musikr: make cover files more concrete

This should allow me to implement a solid ContentProvider.

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

@@ -35,6 +35,6 @@ class NullCovers(private val context: Context, private val identifier: CoverIden
     }
 }
 
-private class NullCover(override val id: String) : Cover {
+class NullCover(override val id: String) : Cover {
     override suspend fun open() = null
 }

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

@@ -23,24 +23,26 @@ import java.io.File
 import kotlinx.coroutines.Dispatchers
 import kotlinx.coroutines.withContext
 import org.oxycblt.musikr.cover.Cover
-import org.oxycblt.musikr.cover.CoverFiles
+import org.oxycblt.musikr.fs.app.AppFiles
 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.ObtainResult
 
-class SiloedCovers(
+class SiloedCovers
+private constructor(
     private val rootDir: File,
     private val silo: CoverSilo,
-    private val inner: MutableCovers
+    private val inner: FileCovers
 ) : MutableCovers {
-    override suspend fun obtain(id: String): ObtainResult {
+    override suspend fun obtain(id: String): ObtainResult<SiloedCover> {
-        val coverId = SiloedCoverId.parse(id) ?: return ObtainResult.Miss
+        val coverId = SiloedCoverId.parse(id) ?: return ObtainResult.Miss()
-        if (coverId.silo != silo) return ObtainResult.Miss
+        if (coverId.silo != silo) return ObtainResult.Miss()
         return when (val result = inner.obtain(coverId.id)) {
             is ObtainResult.Hit -> ObtainResult.Hit(SiloedCover(silo, result.cover))
-            is ObtainResult.Miss -> ObtainResult.Miss
+            is ObtainResult.Miss -> ObtainResult.Miss()
         }
     }
 
@@ -68,14 +70,14 @@ class SiloedCovers(
                 rootDir = context.coversDir()
                 revisionDir = rootDir.resolve(silo.toString()).apply { mkdirs() }
             }
-            val files = CoverFiles.at(revisionDir)
+            val files = AppFiles.at(revisionDir)
             val format = CoverFormat.jpeg(silo.params)
-            return SiloedCovers(rootDir, silo, Covers.from(files, format, identifier))
+            return SiloedCovers(rootDir, silo, FileCovers(files, format, identifier))
         }
     }
 }
 
-class SiloedCover(silo: CoverSilo, val innerCover: Cover) : Cover by innerCover {
+class SiloedCover(silo: CoverSilo, val innerCover: FileCover) : FileCover by innerCover {
     private val innerId = SiloedCoverId(silo, innerCover.id)
     override val id = innerId.toString()
 }

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

@@ -1,40 +0,0 @@
-/*
- * Copyright (c) 2023 Auxio Project
- * Cover.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.cover
-
-import java.io.InputStream
-
-interface Cover {
-    val id: String
-
-    suspend fun open(): InputStream?
-}
-
-class CoverCollection private constructor(val covers: List<Cover>) {
-    companion object {
-        fun from(covers: Collection<Cover>) =
-            CoverCollection(
-                covers
-                    .groupBy { it.id }
-                    .entries
-                    .sortedByDescending { it.key }
-                    .sortedByDescending { it.value.size }
-                    .map { it.value.first() })
-    }
-}

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

@@ -18,16 +18,10 @@
  
 package org.oxycblt.musikr.cover
 
-interface Covers {
+import java.io.InputStream
-    suspend fun obtain(id: String): ObtainResult
 
-    companion object {
+interface Covers {
-        fun from(
+    suspend fun obtain(id: String): ObtainResult<out Cover>
-            coverFiles: CoverFiles,
-            coverFormat: CoverFormat,
-            identifier: CoverIdentifier = CoverIdentifier.md5()
-        ): MutableCovers = FileCovers(coverFiles, coverFormat, identifier)
-    }
 }
 
 interface MutableCovers : Covers {
@@ -36,40 +30,27 @@ interface MutableCovers : Covers {
     suspend fun cleanup(excluding: Collection<Cover>)
 }
 
-sealed interface ObtainResult {
+interface Cover {
-    data class Hit(val cover: Cover) : ObtainResult
+    val id: String
 
-    data object Miss : ObtainResult
+    suspend fun open(): InputStream?
 }
 
-private class FileCovers(
+class CoverCollection private constructor(val covers: List<Cover>) {
-    private val coverFiles: CoverFiles,
+    companion object {
-    private val coverFormat: CoverFormat,
+        fun from(covers: Collection<Cover>) =
-    private val coverIdentifier: CoverIdentifier,
+            CoverCollection(
-) : Covers, MutableCovers {
+                covers
-    override suspend fun obtain(id: String): ObtainResult {
+                    .groupBy { it.id }
-        val file = coverFiles.find(getFileName(id))
+                    .entries
-        return if (file != null) {
+                    .sortedByDescending { it.key }
-            ObtainResult.Hit(FileCover(id, file))
+                    .sortedByDescending { it.value.size }
-        } else {
+                    .map { it.value.first() })
-            ObtainResult.Miss
-        }
     }
-
-    override suspend fun write(data: ByteArray): Cover {
-        val id = coverIdentifier.identify(data)
-        val file = coverFiles.write(getFileName(id)) { coverFormat.transcodeInto(data, it) }
-        return FileCover(id, file)
-    }
-
-    override suspend fun cleanup(excluding: Collection<Cover>) {
-        val used = excluding.mapTo(mutableSetOf()) { getFileName(it.id) }
-        coverFiles.deleteWhere { it !in used }
-    }
-
-    private fun getFileName(id: String) = "$id.${coverFormat.extension}"
 }
 
-private class FileCover(override val id: String, private val coverFile: CoverFile) : Cover {
+sealed interface ObtainResult<T : Cover> {
-    override suspend fun open() = coverFile.open()
+    data class Hit<T : Cover>(val cover: T) : ObtainResult<T>
+
+    class Miss<T : Cover> : ObtainResult<T>
 }

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

@@ -0,0 +1,61 @@
+/*
+ * Copyright (c) 2025 Auxio Project
+ * FileCovers.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.cover
+
+import android.os.ParcelFileDescriptor
+import org.oxycblt.musikr.fs.app.AppFile
+import org.oxycblt.musikr.fs.app.AppFiles
+
+class FileCovers(
+    private val appFiles: AppFiles,
+    private val coverFormat: CoverFormat,
+    private val coverIdentifier: CoverIdentifier,
+) : Covers, MutableCovers {
+    override suspend fun obtain(id: String): ObtainResult<FileCover> {
+        val file = appFiles.find(getFileName(id))
+        return if (file != null) {
+            ObtainResult.Hit(FileCoverImpl(id, file))
+        } else {
+            ObtainResult.Miss()
+        }
+    }
+
+    override suspend fun write(data: ByteArray): FileCover {
+        val id = coverIdentifier.identify(data)
+        val file = appFiles.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 }
+    }
+
+    private fun getFileName(id: String) = "$id.${coverFormat.extension}"
+}
+
+interface FileCover : Cover {
+    suspend fun fd(): ParcelFileDescriptor?
+}
+
+private class FileCoverImpl(override val id: String, private val appFile: AppFile) : FileCover {
+    override suspend fun fd() = appFile.fd()
+
+    override suspend fun open() = appFile.open()
+}

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

@@ -23,7 +23,7 @@ import android.content.Intent
 import android.net.Uri
 import android.provider.DocumentsContract
 import org.oxycblt.musikr.fs.path.DocumentPathFactory
-import org.oxycblt.musikr.fs.query.contentResolverSafe
+import org.oxycblt.musikr.fs.device.contentResolverSafe
 import org.oxycblt.musikr.util.splitEscaped
 
 class MusicLocation private constructor(val uri: Uri, val path: Path) {

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

@@ -16,8 +16,9 @@
  * along with this program.  If not, see <https://www.gnu.org/licenses/>.
  */
  
-package org.oxycblt.musikr.cover
+package org.oxycblt.musikr.fs.app
 
+import android.os.ParcelFileDescriptor
 import java.io.File
 import java.io.IOException
 import java.io.InputStream
@@ -27,26 +28,28 @@ import kotlinx.coroutines.sync.Mutex
 import kotlinx.coroutines.sync.withLock
 import kotlinx.coroutines.withContext
 
-interface CoverFiles {
+interface AppFiles {
-    suspend fun find(name: String): CoverFile?
+    suspend fun find(name: String): AppFile?
 
-    suspend fun write(name: String, block: suspend (OutputStream) -> Unit): CoverFile
+    suspend fun write(name: String, block: suspend (OutputStream) -> Unit): AppFile
 
     suspend fun deleteWhere(block: (String) -> Boolean)
 
     companion object {
-        suspend fun at(dir: File): CoverFiles {
+        suspend fun at(dir: File): AppFiles {
             withContext(Dispatchers.IO) { check(dir.exists() && dir.isDirectory) }
-            return CoverFilesImpl(dir)
+            return AppFilesImpl(dir)
         }
     }
 }
 
-interface CoverFile {
+interface AppFile {
+    suspend fun fd(): ParcelFileDescriptor?
+
     suspend fun open(): InputStream?
 }
 
-private class CoverFilesImpl(private val dir: File) : CoverFiles {
+private class AppFilesImpl(private val dir: File) : AppFiles {
     private val fileMutexes = mutableMapOf<String, Mutex>()
     private val mapMutex = Mutex()
 
@@ -54,16 +57,16 @@ private class CoverFilesImpl(private val dir: File) : CoverFiles {
         return mapMutex.withLock { fileMutexes.getOrPut(file) { Mutex() } }
     }
 
-    override suspend fun find(name: String): CoverFile? =
+    override suspend fun find(name: String): AppFile? =
         withContext(Dispatchers.IO) {
             try {
-                File(dir, name).takeIf { it.exists() }?.let { CoverFileImpl(it) }
+                File(dir, name).takeIf { it.exists() }?.let { AppFileImpl(it) }
             } catch (e: IOException) {
                 null
             }
         }
 
-    override suspend fun write(name: String, block: suspend (OutputStream) -> Unit): CoverFile {
+    override suspend fun write(name: String, block: suspend (OutputStream) -> Unit): AppFile {
         val fileMutex = getMutexForFile(name)
         return fileMutex.withLock {
             val targetFile = File(dir, name)
@@ -74,14 +77,14 @@ private class CoverFilesImpl(private val dir: File) : CoverFiles {
                     try {
                         tempFile.outputStream().use { block(it) }
                         tempFile.renameTo(targetFile)
-                        CoverFileImpl(targetFile)
+                        AppFileImpl(targetFile)
                     } catch (e: IOException) {
                         tempFile.delete()
                         throw e
                     }
                 }
             } else {
-                CoverFileImpl(targetFile)
+                AppFileImpl(targetFile)
             }
         }
     }
@@ -93,6 +96,15 @@ private class CoverFilesImpl(private val dir: File) : CoverFiles {
     }
 }
 
-private class CoverFileImpl(private val file: File) : CoverFile {
+private class AppFileImpl(private val file: File) : AppFile {
+    override suspend fun fd() =
+        withContext(Dispatchers.IO) {
+            try {
+                ParcelFileDescriptor.open(file, ParcelFileDescriptor.MODE_READ_ONLY)
+            } catch (e: IOException) {
+                null
+            }
+        }
+
     override suspend fun open() = withContext(Dispatchers.IO) { file.inputStream() }
 }

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

@@ -16,7 +16,7 @@
  * along with this program.  If not, see <https://www.gnu.org/licenses/>.
  */
  
-package org.oxycblt.musikr.fs.query
+package org.oxycblt.musikr.fs.device
 
 import android.content.ContentResolver
 import android.content.Context

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

@@ -16,7 +16,7 @@
  * along with this program.  If not, see <https://www.gnu.org/licenses/>.
  */
  
-package org.oxycblt.musikr.fs.query
+package org.oxycblt.musikr.fs.device
 
 import android.content.ContentResolver
 import android.content.Context

musikr/src/main/java/org/oxycblt/musikr/fs/path/DocumentPathFactory.kt

@@ -26,8 +26,8 @@ import java.io.File
 import org.oxycblt.musikr.fs.Components
 import org.oxycblt.musikr.fs.Path
 import org.oxycblt.musikr.fs.Volume
-import org.oxycblt.musikr.fs.query.contentResolverSafe
+import org.oxycblt.musikr.fs.device.contentResolverSafe
-import org.oxycblt.musikr.fs.query.useQuery
+import org.oxycblt.musikr.fs.device.useQuery
 
 /**
  * A factory for parsing the reverse-engineered format of the URIs obtained from document picker.

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

@@ -32,7 +32,7 @@ import kotlinx.coroutines.flow.merge
 import org.oxycblt.musikr.Storage
 import org.oxycblt.musikr.fs.DeviceFile
 import org.oxycblt.musikr.fs.MusicLocation
-import org.oxycblt.musikr.fs.query.DeviceFiles
+import org.oxycblt.musikr.fs.device.DeviceFiles
 import org.oxycblt.musikr.playlist.PlaylistFile
 import org.oxycblt.musikr.playlist.db.StoredPlaylists
 import org.oxycblt.musikr.playlist.m3u.M3U

musikr/src/main/java/org/oxycblt/musikr/playlist/ExternalPlaylistManager.kt

@@ -24,7 +24,7 @@ import org.oxycblt.musikr.Playlist
 import org.oxycblt.musikr.fs.Components
 import org.oxycblt.musikr.fs.Path
 import org.oxycblt.musikr.fs.path.DocumentPathFactory
-import org.oxycblt.musikr.fs.query.contentResolverSafe
+import org.oxycblt.musikr.fs.device.contentResolverSafe
 import org.oxycblt.musikr.playlist.m3u.M3U
 
 /**