music: make extractors injectable

Refactor the music module to make each individual extractor able to be
injected directly.

app/src/main/java/org/oxycblt/auxio/detail/AlbumDetailFragment.kt

@@ -32,6 +32,7 @@ import org.oxycblt.auxio.databinding.FragmentDetailBinding
 import org.oxycblt.auxio.detail.recycler.AlbumDetailAdapter
 import org.oxycblt.auxio.list.Item
 import org.oxycblt.auxio.list.ListFragment
+import org.oxycblt.auxio.list.Sort
 import org.oxycblt.auxio.list.adapter.BasicListInstructions
 import org.oxycblt.auxio.list.selection.SelectionViewModel
 import org.oxycblt.auxio.music.Album
@@ -40,7 +41,6 @@ import org.oxycblt.auxio.music.Music
 import org.oxycblt.auxio.music.MusicMode
 import org.oxycblt.auxio.music.MusicParent
 import org.oxycblt.auxio.music.Song
-import org.oxycblt.auxio.list.Sort
 import org.oxycblt.auxio.playback.PlaybackViewModel
 import org.oxycblt.auxio.ui.NavigationViewModel
 import org.oxycblt.auxio.util.*

app/src/main/java/org/oxycblt/auxio/detail/ArtistDetailFragment.kt

@@ -32,6 +32,7 @@ import org.oxycblt.auxio.detail.recycler.ArtistDetailAdapter
 import org.oxycblt.auxio.detail.recycler.DetailAdapter
 import org.oxycblt.auxio.list.Item
 import org.oxycblt.auxio.list.ListFragment
+import org.oxycblt.auxio.list.Sort
 import org.oxycblt.auxio.list.adapter.BasicListInstructions
 import org.oxycblt.auxio.list.selection.SelectionViewModel
 import org.oxycblt.auxio.music.Album
@@ -39,7 +40,6 @@ import org.oxycblt.auxio.music.Artist
 import org.oxycblt.auxio.music.Music
 import org.oxycblt.auxio.music.MusicParent
 import org.oxycblt.auxio.music.Song
-import org.oxycblt.auxio.list.Sort
 import org.oxycblt.auxio.playback.PlaybackViewModel
 import org.oxycblt.auxio.ui.NavigationViewModel
 import org.oxycblt.auxio.util.collect

app/src/main/java/org/oxycblt/auxio/detail/DetailViewModel.kt

@@ -32,12 +32,12 @@ import org.oxycblt.auxio.R
 import org.oxycblt.auxio.detail.recycler.SortHeader
 import org.oxycblt.auxio.list.BasicHeader
 import org.oxycblt.auxio.list.Item
-import org.oxycblt.auxio.music.*
-import org.oxycblt.auxio.music.library.Library
 import org.oxycblt.auxio.list.Sort
+import org.oxycblt.auxio.music.*
 import org.oxycblt.auxio.music.metadata.AudioInfo
 import org.oxycblt.auxio.music.metadata.Disc
 import org.oxycblt.auxio.music.metadata.ReleaseType
+import org.oxycblt.auxio.music.model.Library
 import org.oxycblt.auxio.playback.PlaybackSettings
 import org.oxycblt.auxio.util.*
 

app/src/main/java/org/oxycblt/auxio/detail/GenreDetailFragment.kt

@@ -32,6 +32,7 @@ import org.oxycblt.auxio.detail.recycler.DetailAdapter
 import org.oxycblt.auxio.detail.recycler.GenreDetailAdapter
 import org.oxycblt.auxio.list.Item
 import org.oxycblt.auxio.list.ListFragment
+import org.oxycblt.auxio.list.Sort
 import org.oxycblt.auxio.list.adapter.BasicListInstructions
 import org.oxycblt.auxio.list.selection.SelectionViewModel
 import org.oxycblt.auxio.music.Album
@@ -40,7 +41,6 @@ import org.oxycblt.auxio.music.Genre
 import org.oxycblt.auxio.music.Music
 import org.oxycblt.auxio.music.MusicParent
 import org.oxycblt.auxio.music.Song
-import org.oxycblt.auxio.list.Sort
 import org.oxycblt.auxio.playback.PlaybackViewModel
 import org.oxycblt.auxio.ui.NavigationViewModel
 import org.oxycblt.auxio.util.collect

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

@@ -50,11 +50,11 @@ import org.oxycblt.auxio.home.list.ArtistListFragment
 import org.oxycblt.auxio.home.list.GenreListFragment
 import org.oxycblt.auxio.home.list.SongListFragment
 import org.oxycblt.auxio.home.tabs.AdaptiveTabStrategy
+import org.oxycblt.auxio.list.Sort
 import org.oxycblt.auxio.list.selection.SelectionFragment
 import org.oxycblt.auxio.list.selection.SelectionViewModel
 import org.oxycblt.auxio.music.*
-import org.oxycblt.auxio.music.library.Library
+import org.oxycblt.auxio.music.model.Library
-import org.oxycblt.auxio.list.Sort
 import org.oxycblt.auxio.music.system.Indexer
 import org.oxycblt.auxio.playback.PlaybackViewModel
 import org.oxycblt.auxio.ui.MainNavigationAction

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

@@ -23,9 +23,9 @@ import javax.inject.Inject
 import kotlinx.coroutines.flow.MutableStateFlow
 import kotlinx.coroutines.flow.StateFlow
 import org.oxycblt.auxio.home.tabs.Tab
-import org.oxycblt.auxio.music.*
-import org.oxycblt.auxio.music.library.Library
 import org.oxycblt.auxio.list.Sort
+import org.oxycblt.auxio.music.*
+import org.oxycblt.auxio.music.model.Library
 import org.oxycblt.auxio.playback.PlaybackSettings
 import org.oxycblt.auxio.util.logD
 

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

@@ -31,13 +31,13 @@ import org.oxycblt.auxio.home.HomeViewModel
 import org.oxycblt.auxio.home.fastscroll.FastScrollRecyclerView
 import org.oxycblt.auxio.list.*
 import org.oxycblt.auxio.list.ListFragment
+import org.oxycblt.auxio.list.Sort
 import org.oxycblt.auxio.list.adapter.BasicListInstructions
 import org.oxycblt.auxio.list.adapter.ListDiffer
 import org.oxycblt.auxio.list.adapter.SelectionIndicatorAdapter
 import org.oxycblt.auxio.list.recycler.AlbumViewHolder
 import org.oxycblt.auxio.list.selection.SelectionViewModel
 import org.oxycblt.auxio.music.*
-import org.oxycblt.auxio.list.Sort
 import org.oxycblt.auxio.playback.PlaybackViewModel
 import org.oxycblt.auxio.playback.formatDurationMs
 import org.oxycblt.auxio.playback.secsToMs

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

@@ -29,6 +29,7 @@ import org.oxycblt.auxio.home.HomeViewModel
 import org.oxycblt.auxio.home.fastscroll.FastScrollRecyclerView
 import org.oxycblt.auxio.list.*
 import org.oxycblt.auxio.list.ListFragment
+import org.oxycblt.auxio.list.Sort
 import org.oxycblt.auxio.list.adapter.BasicListInstructions
 import org.oxycblt.auxio.list.adapter.ListDiffer
 import org.oxycblt.auxio.list.adapter.SelectionIndicatorAdapter
@@ -38,7 +39,6 @@ import org.oxycblt.auxio.music.Artist
 import org.oxycblt.auxio.music.Music
 import org.oxycblt.auxio.music.MusicMode
 import org.oxycblt.auxio.music.MusicParent
-import org.oxycblt.auxio.list.Sort
 import org.oxycblt.auxio.playback.PlaybackViewModel
 import org.oxycblt.auxio.playback.formatDurationMs
 import org.oxycblt.auxio.ui.NavigationViewModel

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

@@ -29,6 +29,7 @@ import org.oxycblt.auxio.home.HomeViewModel
 import org.oxycblt.auxio.home.fastscroll.FastScrollRecyclerView
 import org.oxycblt.auxio.list.*
 import org.oxycblt.auxio.list.ListFragment
+import org.oxycblt.auxio.list.Sort
 import org.oxycblt.auxio.list.adapter.BasicListInstructions
 import org.oxycblt.auxio.list.adapter.ListDiffer
 import org.oxycblt.auxio.list.adapter.SelectionIndicatorAdapter
@@ -38,7 +39,6 @@ import org.oxycblt.auxio.music.Genre
 import org.oxycblt.auxio.music.Music
 import org.oxycblt.auxio.music.MusicMode
 import org.oxycblt.auxio.music.MusicParent
-import org.oxycblt.auxio.list.Sort
 import org.oxycblt.auxio.playback.PlaybackViewModel
 import org.oxycblt.auxio.playback.formatDurationMs
 import org.oxycblt.auxio.ui.NavigationViewModel

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

@@ -31,6 +31,7 @@ import org.oxycblt.auxio.home.HomeViewModel
 import org.oxycblt.auxio.home.fastscroll.FastScrollRecyclerView
 import org.oxycblt.auxio.list.*
 import org.oxycblt.auxio.list.ListFragment
+import org.oxycblt.auxio.list.Sort
 import org.oxycblt.auxio.list.adapter.BasicListInstructions
 import org.oxycblt.auxio.list.adapter.ListDiffer
 import org.oxycblt.auxio.list.adapter.SelectionIndicatorAdapter
@@ -40,7 +41,6 @@ import org.oxycblt.auxio.music.Music
 import org.oxycblt.auxio.music.MusicMode
 import org.oxycblt.auxio.music.MusicParent
 import org.oxycblt.auxio.music.Song
-import org.oxycblt.auxio.list.Sort
 import org.oxycblt.auxio.playback.PlaybackViewModel
 import org.oxycblt.auxio.playback.formatDurationMs
 import org.oxycblt.auxio.playback.secsToMs

app/src/main/java/org/oxycblt/auxio/image/extractor/Components.kt

@@ -30,12 +30,12 @@ import coil.size.Size
 import kotlin.math.min
 import okio.buffer
 import okio.source
+import org.oxycblt.auxio.list.Sort
 import org.oxycblt.auxio.music.Album
 import org.oxycblt.auxio.music.Artist
 import org.oxycblt.auxio.music.Genre
 import org.oxycblt.auxio.music.Music
 import org.oxycblt.auxio.music.Song
-import org.oxycblt.auxio.list.Sort
 
 /**
  * A [Keyer] implementation for [Music] data.

app/src/main/java/org/oxycblt/auxio/list/Sort.kt

@@ -21,8 +21,8 @@ import androidx.annotation.IdRes
 import kotlin.math.max
 import org.oxycblt.auxio.IntegerTable
 import org.oxycblt.auxio.R
-import org.oxycblt.auxio.music.*
 import org.oxycblt.auxio.list.Sort.Mode
+import org.oxycblt.auxio.music.*
 import org.oxycblt.auxio.music.metadata.Date
 import org.oxycblt.auxio.music.metadata.Disc
 

app/src/main/java/org/oxycblt/auxio/list/selection/SelectionViewModel.kt

@@ -23,7 +23,7 @@ import javax.inject.Inject
 import kotlinx.coroutines.flow.MutableStateFlow
 import kotlinx.coroutines.flow.StateFlow
 import org.oxycblt.auxio.music.*
-import org.oxycblt.auxio.music.library.Library
+import org.oxycblt.auxio.music.model.Library
 
 /**
  * A [ViewModel] that manages the current selection.

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

@@ -17,22 +17,18 @@
  
 package org.oxycblt.auxio.music
 
-import android.content.Context
+import dagger.Binds
 import dagger.Module
-import dagger.Provides
 import dagger.hilt.InstallIn
-import dagger.hilt.android.qualifiers.ApplicationContext
 import dagger.hilt.components.SingletonComponent
 import javax.inject.Singleton
-import org.oxycblt.auxio.music.metadata.AudioInfo
 import org.oxycblt.auxio.music.system.Indexer
+import org.oxycblt.auxio.music.system.IndexerImpl
 
 @Module
 @InstallIn(SingletonComponent::class)
-class MusicModule {
+interface MusicModule {
-    @Singleton @Provides fun musicRepository() = MusicRepository.new()
+    @Singleton @Binds fun musicRepository(musicRepository: MusicRepositoryImpl): MusicRepository
-    @Singleton @Provides fun indexer() = Indexer.new()
+    @Singleton @Binds fun indexer(indexer: IndexerImpl): Indexer
-    @Provides fun settings(@ApplicationContext context: Context) = MusicSettings.from(context)
+    @Binds fun settings(musicSettingsImpl: MusicSettingsImpl): MusicSettings
-    @Provides
-    fun audioInfoProvider(@ApplicationContext context: Context) = AudioInfo.Provider.from(context)
 }

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

@@ -17,7 +17,8 @@
  
 package org.oxycblt.auxio.music
 
-import org.oxycblt.auxio.music.library.Library
+import javax.inject.Inject
+import org.oxycblt.auxio.music.model.Library
 
 /**
  * A repository granting access to the music library.
@@ -60,17 +61,9 @@ interface MusicRepository {
          */
         fun onLibraryChanged(library: Library?)
     }
-
-    companion object {
-        /**
-         * Create a new instance.
-         * @return A newly-created implementation of [MusicRepository].
-         */
-        fun new(): MusicRepository = RealMusicRepository()
-    }
 }
 
-private class RealMusicRepository : MusicRepository {
+class MusicRepositoryImpl @Inject constructor() : MusicRepository {
     private val listeners = mutableListOf<MusicRepository.Listener>()
 
     @Volatile

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

@@ -20,6 +20,8 @@ package org.oxycblt.auxio.music
 import android.content.Context
 import android.os.storage.StorageManager
 import androidx.core.content.edit
+import dagger.hilt.android.qualifiers.ApplicationContext
+import javax.inject.Inject
 import org.oxycblt.auxio.R
 import org.oxycblt.auxio.list.Sort
 import org.oxycblt.auxio.music.storage.Directory
@@ -67,11 +69,11 @@ interface MusicSettings : Settings<MusicSettings.Listener> {
          * Get a framework-backed implementation.
          * @param context [Context] required.
          */
-        fun from(context: Context): MusicSettings = RealMusicSettings(context)
+        fun from(context: Context): MusicSettings = MusicSettingsImpl(context)
     }
 }
 
-private class RealMusicSettings(context: Context) :
+class MusicSettingsImpl @Inject constructor(@ApplicationContext context: Context) :
     Settings.Real<MusicSettings.Listener>(context), MusicSettings {
     private val storageManager = context.getSystemServiceCompat(StorageManager::class)
 

app/src/main/java/org/oxycblt/auxio/music/cache/CacheDatabase.kt

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2022 Auxio Project
+ * Copyright (c) 2023 Auxio Project
  *
  * 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
@@ -15,7 +15,7 @@
  * along with this program.  If not, see <https://www.gnu.org/licenses/>.
  */
  
-package org.oxycblt.auxio.music.extractor
+package org.oxycblt.auxio.music.cache
 
 import android.content.Context
 import androidx.room.Dao
@@ -28,126 +28,23 @@ import androidx.room.Room
 import androidx.room.RoomDatabase
 import androidx.room.TypeConverter
 import androidx.room.TypeConverters
-import org.oxycblt.auxio.music.Song
-import org.oxycblt.auxio.music.library.RawSong
 import org.oxycblt.auxio.music.metadata.Date
 import org.oxycblt.auxio.music.metadata.correctWhitespace
 import org.oxycblt.auxio.music.metadata.splitEscaped
-import org.oxycblt.auxio.util.*
+import org.oxycblt.auxio.music.model.RawSong
-
-/**
- * A cache of music metadata obtained in prior music loading operations. Obtain an instance with
- * [MetadataCacheRepository].
- * @author Alexander Capehart (OxygenCobalt)
- */
-interface MetadataCache {
-    /** Whether this cache has encountered a [RawSong] that did not have a cache entry. */
-    val invalidated: Boolean
-
-    /**
-     * Populate a [RawSong] from a cache entry, if it exists.
-     * @param rawSong The [RawSong] to populate.
-     * @return true if a cache entry could be applied to [rawSong], false otherwise.
-     */
-    fun populate(rawSong: RawSong): Boolean
-}
-
-private class RealMetadataCache(cachedSongs: List<CachedSong>) : MetadataCache {
-    private val cacheMap = buildMap {
-        for (cachedSong in cachedSongs) {
-            put(cachedSong.mediaStoreId, cachedSong)
-        }
-    }
-
-    override var invalidated = false
-    override fun populate(rawSong: RawSong): Boolean {
-
-        // For a cached raw song to be used, it must exist within the cache and have matching
-        // addition and modification timestamps. Technically the addition timestamp doesn't
-        // exist, but to safeguard against possible OEM-specific timestamp incoherence, we
-        // check for it anyway.
-        val cachedSong = cacheMap[rawSong.mediaStoreId]
-        if (cachedSong != null &&
-            cachedSong.dateAdded == rawSong.dateAdded &&
-            cachedSong.dateModified == rawSong.dateModified) {
-            cachedSong.copyToRaw(rawSong)
-            return true
-        }
-
-        // We could not populate this song. This means our cache is stale and should be
-        // re-written with newly-loaded music.
-        invalidated = true
-        return false
-    }
-}
-
-/**
- * A repository allowing access to cached metadata obtained in prior music loading operations.
- * @author Alexander Capehart (OxygenCobalt)
- */
-interface MetadataCacheRepository {
-    /**
-     * Read the current [MetadataCache], if it exists.
-     * @return The stored [MetadataCache], or null if it could not be obtained.
-     */
-    suspend fun readCache(): MetadataCache?
-
-    /**
-     * Write the list of newly-loaded [RawSong]s to the cache, replacing the prior data.
-     * @param rawSongs The [rawSongs] to write to the cache.
-     */
-    suspend fun writeCache(rawSongs: List<RawSong>)
-
-    companion object {
-        /**
-         * Create a framework-backed instance.
-         * @param context [Context] required.
-         * @return A new instance.
-         */
-        fun from(context: Context): MetadataCacheRepository = RealMetadataCacheRepository(context)
-    }
-}
-
-private class RealMetadataCacheRepository(private val context: Context) : MetadataCacheRepository {
-    private val cachedSongsDao: CachedSongsDao by lazy {
-        MetadataCacheDatabase.getInstance(context).cachedSongsDao()
-    }
-
-    override suspend fun readCache() =
-        try {
-            // Faster to load the whole database into memory than do a query on each
-            // populate call.
-            RealMetadataCache(cachedSongsDao.readSongs())
-        } catch (e: Exception) {
-            logE("Unable to load cache database.")
-            logE(e.stackTraceToString())
-            null
-        }
-
-    override suspend fun writeCache(rawSongs: List<RawSong>) {
-        try {
-            // Still write out whatever data was extracted.
-            cachedSongsDao.nukeSongs()
-            cachedSongsDao.insertSongs(rawSongs.map(CachedSong::fromRaw))
-        } catch (e: Exception) {
-            logE("Unable to save cache database.")
-            logE(e.stackTraceToString())
-        }
-    }
-}
 
 @Database(entities = [CachedSong::class], version = 27, exportSchema = false)
-private abstract class MetadataCacheDatabase : RoomDatabase() {
+abstract class CacheDatabase : RoomDatabase() {
     abstract fun cachedSongsDao(): CachedSongsDao
 
     companion object {
-        @Volatile private var INSTANCE: MetadataCacheDatabase? = null
+        @Volatile private var INSTANCE: CacheDatabase? = null
 
         /**
          * Get/create the shared instance of this database.
          * @param context [Context] required.
          */
-        fun getInstance(context: Context): MetadataCacheDatabase {
+        fun getInstance(context: Context): CacheDatabase {
             val instance = INSTANCE
             if (instance != null) {
                 return instance
@@ -157,8 +54,8 @@ private abstract class MetadataCacheDatabase : RoomDatabase() {
                 val newInstance =
                     Room.databaseBuilder(
                             context.applicationContext,
-                            MetadataCacheDatabase::class.java,
+                            CacheDatabase::class.java,
-                            "auxio_metadata_cache.db")
+                            "auxio_tag_cache.db")
                         .fallbackToDestructiveMigration()
                         .fallbackToDestructiveMigrationFrom(0)
                         .fallbackToDestructiveMigrationOnDowngrade()
@@ -171,7 +68,7 @@ private abstract class MetadataCacheDatabase : RoomDatabase() {
 }
 
 @Dao
-private interface CachedSongsDao {
+interface CachedSongsDao {
     @Query("SELECT * FROM ${CachedSong.TABLE_NAME}") suspend fun readSongs(): List<CachedSong>
     @Query("DELETE FROM ${CachedSong.TABLE_NAME}") suspend fun nukeSongs()
     @Insert suspend fun insertSongs(songs: List<CachedSong>)
@@ -179,7 +76,7 @@ private interface CachedSongsDao {
 
 @Entity(tableName = CachedSong.TABLE_NAME)
 @TypeConverters(CachedSong.Converters::class)
-private data class CachedSong(
+data class CachedSong(
     /**
      * The ID of the [Song]'s audio file, obtained from MediaStore. Note that this ID is highly
      * unstable and should only be used for accessing the audio file.

app/src/main/java/org/oxycblt/auxio/music/cache/CacheModule.kt

@@ -15,19 +15,19 @@
  * along with this program.  If not, see <https://www.gnu.org/licenses/>.
  */
  
-package org.oxycblt.auxio.playback.persist
+package org.oxycblt.auxio.music.cache
 
-import androidx.room.TypeConverter
+import android.content.Context
-import org.oxycblt.auxio.music.Music
+import dagger.Module
+import dagger.Provides
+import dagger.hilt.InstallIn
+import dagger.hilt.android.qualifiers.ApplicationContext
+import dagger.hilt.components.SingletonComponent
+import org.oxycblt.auxio.music.extractor.CacheRepository
 
-/**
+@Module
- * Defines conversions used in the persistence table.
+@InstallIn(SingletonComponent::class)
- * @author Alexander Capehart (OxygenCobalt)
+class CacheModule {
- */
+    @Provides
-object PersistenceConverters {
+    fun cacheRepository(@ApplicationContext context: Context) = CacheRepository.from(context)
-    /** @see [Music.UID.toString] */
-    @TypeConverter fun fromMusicUID(uid: Music.UID?) = uid?.toString()
-
-    /** @see [Music.UID.fromString] */
-    @TypeConverter fun toMusicUid(string: String?) = string?.let(Music.UID::fromString)
 }

app/src/main/java/org/oxycblt/auxio/music/cache/CacheRepository.kt

@@ -0,0 +1,126 @@
+/*
+ * Copyright (c) 2022 Auxio Project
+ *
+ * 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.extractor
+
+import android.content.Context
+import org.oxycblt.auxio.music.cache.CacheDatabase
+import org.oxycblt.auxio.music.cache.CachedSong
+import org.oxycblt.auxio.music.cache.CachedSongsDao
+import org.oxycblt.auxio.music.model.RawSong
+import org.oxycblt.auxio.util.*
+
+/**
+ * A cache of music metadata obtained in prior music loading operations. Obtain an instance with
+ * [CacheRepository].
+ * @author Alexander Capehart (OxygenCobalt)
+ */
+interface Cache {
+    /** Whether this cache has encountered a [RawSong] that did not have a cache entry. */
+    val invalidated: Boolean
+
+    /**
+     * Populate a [RawSong] from a cache entry, if it exists.
+     * @param rawSong The [RawSong] to populate.
+     * @return true if a cache entry could be applied to [rawSong], false otherwise.
+     */
+    fun populate(rawSong: RawSong): Boolean
+}
+
+private class RealCache(cachedSongs: List<CachedSong>) : Cache {
+    private val cacheMap = buildMap {
+        for (cachedSong in cachedSongs) {
+            put(cachedSong.mediaStoreId, cachedSong)
+        }
+    }
+
+    override var invalidated = false
+    override fun populate(rawSong: RawSong): Boolean {
+
+        // For a cached raw song to be used, it must exist within the cache and have matching
+        // addition and modification timestamps. Technically the addition timestamp doesn't
+        // exist, but to safeguard against possible OEM-specific timestamp incoherence, we
+        // check for it anyway.
+        val cachedSong = cacheMap[rawSong.mediaStoreId]
+        if (cachedSong != null &&
+            cachedSong.dateAdded == rawSong.dateAdded &&
+            cachedSong.dateModified == rawSong.dateModified) {
+            cachedSong.copyToRaw(rawSong)
+            return true
+        }
+
+        // We could not populate this song. This means our cache is stale and should be
+        // re-written with newly-loaded music.
+        invalidated = true
+        return false
+    }
+}
+
+/**
+ * A repository allowing access to cached metadata obtained in prior music loading operations.
+ * @author Alexander Capehart (OxygenCobalt)
+ */
+interface CacheRepository {
+    /**
+     * Read the current [Cache], if it exists.
+     * @return The stored [Cache], or null if it could not be obtained.
+     */
+    suspend fun readCache(): Cache?
+
+    /**
+     * Write the list of newly-loaded [RawSong]s to the cache, replacing the prior data.
+     * @param rawSongs The [rawSongs] to write to the cache.
+     */
+    suspend fun writeCache(rawSongs: List<RawSong>)
+
+    companion object {
+        /**
+         * Create a framework-backed instance.
+         * @param context [Context] required.
+         * @return A new instance.
+         */
+        fun from(context: Context): CacheRepository = RealCacheRepository(context)
+    }
+}
+
+private class RealCacheRepository(private val context: Context) : CacheRepository {
+    private val cachedSongsDao: CachedSongsDao by lazy {
+        CacheDatabase.getInstance(context).cachedSongsDao()
+    }
+
+    override suspend fun readCache() =
+        try {
+            // Faster to load the whole database into memory than do a query on each
+            // populate call.
+            RealCache(cachedSongsDao.readSongs())
+        } catch (e: Exception) {
+            logE("Unable to load cache database.")
+            logE(e.stackTraceToString())
+            null
+        }
+
+    override suspend fun writeCache(rawSongs: List<RawSong>) {
+        try {
+            // Still write out whatever data was extracted.
+            cachedSongsDao.nukeSongs()
+            cachedSongsDao.insertSongs(rawSongs.map(CachedSong::fromRaw))
+        } catch (e: Exception) {
+            logE("Unable to save cache database.")
+            logE(e.stackTraceToString())
+        }
+    }
+}

app/src/main/java/org/oxycblt/auxio/music/metadata/AudioInfo.kt

@@ -20,6 +20,8 @@ package org.oxycblt.auxio.music.metadata
 import android.content.Context
 import android.media.MediaExtractor
 import android.media.MediaFormat
+import dagger.hilt.android.qualifiers.ApplicationContext
+import javax.inject.Inject
 import org.oxycblt.auxio.music.Song
 import org.oxycblt.auxio.music.storage.MimeType
 import org.oxycblt.auxio.util.logD
@@ -46,18 +48,15 @@ data class AudioInfo(
          * @return The [AudioInfo] of the [Song], if possible to obtain.
          */
         suspend fun extract(song: Song): AudioInfo
-
-        companion object {
-            /**
-             * Get a framework-backed implementation.
-             * @param context [Context] required.
-             */
-            fun from(context: Context): Provider = RealAudioInfoProvider(context)
-        }
     }
 }
 
-private class RealAudioInfoProvider(private val context: Context) : AudioInfo.Provider {
+/**
+ * A framework-backed implementation of [AudioInfo.Provider].
+ * @param context [Context] required to read audio files.
+ */
+class AudioInfoProviderImpl @Inject constructor(@ApplicationContext private val context: Context) :
+    AudioInfo.Provider {
     // While we would use ExoPlayer to extract this information, it doesn't support
     // common data like bit rate in progressive data sources due to there being no
     // demand. Thus, we are stuck with the inferior OS-provided MediaExtractor.

app/src/main/java/org/oxycblt/auxio/music/metadata/MetadataModule.kt

@@ -0,0 +1,30 @@
+/*
+ * Copyright (c) 2023 Auxio Project
+ *
+ * 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.metadata
+
+import dagger.Binds
+import dagger.Module
+import dagger.hilt.InstallIn
+import dagger.hilt.components.SingletonComponent
+
+@Module
+@InstallIn(SingletonComponent::class)
+interface MetadataModule {
+    @Binds fun tagExtractor(tagExtractor: TagExtractorImpl): TagExtractor
+    @Binds fun audioInfoProvider(audioInfoProvider: AudioInfoProviderImpl): AudioInfo.Provider
+}

app/src/main/java/org/oxycblt/auxio/music/metadata/TagExtractor.kt

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2022 Auxio Project
+ * Copyright (c) 2023 Auxio Project
  *
  * 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
@@ -15,19 +15,17 @@
  * along with this program.  If not, see <https://www.gnu.org/licenses/>.
  */
  
-package org.oxycblt.auxio.music.extractor
+package org.oxycblt.auxio.music.metadata
 
 import android.content.Context
 import androidx.core.text.isDigitsOnly
 import com.google.android.exoplayer2.MediaItem
 import com.google.android.exoplayer2.MetadataRetriever
+import dagger.hilt.android.qualifiers.ApplicationContext
+import javax.inject.Inject
 import kotlinx.coroutines.channels.Channel
 import kotlinx.coroutines.yield
-import org.oxycblt.auxio.music.library.RawSong
+import org.oxycblt.auxio.music.model.RawSong
-import org.oxycblt.auxio.music.metadata.Date
-import org.oxycblt.auxio.music.metadata.TextTags
-import org.oxycblt.auxio.music.metadata.parseId3v2PositionField
-import org.oxycblt.auxio.music.metadata.parseVorbisPositionField
 import org.oxycblt.auxio.music.storage.toAudioUri
 import org.oxycblt.auxio.util.logD
 import org.oxycblt.auxio.util.logW
@@ -35,17 +33,30 @@ import org.oxycblt.auxio.util.logW
 /**
  * The extractor that leverages ExoPlayer's [MetadataRetriever] API to parse metadata. This is the
  * last step in the music extraction process and is mostly responsible for papering over the bad
- * metadata that [RealMediaStoreExtractor] produces.
+ * metadata that other extractors produce.
  *
- * @param context [Context] required for reading audio files.
  * @author Alexander Capehart (OxygenCobalt)
  */
-class MetadataExtractor(private val context: Context) {
+interface TagExtractor {
+    /**
+     * Extract the metadata of songs from [incompleteSongs] and send them to [completeSongs]. Will
+     * terminate as soon as [incompleteSongs] is closed.
+     * @param incompleteSongs A [Channel] of incomplete songs to process.
+     * @param completeSongs A [Channel] to send completed songs to.
+     */
+    suspend fun consume(incompleteSongs: Channel<RawSong>, completeSongs: Channel<RawSong>)
+}
+
+class TagExtractorImpl @Inject constructor(@ApplicationContext private val context: Context) :
+    TagExtractor {
+    override suspend fun consume(
+        incompleteSongs: Channel<RawSong>,
+        completeSongs: Channel<RawSong>
+    ) {
         // We can parallelize MetadataRetriever Futures to work around it's speed issues,
         // producing similar throughput's to other kinds of manual metadata extraction.
-    private val taskPool: Array<Task?> = arrayOfNulls(TASK_CAPACITY)
+        val taskPool: Array<Task?> = arrayOfNulls(TASK_CAPACITY)
 
-    suspend fun consume(incompleteSongs: Channel<RawSong>, completeSongs: Channel<RawSong>) {
         spin@ while (true) {
             // Spin until there is an open slot we can insert a task in.
             for (i in taskPool.indices) {
@@ -94,7 +105,7 @@ class MetadataExtractor(private val context: Context) {
 }
 
 /**
- * Wraps a [MetadataExtractor] future and processes it into a [RawSong] when completed.
+ * Wraps a [TagExtractor] future and processes it into a [RawSong] when completed.
  * @param context [Context] required to open the audio file.
  * @param rawSong [RawSong] to process.
  * @author Alexander Capehart (OxygenCobalt)

app/src/main/java/org/oxycblt/auxio/music/model/Library.kt

@@ -15,7 +15,7 @@
  * along with this program.  If not, see <https://www.gnu.org/licenses/>.
  */
  
-package org.oxycblt.auxio.music.library
+package org.oxycblt.auxio.music.model
 
 import android.content.Context
 import android.net.Uri

app/src/main/java/org/oxycblt/auxio/music/model/RawMusic.kt

@@ -15,7 +15,7 @@
  * along with this program.  If not, see <https://www.gnu.org/licenses/>.
  */
  
-package org.oxycblt.auxio.music.library
+package org.oxycblt.auxio.music.model
 
 import java.util.UUID
 import org.oxycblt.auxio.music.*

app/src/main/java/org/oxycblt/auxio/music/model/RealMusic.kt

@@ -15,7 +15,7 @@
  * along with this program.  If not, see <https://www.gnu.org/licenses/>.
  */
  
-package org.oxycblt.auxio.music.library
+package org.oxycblt.auxio.music.model
 
 import android.content.Context
 import androidx.annotation.VisibleForTesting

app/src/main/java/org/oxycblt/auxio/music/storage/MediaStoreExtractor.kt

@@ -15,13 +15,12 @@
  * along with this program.  If not, see <https://www.gnu.org/licenses/>.
  */
  
-package org.oxycblt.auxio.music.extractor
+package org.oxycblt.auxio.music.storage
 
 import android.content.Context
 import android.database.Cursor
 import android.os.Build
 import android.os.storage.StorageManager
-import android.os.storage.StorageVolume
 import android.provider.MediaStore
 import androidx.annotation.RequiresApi
 import androidx.core.database.getIntOrNull
@@ -30,91 +29,77 @@ import java.io.File
 import kotlinx.coroutines.channels.Channel
 import kotlinx.coroutines.yield
 import org.oxycblt.auxio.music.MusicSettings
-import org.oxycblt.auxio.music.library.RawSong
+import org.oxycblt.auxio.music.extractor.Cache
 import org.oxycblt.auxio.music.metadata.Date
 import org.oxycblt.auxio.music.metadata.parseId3v2PositionField
 import org.oxycblt.auxio.music.metadata.transformPositionField
-import org.oxycblt.auxio.music.storage.Directory
+import org.oxycblt.auxio.music.model.RawSong
-import org.oxycblt.auxio.music.storage.contentResolverSafe
-import org.oxycblt.auxio.music.storage.directoryCompat
-import org.oxycblt.auxio.music.storage.mediaStoreVolumeNameCompat
-import org.oxycblt.auxio.music.storage.safeQuery
-import org.oxycblt.auxio.music.storage.storageVolumesCompat
-import org.oxycblt.auxio.music.storage.useQuery
 import org.oxycblt.auxio.util.getSystemServiceCompat
 import org.oxycblt.auxio.util.logD
 
 /**
  * The layer that loads music from the [MediaStore] database. This is an intermediate step in the
  * music extraction process and primarily intended for redundancy for files not natively supported
- * by [MetadataExtractor]. Solely relying on this is not recommended, as it often produces bad
+ * by other extractors. Solely relying on this is not recommended, as it often produces bad
  * metadata.
  * @author Alexander Capehart (OxygenCobalt)
  */
 interface MediaStoreExtractor {
     /**
-     * Query the media database, initializing this instance in the process.
+     * Query the media database.
-     * @return The new [Cursor] returned by the media databases.
+     * @return A new [Query] returned from the media database.
      */
-    suspend fun query(): Cursor
+    suspend fun query(): Query
 
     /**
      * Consume the [Cursor] loaded after [query].
-     * @param cache A [MetadataCache] used to avoid extracting metadata for cached songs, or null if
+     * @param query The [Query] to consume.
-     * no [MetadataCache] was available.
+     * @param cache A [Cache] used to avoid extracting metadata for cached songs, or null if no
-     * @param incompleteSongs A channel where songs that could not be retrieved from the
+     * [Cache] was available.
-     * [MetadataCache] should be sent to.
+     * @param incompleteSongs A channel where songs that could not be retrieved from the [Cache]
+     * should be sent to.
      * @param completeSongs A channel where completed songs should be sent to.
      */
     suspend fun consume(
-        cache: MetadataCache?,
+        query: Query,
+        cache: Cache?,
         incompleteSongs: Channel<RawSong>,
         completeSongs: Channel<RawSong>
     )
 
+    /** A black-box interface representing a query from the media database. */
+    interface Query {
+        val projectedTotal: Int
+        fun moveToNext(): Boolean
+        fun close()
+        fun populateFileInfo(rawSong: RawSong)
+        fun populateTags(rawSong: RawSong)
+    }
+
     companion object {
         /**
          * Create a framework-backed instance.
          * @param context [Context] required.
+         * @param musicSettings [MusicSettings] required.
          * @return A new [RealMediaStoreExtractor] that will work best on the device's API level.
          */
-        fun from(context: Context): MediaStoreExtractor =
+        fun from(context: Context, musicSettings: MusicSettings): MediaStoreExtractor =
             when {
-                Build.VERSION.SDK_INT >= Build.VERSION_CODES.R -> Api30MediaStoreExtractor(context)
+                Build.VERSION.SDK_INT >= Build.VERSION_CODES.R ->
-                Build.VERSION.SDK_INT >= Build.VERSION_CODES.Q -> Api29MediaStoreExtractor(context)
+                    Api30MediaStoreExtractor(context, musicSettings)
-                else -> Api21MediaStoreExtractor(context)
+                Build.VERSION.SDK_INT >= Build.VERSION_CODES.Q ->
+                    Api29MediaStoreExtractor(context, musicSettings)
+                else -> Api21MediaStoreExtractor(context, musicSettings)
             }
     }
 }
 
-private abstract class RealMediaStoreExtractor(private val context: Context) : MediaStoreExtractor {
+private abstract class RealMediaStoreExtractor(
-    private var cursor: Cursor? = null
+    protected val context: Context,
-    private var idIndex = -1
+    private val musicSettings: MusicSettings
-    private var titleIndex = -1
+) : MediaStoreExtractor {
-    private var displayNameIndex = -1
+    final override suspend fun query(): MediaStoreExtractor.Query {
-    private var mimeTypeIndex = -1
-    private var sizeIndex = -1
-    private var dateAddedIndex = -1
-    private var dateModifiedIndex = -1
-    private var durationIndex = -1
-    private var yearIndex = -1
-    private var albumIndex = -1
-    private var albumIdIndex = -1
-    private var artistIndex = -1
-    private var albumArtistIndex = -1
-    private val genreNamesMap = mutableMapOf<Long, String>()
-
-    /**
-     * The [StorageVolume]s currently scanned by [MediaStore]. This should be used to transform path
-     * information from the database into volume-aware paths.
-     */
-    protected var volumes = listOf<StorageVolume>()
-        private set
-
-    override suspend fun query(): Cursor {
         val start = System.currentTimeMillis()
-        val musicSettings = MusicSettings.from(context)
-        val storageManager = context.getSystemServiceCompat(StorageManager::class)
 
         val args = mutableListOf<String>()
         var selector = BASE_SELECTOR
@@ -156,30 +141,14 @@ private abstract class RealMediaStoreExtractor(private val context: Context) : M
         // Now we can actually query MediaStore.
         logD("Starting song query [proj: ${projection.toList()}, selector: $selector, args: $args]")
         val cursor =
-            context.contentResolverSafe
+            context.contentResolverSafe.safeQuery(
-                .safeQuery(
                 MediaStore.Audio.Media.EXTERNAL_CONTENT_URI,
                 projection,
                 selector,
                 args.toTypedArray())
-                .also { cursor = it }
         logD("Song query succeeded [Projected total: ${cursor.count}]")
 
-        // Set up cursor indices for later use.
+        val genreNamesMap = mutableMapOf<Long, String>()
-        idIndex = cursor.getColumnIndexOrThrow(MediaStore.Audio.AudioColumns._ID)
-        titleIndex = cursor.getColumnIndexOrThrow(MediaStore.Audio.AudioColumns.TITLE)
-        displayNameIndex = cursor.getColumnIndexOrThrow(MediaStore.Audio.AudioColumns.DISPLAY_NAME)
-        mimeTypeIndex = cursor.getColumnIndexOrThrow(MediaStore.Audio.AudioColumns.MIME_TYPE)
-        sizeIndex = cursor.getColumnIndexOrThrow(MediaStore.Audio.AudioColumns.SIZE)
-        dateAddedIndex = cursor.getColumnIndexOrThrow(MediaStore.Audio.AudioColumns.DATE_ADDED)
-        dateModifiedIndex =
-            cursor.getColumnIndexOrThrow(MediaStore.Audio.AudioColumns.DATE_MODIFIED)
-        durationIndex = cursor.getColumnIndexOrThrow(MediaStore.Audio.AudioColumns.DURATION)
-        yearIndex = cursor.getColumnIndexOrThrow(MediaStore.Audio.AudioColumns.YEAR)
-        albumIndex = cursor.getColumnIndexOrThrow(MediaStore.Audio.AudioColumns.ALBUM)
-        albumIdIndex = cursor.getColumnIndexOrThrow(MediaStore.Audio.AudioColumns.ALBUM_ID)
-        artistIndex = cursor.getColumnIndexOrThrow(MediaStore.Audio.AudioColumns.ARTIST)
-        albumArtistIndex = cursor.getColumnIndexOrThrow(AUDIO_COLUMN_ALBUM_ARTIST)
 
         // Since we can't obtain the genre tag from a song query, we must construct our own
         // equivalent from genre database queries. Theoretically, this isn't needed since
@@ -211,34 +180,31 @@ private abstract class RealMediaStoreExtractor(private val context: Context) : M
             }
         }
 
-        volumes = storageManager.storageVolumesCompat
         logD("Finished initialization in ${System.currentTimeMillis() - start}ms")
-
+        return wrapQuery(cursor, genreNamesMap)
-        return cursor
     }
 
-    override suspend fun consume(
+    final override suspend fun consume(
-        cache: MetadataCache?,
+        query: MediaStoreExtractor.Query,
+        cache: Cache?,
         incompleteSongs: Channel<RawSong>,
         completeSongs: Channel<RawSong>
     ) {
-        val cursor = requireNotNull(cursor) { "Must call query first before running consume" }
+        while (query.moveToNext()) {
-        while (cursor.moveToNext()) {
             val rawSong = RawSong()
-            populateFileData(cursor, rawSong)
+            query.populateFileInfo(rawSong)
             if (cache?.populate(rawSong) == true) {
                 completeSongs.send(rawSong)
             } else {
-                populateMetadata(cursor, rawSong)
+                query.populateFileInfo(rawSong)
                 incompleteSongs.send(rawSong)
             }
             yield()
         }
         // Free the cursor and signal that no more incomplete songs will be produced by
         // this extractor.
-        cursor.close()
+        query.close()
         incompleteSongs.close()
-        this.cursor = null
     }
 
     /**
@@ -280,19 +246,43 @@ private abstract class RealMediaStoreExtractor(private val context: Context) : M
      */
     protected abstract fun addDirToSelector(dir: Directory, args: MutableList<String>): Boolean
 
-    /**
+    protected abstract fun wrapQuery(
-     * Populate a [RawSong] with the "File Data" of the given [MediaStore] [Cursor], which is the
+        cursor: Cursor,
-     * data that cannot be cached. This includes any information not intrinsic to the file and
+        genreNamesMap: Map<Long, String>
-     * instead dependent on the file-system, which could change without invalidating the cache due
+    ): MediaStoreExtractor.Query
-     * to volume additions or removals.
+
-     * @param cursor The [Cursor] to read from.
+    abstract class Query(
-     * @param rawSong The [RawSong] to populate.
+        protected val cursor: Cursor,
-     * @see populateMetadata
+        private val genreNamesMap: Map<Long, String>
-     */
+    ) : MediaStoreExtractor.Query {
-    protected open fun populateFileData(cursor: Cursor, rawSong: RawSong) {
+        private val idIndex = cursor.getColumnIndexOrThrow(MediaStore.Audio.AudioColumns._ID)
+        private val titleIndex = cursor.getColumnIndexOrThrow(MediaStore.Audio.AudioColumns.TITLE)
+        private val displayNameIndex =
+            cursor.getColumnIndexOrThrow(MediaStore.Audio.AudioColumns.DISPLAY_NAME)
+        private val mimeTypeIndex =
+            cursor.getColumnIndexOrThrow(MediaStore.Audio.AudioColumns.MIME_TYPE)
+        private val sizeIndex = cursor.getColumnIndexOrThrow(MediaStore.Audio.AudioColumns.SIZE)
+        private val dateAddedIndex =
+            cursor.getColumnIndexOrThrow(MediaStore.Audio.AudioColumns.DATE_ADDED)
+        private val dateModifiedIndex =
+            cursor.getColumnIndexOrThrow(MediaStore.Audio.AudioColumns.DATE_MODIFIED)
+        private val durationIndex =
+            cursor.getColumnIndexOrThrow(MediaStore.Audio.AudioColumns.DURATION)
+        private val yearIndex = cursor.getColumnIndexOrThrow(MediaStore.Audio.AudioColumns.YEAR)
+        private val albumIndex = cursor.getColumnIndexOrThrow(MediaStore.Audio.AudioColumns.ALBUM)
+        private val albumIdIndex =
+            cursor.getColumnIndexOrThrow(MediaStore.Audio.AudioColumns.ALBUM_ID)
+        private val artistIndex = cursor.getColumnIndexOrThrow(MediaStore.Audio.AudioColumns.ARTIST)
+        private val albumArtistIndex = cursor.getColumnIndexOrThrow(AUDIO_COLUMN_ALBUM_ARTIST)
+
+        final override val projectedTotal = cursor.count
+        final override fun moveToNext() = cursor.moveToNext()
+        final override fun close() = cursor.close()
+
+        override fun populateFileInfo(rawSong: RawSong) {
             rawSong.mediaStoreId = cursor.getLong(idIndex)
             rawSong.dateAdded = cursor.getLong(dateAddedIndex)
-        rawSong.dateModified = cursor.getLong(dateAddedIndex)
+            rawSong.dateModified = cursor.getLong(dateModifiedIndex)
             // Try to use the DISPLAY_NAME column to obtain a (probably sane) file name
             // from the android system.
             rawSong.fileName = cursor.getStringOrNull(displayNameIndex)
@@ -300,15 +290,7 @@ private abstract class RealMediaStoreExtractor(private val context: Context) : M
             rawSong.albumMediaStoreId = cursor.getLong(albumIdIndex)
         }
 
-    /**
+        override fun populateTags(rawSong: RawSong) {
-     * Populate a [RawSong] with the Metadata of the given [MediaStore] [Cursor], which is the data
-     * about a [RawSong] that can be cached. This includes any information intrinsic to the file or
-     * it's file format, such as music tags.
-     * @param cursor The [Cursor] to read from.
-     * @param rawSong The [RawSong] to populate.
-     * @see populateFileData
-     */
-    protected open fun populateMetadata(cursor: Cursor, rawSong: RawSong) {
             // Song title
             rawSong.name = cursor.getString(titleIndex)
             // Size (in bytes)
@@ -320,7 +302,8 @@ private abstract class RealMediaStoreExtractor(private val context: Context) : M
             // This is one of the major weaknesses of using MediaStore, hence the redundancy layers.
             rawSong.date = cursor.getStringOrNull(yearIndex)?.let(Date::from)
             // A non-existent album name should theoretically be the name of the folder it contained
-        // in, but in practice it is more often "0" (as in /storage/emulated/0), even when it the
+            // in, but in practice it is more often "0" (as in /storage/emulated/0), even when it
+            // the
             // file is not actually in the root internal storage directory. We can't do anything to
             // fix this, really.
             rawSong.albumName = cursor.getString(albumIndex)
@@ -337,6 +320,7 @@ private abstract class RealMediaStoreExtractor(private val context: Context) : M
             // Get the genre value we had to query for in initialization
             genreNamesMap[rawSong.mediaStoreId]?.let { rawSong.genreNames = listOf(it) }
         }
+    }
 
     companion object {
         /**
@@ -364,18 +348,11 @@ private abstract class RealMediaStoreExtractor(private val context: Context) : M
 // Note: The separation between version-specific backends may not be the cleanest. To preserve
 // speed, we only want to add redundancy on known issues, not with possible issues.
 
-private class Api21MediaStoreExtractor(context: Context) : RealMediaStoreExtractor(context) {
+// Note: The separation between version-specific backends may not be the cleanest. To preserve
-    private var trackIndex = -1
+// speed, we only want to add redundancy on known issues, not with possible issues.
-    private var dataIndex = -1
-
-    override suspend fun query(): Cursor {
-        val cursor = super.query()
-        // Set up cursor indices for later use.
-        trackIndex = cursor.getColumnIndexOrThrow(MediaStore.Audio.AudioColumns.TRACK)
-        dataIndex = cursor.getColumnIndexOrThrow(MediaStore.Audio.AudioColumns.DATA)
-        return cursor
-    }
 
+private class Api21MediaStoreExtractor(context: Context, musicSettings: MusicSettings) :
+    RealMediaStoreExtractor(context, musicSettings) {
     override val projection: Array<String>
         get() =
             super.projection +
@@ -398,11 +375,26 @@ private class Api21MediaStoreExtractor(context: Context) : RealMediaStoreExtract
         return true
     }
 
-    override fun populateFileData(cursor: Cursor, rawSong: RawSong) {
+    override fun wrapQuery(
-        super.populateFileData(cursor, rawSong)
+        cursor: Cursor,
+        genreNamesMap: Map<Long, String>,
+    ): MediaStoreExtractor.Query =
+        Query(cursor, genreNamesMap, context.getSystemServiceCompat(StorageManager::class))
+
+    private class Query(
+        cursor: Cursor,
+        genreNamesMap: Map<Long, String>,
+        storageManager: StorageManager
+    ) : RealMediaStoreExtractor.Query(cursor, genreNamesMap) {
+        // Set up cursor indices for later use.
+        private val trackIndex = cursor.getColumnIndexOrThrow(MediaStore.Audio.AudioColumns.TRACK)
+        private val dataIndex = cursor.getColumnIndexOrThrow(MediaStore.Audio.AudioColumns.DATA)
+        private val volumes = storageManager.storageVolumesCompat
+
+        override fun populateFileInfo(rawSong: RawSong) {
+            super.populateFileInfo(rawSong)
 
             val data = cursor.getString(dataIndex)
-
             // On some OEM devices below API 29, DISPLAY_NAME may not be present. I assume
             // that this only applies to below API 29, as beyond API 29, this column not being
             // present would completely break the scoped storage system. Fill it in with DATA
@@ -424,8 +416,8 @@ private class Api21MediaStoreExtractor(context: Context) : RealMediaStoreExtract
             }
         }
 
-    override fun populateMetadata(cursor: Cursor, rawSong: RawSong) {
+        override fun populateTags(rawSong: RawSong) {
-        super.populateMetadata(cursor, rawSong)
+            super.populateTags(rawSong)
             // See unpackTrackNo/unpackDiscNo for an explanation
             // of how this column is set up.
             val rawTrack = cursor.getIntOrNull(trackIndex)
@@ -434,6 +426,7 @@ private class Api21MediaStoreExtractor(context: Context) : RealMediaStoreExtract
                 rawTrack.unpackDiscNo()?.let { rawSong.disc = it }
             }
         }
+    }
 }
 
 /**
@@ -442,20 +435,10 @@ private class Api21MediaStoreExtractor(context: Context) : RealMediaStoreExtract
  * @author Alexander Capehart (OxygenCobalt)
  */
 @RequiresApi(Build.VERSION_CODES.Q)
-private open class BaseApi29MediaStoreExtractor(context: Context) :
+private abstract class BaseApi29MediaStoreExtractor(
-    RealMediaStoreExtractor(context) {
+    context: Context,
-    private var volumeIndex = -1
+    musicSettings: MusicSettings
-    private var relativePathIndex = -1
+) : RealMediaStoreExtractor(context, musicSettings) {
-
-    override suspend fun query(): Cursor {
-        val cursor = super.query()
-        // Set up cursor indices for later use.
-        volumeIndex = cursor.getColumnIndexOrThrow(MediaStore.Audio.AudioColumns.VOLUME_NAME)
-        relativePathIndex =
-            cursor.getColumnIndexOrThrow(MediaStore.Audio.AudioColumns.RELATIVE_PATH)
-        return cursor
-    }
-
     override val projection: Array<String>
         get() =
             super.projection +
@@ -484,8 +467,19 @@ private open class BaseApi29MediaStoreExtractor(context: Context) :
         return true
     }
 
-    override fun populateFileData(cursor: Cursor, rawSong: RawSong) {
+    abstract class Query(
-        super.populateFileData(cursor, rawSong)
+        cursor: Cursor,
+        genreNamesMap: Map<Long, String>,
+        storageManager: StorageManager
+    ) : RealMediaStoreExtractor.Query(cursor, genreNamesMap) {
+        private val volumeIndex =
+            cursor.getColumnIndexOrThrow(MediaStore.Audio.AudioColumns.VOLUME_NAME)
+        private val relativePathIndex =
+            cursor.getColumnIndexOrThrow(MediaStore.Audio.AudioColumns.RELATIVE_PATH)
+        private val volumes = storageManager.storageVolumesCompat
+
+        final override fun populateFileInfo(rawSong: RawSong) {
+            super.populateFileInfo(rawSong)
             // Find the StorageVolume whose MediaStore name corresponds to this song.
             // This is combined with the plain relative path column to create the directory.
             val volumeName = cursor.getString(volumeIndex)
@@ -495,6 +489,7 @@ private open class BaseApi29MediaStoreExtractor(context: Context) :
                 rawSong.directory = Directory.from(volume, relativePath)
             }
         }
+    }
 }
 
 /**
@@ -505,22 +500,26 @@ private open class BaseApi29MediaStoreExtractor(context: Context) :
  * @author Alexander Capehart (OxygenCobalt)
  */
 @RequiresApi(Build.VERSION_CODES.Q)
-private open class Api29MediaStoreExtractor(context: Context) :
+private class Api29MediaStoreExtractor(context: Context, musicSettings: MusicSettings) :
-    BaseApi29MediaStoreExtractor(context) {
+    BaseApi29MediaStoreExtractor(context, musicSettings) {
-    private var trackIndex = -1
-
-    override suspend fun query(): Cursor {
-        val cursor = super.query()
-        // Set up cursor indices for later use.
-        trackIndex = cursor.getColumnIndexOrThrow(MediaStore.Audio.AudioColumns.TRACK)
-        return cursor
-    }
 
     override val projection: Array<String>
         get() = super.projection + arrayOf(MediaStore.Audio.AudioColumns.TRACK)
 
-    override fun populateMetadata(cursor: Cursor, rawSong: RawSong) {
+    override fun wrapQuery(
-        super.populateMetadata(cursor, rawSong)
+        cursor: Cursor,
+        genreNamesMap: Map<Long, String>
+    ): MediaStoreExtractor.Query =
+        Query(cursor, genreNamesMap, context.getSystemServiceCompat(StorageManager::class))
+
+    private class Query(
+        cursor: Cursor,
+        genreNamesMap: Map<Long, String>,
+        storageManager: StorageManager
+    ) : BaseApi29MediaStoreExtractor.Query(cursor, genreNamesMap, storageManager) {
+        private val trackIndex = cursor.getColumnIndexOrThrow(MediaStore.Audio.AudioColumns.TRACK)
+        override fun populateTags(rawSong: RawSong) {
+            super.populateTags(rawSong)
             // This extractor is volume-aware, but does not support the modern track columns.
             // Use the old column instead. See unpackTrackNo/unpackDiscNo for an explanation
             // of how this column is set up.
@@ -530,6 +529,7 @@ private open class Api29MediaStoreExtractor(context: Context) :
                 rawTrack.unpackDiscNo()?.let { rawSong.disc = it }
             }
         }
+    }
 }
 
 /**
@@ -539,18 +539,8 @@ private open class Api29MediaStoreExtractor(context: Context) :
  * @author Alexander Capehart (OxygenCobalt)
  */
 @RequiresApi(Build.VERSION_CODES.R)
-private class Api30MediaStoreExtractor(context: Context) : BaseApi29MediaStoreExtractor(context) {
+private class Api30MediaStoreExtractor(context: Context, musicSettings: MusicSettings) :
-    private var trackIndex: Int = -1
+    BaseApi29MediaStoreExtractor(context, musicSettings) {
-    private var discIndex: Int = -1
-
-    override suspend fun query(): Cursor {
-        val cursor = super.query()
-        // Set up cursor indices for later use.
-        trackIndex = cursor.getColumnIndexOrThrow(MediaStore.Audio.AudioColumns.CD_TRACK_NUMBER)
-        discIndex = cursor.getColumnIndexOrThrow(MediaStore.Audio.AudioColumns.DISC_NUMBER)
-        return cursor
-    }
-
     override val projection: Array<String>
         get() =
             super.projection +
@@ -560,15 +550,34 @@ private class Api30MediaStoreExtractor(context: Context) : BaseApi29MediaStoreEx
                     MediaStore.Audio.AudioColumns.CD_TRACK_NUMBER,
                     MediaStore.Audio.AudioColumns.DISC_NUMBER)
 
-    override fun populateMetadata(cursor: Cursor, rawSong: RawSong) {
+    override fun wrapQuery(
-        super.populateMetadata(cursor, rawSong)
+        cursor: Cursor,
+        genreNamesMap: Map<Long, String>
+    ): MediaStoreExtractor.Query =
+        Query(cursor, genreNamesMap, context.getSystemServiceCompat(StorageManager::class))
+
+    private class Query(
+        cursor: Cursor,
+        genreNamesMap: Map<Long, String>,
+        storageManager: StorageManager
+    ) : BaseApi29MediaStoreExtractor.Query(cursor, genreNamesMap, storageManager) {
+        private val trackIndex =
+            cursor.getColumnIndexOrThrow(MediaStore.Audio.AudioColumns.CD_TRACK_NUMBER)
+        private val discIndex =
+            cursor.getColumnIndexOrThrow(MediaStore.Audio.AudioColumns.DISC_NUMBER)
+
+        override fun populateTags(rawSong: RawSong) {
+            super.populateTags(rawSong)
             // Both CD_TRACK_NUMBER and DISC_NUMBER tend to be formatted as they are in
             // the tag itself, which is to say that it is formatted as NN/TT tracks, where
             // N is the number and T is the total. Parse the number while ignoring the
             // total, as we have no use for it.
-        cursor.getStringOrNull(trackIndex)?.parseId3v2PositionField()?.let { rawSong.track = it }
+            cursor.getStringOrNull(trackIndex)?.parseId3v2PositionField()?.let {
+                rawSong.track = it
+            }
             cursor.getStringOrNull(discIndex)?.parseId3v2PositionField()?.let { rawSong.disc = it }
         }
+    }
 }
 
 /**

app/src/main/java/org/oxycblt/auxio/music/storage/StorageModule.kt

@@ -0,0 +1,34 @@
+/*
+ * Copyright (c) 2023 Auxio Project
+ *
+ * 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.storage
+
+import android.content.Context
+import dagger.Module
+import dagger.Provides
+import dagger.hilt.InstallIn
+import dagger.hilt.android.qualifiers.ApplicationContext
+import dagger.hilt.components.SingletonComponent
+import org.oxycblt.auxio.music.MusicSettings
+
+@Module
+@InstallIn(SingletonComponent::class)
+class StorageModule {
+    @Provides
+    fun mediaStoreExtractor(@ApplicationContext context: Context, musicSettings: MusicSettings) =
+        MediaStoreExtractor.from(context, musicSettings)
+}

app/src/main/java/org/oxycblt/auxio/music/system/Indexer.kt

@@ -23,6 +23,7 @@ import android.content.pm.PackageManager
 import android.os.Build
 import androidx.core.content.ContextCompat
 import java.util.LinkedList
+import javax.inject.Inject
 import kotlinx.coroutines.CancellationException
 import kotlinx.coroutines.CoroutineScope
 import kotlinx.coroutines.Dispatchers
@@ -35,8 +36,10 @@ import kotlinx.coroutines.yield
 import org.oxycblt.auxio.BuildConfig
 import org.oxycblt.auxio.music.*
 import org.oxycblt.auxio.music.extractor.*
-import org.oxycblt.auxio.music.library.Library
+import org.oxycblt.auxio.music.metadata.TagExtractor
-import org.oxycblt.auxio.music.library.RawSong
+import org.oxycblt.auxio.music.model.Library
+import org.oxycblt.auxio.music.model.RawSong
+import org.oxycblt.auxio.music.storage.MediaStoreExtractor
 import org.oxycblt.auxio.util.logD
 import org.oxycblt.auxio.util.logE
 import org.oxycblt.auxio.util.logW
@@ -211,16 +214,17 @@ interface Indexer {
             } else {
                 Manifest.permission.READ_EXTERNAL_STORAGE
             }
-
-        /**
-         * Create a new instance.
-         * @return A newly-created implementation of [Indexer].
-         */
-        fun new(): Indexer = RealIndexer()
     }
 }
 
-private class RealIndexer : Indexer {
+class IndexerImpl
+@Inject
+constructor(
+    private val musicSettings: MusicSettings,
+    private val cacheRepository: CacheRepository,
+    private val mediaStoreExtractor: MediaStoreExtractor,
+    private val tagExtractor: TagExtractor
+) : Indexer {
     @Volatile private var lastResponse: Result<Library>? = null
     @Volatile private var indexingState: Indexer.Indexing? = null
     @Volatile private var controller: Indexer.Controller? = null
@@ -332,19 +336,15 @@ private class RealIndexer : Indexer {
         // how long a media database query will take.
         emitIndexing(Indexer.Indexing.Indeterminate)
 
-        val metadataCacheRepository = MetadataCacheRepository.from(context)
-        val mediaStoreExtractor = MediaStoreExtractor.from(context)
-        val metadataExtractor = MetadataExtractor(context)
-
         // Do the initial query of the cache and media databases in parallel.
         val mediaStoreQueryJob = scope.async { mediaStoreExtractor.query() }
         val cache =
             if (withCache) {
-                metadataCacheRepository.readCache()
+                cacheRepository.readCache()
             } else {
                 null
             }
-        val total = mediaStoreQueryJob.await().count
+        val query = mediaStoreQueryJob.await()
 
         // Now start processing the queried song information in parallel. Songs that can't be
         // received from the cache are consisted incomplete and pushed to a separate channel
@@ -352,14 +352,16 @@ private class RealIndexer : Indexer {
         val completeSongs = Channel<RawSong>(Channel.UNLIMITED)
         val incompleteSongs = Channel<RawSong>(Channel.UNLIMITED)
         val mediaStoreJob =
-            scope.async { mediaStoreExtractor.consume(cache, incompleteSongs, completeSongs) }
+            scope.async {
-        val metadataJob = scope.async { metadataExtractor.consume(incompleteSongs, completeSongs) }
+                mediaStoreExtractor.consume(query, cache, incompleteSongs, completeSongs)
+            }
+        val metadataJob = scope.async { tagExtractor.consume(incompleteSongs, completeSongs) }
 
         // Await completed raw songs as they are processed.
         val rawSongs = LinkedList<RawSong>()
         for (rawSong in completeSongs) {
             rawSongs.add(rawSong)
-            emitIndexing(Indexer.Indexing.Songs(rawSongs.size, total))
+            emitIndexing(Indexer.Indexing.Songs(rawSongs.size, query.projectedTotal))
         }
         mediaStoreJob.await()
         metadataJob.await()
@@ -367,10 +369,9 @@ private class RealIndexer : Indexer {
         // Successfully loaded the library, now save the cache and create the library in
         // parallel.
         emitIndexing(Indexer.Indexing.Indeterminate)
-        val libraryJob =
+        val libraryJob = scope.async(Dispatchers.Main) { Library.from(rawSongs, musicSettings) }
-            scope.async(Dispatchers.Main) { Library.from(rawSongs, MusicSettings.from(context)) }
         if (cache == null || cache.invalidated) {
-            metadataCacheRepository.writeCache(rawSongs)
+            cacheRepository.writeCache(rawSongs)
         }
         return libraryJob.await()
     }

app/src/main/java/org/oxycblt/auxio/picker/PickerViewModel.kt

@@ -23,7 +23,7 @@ import javax.inject.Inject
 import kotlinx.coroutines.flow.MutableStateFlow
 import kotlinx.coroutines.flow.StateFlow
 import org.oxycblt.auxio.music.*
-import org.oxycblt.auxio.music.library.Library
+import org.oxycblt.auxio.music.model.Library
 import org.oxycblt.auxio.util.unlikelyToBeNull
 
 /**

app/src/main/java/org/oxycblt/auxio/playback/persist/PersistenceDatabase.kt

@@ -27,6 +27,7 @@ import androidx.room.PrimaryKey
 import androidx.room.Query
 import androidx.room.Room
 import androidx.room.RoomDatabase
+import androidx.room.TypeConverter
 import androidx.room.TypeConverters
 import org.oxycblt.auxio.music.Music
 import org.oxycblt.auxio.playback.state.RepeatMode
@@ -39,7 +40,7 @@ import org.oxycblt.auxio.playback.state.RepeatMode
     entities = [PlaybackState::class, QueueHeapItem::class, QueueMappingItem::class],
     version = 27,
     exportSchema = false)
-@TypeConverters(PersistenceConverters::class)
+@TypeConverters(PersistenceDatabase.Converters::class)
 abstract class PersistenceDatabase : RoomDatabase() {
     /**
      * Get the current [PlaybackStateDao].
@@ -53,6 +54,14 @@ abstract class PersistenceDatabase : RoomDatabase() {
      */
     abstract fun queueDao(): QueueDao
 
+    object Converters {
+        /** @see [Music.UID.toString] */
+        @TypeConverter fun fromMusicUID(uid: Music.UID?) = uid?.toString()
+
+        /** @see [Music.UID.fromString] */
+        @TypeConverter fun toMusicUid(string: String?) = string?.let(Music.UID::fromString)
+    }
+
     companion object {
         @Volatile private var INSTANCE: PersistenceDatabase? = null
 
@@ -145,10 +154,6 @@ interface QueueDao {
     suspend fun insertMapping(mapping: List<QueueMappingItem>)
 }
 
-/**
- * A raw representation of the persisted playback state.
- * @author Alexander Capehart
- */
 @Entity(tableName = PlaybackState.TABLE_NAME)
 data class PlaybackState(
     @PrimaryKey val id: Int,
@@ -163,10 +168,6 @@ data class PlaybackState(
     }
 }
 
-/**
- * A raw representation of the an individual item in the persisted queue's heap.
- * @author Alexander Capehart
- */
 @Entity(tableName = QueueHeapItem.TABLE_NAME)
 data class QueueHeapItem(@PrimaryKey val id: Int, val uid: Music.UID) {
     companion object {
@@ -174,10 +175,6 @@ data class QueueHeapItem(@PrimaryKey val id: Int, val uid: Music.UID) {
     }
 }
 
-/**
- * A raw representation of the heap indices at a particular position in the persisted queue.
- * @author Alexander Capehart
- */
 @Entity(tableName = QueueMappingItem.TABLE_NAME)
 data class QueueMappingItem(
     @PrimaryKey val id: Int,

app/src/main/java/org/oxycblt/auxio/playback/persist/PersistenceRepository.kt

@@ -19,7 +19,7 @@ package org.oxycblt.auxio.playback.persist
 
 import android.content.Context
 import org.oxycblt.auxio.music.MusicParent
-import org.oxycblt.auxio.music.library.Library
+import org.oxycblt.auxio.music.model.Library
 import org.oxycblt.auxio.playback.queue.Queue
 import org.oxycblt.auxio.playback.state.PlaybackStateManager
 import org.oxycblt.auxio.util.logD

app/src/main/java/org/oxycblt/auxio/playback/system/PlaybackService.kt

@@ -48,7 +48,7 @@ import org.oxycblt.auxio.BuildConfig
 import org.oxycblt.auxio.music.MusicRepository
 import org.oxycblt.auxio.music.MusicSettings
 import org.oxycblt.auxio.music.Song
-import org.oxycblt.auxio.music.library.Library
+import org.oxycblt.auxio.music.model.Library
 import org.oxycblt.auxio.playback.PlaybackSettings
 import org.oxycblt.auxio.playback.persist.PersistenceRepository
 import org.oxycblt.auxio.playback.replaygain.ReplayGainAudioProcessor

app/src/main/java/org/oxycblt/auxio/search/SearchViewModel.kt

@@ -30,9 +30,9 @@ import kotlinx.coroutines.yield
 import org.oxycblt.auxio.R
 import org.oxycblt.auxio.list.BasicHeader
 import org.oxycblt.auxio.list.Item
-import org.oxycblt.auxio.music.*
-import org.oxycblt.auxio.music.library.Library
 import org.oxycblt.auxio.list.Sort
+import org.oxycblt.auxio.music.*
+import org.oxycblt.auxio.music.model.Library
 import org.oxycblt.auxio.playback.PlaybackSettings
 import org.oxycblt.auxio.util.logD
 

app/src/test/java/org/oxycblt/auxio/music/model/RawMusicTest.kt

@@ -15,7 +15,7 @@
  * along with this program.  If not, see <https://www.gnu.org/licenses/>.
  */
  
-package org.oxycblt.auxio.music.library
+package org.oxycblt.auxio.music.model
 
 import java.util.*
 import org.junit.Assert.assertEquals