tags.date,
+                albumMusicBrainzId = song.tags.albumMusicBrainzId,
+                albumName = song.tags.albumName,
+                albumSortName = song.tags.albumSortName,
+                releaseTypes = song.tags.releaseTypes,
+                artistMusicBrainzIds = song.tags.artistMusicBrainzIds,
+                artistNames = song.tags.artistNames,
+                artistSortNames = song.tags.artistSortNames,
+                albumArtistMusicBrainzIds = song.tags.albumArtistMusicBrainzIds,
+                albumArtistNames = song.tags.albumArtistNames,
+                albumArtistSortNames = song.tags.albumArtistSortNames,
+                genreNames = song.tags.genreNames,
+                replayGainTrackAdjustment = song.tags.replayGainTrackAdjustment,
+                replayGainAlbumAdjustment = song.tags.replayGainAlbumAdjustment,
+                coverId = song.coverId))
+    }
+
+    override suspend fun cleanup(exclude: Collection<Song>) {
+        writeDao.deleteExcludingUris(exclude.map { it.uri.toString() })
+    }
+
+    companion object {
+        fun from(context: Context) =
+            CacheDatabase.from(context).run { DBSongCache(readDao(), writeDao()) }
+    }
+}

musikr/src/main/java/org/oxycblt/musikr/cache/db/SongCacheDatabase.kt

@@ -0,0 +1,122 @@
+/*
+ * Copyright (c) 2023 Auxio Project
+ * SongCacheDatabase.kt is part of Auxio.
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+ 
+package org.oxycblt.musikr.cache.db
+
+import android.content.Context
+import androidx.room.Dao
+import androidx.room.Database
+import androidx.room.Entity
+import androidx.room.Insert
+import androidx.room.OnConflictStrategy
+import androidx.room.PrimaryKey
+import androidx.room.Query
+import androidx.room.Room
+import androidx.room.RoomDatabase
+import androidx.room.Transaction
+import androidx.room.TypeConverter
+import androidx.room.TypeConverters
+import org.oxycblt.musikr.tag.Date
+import org.oxycblt.musikr.util.correctWhitespace
+import org.oxycblt.musikr.util.splitEscaped
+
+@Database(entities = [CachedSongData::class], version = 57, exportSchema = false)
+internal abstract class CacheDatabase : RoomDatabase() {
+    abstract fun readDao(): CacheReadDao
+
+    abstract fun writeDao(): CacheWriteDao
+
+    companion object {
+        fun from(context: Context) =
+            Room.databaseBuilder(
+                    context.applicationContext, CacheDatabase::class.java, "music_cache.db")
+                .fallbackToDestructiveMigration()
+                .build()
+    }
+}
+
+@Dao
+internal interface CacheReadDao {
+    @Query("SELECT * FROM CachedSongData WHERE uri = :uri")
+    suspend fun selectSong(uri: String): CachedSongData?
+}
+
+@Dao
+internal interface CacheWriteDao {
+    @Insert(onConflict = OnConflictStrategy.REPLACE)
+    suspend fun updateSong(cachedSong: CachedSongData)
+
+    /** Delete every CachedSong whose URI is not in the uris list */
+    @Transaction
+    suspend fun deleteExcludingUris(uris: List<String>) {
+        // SQLite has a limit of 999 variables in a query
+        val chunks = uris.chunked(999)
+        for (chunk in chunks) {
+            deleteExcludingUriChunk(chunk)
+        }
+    }
+
+    @Query("DELETE FROM CachedSongData WHERE uri NOT IN (:uris)")
+    suspend fun deleteExcludingUriChunk(uris: List<String>)
+}
+
+@Entity
+@TypeConverters(CachedSongData.Converters::class)
+internal data class CachedSongData(
+    @PrimaryKey val uri: String,
+    val modifiedMs: Long,
+    val addedMs: Long,
+    val mimeType: String,
+    val durationMs: Long,
+    val bitrateHz: Int,
+    val sampleRateHz: Int,
+    val musicBrainzId: String?,
+    val name: String,
+    val sortName: String?,
+    val track: Int?,
+    val disc: Int?,
+    val subtitle: String?,
+    val date: Date?,
+    val albumMusicBrainzId: String?,
+    val albumName: String?,
+    val albumSortName: String?,
+    val releaseTypes: List<String>,
+    val artistMusicBrainzIds: List<String>,
+    val artistNames: List<String>,
+    val artistSortNames: List<String>,
+    val albumArtistMusicBrainzIds: List<String>,
+    val albumArtistNames: List<String>,
+    val albumArtistSortNames: List<String>,
+    val genreNames: List<String>,
+    val replayGainTrackAdjustment: Float?,
+    val replayGainAlbumAdjustment: Float?,
+    val coverId: String?,
+) {
+    object Converters {
+        @TypeConverter
+        fun fromMultiValue(values: List<String>) =
+            values.joinToString(";") { it.replace(";", "\\;") }
+
+        @TypeConverter
+        fun toMultiValue(string: String) = string.splitEscaped { it == ';' }.correctWhitespace()
+
+        @TypeConverter fun fromDate(date: Date?) = date?.toString()
+
+        @TypeConverter fun toDate(string: String?) = string?.let(Date::from)
+    }
+}

musikr/src/main/java/org/oxycblt/musikr/cover/Covers.kt

@@ -20,22 +20,6 @@ package org.oxycblt.musikr.cover
 
 import java.io.InputStream
 
-interface Covers {
-    suspend fun obtain(id: String): ObtainResult<out Cover>
-}
-
-interface MutableCovers : Covers {
-    suspend fun write(data: ByteArray): Cover
-
-    suspend fun cleanup(excluding: Collection<Cover>)
-}
-
-sealed interface ObtainResult<T : Cover> {
-    data class Hit<T : Cover>(val cover: T) : ObtainResult<T>
-
-    class Miss<T : Cover> : ObtainResult<T>
-}
-
 interface Cover {
     val id: String
 
@@ -58,3 +42,19 @@ class CoverCollection private constructor(val covers: List<Cover>) {
                     .map { it.value.first() })
     }
 }
+
+interface Covers {
+    suspend fun obtain(id: String): ObtainResult<out Cover>
+}
+
+interface MutableCovers : Covers {
+    suspend fun write(data: ByteArray): Cover
+
+    suspend fun cleanup(excluding: Collection<Cover>)
+}
+
+sealed interface ObtainResult<T : Cover> {
+    data class Hit<T : Cover>(val cover: T) : ObtainResult<T>
+
+    class Miss<T : Cover> : ObtainResult<T>
+}

musikr/src/main/java/org/oxycblt/musikr/cover/fs/CoverFormat.kt

@@ -16,7 +16,7 @@
  * along with this program.  If not, see <https://www.gnu.org/licenses/>.
  */
  
-package org.oxycblt.musikr.cover
+package org.oxycblt.musikr.cover.fs
 
 import android.graphics.Bitmap
 import android.graphics.BitmapFactory

musikr/src/main/java/org/oxycblt/musikr/cover/fs/CoverIdentifier.kt

@@ -16,7 +16,7 @@
  * along with this program.  If not, see <https://www.gnu.org/licenses/>.
  */
  
-package org.oxycblt.musikr.cover
+package org.oxycblt.musikr.cover.fs
 
 import java.security.MessageDigest
 

musikr/src/main/java/org/oxycblt/musikr/cover/fs/CoverParams.kt

@@ -16,7 +16,7 @@
  * along with this program.  If not, see <https://www.gnu.org/licenses/>.
  */
  
-package org.oxycblt.musikr.cover
+package org.oxycblt.musikr.cover.fs
 
 class CoverParams private constructor(val resolution: Int, val quality: Int) {
     override fun hashCode() = 31 * resolution + quality

musikr/src/main/java/org/oxycblt/musikr/cover/fs/FSCovers.kt

@@ -1,6 +1,6 @@
 /*
  * Copyright (c) 2025 Auxio Project
- * FileCovers.kt is part of Auxio.
+ * FSCovers.kt is part of Auxio.
  *
  * This program is free software: you can redistribute it and/or modify
  * it under the terms of the GNU General Public License as published by
@@ -16,16 +16,19 @@
  * along with this program.  If not, see <https://www.gnu.org/licenses/>.
  */
  
-package org.oxycblt.musikr.cover
+package org.oxycblt.musikr.cover.fs
 
 import android.os.ParcelFileDescriptor
+import org.oxycblt.musikr.cover.Cover
+import org.oxycblt.musikr.cover.Covers
+import org.oxycblt.musikr.cover.MutableCovers
+import org.oxycblt.musikr.cover.ObtainResult
+import org.oxycblt.musikr.fs.app.AppFS
 import org.oxycblt.musikr.fs.app.AppFile
-import org.oxycblt.musikr.fs.app.AppFiles
 
-open class FileCovers(private val appFiles: AppFiles, private val coverFormat: CoverFormat) :
-    Covers {
+open class FSCovers(private val appFS: AppFS, private val coverFormat: CoverFormat) : Covers {
     override suspend fun obtain(id: String): ObtainResult<FileCover> {
-        val file = appFiles.find(getFileName(id))
+        val file = appFS.find(getFileName(id))
         return if (file != null) {
             ObtainResult.Hit(FileCoverImpl(id, file))
         } else {
@@ -36,20 +39,20 @@ open class FileCovers(private val appFiles: AppFiles, private val coverFormat: C
     protected fun getFileName(id: String) = "$id.${coverFormat.extension}"
 }
 
-class MutableFileCovers(
-    private val appFiles: AppFiles,
+class MutableFSCovers(
+    private val appFS: AppFS,
     private val coverFormat: CoverFormat,
     private val coverIdentifier: CoverIdentifier
-) : FileCovers(appFiles, coverFormat), MutableCovers {
+) : FSCovers(appFS, coverFormat), MutableCovers {
     override suspend fun write(data: ByteArray): FileCover {
         val id = coverIdentifier.identify(data)
-        val file = appFiles.write(getFileName(id)) { coverFormat.transcodeInto(data, it) }
+        val file = appFS.write(getFileName(id)) { coverFormat.transcodeInto(data, it) }
         return FileCoverImpl(id, file)
     }
 
     override suspend fun cleanup(excluding: Collection<Cover>) {
         val used = excluding.mapTo(mutableSetOf()) { getFileName(it.id) }
-        appFiles.deleteWhere { it !in used }
+        appFS.deleteWhere { it !in used }
     }
 }
 

musikr/src/main/java/org/oxycblt/musikr/fs/DeviceFile.kt

@@ -1,29 +0,0 @@
-/*
- * Copyright (c) 2024 Auxio Project
- * DeviceFile.kt is part of Auxio.
- *
- * This program is free software: you can redistribute it and/or modify
- * it under the terms of the GNU General Public License as published by
- * the Free Software Foundation, either version 3 of the License, or
- * (at your option) any later version.
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
- * GNU General Public License for more details.
- *
- * You should have received a copy of the GNU General Public License
- * along with this program.  If not, see <https://www.gnu.org/licenses/>.
- */
- 
-package org.oxycblt.musikr.fs
-
-import android.net.Uri
-
-internal data class DeviceFile(
-    val uri: Uri,
-    val mimeType: String,
-    val path: Path,
-    val size: Long,
-    val modifiedMs: Long
-)

musikr/src/main/java/org/oxycblt/musikr/fs/app/AppFS.kt

@@ -1,6 +1,6 @@
 /*
  * Copyright (c) 2024 Auxio Project
- * AppFiles.kt is part of Auxio.
+ * AppFS.kt is part of Auxio.
  *
  * This program is free software: you can redistribute it and/or modify
  * it under the terms of the GNU General Public License as published by
@@ -28,7 +28,7 @@ import kotlinx.coroutines.sync.Mutex
 import kotlinx.coroutines.sync.withLock
 import kotlinx.coroutines.withContext
 
-interface AppFiles {
+interface AppFS {
     suspend fun find(name: String): AppFile?
 
     suspend fun write(name: String, block: suspend (OutputStream) -> Unit): AppFile
@@ -36,9 +36,9 @@ interface AppFiles {
     suspend fun deleteWhere(block: (String) -> Boolean)
 
     companion object {
-        suspend fun at(dir: File): AppFiles {
+        suspend fun at(dir: File): AppFS {
             withContext(Dispatchers.IO) { check(dir.exists() && dir.isDirectory) }
-            return AppFilesImpl(dir)
+            return AppFSImpl(dir)
         }
     }
 }
@@ -49,7 +49,7 @@ interface AppFile {
     suspend fun open(): InputStream?
 }
 
-private class AppFilesImpl(private val dir: File) : AppFiles {
+private class AppFSImpl(private val dir: File) : AppFS {
     private val fileMutexes = mutableMapOf<String, Mutex>()
     private val mapMutex = Mutex()
 

musikr/src/main/java/org/oxycblt/musikr/fs/device/DeviceFS.kt

@@ -1,6 +1,6 @@
 /*
  * Copyright (c) 2024 Auxio Project
- * DeviceFiles.kt is part of Auxio.
+ * DeviceFS.kt is part of Auxio.
  *
  * This program is free software: you can redistribute it and/or modify
  * it under the terms of the GNU General Public License as published by
@@ -29,20 +29,27 @@ import kotlinx.coroutines.flow.emitAll
 import kotlinx.coroutines.flow.flatMapMerge
 import kotlinx.coroutines.flow.flattenMerge
 import kotlinx.coroutines.flow.flow
-import org.oxycblt.musikr.fs.DeviceFile
 import org.oxycblt.musikr.fs.MusicLocation
 import org.oxycblt.musikr.fs.Path
 
-internal interface DeviceFiles {
+internal interface DeviceFS {
     fun explore(locations: Flow<MusicLocation>): Flow<DeviceFile>
 
     companion object {
-        fun from(context: Context): DeviceFiles = DeviceFilesImpl(context.contentResolverSafe)
+        fun from(context: Context): DeviceFS = DeviceFSImpl(context.contentResolverSafe)
     }
 }
 
+data class DeviceFile(
+    val uri: Uri,
+    val mimeType: String,
+    val path: Path,
+    val size: Long,
+    val modifiedMs: Long
+)
+
 @OptIn(ExperimentalCoroutinesApi::class)
-private class DeviceFilesImpl(private val contentResolver: ContentResolver) : DeviceFiles {
+private class DeviceFSImpl(private val contentResolver: ContentResolver) : DeviceFS {
     override fun explore(locations: Flow<MusicLocation>): Flow<DeviceFile> =
         locations.flatMapMerge { location ->
             exploreImpl(

musikr/src/main/java/org/oxycblt/musikr/graph/AlbumGraph.kt

@@ -0,0 +1,118 @@
+/*
+ * Copyright (c) 2025 Auxio Project
+ * AlbumGraph.kt is part of Auxio.
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+ 
+package org.oxycblt.musikr.graph
+
+import org.oxycblt.musikr.tag.interpret.PreAlbum
+import org.oxycblt.musikr.util.unlikelyToBeNull
+
+internal class AlbumGraph(private val artistGraph: ArtistGraph) {
+    private val vertices = mutableMapOf<PreAlbum, AlbumVertex>()
+
+    fun link(vertex: SongVertex) {
+        // Albums themselves have their own parent artists that also need to be
+        // linked up.
+        val preAlbum = vertex.preSong.preAlbum
+        val albumVertex =
+            vertices.getOrPut(preAlbum) { AlbumVertex(preAlbum).also { artistGraph.link(it) } }
+        vertex.albumVertex = albumVertex
+        albumVertex.songVertices.add(vertex)
+    }
+
+    fun solve(): Collection<AlbumVertex> {
+        val albumClusters = vertices.values.groupBy { it.preAlbum.rawName?.lowercase() }
+        for (cluster in albumClusters.values) {
+            simplifyAlbumCluster(cluster)
+        }
+        // Remove any edges that wound up connecting to the same artist or genre
+        // in the end after simplification.
+        vertices.values.forEach { it.artistVertices = it.artistVertices.distinct().toMutableList() }
+        return vertices.values
+    }
+
+    private fun simplifyAlbumCluster(cluster: Collection<AlbumVertex>) {
+        if (cluster.size == 1) {
+            // Nothing to do.
+            return
+        }
+        val fullMusicBrainzIdCoverage = cluster.all { it.preAlbum.musicBrainzId != null }
+        if (fullMusicBrainzIdCoverage) {
+            // All albums have MBIDs, nothing needs to be merged.
+            val mbidClusters = cluster.groupBy { unlikelyToBeNull(it.preAlbum.musicBrainzId) }
+            for (mbidCluster in mbidClusters.values) {
+                simplifyAlbumClusterImpl(mbidCluster)
+            }
+            return
+        }
+        // No full MBID coverage, discard the MBIDs from the graph.
+        val strippedCluster =
+            cluster.map {
+                val noMbidPreAlbum = it.preAlbum.copy(musicBrainzId = null)
+                val simpleMbidVertex =
+                    vertices.getOrPut(noMbidPreAlbum) {
+                        AlbumVertex(noMbidPreAlbum).apply { artistVertices = it.artistVertices }
+                    }
+                meldAlbumVertices(it, simpleMbidVertex)
+                simpleMbidVertex
+            }
+        simplifyAlbumClusterImpl(strippedCluster)
+    }
+
+    private fun simplifyAlbumClusterImpl(cluster: Collection<AlbumVertex>) {
+        // All of these albums are semantically equivalent. Pick the most popular variation
+        // and merge all the others into it.
+        if (cluster.size == 1) {
+            // Nothing to do.
+            return
+        }
+        val clusterSet = cluster.toMutableSet()
+        val dst = clusterSet.maxBy { it.songVertices.size }
+        clusterSet.remove(dst)
+        for (src in clusterSet) {
+            meldAlbumVertices(src, dst)
+        }
+    }
+
+    private fun meldAlbumVertices(src: AlbumVertex, dst: AlbumVertex) {
+        if (src == dst) {
+            // Same vertex, do nothing
+            return
+        }
+        // Link all songs and artists from the irrelevant album to the relevant album.
+        dst.songVertices.addAll(src.songVertices)
+        dst.artistVertices.addAll(src.artistVertices)
+        // Update all songs and artists to point to the relevant album.
+        src.songVertices.forEach { it.albumVertex = dst }
+        src.artistVertices.forEach {
+            it.albumVertices.remove(src)
+            it.albumVertices.add(dst)
+        }
+        // Remove the irrelevant album from the graph.
+        vertices.remove(src.preAlbum)
+    }
+}
+
+internal class AlbumVertex(
+    val preAlbum: PreAlbum,
+) : Vertex {
+    var artistVertices = mutableListOf<ArtistVertex>()
+    val songVertices = mutableSetOf<SongVertex>()
+    override var tag: Any? = null
+
+    override fun toString() = "AlbumVertex(preAlbum=$preAlbum)"
+}

musikr/src/main/java/org/oxycblt/musikr/graph/ArtistGraph.kt

@@ -0,0 +1,127 @@
+/*
+ * Copyright (c) 2025 Auxio Project
+ * ArtistGraph.kt is part of Auxio.
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+ 
+package org.oxycblt.musikr.graph
+
+import org.oxycblt.musikr.tag.interpret.PreArtist
+import org.oxycblt.musikr.util.unlikelyToBeNull
+
+internal class ArtistGraph {
+    private val vertices = mutableMapOf<PreArtist, ArtistVertex>()
+
+    fun link(songVertex: SongVertex) {
+        val preArtists = songVertex.preSong.preArtists
+        val artistVertices = preArtists.map { vertices.getOrPut(it) { ArtistVertex(it) } }
+        songVertex.artistVertices.addAll(artistVertices)
+        artistVertices.forEach { it.songVertices.add(songVertex) }
+    }
+
+    fun link(albumVertex: AlbumVertex) {
+        val preArtists = albumVertex.preAlbum.preArtists
+        val artistVertices = preArtists.map { vertices.getOrPut(it) { ArtistVertex(it) } }
+        albumVertex.artistVertices = artistVertices.toMutableList()
+        artistVertices.forEach { it.albumVertices.add(albumVertex) }
+    }
+
+    fun solve(): Collection<ArtistVertex> {
+        val artistClusters = vertices.values.groupBy { it.preArtist.rawName?.lowercase() }
+        for (cluster in artistClusters.values) {
+            simplifyArtistCluster(cluster)
+        }
+        return vertices.values
+    }
+
+    private fun simplifyArtistCluster(cluster: Collection<ArtistVertex>) {
+        if (cluster.size == 1) {
+            // Nothing to do.
+            return
+        }
+        val fullMusicBrainzIdCoverage = cluster.all { it.preArtist.musicBrainzId != null }
+        if (fullMusicBrainzIdCoverage) {
+            // All artists have MBIDs, nothing needs to be merged.
+            val mbidClusters = cluster.groupBy { unlikelyToBeNull(it.preArtist.musicBrainzId) }
+            for (mbidCluster in mbidClusters.values) {
+                simplifyArtistClusterImpl(mbidCluster)
+            }
+            return
+        }
+        // No full MBID coverage, discard the MBIDs from the graph.
+        val strippedCluster =
+            cluster.map {
+                val noMbidPreArtist = it.preArtist.copy(musicBrainzId = null)
+                val simpleMbidVertex =
+                    vertices.getOrPut(noMbidPreArtist) { ArtistVertex(noMbidPreArtist) }
+                meldArtistVertices(it, simpleMbidVertex)
+                simpleMbidVertex
+            }
+        simplifyArtistClusterImpl(strippedCluster)
+    }
+
+    private fun simplifyArtistClusterImpl(cluster: Collection<ArtistVertex>) {
+        if (cluster.size == 1) {
+            // One canonical artist, nothing to collapse
+            return
+        }
+        val clusterSet = cluster.toMutableSet()
+        val relevantArtistVertex = clusterSet.maxBy { it.songVertices.size }
+        clusterSet.remove(relevantArtistVertex)
+        for (irrelevantArtistVertex in clusterSet) {
+            meldArtistVertices(irrelevantArtistVertex, relevantArtistVertex)
+        }
+    }
+
+    private fun meldArtistVertices(src: ArtistVertex, dst: ArtistVertex) {
+        if (src == dst) {
+            // Same vertex, do nothing
+            return
+        }
+        // Link all songs and albums from the irrelevant artist to the relevant artist.
+        dst.songVertices.addAll(src.songVertices)
+        dst.albumVertices.addAll(src.albumVertices)
+        dst.genreVertices.addAll(src.genreVertices)
+        // Update all songs, albums, and genres to point to the relevant artist.
+        src.songVertices.forEach {
+            val index = it.artistVertices.indexOf(src)
+            check(index >= 0) { "Illegal state: directed edge between artist and song" }
+            it.artistVertices[index] = dst
+        }
+        src.albumVertices.forEach {
+            val index = it.artistVertices.indexOf(src)
+            check(index >= 0) { "Illegal state: directed edge between artist and album" }
+            it.artistVertices[index] = dst
+        }
+        src.genreVertices.forEach {
+            it.artistVertices.remove(src)
+            it.artistVertices.add(dst)
+        }
+
+        // Remove the irrelevant artist from the graph.
+        vertices.remove(src.preArtist)
+    }
+}
+
+internal class ArtistVertex(
+    val preArtist: PreArtist,
+) : Vertex {
+    val songVertices = mutableSetOf<SongVertex>()
+    val albumVertices = mutableSetOf<AlbumVertex>()
+    val genreVertices = mutableSetOf<GenreVertex>()
+    override var tag: Any? = null
+
+    override fun toString() = "ArtistVertex(preArtist=$preArtist)"
+}

musikr/src/main/java/org/oxycblt/musikr/graph/GenreGraph.kt

@@ -0,0 +1,94 @@
+/*
+ * Copyright (c) 2025 Auxio Project
+ * GenreGraph.kt is part of Auxio.
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+ 
+package org.oxycblt.musikr.graph
+
+import org.oxycblt.musikr.tag.interpret.PreGenre
+
+internal class GenreGraph {
+    private val vertices = mutableMapOf<PreGenre, GenreVertex>()
+
+    fun link(vertex: SongVertex) {
+        val preGenres = vertex.preSong.preGenres
+        val artistVertices = vertex.artistVertices
+
+        for (preGenre in preGenres) {
+            val genreVertex = vertices.getOrPut(preGenre) { GenreVertex(preGenre) }
+            vertex.genreVertices.add(genreVertex)
+            genreVertex.songVertices.add(vertex)
+
+            for (artistVertex in artistVertices) {
+                genreVertex.artistVertices.add(artistVertex)
+                artistVertex.genreVertices.add(genreVertex)
+            }
+        }
+    }
+
+    fun solve(): Collection<GenreVertex> {
+        val genreClusters = vertices.values.groupBy { it.preGenre.rawName?.lowercase() }
+        for (cluster in genreClusters.values) {
+            simplifyGenreCluster(cluster)
+        }
+        return vertices.values
+    }
+
+    private fun simplifyGenreCluster(cluster: Collection<GenreVertex>) {
+        if (cluster.size == 1) {
+            // Nothing to do.
+            return
+        }
+        // All of these genres are semantically equivalent. Pick the most popular variation
+        // and merge all the others into it.
+        val clusterSet = cluster.toMutableSet()
+        val dst = clusterSet.maxBy { it.songVertices.size }
+        clusterSet.remove(dst)
+        for (src in clusterSet) {
+            meldGenreVertices(src, dst)
+        }
+    }
+
+    private fun meldGenreVertices(src: GenreVertex, dst: GenreVertex) {
+        if (src == dst) {
+            // Same vertex, do nothing
+            return
+        }
+        // Link all songs and artists from the irrelevant genre to the relevant genre.
+        dst.songVertices.addAll(src.songVertices)
+        dst.artistVertices.addAll(src.artistVertices)
+        // Update all songs and artists to point to the relevant genre.
+        src.songVertices.forEach {
+            val index = it.genreVertices.indexOf(src)
+            check(index >= 0) { "Illegal state: directed edge between genre and song" }
+            it.genreVertices[index] = dst
+        }
+        src.artistVertices.forEach {
+            it.genreVertices.remove(src)
+            it.genreVertices.add(dst)
+        }
+        // Remove the irrelevant genre from the graph.
+        vertices.remove(src.preGenre)
+    }
+}
+
+internal class GenreVertex(val preGenre: PreGenre) : Vertex {
+    val songVertices = mutableSetOf<SongVertex>()
+    val artistVertices = mutableSetOf<ArtistVertex>()
+    override var tag: Any? = null
+
+    override fun toString() = "GenreVertex(preGenre=$preGenre)"
+}

musikr/src/main/java/org/oxycblt/musikr/graph/MusicGraph.kt

@@ -18,21 +18,15 @@
  
 package org.oxycblt.musikr.graph
 
-import org.oxycblt.musikr.Music
-import org.oxycblt.musikr.playlist.SongPointer
 import org.oxycblt.musikr.playlist.interpret.PrePlaylist
-import org.oxycblt.musikr.tag.interpret.PreAlbum
-import org.oxycblt.musikr.tag.interpret.PreArtist
-import org.oxycblt.musikr.tag.interpret.PreGenre
 import org.oxycblt.musikr.tag.interpret.PreSong
-import org.oxycblt.musikr.util.unlikelyToBeNull
 
 internal data class MusicGraph(
-    val songVertex: List<SongVertex>,
-    val albumVertex: List<AlbumVertex>,
-    val artistVertex: List<ArtistVertex>,
-    val genreVertex: List<GenreVertex>,
-    val playlistVertex: Set<PlaylistVertex>
+    val songVertices: Collection<SongVertex>,
+    val albumVertices: Collection<AlbumVertex>,
+    val artistVertices: Collection<ArtistVertex>,
+    val genreVertices: Collection<GenreVertex>,
+    val playlistVertices: Collection<PlaylistVertex>
 ) {
     interface Builder {
         fun add(preSong: PreSong)
@@ -47,333 +41,32 @@ internal data class MusicGraph(
     }
 }
 
-private class MusicGraphBuilderImpl : MusicGraph.Builder {
-    private val songVertices = mutableMapOf<Music.UID, SongVertex>()
-    private val albumVertices = mutableMapOf<PreAlbum, AlbumVertex>()
-    private val artistVertices = mutableMapOf<PreArtist, ArtistVertex>()
-    private val genreVertices = mutableMapOf<PreGenre, GenreVertex>()
-    private val playlistVertices = mutableSetOf<PlaylistVertex>()
-
-    override fun add(preSong: PreSong) {
-        val uid = preSong.uid
-        if (songVertices.containsKey(uid)) {
-            return
-        }
-
-        val songGenreVertices =
-            preSong.preGenres.map { preGenre ->
-                genreVertices.getOrPut(preGenre) { GenreVertex(preGenre) }
-            }
-
-        val songArtistVertices =
-            preSong.preArtists.map { preArtist ->
-                artistVertices.getOrPut(preArtist) { ArtistVertex(preArtist) }
-            }
-
-        val albumVertex =
-            albumVertices.getOrPut(preSong.preAlbum) {
-                // Albums themselves have their own parent artists that also need to be
-                // linked up.
-                val albumArtistVertices =
-                    preSong.preAlbum.preArtists.map { preArtist ->
-                        artistVertices.getOrPut(preArtist) { ArtistVertex(preArtist) }
-                    }
-                val albumVertex = AlbumVertex(preSong.preAlbum, albumArtistVertices.toMutableList())
-                // Album vertex is linked, now link artists back to album.
-                albumArtistVertices.forEach { artistVertex ->
-                    artistVertex.albumVertices.add(albumVertex)
-                }
-                albumVertex
-            }
-
-        val songVertex =
-            SongVertex(
-                preSong,
-                albumVertex,
-                songArtistVertices.toMutableList(),
-                songGenreVertices.toMutableList())
-        albumVertex.songVertices.add(songVertex)
-
-        songArtistVertices.forEach { artistVertex ->
-            artistVertex.songVertices.add(songVertex)
-            songGenreVertices.forEach { genreVertex ->
-                // Mutually link any new genres to the artist
-                artistVertex.genreVertices.add(genreVertex)
-                genreVertex.artistVertices.add(artistVertex)
-            }
-        }
-
-        songGenreVertices.forEach { genreVertex -> genreVertex.songVertices.add(songVertex) }
-
-        songVertices[uid] = songVertex
-    }
-
-    override fun add(prePlaylist: PrePlaylist) {
-        playlistVertices.add(PlaylistVertex(prePlaylist))
-    }
-
-    override fun build(): MusicGraph {
-        val genreClusters = genreVertices.values.groupBy { it.preGenre.rawName?.lowercase() }
-        for (cluster in genreClusters.values) {
-            simplifyGenreCluster(cluster)
-        }
-
-        val artistClusters = artistVertices.values.groupBy { it.preArtist.rawName?.lowercase() }
-        for (cluster in artistClusters.values) {
-            simplifyArtistCluster(cluster)
-        }
-
-        val albumClusters = albumVertices.values.groupBy { it.preAlbum.rawName?.lowercase() }
-        for (cluster in albumClusters.values) {
-            simplifyAlbumCluster(cluster)
-        }
-
-        // Remove any edges that wound up connecting to the same artist or genre
-        // in the end after simplification.
-        albumVertices.values.forEach {
-            it.artistVertices = it.artistVertices.distinct().toMutableList()
-        }
-
-        songVertices.entries.forEach { entry ->
-            val vertex = entry.value
-            vertex.artistVertices = vertex.artistVertices.distinct().toMutableList()
-            vertex.genreVertices = vertex.genreVertices.distinct().toMutableList()
-
-            playlistVertices.forEach {
-                val pointer = SongPointer.UID(entry.key)
-                val index = it.pointerMap[pointer]
-                if (index != null) {
-                    it.songVertices[index] = vertex
-                }
-            }
-        }
-
-        val graph =
-            MusicGraph(
-                songVertices.values.toList(),
-                albumVertices.values.toList(),
-                artistVertices.values.toList(),
-                genreVertices.values.toList(),
-                playlistVertices)
-
-        return graph
-    }
-
-    private fun simplifyGenreCluster(cluster: Collection<GenreVertex>) {
-        if (cluster.size == 1) {
-            // Nothing to do.
-            return
-        }
-        // All of these genres are semantically equivalent. Pick the most popular variation
-        // and merge all the others into it.
-        val clusterSet = cluster.toMutableSet()
-        val dst = clusterSet.maxBy { it.songVertices.size }
-        clusterSet.remove(dst)
-        for (src in clusterSet) {
-            meldGenreVertices(src, dst)
-        }
-    }
-
-    private fun meldGenreVertices(src: GenreVertex, dst: GenreVertex) {
-        if (src == dst) {
-            // Same vertex, do nothing
-            return
-        }
-        // Link all songs and artists from the irrelevant genre to the relevant genre.
-        dst.songVertices.addAll(src.songVertices)
-        dst.artistVertices.addAll(src.artistVertices)
-        // Update all songs and artists to point to the relevant genre.
-        src.songVertices.forEach {
-            val index = it.genreVertices.indexOf(src)
-            check(index >= 0) { "Illegal state: directed edge between genre and song" }
-            it.genreVertices[index] = dst
-        }
-        src.artistVertices.forEach {
-            it.genreVertices.remove(src)
-            it.genreVertices.add(dst)
-        }
-        // Remove the irrelevant genre from the graph.
-        genreVertices.remove(src.preGenre)
-    }
-
-    private fun simplifyArtistCluster(cluster: Collection<ArtistVertex>) {
-        if (cluster.size == 1) {
-            // Nothing to do.
-            return
-        }
-        val fullMusicBrainzIdCoverage = cluster.all { it.preArtist.musicBrainzId != null }
-        if (fullMusicBrainzIdCoverage) {
-            // All artists have MBIDs, nothing needs to be merged.
-            val mbidClusters = cluster.groupBy { unlikelyToBeNull(it.preArtist.musicBrainzId) }
-            for (mbidCluster in mbidClusters.values) {
-                simplifyArtistClusterImpl(mbidCluster)
-            }
-            return
-        }
-        // No full MBID coverage, discard the MBIDs from the graph.
-        val strippedCluster =
-            cluster.map {
-                val noMbidPreArtist = it.preArtist.copy(musicBrainzId = null)
-                val simpleMbidVertex =
-                    artistVertices.getOrPut(noMbidPreArtist) { ArtistVertex(noMbidPreArtist) }
-                meldArtistVertices(it, simpleMbidVertex)
-                simpleMbidVertex
-            }
-        simplifyArtistClusterImpl(strippedCluster)
-    }
-
-    private fun simplifyArtistClusterImpl(cluster: Collection<ArtistVertex>) {
-        if (cluster.size == 1) {
-            // One canonical artist, nothing to collapse
-            return
-        }
-        val clusterSet = cluster.toMutableSet()
-        val relevantArtistVertex = clusterSet.maxBy { it.songVertices.size }
-        clusterSet.remove(relevantArtistVertex)
-        for (irrelevantArtistVertex in clusterSet) {
-            meldArtistVertices(irrelevantArtistVertex, relevantArtistVertex)
-        }
-    }
-
-    private fun meldArtistVertices(src: ArtistVertex, dst: ArtistVertex) {
-        if (src == dst) {
-            // Same vertex, do nothing
-            return
-        }
-        // Link all songs and albums from the irrelevant artist to the relevant artist.
-        dst.songVertices.addAll(src.songVertices)
-        dst.albumVertices.addAll(src.albumVertices)
-        dst.genreVertices.addAll(src.genreVertices)
-        // Update all songs, albums, and genres to point to the relevant artist.
-        src.songVertices.forEach {
-            val index = it.artistVertices.indexOf(src)
-            check(index >= 0) { "Illegal state: directed edge between artist and song" }
-            it.artistVertices[index] = dst
-        }
-        src.albumVertices.forEach {
-            val index = it.artistVertices.indexOf(src)
-            check(index >= 0) { "Illegal state: directed edge between artist and album" }
-            it.artistVertices[index] = dst
-        }
-        src.genreVertices.forEach {
-            it.artistVertices.remove(src)
-            it.artistVertices.add(dst)
-        }
-
-        // Remove the irrelevant artist from the graph.
-        artistVertices.remove(src.preArtist)
-    }
-
-    private fun simplifyAlbumCluster(cluster: Collection<AlbumVertex>) {
-        if (cluster.size == 1) {
-            // Nothing to do.
-            return
-        }
-        val fullMusicBrainzIdCoverage = cluster.all { it.preAlbum.musicBrainzId != null }
-        if (fullMusicBrainzIdCoverage) {
-            // All albums have MBIDs, nothing needs to be merged.
-            val mbidClusters = cluster.groupBy { unlikelyToBeNull(it.preAlbum.musicBrainzId) }
-            for (mbidCluster in mbidClusters.values) {
-                simplifyAlbumClusterImpl(mbidCluster)
-            }
-            return
-        }
-        // No full MBID coverage, discard the MBIDs from the graph.
-        val strippedCluster =
-            cluster.map {
-                val noMbidPreAlbum = it.preAlbum.copy(musicBrainzId = null)
-                val simpleMbidVertex =
-                    albumVertices.getOrPut(noMbidPreAlbum) {
-                        AlbumVertex(noMbidPreAlbum, it.artistVertices.toMutableList())
-                    }
-                meldAlbumVertices(it, simpleMbidVertex)
-                simpleMbidVertex
-            }
-        simplifyAlbumClusterImpl(strippedCluster)
-    }
-
-    private fun simplifyAlbumClusterImpl(cluster: Collection<AlbumVertex>) {
-        // All of these albums are semantically equivalent. Pick the most popular variation
-        // and merge all the others into it.
-        if (cluster.size == 1) {
-            // Nothing to do.
-            return
-        }
-        val clusterSet = cluster.toMutableSet()
-        val dst = clusterSet.maxBy { it.songVertices.size }
-        clusterSet.remove(dst)
-        for (src in clusterSet) {
-            meldAlbumVertices(src, dst)
-        }
-    }
-
-    private fun meldAlbumVertices(src: AlbumVertex, dst: AlbumVertex) {
-        if (src == dst) {
-            // Same vertex, do nothing
-            return
-        }
-        // Link all songs and artists from the irrelevant album to the relevant album.
-        dst.songVertices.addAll(src.songVertices)
-        dst.artistVertices.addAll(src.artistVertices)
-        // Update all songs and artists to point to the relevant album.
-        src.songVertices.forEach { it.albumVertex = dst }
-        src.artistVertices.forEach {
-            it.albumVertices.remove(src)
-            it.albumVertices.add(dst)
-        }
-        // Remove the irrelevant album from the graph.
-        albumVertices.remove(src.preAlbum)
-    }
-}
-
 internal interface Vertex {
     val tag: Any?
 }
 
-internal class SongVertex(
-    val preSong: PreSong,
-    var albumVertex: AlbumVertex,
-    var artistVertices: MutableList<ArtistVertex>,
-    var genreVertices: MutableList<GenreVertex>
-) : Vertex {
-    override var tag: Any? = null
+private class MusicGraphBuilderImpl : MusicGraph.Builder {
+    private val genreGraph = GenreGraph()
+    private val artistGraph = ArtistGraph()
+    private val albumGraph = AlbumGraph(artistGraph)
+    private val playlistGraph = PlaylistGraph()
+    private val songGraph = SongGraph(albumGraph, artistGraph, genreGraph, playlistGraph)
 
-    override fun toString() = "SongVertex(preSong=$preSong)"
+    override fun add(preSong: PreSong) {
+        songGraph.link(SongVertex(preSong))
     }
 
-internal class AlbumVertex(val preAlbum: PreAlbum, var artistVertices: MutableList<ArtistVertex>) :
-    Vertex {
-    val songVertices = mutableSetOf<SongVertex>()
-    override var tag: Any? = null
-
-    override fun toString() = "AlbumVertex(preAlbum=$preAlbum)"
+    override fun add(prePlaylist: PrePlaylist) {
+        playlistGraph.link(PlaylistVertex(prePlaylist))
     }
 
-internal class ArtistVertex(
-    val preArtist: PreArtist,
-) : Vertex {
-    val songVertices = mutableSetOf<SongVertex>()
-    val albumVertices = mutableSetOf<AlbumVertex>()
-    val genreVertices = mutableSetOf<GenreVertex>()
-    override var tag: Any? = null
-
-    override fun toString() = "ArtistVertex(preArtist=$preArtist)"
+    override fun build(): MusicGraph {
+        val genreVertices = genreGraph.solve()
+        val artistVertices = artistGraph.solve()
+        val albumVertices = albumGraph.solve()
+        val songVertices = songGraph.solve()
+        val playlistVertices = playlistGraph.solve()
+        return MusicGraph(
+            songVertices, albumVertices, artistVertices, genreVertices, playlistVertices)
     }
-
-internal class GenreVertex(val preGenre: PreGenre) : Vertex {
-    val songVertices = mutableSetOf<SongVertex>()
-    val artistVertices = mutableSetOf<ArtistVertex>()
-    override var tag: Any? = null
-
-    override fun toString() = "GenreVertex(preGenre=$preGenre)"
-}
-
-internal class PlaylistVertex(val prePlaylist: PrePlaylist) {
-    val songVertices = Array<SongVertex?>(prePlaylist.songPointers.size) { null }
-    val pointerMap =
-        prePlaylist.songPointers
-            .withIndex()
-            .associateBy { it.value }
-            .mapValuesTo(mutableMapOf()) { it.value.index }
-    val tag: Any? = null
 }

musikr/src/main/java/org/oxycblt/musikr/graph/PlaylistGraph.kt

@@ -0,0 +1,58 @@
+/*
+ * Copyright (c) 2025 Auxio Project
+ * PlaylistGraph.kt is part of Auxio.
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+ 
+package org.oxycblt.musikr.graph
+
+import org.oxycblt.musikr.playlist.SongPointer
+import org.oxycblt.musikr.playlist.interpret.PrePlaylist
+
+internal class PlaylistGraph {
+    private val pointerMap = mutableMapOf<SongPointer, SongVertex>()
+    private val vertices = mutableSetOf<PlaylistVertex>()
+
+    fun link(vertex: PlaylistVertex) {
+        for ((pointer, songVertex) in pointerMap) {
+            // Link the vertices we are already aware of to this vertex.
+            vertex.pointerMap[pointer]?.forEach { index -> vertex.songVertices[index] = songVertex }
+        }
+        vertices.add(vertex)
+    }
+
+    fun link(vertex: SongVertex) {
+        val pointer = SongPointer.UID(vertex.preSong.uid)
+        pointerMap[pointer] = vertex
+        for (playlistVertex in vertices) {
+            // Retroactively update previously known playlists to add the new vertex.
+            playlistVertex.pointerMap[pointer]?.forEach { index ->
+                playlistVertex.songVertices[index] = vertex
+            }
+        }
+    }
+
+    fun solve(): Collection<PlaylistVertex> = vertices
+}
+
+internal class PlaylistVertex(val prePlaylist: PrePlaylist) {
+    val songVertices = Array<SongVertex?>(prePlaylist.songPointers.size) { null }
+    val pointerMap =
+        prePlaylist.songPointers
+            .withIndex()
+            .groupBy { it.value }
+            .mapValuesTo(mutableMapOf()) { indexed -> indexed.value.map { it.index } }
+    val tag: Any? = null
+}

musikr/src/main/java/org/oxycblt/musikr/graph/SongGraph.kt

@@ -0,0 +1,67 @@
+/*
+ * Copyright (c) 2025 Auxio Project
+ * SongGraph.kt is part of Auxio.
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+ 
+package org.oxycblt.musikr.graph
+
+import org.oxycblt.musikr.Music
+import org.oxycblt.musikr.tag.interpret.PreSong
+
+internal class SongGraph(
+    private val albumGraph: AlbumGraph,
+    private val artistGraph: ArtistGraph,
+    private val genreGraph: GenreGraph,
+    private val playlistGraph: PlaylistGraph
+) {
+    private val vertices = mutableMapOf<Music.UID, SongVertex>()
+
+    fun link(vertex: SongVertex): Boolean {
+        val uid = vertex.preSong.uid
+        if (vertices.containsKey(uid)) {
+            // Discard songs with duplicate ID's, they wreck the entire
+            // music model and they're pretty much always the same file.
+            return false
+        }
+        // Link the vertex to the rest of the graph now.
+        albumGraph.link(vertex)
+        artistGraph.link(vertex)
+        genreGraph.link(vertex)
+        playlistGraph.link(vertex)
+        vertices[uid] = vertex
+        return true
+    }
+
+    fun solve(): Collection<SongVertex> {
+        vertices.entries.forEach { entry ->
+            val vertex = entry.value
+            vertex.artistVertices = vertex.artistVertices.distinct().toMutableList()
+            vertex.genreVertices = vertex.genreVertices.distinct().toMutableList()
+        }
+        return vertices.values
+    }
+}
+
+internal class SongVertex(
+    val preSong: PreSong,
+) : Vertex {
+    var albumVertex: AlbumVertex? = null
+    var artistVertices = mutableListOf<ArtistVertex>()
+    var genreVertices = mutableListOf<GenreVertex>()
+    override var tag: Any? = null
+
+    override fun toString() = "SongVertex(preSong=$preSong)"
+}

musikr/src/main/java/org/oxycblt/musikr/log/Logger.kt

@@ -0,0 +1,63 @@
+/*
+ * Copyright (c) 2025 Auxio Project
+ * Logger.kt is part of Auxio.
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+ 
+package org.oxycblt.musikr.log
+
+import android.util.Log
+
+interface Logger {
+    fun v(vararg msgs: Any)
+
+    fun d(vararg msgs: Any)
+
+    fun w(vararg msgs: Any)
+
+    fun e(vararg msgs: Any)
+
+    fun primary(tag: String): Logger
+
+    fun secondary(tag: String): Logger
+
+    companion object {
+        fun root(): Logger = LoggerImpl("mskr", null)
+    }
+}
+
+private class LoggerImpl(private val primaryTag: String, private val secondaryTag: String?) :
+    Logger {
+    override fun v(vararg msgs: Any) {
+        Log.v(primaryTag, "[$secondaryTag] ${msgs.joinToString(" ")}")
+    }
+
+    override fun d(vararg msgs: Any) {
+        Log.d(primaryTag, "[$secondaryTag] ${msgs.joinToString(" ")}")
+    }
+
+    override fun w(vararg msgs: Any) {
+        Log.w(primaryTag, "[$secondaryTag] ${msgs.joinToString(" ")}")
+    }
+
+    override fun e(vararg msgs: Any) {
+        Log.e(primaryTag, "[$secondaryTag] ${msgs.joinToString(" ")}")
+    }
+
+    override fun primary(tag: String) = LoggerImpl("${primaryTag}.${tag}", secondaryTag)
+
+    override fun secondary(tag: String) =
+        LoggerImpl(primaryTag, secondaryTag?.let { "$it.$tag" } ?: tag)
+}

musikr/src/main/java/org/oxycblt/musikr/metadata/Metadata.kt

@@ -53,7 +53,7 @@ internal data class Metadata(
     }
 }
 
-internal data class Properties(
+data class Properties(
     val mimeType: String,
     val durationMs: Long,
     val bitrateKbps: Int,

musikr/src/main/java/org/oxycblt/musikr/metadata/MetadataExtractor.kt

@@ -18,24 +18,47 @@
  
 package org.oxycblt.musikr.metadata
 
+import android.annotation.SuppressLint
+import android.content.Context
 import android.os.ParcelFileDescriptor
 import java.io.FileInputStream
 import kotlinx.coroutines.Dispatchers
 import kotlinx.coroutines.withContext
-import org.oxycblt.musikr.fs.DeviceFile
+import org.oxycblt.musikr.fs.device.DeviceFile
 
 internal interface MetadataExtractor {
-    suspend fun extract(deviceFile: DeviceFile, fd: ParcelFileDescriptor): Metadata?
+    suspend fun open(deviceFile: DeviceFile): MetadataHandle?
 
     companion object {
-        fun new(): MetadataExtractor = MetadataExtractorImpl
+        fun new(context: Context): MetadataExtractor = MetadataExtractorImpl(context)
     }
 }
 
-private object MetadataExtractorImpl : MetadataExtractor {
-    override suspend fun extract(deviceFile: DeviceFile, fd: ParcelFileDescriptor) =
+internal interface MetadataHandle {
+    suspend fun extract(): Metadata?
+}
+
+private class MetadataExtractorImpl(private val context: Context) : MetadataExtractor {
+    @SuppressLint("Recycle")
+    override suspend fun open(deviceFile: DeviceFile): MetadataHandle? {
+        val fd =
+            withContext(Dispatchers.IO) {
+                context.contentResolver.openFileDescriptor(deviceFile.uri, "r")
+            }
+        return MetadataHandleImpl(deviceFile, fd ?: return null)
+    }
+}
+
+private class MetadataHandleImpl(
+    private val file: DeviceFile,
+    private val fd: ParcelFileDescriptor
+) : MetadataHandle {
+    override suspend fun extract() =
         withContext(Dispatchers.IO) {
             val fis = FileInputStream(fd.fileDescriptor)
-            TagLibJNI.open(deviceFile, fis).also { fis.close() }
+            TagLibJNI.open(file, fis).also {
+                fis.close()
+                fd.close()
+            }
         }
 }

musikr/src/main/java/org/oxycblt/musikr/metadata/NativeInputStream.kt

@@ -21,7 +21,7 @@ package org.oxycblt.musikr.metadata
 import android.util.Log
 import java.io.FileInputStream
 import java.nio.ByteBuffer
-import org.oxycblt.musikr.fs.DeviceFile
+import org.oxycblt.musikr.fs.device.DeviceFile
 
 internal class NativeInputStream(private val deviceFile: DeviceFile, fis: FileInputStream) {
     private val channel = fis.channel

musikr/src/main/java/org/oxycblt/musikr/metadata/TagLibJNI.kt

@@ -19,7 +19,7 @@
 package org.oxycblt.musikr.metadata
 
 import java.io.FileInputStream
-import org.oxycblt.musikr.fs.DeviceFile
+import org.oxycblt.musikr.fs.device.DeviceFile
 
 internal object TagLibJNI {
     init {

musikr/src/main/java/org/oxycblt/musikr/model/LibraryFactory.kt

@@ -53,23 +53,23 @@ private class LibraryFactoryImpl() : LibraryFactory {
         playlistInterpreter: PlaylistInterpreter
     ): MutableLibrary {
         val songs =
-            graph.songVertex.mapTo(mutableSetOf()) { vertex ->
+            graph.songVertices.mapTo(mutableSetOf()) { vertex ->
                 SongImpl(SongVertexCore(vertex)).also { vertex.tag = it }
             }
         val albums =
-            graph.albumVertex.mapTo(mutableSetOf()) { vertex ->
+            graph.albumVertices.mapTo(mutableSetOf()) { vertex ->
                 AlbumImpl(AlbumVertexCore(vertex)).also { vertex.tag = it }
             }
         val artists =
-            graph.artistVertex.mapTo(mutableSetOf()) { vertex ->
+            graph.artistVertices.mapTo(mutableSetOf()) { vertex ->
                 ArtistImpl(ArtistVertexCore(vertex)).also { vertex.tag = it }
             }
         val genres =
-            graph.genreVertex.mapTo(mutableSetOf()) { vertex ->
+            graph.genreVertices.mapTo(mutableSetOf()) { vertex ->
                 GenreImpl(GenreVertexCore(vertex)).also { vertex.tag = it }
             }
         val playlists =
-            graph.playlistVertex.mapTo(mutableSetOf()) { vertex ->
+            graph.playlistVertices.mapTo(mutableSetOf()) { vertex ->
                 PlaylistImpl(PlaylistVertexCore(vertex))
             }
         return LibraryImpl(
@@ -121,8 +121,8 @@ private class LibraryFactoryImpl() : LibraryFactory {
     }
 
     private companion object {
-        private inline fun <reified T : Music> tag(vertex: Vertex): T {
-            val tag = vertex.tag
+        private inline fun <reified T : Music> tag(vertex: Vertex?): T {
+            val tag = vertex?.tag
             check(tag is T) { "Dead Vertex Detected: $vertex" }
             return tag
         }

musikr/src/main/java/org/oxycblt/musikr/pipeline/EvaluateStep.kt

@@ -23,66 +23,77 @@ import kotlinx.coroutines.channels.Channel
 import kotlinx.coroutines.flow.Flow
 import kotlinx.coroutines.flow.buffer
 import kotlinx.coroutines.flow.collect
-import kotlinx.coroutines.flow.filterIsInstance
 import kotlinx.coroutines.flow.flowOn
-import kotlinx.coroutines.flow.map
 import kotlinx.coroutines.flow.merge
 import kotlinx.coroutines.flow.onEach
+import kotlinx.coroutines.sync.Mutex
+import kotlinx.coroutines.sync.withLock
 import org.oxycblt.musikr.Interpretation
 import org.oxycblt.musikr.MutableLibrary
 import org.oxycblt.musikr.Storage
 import org.oxycblt.musikr.graph.MusicGraph
+import org.oxycblt.musikr.log.Logger
 import org.oxycblt.musikr.model.LibraryFactory
 import org.oxycblt.musikr.playlist.db.StoredPlaylists
 import org.oxycblt.musikr.playlist.interpret.PlaylistInterpreter
-import org.oxycblt.musikr.tag.interpret.TagInterpreter
+import org.oxycblt.musikr.tag.interpret.Interpreter
 
 internal interface EvaluateStep {
-    suspend fun evaluate(extractedMusic: Flow<ExtractedMusic>): MutableLibrary
+    suspend fun evaluate(complete: Flow<Complete>): MutableLibrary
 
     companion object {
-        fun new(storage: Storage, interpretation: Interpretation): EvaluateStep =
+        fun new(storage: Storage, interpretation: Interpretation, logger: Logger): EvaluateStep =
             EvaluateStepImpl(
-                TagInterpreter.new(interpretation),
+                Interpreter.new(interpretation),
                 PlaylistInterpreter.new(interpretation),
                 storage.storedPlaylists,
-                LibraryFactory.new())
+                LibraryFactory.new(),
+                logger.primary("eval"))
     }
 }
 
 private class EvaluateStepImpl(
-    private val tagInterpreter: TagInterpreter,
+    private val interpreter: Interpreter,
     private val playlistInterpreter: PlaylistInterpreter,
     private val storedPlaylists: StoredPlaylists,
-    private val libraryFactory: LibraryFactory
+    private val libraryFactory: LibraryFactory,
+    private val logger: Logger
 ) : EvaluateStep {
-    override suspend fun evaluate(extractedMusic: Flow<ExtractedMusic>): MutableLibrary {
+    override suspend fun evaluate(complete: Flow<Complete>): MutableLibrary {
+        logger.d("evaluate start.")
         val filterFlow =
-            extractedMusic.filterIsInstance<ExtractedMusic.Valid>().divert {
+            complete.divert {
                 when (it) {
-                    is ExtractedMusic.Valid.Song -> Divert.Right(it.song)
-                    is ExtractedMusic.Valid.Playlist -> Divert.Left(it.file)
+                    is RawSong -> Divert.Right(it)
+                    is RawPlaylist -> Divert.Left(it.file)
                 }
             }
         val rawSongs = filterFlow.right
         val preSongs =
             rawSongs
-                .map { wrap(it, tagInterpreter::interpret) }
+                .tryMap { interpreter.interpret(it) }
                 .flowOn(Dispatchers.Default)
                 .buffer(Channel.UNLIMITED)
         val prePlaylists =
             filterFlow.left
-                .map { wrap(it, playlistInterpreter::interpret) }
+                .tryMap { playlistInterpreter.interpret(it) }
                 .flowOn(Dispatchers.Default)
                 .buffer(Channel.UNLIMITED)
         val graphBuilder = MusicGraph.builder()
+        // Concurrent addition of playlists and songs could easily
+        // break the grapher (remember, individual pipeline elements
+        // are generally unaware of the highly concurrent nature of
+        // the pipeline), prevent that with a mutex.
+        val graphLock = Mutex()
         val graphBuild =
             merge(
                 filterFlow.manager,
-                preSongs.onEach { wrap(it, graphBuilder::add) },
-                prePlaylists.onEach { wrap(it, graphBuilder::add) })
+                preSongs.onEach { graphLock.withLock { graphBuilder.add(it) } },
+                prePlaylists.onEach { graphLock.withLock { graphBuilder.add(it) } })
         graphBuild.collect()
+        logger.d("starting graph build")
         val graph = graphBuilder.build()
+        logger.d("graph build done, creating library")
         return libraryFactory.create(graph, storedPlaylists, playlistInterpreter)
     }
 }

musikr/src/main/java/org/oxycblt/musikr/pipeline/ExploreStep.kt

@@ -24,56 +24,83 @@ import kotlinx.coroutines.flow.Flow
 import kotlinx.coroutines.flow.asFlow
 import kotlinx.coroutines.flow.buffer
 import kotlinx.coroutines.flow.emitAll
+import kotlinx.coroutines.flow.filter
 import kotlinx.coroutines.flow.flow
 import kotlinx.coroutines.flow.flowOn
 import kotlinx.coroutines.flow.map
-import kotlinx.coroutines.flow.mapNotNull
 import kotlinx.coroutines.flow.merge
 import org.oxycblt.musikr.Storage
-import org.oxycblt.musikr.fs.DeviceFile
+import org.oxycblt.musikr.cache.CacheResult
+import org.oxycblt.musikr.cache.SongCache
+import org.oxycblt.musikr.cover.Covers
+import org.oxycblt.musikr.cover.ObtainResult
 import org.oxycblt.musikr.fs.MusicLocation
-import org.oxycblt.musikr.fs.device.DeviceFiles
-import org.oxycblt.musikr.playlist.PlaylistFile
+import org.oxycblt.musikr.fs.device.DeviceFS
+import org.oxycblt.musikr.log.Logger
 import org.oxycblt.musikr.playlist.db.StoredPlaylists
 import org.oxycblt.musikr.playlist.m3u.M3U
 
 internal interface ExploreStep {
-    fun explore(locations: List<MusicLocation>): Flow<ExploreNode>
+    fun explore(locations: List<MusicLocation>): Flow<Explored>
 
     companion object {
-        fun from(context: Context, storage: Storage): ExploreStep =
-            ExploreStepImpl(DeviceFiles.from(context), storage.storedPlaylists)
+        fun from(context: Context, storage: Storage, logger: Logger): ExploreStep =
+            ExploreStepImpl(
+                DeviceFS.from(context),
+                storage.storedPlaylists,
+                storage.cache,
+                storage.covers,
+                logger.primary("expl"),
+            )
     }
 }
 
 private class ExploreStepImpl(
-    private val deviceFiles: DeviceFiles,
-    private val storedPlaylists: StoredPlaylists
+    private val deviceFS: DeviceFS,
+    private val storedPlaylists: StoredPlaylists,
+    private val songCache: SongCache,
+    private val covers: Covers,
+    private val logger: Logger,
 ) : ExploreStep {
-    override fun explore(locations: List<MusicLocation>): Flow<ExploreNode> {
-        val audios =
-            deviceFiles
+    override fun explore(locations: List<MusicLocation>): Flow<Explored> {
+        logger.d("explore start.")
+        val audioFiles =
+            deviceFS
                 .explore(locations.asFlow())
-                .mapNotNull {
-                    when {
-                        it.mimeType == M3U.MIME_TYPE -> null
-                        it.mimeType.startsWith("audio/") -> ExploreNode.Audio(it)
-                        else -> null
+                .filter { it.mimeType.startsWith("audio/") || it.mimeType == M3U.MIME_TYPE }
+                .flowOn(Dispatchers.IO)
+                .buffer()
+        val readDistribution = audioFiles.distribute(8)
+        val read =
+            readDistribution.flows.mapx { flow ->
+                flow
+                    .tryMap { file ->
+                        when (val cacheResult = songCache.read(file)) {
+                            is CacheResult.Hit -> {
+                                val cachedSong = cacheResult.song
+                                val coverResult = cachedSong.coverId?.let { covers.obtain(it) }
+                                if (coverResult !is ObtainResult.Hit) {
+                                    return@tryMap NewSong(file, cachedSong.addedMs)
+                                }
+                                RawSong(
+                                    cachedSong.file,
+                                    cachedSong.properties,
+                                    cachedSong.tags,
+                                    coverResult.cover,
+                                    cachedSong.addedMs)
+                            }
+                            is CacheResult.Outdated -> NewSong(file, cacheResult.addedMs)
+                            is CacheResult.Miss -> NewSong(file, System.currentTimeMillis())
                         }
                     }
                     .flowOn(Dispatchers.IO)
                     .buffer()
-        val playlists =
+            }
+        val storedPlaylists =
             flow { emitAll(storedPlaylists.read().asFlow()) }
-                .map { ExploreNode.Playlist(it) }
+                .map { RawPlaylist(it) }
                 .flowOn(Dispatchers.IO)
                 .buffer()
-        return merge(audios, playlists)
+        return merge(readDistribution.manager, *read, storedPlaylists)
     }
 }
-
-internal sealed interface ExploreNode {
-    data class Audio(val file: DeviceFile) : ExploreNode
-
-    data class Playlist(val file: PlaylistFile) : ExploreNode
-}

musikr/src/main/java/org/oxycblt/musikr/pipeline/ExtractStep.kt

@@ -20,106 +20,69 @@ package org.oxycblt.musikr.pipeline
 
 import android.content.Context
 import kotlinx.coroutines.Dispatchers
-import kotlinx.coroutines.ExperimentalCoroutinesApi
 import kotlinx.coroutines.channels.Channel
 import kotlinx.coroutines.flow.Flow
 import kotlinx.coroutines.flow.buffer
-import kotlinx.coroutines.flow.flattenMerge
+import kotlinx.coroutines.flow.filterIsInstance
 import kotlinx.coroutines.flow.flowOn
 import kotlinx.coroutines.flow.map
-import kotlinx.coroutines.flow.mapNotNull
 import kotlinx.coroutines.flow.merge
-import kotlinx.coroutines.flow.onCompletion
-import kotlinx.coroutines.withContext
 import org.oxycblt.musikr.Storage
-import org.oxycblt.musikr.cache.Cache
-import org.oxycblt.musikr.cache.CacheResult
-import org.oxycblt.musikr.cover.Cover
+import org.oxycblt.musikr.cache.CachedSong
+import org.oxycblt.musikr.cache.MutableSongCache
 import org.oxycblt.musikr.cover.MutableCovers
-import org.oxycblt.musikr.fs.DeviceFile
+import org.oxycblt.musikr.log.Logger
+import org.oxycblt.musikr.metadata.Metadata
 import org.oxycblt.musikr.metadata.MetadataExtractor
-import org.oxycblt.musikr.metadata.Properties
-import org.oxycblt.musikr.playlist.PlaylistFile
-import org.oxycblt.musikr.tag.parse.ParsedTags
+import org.oxycblt.musikr.metadata.MetadataHandle
 import org.oxycblt.musikr.tag.parse.TagParser
 
 internal interface ExtractStep {
-    fun extract(nodes: Flow<ExploreNode>): Flow<ExtractedMusic>
+    fun extract(nodes: Flow<Explored.New>): Flow<Extracted>
 
     companion object {
-        fun from(context: Context, storage: Storage): ExtractStep =
+        fun from(context: Context, storage: Storage, logger: Logger): ExtractStep =
             ExtractStepImpl(
-                context,
-                MetadataExtractor.new(),
+                MetadataExtractor.new(context),
                 TagParser.new(),
                 storage.cache,
-                storage.storedCovers)
+                storage.covers,
+                logger.primary("exct"),
+            )
     }
 }
 
 private class ExtractStepImpl(
-    private val context: Context,
     private val metadataExtractor: MetadataExtractor,
     private val tagParser: TagParser,
-    private val cacheFactory: Cache.Factory,
-    private val storedCovers: MutableCovers
+    private val cache: MutableSongCache,
+    private val storedCovers: MutableCovers,
+    private val logger: Logger
 ) : ExtractStep {
-    @OptIn(ExperimentalCoroutinesApi::class)
-    override fun extract(nodes: Flow<ExploreNode>): Flow<ExtractedMusic> {
-        val cache = cacheFactory.open()
-        val addingMs = System.currentTimeMillis()
-        val filterFlow =
-            nodes.divert {
-                when (it) {
-                    is ExploreNode.Audio -> Divert.Right(it.file)
-                    is ExploreNode.Playlist -> Divert.Left(it.file)
-                }
-            }
-        val audioNodes = filterFlow.right
-        val playlistNodes = filterFlow.left.map { ExtractedMusic.Valid.Playlist(it) }
+    override fun extract(nodes: Flow<Explored.New>): Flow<Extracted> {
+        logger.d("extract start.")
 
-        val readDistributedFlow = audioNodes.distribute(8)
-        val cacheResults =
-            readDistributedFlow.flows
-                .map { flow ->
-                    flow
-                        .map { wrap(it) { file -> cache.read(file, storedCovers) } }
-                        .flowOn(Dispatchers.IO)
-                        .buffer(Channel.UNLIMITED)
-                }
-                .flattenMerge()
-                .buffer(Channel.UNLIMITED)
-        val cacheFlow =
-            cacheResults.divert {
-                when (it) {
-                    is CacheResult.Hit -> Divert.Left(it.song)
-                    is CacheResult.Miss -> Divert.Right(it.file)
-                }
-            }
-        val cachedSongs = cacheFlow.left.map { ExtractedMusic.Valid.Song(it) }
-        val uncachedSongs = cacheFlow.right
+        val newSongs = nodes.filterIsInstance<NewSong>()
 
-        val fds =
-            uncachedSongs
-                .mapNotNull {
-                    wrap(it) { file ->
-                        withContext(Dispatchers.IO) {
-                            context.contentResolver.openFileDescriptor(file.uri, "r")?.let { fd ->
-                                FileWith(file, fd)
-                            }
-                        }
-                    }
+        val handles =
+            newSongs
+                .tryMap {
+                    val handle = metadataExtractor.open(it.file)
+                    if (handle != null) NewSongHandle(it, handle) else ExtractFailed
                 }
                 .flowOn(Dispatchers.IO)
                 .buffer(Channel.UNLIMITED)
 
-        val metadata =
-            fds.mapNotNull { fileWith ->
-                    wrap(fileWith.file) { _ ->
-                        metadataExtractor
-                            .extract(fileWith.file, fileWith.with)
-                            .let { FileWith(fileWith.file, it) }
-                            .also { withContext(Dispatchers.IO) { fileWith.with.close() } }
+        val extracted =
+            handles
+                .tryMap { item ->
+                    when (item) {
+                        is NewSongHandle -> {
+                            val metadata = item.handle.extract()
+                            if (metadata != null) NewSongMetadata(item.song, metadata)
+                            else ExtractFailed
+                        }
+                        is ExtractFailed -> ExtractFailed
                     }
                 }
                 .flowOn(Dispatchers.IO)
@@ -127,74 +90,58 @@ private class ExtractStepImpl(
                 // 8 to minimize GCs.
                 .buffer(8)
 
-        val extractedSongs =
-            metadata
-                .map { fileWith ->
-                    if (fileWith.with != null) {
-                        val tags = tagParser.parse(fileWith.file, fileWith.with)
-                        val cover = fileWith.with.cover?.let { storedCovers.write(it) }
-                        RawSong(fileWith.file, fileWith.with.properties, tags, cover, addingMs)
-                    } else {
-                        null
+        val validDiversion =
+            extracted.divert {
+                when (it) {
+                    is NewSongMetadata -> Divert.Right(it)
+                    is ExtractFailed -> Divert.Left(it)
                 }
             }
+
+        val success = validDiversion.right
+        val failed = validDiversion.left
+
+        val parsed =
+            success
+                .tryMap { item ->
+                    val tags = tagParser.parse(item.song.file, item.metadata)
+                    val cover = item.metadata.cover?.let { storedCovers.write(it) }
+                    RawSong(
+                        item.song.file, item.metadata.properties, tags, cover, item.song.addedMs)
+                }
                 .flowOn(Dispatchers.IO)
                 .buffer(Channel.UNLIMITED)
 
-        val extractedFilter =
-            extractedSongs.divert {
-                if (it != null) Divert.Left(it) else Divert.Right(ExtractedMusic.Invalid)
-            }
-
-        val write = extractedFilter.left
-        val invalid = extractedFilter.right
-
-        val writeDistributedFlow = write.distribute(8)
+        val writeDistribution = parsed.distribute(8)
         val writtenSongs =
-            writeDistributedFlow.flows
-                .map { flow ->
+            writeDistribution.flows.mapx { flow ->
                 flow
-                        .map {
-                            wrap(it, cache::write)
-                            ExtractedMusic.Valid.Song(it)
+                    .tryMap {
+                        val cachedSong =
+                            CachedSong(it.file, it.properties, it.tags, it.cover?.id, it.addedMs)
+                        cache.write(cachedSong)
+                        it
                     }
                     .flowOn(Dispatchers.IO)
                     .buffer(Channel.UNLIMITED)
             }
-                .flattenMerge()
 
-        val merged =
-            merge(
-                filterFlow.manager,
-                readDistributedFlow.manager,
-                cacheFlow.manager,
-                cachedSongs,
-                extractedFilter.manager,
-                writeDistributedFlow.manager,
-                writtenSongs,
-                invalid,
-                playlistNodes)
+        val invalidSongs = failed.map { InvalidSong }
 
-        return merged.onCompletion { cache.finalize() }
+        return merge(validDiversion.manager, writeDistribution.manager, *writtenSongs, invalidSongs)
     }
 
-    private data class FileWith<T>(val file: DeviceFile, val with: T)
+    private sealed interface ExtractedInternal {
+        sealed interface Pre : ExtractedInternal
+
+        sealed interface Post : ExtractedInternal
     }
 
-internal data class RawSong(
-    val file: DeviceFile,
-    val properties: Properties,
-    val tags: ParsedTags,
-    val cover: Cover?,
-    val addedMs: Long
-)
+    private data class NewSongHandle(val song: NewSong, val handle: MetadataHandle) :
+        ExtractedInternal.Pre
 
-internal sealed interface ExtractedMusic {
-    sealed interface Valid : ExtractedMusic {
-        data class Song(val song: RawSong) : Valid
+    private data class NewSongMetadata(val song: NewSong, val metadata: Metadata) :
+        ExtractedInternal.Post
 
-        data class Playlist(val file: PlaylistFile) : Valid
-    }
-
-    data object Invalid : ExtractedMusic
+    private data object ExtractFailed : ExtractedInternal.Pre, ExtractedInternal.Post
 }

musikr/src/main/java/org/oxycblt/musikr/pipeline/FlowUtil.kt

@@ -20,9 +20,7 @@ package org.oxycblt.musikr.pipeline
 
 import kotlinx.coroutines.channels.Channel
 import kotlinx.coroutines.flow.Flow
-import kotlinx.coroutines.flow.asFlow
 import kotlinx.coroutines.flow.flow
-import kotlinx.coroutines.flow.map
 import kotlinx.coroutines.flow.receiveAsFlow
 import kotlinx.coroutines.flow.withIndex
 
@@ -57,7 +55,7 @@ internal inline fun <T, L, R> Flow<T>.divert(
     return DivertedFlow(managedFlow, leftChannel.receiveAsFlow(), rightChannel.receiveAsFlow())
 }
 
-internal class DistributedFlow<T>(val manager: Flow<Nothing>, val flows: Flow<Flow<T>>)
+internal class DistributedFlow<T>(val manager: Flow<Nothing>, val flows: Array<Flow<T>>)
 
 /**
  * Equally "distributes" the values of some flow across n new flows.
@@ -66,7 +64,7 @@ internal class DistributedFlow<T>(val manager: Flow<Nothing>, val flows: Flow<Fl
  * order to function. Without this, all of the newly split flows will simply block.
  */
 internal fun <T> Flow<T>.distribute(n: Int): DistributedFlow<T> {
-    val posChannels = List(n) { Channel<T>(Channel.UNLIMITED) }
+    val posChannels = Array(n) { Channel<T>(Channel.UNLIMITED) }
     val managerFlow =
         flow<Nothing> {
             withIndex().collect {
@@ -77,6 +75,9 @@ internal fun <T> Flow<T>.distribute(n: Int): DistributedFlow<T> {
                 channel.close()
             }
         }
-    val hotFlows = posChannels.asFlow().map { it.receiveAsFlow() }
+    val hotFlows = posChannels.mapx { it.receiveAsFlow() }
     return DistributedFlow(managerFlow, hotFlows)
 }
+
+internal inline fun <T, reified R> Array<T>.mapx(transform: (T) -> R) =
+    Array(size) { index -> transform(this[index]) }

musikr/src/main/java/org/oxycblt/musikr/pipeline/PipelineException.kt

@@ -18,71 +18,20 @@
  
 package org.oxycblt.musikr.pipeline
 
-import org.oxycblt.musikr.fs.DeviceFile
-import org.oxycblt.musikr.playlist.PlaylistFile
-import org.oxycblt.musikr.playlist.interpret.PrePlaylist
-import org.oxycblt.musikr.tag.interpret.PreSong
+import kotlinx.coroutines.flow.Flow
+import kotlinx.coroutines.flow.map
 
-class PipelineException(val processing: WhileProcessing, val error: Exception) : Exception() {
+class PipelineException(val processing: Any?, val error: Exception) : Exception() {
     override val cause = error
 
-    override val message = "Error while processing ${processing}: ${error.stackTraceToString()}"
+    override val message =
+        "Error while processing a ${processing?.let { it::class.simpleName} } ${processing}: ${error.stackTraceToString()}"
 }
 
-sealed interface WhileProcessing {
-    class AFile internal constructor(private val file: DeviceFile) : WhileProcessing {
-        override fun toString() = "File @ ${file.path}"
-    }
-
-    class ARawSong internal constructor(private val rawSong: RawSong) : WhileProcessing {
-        override fun toString() = "Raw Song @ ${rawSong.file.path}"
-    }
-
-    class APlaylistFile internal constructor(private val playlist: PlaylistFile) : WhileProcessing {
-        override fun toString() = "Playlist File @ ${playlist.name}"
-    }
-
-    class APreSong internal constructor(private val preSong: PreSong) : WhileProcessing {
-        override fun toString() = "Pre Song @ ${preSong.path}"
-    }
-
-    class APrePlaylist internal constructor(private val prePlaylist: PrePlaylist) :
-        WhileProcessing {
-        override fun toString() = "Pre Playlist @ ${prePlaylist.name}"
-    }
-}
-
-internal suspend fun <R> wrap(file: DeviceFile, block: suspend (DeviceFile) -> R): R =
+internal fun <T : Any, R> Flow<T>.tryMap(block: suspend (T) -> R): Flow<R> = map {
     try {
-        block(file)
+        block(it)
     } catch (e: Exception) {
-        throw PipelineException(WhileProcessing.AFile(file), e)
+        throw PipelineException(it, e)
     }
-
-internal suspend fun <R> wrap(song: RawSong, block: suspend (RawSong) -> R): R =
-    try {
-        block(song)
-    } catch (e: Exception) {
-        throw PipelineException(WhileProcessing.ARawSong(song), e)
-    }
-
-internal suspend fun <R> wrap(file: PlaylistFile, block: suspend (PlaylistFile) -> R): R =
-    try {
-        block(file)
-    } catch (e: Exception) {
-        throw PipelineException(WhileProcessing.APlaylistFile(file), e)
-    }
-
-internal suspend fun <R> wrap(song: PreSong, block: suspend (PreSong) -> R): R =
-    try {
-        block(song)
-    } catch (e: Exception) {
-        throw PipelineException(WhileProcessing.APreSong(song), e)
-    }
-
-internal suspend fun <R> wrap(playlist: PrePlaylist, block: suspend (PrePlaylist) -> R): R =
-    try {
-        block(playlist)
-    } catch (e: Exception) {
-        throw PipelineException(WhileProcessing.APrePlaylist(playlist), e)
 }

musikr/src/main/java/org/oxycblt/musikr/pipeline/PipelineItem.kt

@@ -0,0 +1,57 @@
+/*
+ * Copyright (c) 2025 Auxio Project
+ * PipelineItem.kt is part of Auxio.
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+ 
+package org.oxycblt.musikr.pipeline
+
+import org.oxycblt.musikr.cover.Cover
+import org.oxycblt.musikr.fs.device.DeviceFile
+import org.oxycblt.musikr.metadata.Properties
+import org.oxycblt.musikr.playlist.PlaylistFile
+import org.oxycblt.musikr.tag.parse.ParsedTags
+
+internal sealed interface PipelineItem
+
+internal sealed interface Incomplete : PipelineItem
+
+internal sealed interface Complete : PipelineItem
+
+internal sealed interface Explored : PipelineItem {
+    sealed interface New : Explored, Incomplete
+
+    sealed interface Known : Explored, Complete
+}
+
+internal data class NewSong(val file: DeviceFile, val addedMs: Long) : Explored.New
+
+internal sealed interface Extracted : PipelineItem {
+    sealed interface Valid : Complete, Extracted
+
+    sealed interface Invalid : Extracted
+}
+
+data object InvalidSong : Extracted.Invalid
+
+internal data class RawPlaylist(val file: PlaylistFile) : Explored.Known, Extracted.Valid
+
+internal data class RawSong(
+    val file: DeviceFile,
+    val properties: Properties,
+    val tags: ParsedTags,
+    val cover: Cover?,
+    val addedMs: Long
+) : Explored.Known, Extracted.Valid

musikr/src/main/java/org/oxycblt/musikr/tag/format/Vorbis.kt

@@ -1,70 +0,0 @@
-/*
- * Copyright (c) 2024 Auxio Project
- * Vorbis.kt is part of Auxio.
- *
- * This program is free software: you can redistribute it and/or modify
- * it under the terms of the GNU General Public License as published by
- * the Free Software Foundation, either version 3 of the License, or
- * (at your option) any later version.
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
- * GNU General Public License for more details.
- *
- * You should have received a copy of the GNU General Public License
- * along with this program.  If not, see <https://www.gnu.org/licenses/>.
- */
- 
-package org.oxycblt.musikr.tag.format
-
-import org.oxycblt.musikr.util.positiveOrNull
-
-/**
- * Parse an ID3v2-style position + total [String] field. These fields consist of a number and an
- * (optional) total value delimited by a /.
- *
- * @return The position value extracted from the string field, or null if:
- * - The position could not be parsed
- * - The position was zeroed AND the total value was not present/zeroed
- *
- * @see transformPositionField
- */
-internal fun String.parseSlashPositionField() =
-    split('/', limit = 2).let {
-        transformPositionField(it[0].toIntOrNull(), it.getOrNull(1)?.toIntOrNull())
-    }
-
-/**
- * Parse a vorbis-style position + total field. These fields consist of two fields for the position
- * and total numbers.
- *
- * @param pos The position value, or null if not present.
- * @param total The total value, if not present.
- * @return The position value extracted from the field, or null if:
- * - The position could not be parsed
- * - The position was zeroed AND the total value was not present/zeroed
- *
- * @see transformPositionField
- */
-internal fun parseXiphPositionField(pos: String?, total: String?) =
-    pos?.let { posStr ->
-        posStr.toIntOrNull()?.let { transformPositionField(it, total?.toIntOrNull()) }
-            ?: posStr.parseSlashPositionField()
-    }
-
-/**
- * Transform a raw position + total field into a position a way that tolerates placeholder values.
- *
- * @param pos The position value, or null if not present.
- * @param total The total value, if not present.
- * @return The position value extracted from the field, or null if:
- * - The position could not be parsed
- * - The position was zeroed AND the total value was not present/zeroed
- */
-internal fun transformPositionField(pos: Int?, total: Int?) =
-    if (pos != null && (pos > 0 || (total?.positiveOrNull() != null))) {
-        pos
-    } else {
-        null
-    }

musikr/src/main/java/org/oxycblt/musikr/tag/interpret/ID3Genre.kt

@@ -1,6 +1,6 @@
 /*
- * Copyright (c) 2024 Auxio Project
- * ID3.kt is part of Auxio.
+ * Copyright (c) 2025 Auxio Project
+ * ID3Genre.kt is part of Auxio.
  *
  * This program is free software: you can redistribute it and/or modify
  * it under the terms of the GNU General Public License as published by
@@ -16,9 +16,7 @@
  * along with this program.  If not, see <https://www.gnu.org/licenses/>.
  */
  
-package org.oxycblt.musikr.tag.format
-
-/// --- ID3v2 PARSING ---
+package org.oxycblt.musikr.tag.interpret
 
 /**
  * Parse a multi-value genre name using ID3 rules. This will convert any ID3v1 integer

musikr/src/main/java/org/oxycblt/musikr/tag/interpret/Interpreter.kt

@@ -1,6 +1,6 @@
 /*
  * Copyright (c) 2024 Auxio Project
- * TagInterpreter.kt is part of Auxio.
+ * Interpreter.kt is part of Auxio.
  *
  * This program is free software: you can redistribute it and/or modify
  * it under the terms of the GNU General Public License as published by
@@ -26,19 +26,18 @@ import org.oxycblt.musikr.tag.Name
 import org.oxycblt.musikr.tag.Placeholder
 import org.oxycblt.musikr.tag.ReleaseType
 import org.oxycblt.musikr.tag.ReplayGainAdjustment
-import org.oxycblt.musikr.tag.format.parseId3GenreNames
 import org.oxycblt.musikr.tag.parse.ParsedTags
 import org.oxycblt.musikr.util.toUuidOrNull
 
-internal interface TagInterpreter {
+internal interface Interpreter {
     fun interpret(song: RawSong): PreSong
 
     companion object {
-        fun new(interpretation: Interpretation): TagInterpreter = TagInterpreterImpl(interpretation)
+        fun new(interpretation: Interpretation): Interpreter = InterpreterImpl(interpretation)
     }
 }
 
-private class TagInterpreterImpl(private val interpretation: Interpretation) : TagInterpreter {
+private class InterpreterImpl(private val interpretation: Interpretation) : Interpreter {
     override fun interpret(song: RawSong): PreSong {
         val individualPreArtists =
             makePreArtists(

musikr/src/main/java/org/oxycblt/musikr/tag/parse/ParsedTags.kt

@@ -20,7 +20,7 @@ package org.oxycblt.musikr.tag.parse
 
 import org.oxycblt.musikr.tag.Date
 
-internal data class ParsedTags(
+data class ParsedTags(
     val durationMs: Long,
     val replayGainTrackAdjustment: Float? = null,
     val replayGainAlbumAdjustment: Float? = null,

musikr/src/main/java/org/oxycblt/musikr/tag/parse/TagFields.kt

@@ -21,9 +21,8 @@ package org.oxycblt.musikr.tag.parse
 import androidx.core.text.isDigitsOnly
 import org.oxycblt.musikr.metadata.Metadata
 import org.oxycblt.musikr.tag.Date
-import org.oxycblt.musikr.tag.format.parseSlashPositionField
-import org.oxycblt.musikr.tag.format.parseXiphPositionField
 import org.oxycblt.musikr.util.nonZeroOrNull
+import org.oxycblt.musikr.util.positiveOrNull
 
 // Note: TagLibJNI deliberately uppercases descriptive tags to avoid casing issues,
 // hence why the casing here is matched. Note that MP4 atoms are kept in their
@@ -46,17 +45,44 @@ internal fun Metadata.sortName() = (xiph["TITLESORT"] ?: mp4["sonm"] ?: id3v2["T
 
 // Track.
 internal fun Metadata.track() =
-    (parseXiphPositionField(
+    (parseSeparatedPosition(
         xiph["TRACKNUMBER"]?.first(),
         (xiph["TOTALTRACKS"] ?: xiph["TRACKTOTAL"] ?: xiph["TRACKC"])?.first())
-        ?: (mp4["trkn"] ?: id3v2["TRCK"])?.run { first().parseSlashPositionField() })
+        ?: (mp4["trkn"] ?: id3v2["TRCK"])?.run { first().parseJoinedPosition() })
 
 // Disc and it's subtitle name.
 internal fun Metadata.disc() =
-    (parseXiphPositionField(
+    (parseSeparatedPosition(
         xiph["DISCNUMBER"]?.first(),
         (xiph["TOTALDISCS"] ?: xiph["DISCTOTAL"] ?: xiph["DISCC"])?.run { first() })
-        ?: (mp4["disk"] ?: id3v2["TPOS"])?.run { first().parseSlashPositionField() })
+        ?: (mp4["disk"] ?: id3v2["TPOS"])?.run { first().parseJoinedPosition() })
+
+private fun String.parseJoinedPosition() =
+    split('/', limit = 2).let {
+        transformPosition(it[0].toIntOrNull(), it.getOrNull(1)?.toIntOrNull())
+    }
+
+private fun parseSeparatedPosition(pos: String?, total: String?) =
+    pos?.let { posStr ->
+        posStr.toIntOrNull()?.let { transformPosition(it, total?.toIntOrNull()) }
+            ?: posStr.parseJoinedPosition()
+    }
+
+/**
+ * Transform a raw position + total field into a position a way that tolerates placeholder values.
+ *
+ * @param pos The position value, or null if not present.
+ * @param total The total value, if not present.
+ * @return The position value extracted from the field, or null if:
+ * - The position could not be parsed
+ * - The position was zeroed AND the total value was not present/zeroed
+ */
+private fun transformPosition(pos: Int?, total: Int?) =
+    if (pos != null && (pos > 0 || (total?.positiveOrNull() != null))) {
+        pos
+    } else {
+        null
+    }
 
 internal fun Metadata.subtitle() = (xiph["DISCSUBTITLE"] ?: id3v2["TSST"])?.first()
 
@@ -88,6 +114,40 @@ internal fun Metadata.date() =
             ?: id3v2["TDRL"])
         ?.run { Date.from(first()) } ?: parseId3v23Date())
 
+private fun Metadata.parseId3v23Date(): Date? {
+    // Assume that TDAT/TIME can refer to TYER or TORY depending on if TORY
+    // is present.
+    val year =
+        id3v2["TORY"]?.run { first().toIntOrNull() }
+            ?: id3v2["TYER"]?.run { first().toIntOrNull() }
+            ?: return null
+
+    val tdat = id3v2["TDAT"]
+    return if (tdat != null && tdat.first().length == 4 && tdat.first().isDigitsOnly()) {
+        // TDAT frames consist of a 4-digit string where the first two digits are
+        // the month and the last two digits are the day.
+        val mm = tdat.first().substring(0..1).toInt()
+        val dd = tdat.first().substring(2..3).toInt()
+
+        val time = id3v2["TIME"]
+        if (time != null && time.first().length == 4 && time.first().isDigitsOnly()) {
+            // TIME frames consist of a 4-digit string where the first two digits are
+            // the hour and the last two digits are the minutes. No second value is
+            // possible.
+            val hh = time.first().substring(0..1).toInt()
+            val mi = time.first().substring(2..3).toInt()
+            // Able to returnIts a full date.
+            Date.from(year, mm, dd, hh, mi)
+        } else {
+            // Unable to parse time, just return a date
+            Date.from(year, mm, dd)
+        }
+    } else {
+        // Unable to parse month/day, just return a year
+        return Date.from(year)
+    }
+}
+
 // Album
 internal fun Metadata.albumMusicBrainzId() =
     (xiph["MUSICBRAINZ_ALBUMID"]
@@ -214,7 +274,7 @@ internal fun Metadata.isCompilation() =
         ?: mp4["----:COM.APPLE.ITUNES:ITUNESCOMPILATION"]
         ?: id3v2["TCMP"]
         ?: id3v2["TXXX:COMPILATION"]
-        ?: id3v2["TXXX:ITUNESCOMPILATION"]) == listOf("1")
+        ?: id3v2["TXXX:ITUNESItsCOMPILATION"]) == listOf("1")
 
 // ReplayGain information
 internal fun Metadata.replayGainTrackAdjustment() =
@@ -248,37 +308,3 @@ private fun List<String>.parseReplayGainAdjustment() =
  * https://github.com/vanilla-music/vanilla
  */
 private val REPLAYGAIN_ADJUSTMENT_FILTER_REGEX by lazy { Regex("[^\\d.-]") }
-
-private fun Metadata.parseId3v23Date(): Date? {
-    // Assume that TDAT/TIME can refer to TYER or TORY depending on if TORY
-    // is present.
-    val year =
-        id3v2["TORY"]?.run { first().toIntOrNull() }
-            ?: id3v2["TYER"]?.run { first().toIntOrNull() }
-            ?: return null
-
-    val tdat = id3v2["TDAT"]
-    return if (tdat != null && tdat.first().length == 4 && tdat.first().isDigitsOnly()) {
-        // TDAT frames consist of a 4-digit string where the first two digits are
-        // the month and the last two digits are the day.
-        val mm = tdat.first().substring(0..1).toInt()
-        val dd = tdat.first().substring(2..3).toInt()
-
-        val time = id3v2["TIME"]
-        if (time != null && time.first().length == 4 && time.first().isDigitsOnly()) {
-            // TIME frames consist of a 4-digit string where the first two digits are
-            // the hour and the last two digits are the minutes. No second value is
-            // possible.
-            val hh = time.first().substring(0..1).toInt()
-            val mi = time.first().substring(2..3).toInt()
-            // Able to return a full date.
-            Date.from(year, mm, dd, hh, mi)
-        } else {
-            // Unable to parse time, just return a date
-            Date.from(year, mm, dd)
-        }
-    } else {
-        // Unable to parse month/day, just return a year
-        return Date.from(year)
-    }
-}

musikr/src/main/java/org/oxycblt/musikr/tag/parse/TagParser.kt

@@ -18,7 +18,7 @@
  
 package org.oxycblt.musikr.tag.parse
 
-import org.oxycblt.musikr.fs.DeviceFile
+import org.oxycblt.musikr.fs.device.DeviceFile
 import org.oxycblt.musikr.metadata.Metadata
 import org.oxycblt.musikr.util.unlikelyToBeNull
 

musikr/src/test/java/org/oxycblt/musikr/tag/interpret/ID3GenreTest.kt

@@ -0,0 +1,55 @@
+/*
+ * Copyright (c) 2023 Auxio Project
+ * ID3GenreTest.kt is part of Auxio.
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+ 
+package org.oxycblt.musikr.tag.interpret
+
+import org.junit.Assert.assertEquals
+import org.junit.Test
+
+class ID3GenreTest {
+    @Test
+    fun parseId3v2Genre_multi() {
+        assertEquals(
+            listOf("Post-Rock", "Shoegaze", "Glitch"),
+            listOf("Post-Rock", "Shoegaze", "Glitch").parseId3GenreNames())
+    }
+
+    @Test
+    fun parseId3v2Genre_multiId3v1() {
+        assertEquals(
+            listOf("Post-Rock", "Shoegaze", "Glitch"),
+            listOf("176", "178", "Glitch").parseId3GenreNames())
+    }
+
+    @Test
+    fun parseId3v2Genre_wackId3() {
+        assertEquals(null, listOf("2941").parseId3GenreNames())
+    }
+
+    @Test
+    fun parseId3v2Genre_singleId3v23() {
+        assertEquals(
+            listOf("Post-Rock", "Shoegaze", "Remix", "Cover", "Glitch"),
+            listOf("(176)(178)(RX)(CR)Glitch").parseId3GenreNames())
+    }
+
+    @Test
+    fun parseId3v2Genre_singleId3v1() {
+        assertEquals(listOf("Post-Rock"), listOf("176").parseId3GenreNames())
+    }
+}

musikr/src/test/java/org/oxycblt/musikr/tag/parse/TagUtilTest.kt

@@ -1,146 +0,0 @@
-/*
- * Copyright (c) 2023 Auxio Project
- * TagUtilTest.kt is part of Auxio.
- *
- * This program is free software: you can redistribute it and/or modify
- * it under the terms of the GNU General Public License as published by
- * the Free Software Foundation, either version 3 of the License, or
- * (at your option) any later version.
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
- * GNU General Public License for more details.
- *
- * You should have received a copy of the GNU General Public License
- * along with this program.  If not, see <https://www.gnu.org/licenses/>.
- */
- 
-package org.oxycblt.musikr.tag.parse
-
-import org.junit.Assert.assertEquals
-import org.junit.Test
-import org.oxycblt.musikr.tag.format.parseId3GenreNames
-import org.oxycblt.musikr.tag.format.parseSlashPositionField
-import org.oxycblt.musikr.tag.format.parseXiphPositionField
-import org.oxycblt.musikr.util.correctWhitespace
-import org.oxycblt.musikr.util.splitEscaped
-
-class TagUtilTest {
-    @Test
-    fun splitEscaped_correct() {
-        assertEquals(listOf("a", "b", "c"), "a,b,c".splitEscaped { it == ',' })
-    }
-
-    @Test
-    fun splitEscaped_escaped() {
-        assertEquals(listOf("a,b", "c"), "a\\,b,c".splitEscaped { it == ',' })
-    }
-
-    @Test
-    fun splitEscaped_whitespace() {
-        assertEquals(listOf("a ", " b", " c ", "  "), "a , b, c ,  ".splitEscaped { it == ',' })
-    }
-
-    @Test
-    fun splitEscaped_escapedWhitespace() {
-        assertEquals(listOf("a , b", " c ", "  "), ("a \\, b, c ,  ".splitEscaped { it == ',' }))
-    }
-
-    @Test
-    fun correctWhitespace_stringCorrect() {
-        assertEquals(
-            "asymptotic self-improvement",
-            " asymptotic self-improvement  ".correctWhitespace(),
-        )
-    }
-
-    @Test
-    fun correctWhitespace_stringOopsAllWhitespace() {
-        assertEquals(null, "".correctWhitespace())
-        assertEquals(null, "      ".correctWhitespace())
-    }
-
-    @Test
-    fun correctWhitespace_listCorrect() {
-        assertEquals(
-            listOf("asymptotic self-improvement", "daemons never stop", "tcp phagocyte"),
-            listOf(" asymptotic self-improvement  ", "  daemons never stop", "tcp phagocyte")
-                .correctWhitespace(),
-        )
-    }
-
-    @Test
-    fun correctWhitespace_listOopsAllWhitespace() {
-        assertEquals(
-            listOf("tcp phagocyte"), listOf("      ", "", "  tcp phagocyte").correctWhitespace())
-    }
-
-    @Test
-    fun parseId3v2PositionField_correct() {
-        assertEquals(16, "16/32".parseSlashPositionField())
-        assertEquals(16, "16".parseSlashPositionField())
-    }
-
-    @Test
-    fun parseId3v2PositionField_zeroed() {
-        assertEquals(null, "0".parseSlashPositionField())
-        assertEquals(0, "0/32".parseSlashPositionField())
-    }
-
-    @Test
-    fun parseId3v2PositionField_wack() {
-        assertEquals(16, "16/".parseSlashPositionField())
-        assertEquals(null, "a".parseSlashPositionField())
-        assertEquals(null, "a/b".parseSlashPositionField())
-    }
-
-    @Test
-    fun parseVorbisPositionField_correct() {
-        assertEquals(16, parseXiphPositionField("16", "32"))
-        assertEquals(16, parseXiphPositionField("16", null))
-    }
-
-    @Test
-    fun parseVorbisPositionField_zeroed() {
-        assertEquals(null, parseXiphPositionField("0", null))
-        assertEquals(0, parseXiphPositionField("0", "32"))
-    }
-
-    @Test
-    fun parseVorbisPositionField_wack() {
-        assertEquals(null, parseXiphPositionField("a", null))
-        assertEquals(null, parseXiphPositionField("a", "b"))
-    }
-
-    @Test
-    fun parseId3v2Genre_multi() {
-        assertEquals(
-            listOf("Post-Rock", "Shoegaze", "Glitch"),
-            listOf("Post-Rock", "Shoegaze", "Glitch").parseId3GenreNames())
-    }
-
-    @Test
-    fun parseId3v2Genre_multiId3v1() {
-        assertEquals(
-            listOf("Post-Rock", "Shoegaze", "Glitch"),
-            listOf("176", "178", "Glitch").parseId3GenreNames())
-    }
-
-    @Test
-    fun parseId3v2Genre_wackId3() {
-        assertEquals(null, listOf("2941").parseId3GenreNames())
-    }
-
-    @Test
-    fun parseId3v2Genre_singleId3v23() {
-        assertEquals(
-            listOf("Post-Rock", "Shoegaze", "Remix", "Cover", "Glitch"),
-            listOf("(176)(178)(RX)(CR)Glitch").parseId3GenreNames())
-    }
-
-    @Test
-    fun parsId3v2Genre_singleId3v1() {
-        assertEquals(listOf("Post-Rock"), listOf("176").parseId3GenreNames())
-    }
-}

musikr/src/test/java/org/oxycblt/musikr/util/TagFieldTest.kt

@@ -0,0 +1,73 @@
+/*
+ * Copyright (c) 2023 Auxio Project
+ * TagFieldTest.kt is part of Auxio.
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+ 
+package org.oxycblt.musikr.util
+
+import org.junit.Assert.assertEquals
+import org.junit.Test
+
+class TagFieldTest {
+    @Test
+    fun splitEscaped_correct() {
+        assertEquals(listOf("a", "b", "c"), "a,b,c".splitEscaped { it == ',' })
+    }
+
+    @Test
+    fun splitEscaped_escaped() {
+        assertEquals(listOf("a,b", "c"), "a\\,b,c".splitEscaped { it == ',' })
+    }
+
+    @Test
+    fun splitEscaped_whitespace() {
+        assertEquals(listOf("a ", " b", " c ", "  "), "a , b, c ,  ".splitEscaped { it == ',' })
+    }
+
+    @Test
+    fun splitEscaped_escapedWhitespace() {
+        assertEquals(listOf("a , b", " c ", "  "), ("a \\, b, c ,  ".splitEscaped { it == ',' }))
+    }
+
+    @Test
+    fun correctWhitespace_stringCorrect() {
+        assertEquals(
+            "asymptotic self-improvement",
+            " asymptotic self-improvement  ".correctWhitespace(),
+        )
+    }
+
+    @Test
+    fun correctWhitespace_stringOopsAllWhitespace() {
+        assertEquals(null, "".correctWhitespace())
+        assertEquals(null, "      ".correctWhitespace())
+    }
+
+    @Test
+    fun correctWhitespace_listCorrect() {
+        assertEquals(
+            listOf("asymptotic self-improvement", "daemons never stop", "tcp phagocyte"),
+            listOf(" asymptotic self-improvement  ", "  daemons never stop", "tcp phagocyte")
+                .correctWhitespace(),
+        )
+    }
+
+    @Test
+    fun correctWhitespace_listOopsAllWhitespace() {
+        assertEquals(
+            listOf("tcp phagocyte"), listOf("      ", "", "  tcp phagocyte").correctWhitespace())
+    }
+}