music: add importing backend

Add basic importing infrastructure and an M3U parser to the backend.

app/src/main/java/org/oxycblt/auxio/music/fs/ContentPathResolver.kt

@@ -0,0 +1,111 @@
+package org.oxycblt.auxio.music.fs
+
+import android.content.ContentResolver
+import android.content.Context
+import android.net.Uri
+import android.os.Build
+import android.provider.MediaStore
+import androidx.core.database.getStringOrNull
+import org.oxycblt.auxio.util.logE
+import org.oxycblt.auxio.util.logW
+import javax.inject.Inject
+
+/**
+ * Resolves a content URI into a [Path] instance.
+ * TODO: Integrate this with [MediaStoreExtractor].
+ * @author Alexander Capehart (OxygenCobalt)
+ */
+interface ContentPathResolver {
+    /**
+     * Resolve a content [Uri] into it's corresponding [Path].
+     * @param uri The content [Uri] to resolve.
+     * @return The corresponding [Path], or null if the [Uri] is invalid.
+     */
+    fun resolve(uri: Uri): Path?
+
+    companion object {
+        fun from(context: Context, volumeManager: VolumeManager) =
+            when {
+                Build.VERSION.SDK_INT >= Build.VERSION_CODES.Q ->
+                    Api29ContentPathResolverImpl(context.contentResolverSafe, volumeManager)
+
+                else -> Api21ContentPathResolverImpl(context.contentResolverSafe, volumeManager)
+            }
+    }
+}
+
+private class Api21ContentPathResolverImpl(
+    private val contentResolver: ContentResolver,
+    private val volumeManager: VolumeManager
+) : ContentPathResolver {
+    override fun resolve(uri: Uri): Path? {
+        val rawPath = contentResolver.useQuery(
+            uri, arrayOf(MediaStore.MediaColumns.DATA)
+        ) { cursor ->
+            cursor.moveToFirst()
+            cursor.getStringOrNull(cursor.getColumnIndexOrThrow(MediaStore.MediaColumns.DATA))
+        }
+
+        if (rawPath == null) {
+            logE("No data available for uri $uri")
+            return null
+        }
+
+        val volumes = volumeManager.getVolumes()
+        for (volume in volumes) {
+            val volumePath = (volume.components ?: continue).toString()
+            val strippedPath = rawPath.removePrefix(volumePath)
+            if (strippedPath != rawPath) {
+                return Path(volume, Components.parse(strippedPath))
+            }
+        }
+
+        logE("No volume found for uri $uri")
+        return null
+    }
+}
+
+private class Api29ContentPathResolverImpl(
+    private val contentResolver: ContentResolver,
+    private val volumeManager: VolumeManager
+) : ContentPathResolver {
+    private data class RawPath(val volumeName: String?, val relativePath: String?)
+
+    override fun resolve(uri: Uri): Path? {
+        val rawPath = contentResolver.useQuery(
+            uri, arrayOf(
+                MediaStore.MediaColumns.VOLUME_NAME,
+                MediaStore.MediaColumns.RELATIVE_PATH
+            )
+        ) { cursor ->
+            cursor.moveToFirst()
+            RawPath(
+                cursor.getStringOrNull(
+                    cursor.getColumnIndexOrThrow(
+                        MediaStore.MediaColumns.VOLUME_NAME
+                    )
+                ),
+                cursor.getStringOrNull(
+                    cursor.getColumnIndexOrThrow(
+                        MediaStore.MediaColumns.RELATIVE_PATH
+                    )
+                )
+            )
+        }
+
+        if (rawPath.volumeName == null || rawPath.relativePath == null) {
+            logE("No data available for uri $uri (raw path obtained: $rawPath)")
+            return null
+        }
+
+        // Find the StorageVolume whose MediaStore name corresponds to this song.
+        // This is combined with the plain relative path column to create the directory.
+        val volume = volumeManager.getVolumes().find { it.mediaStoreName == rawPath.volumeName }
+        if (volume != null) {
+            return Path(volume, Components.parse(rawPath.relativePath))
+        }
+
+        logE("No volume found for uri $uri")
+        return null
+    }
+}

app/src/main/java/org/oxycblt/auxio/music/fs/FsModule.kt

@@ -37,4 +37,7 @@ class FsModule {
     @Provides
     fun mediaStoreExtractor(@ApplicationContext context: Context, volumeManager: VolumeManager) =
         MediaStoreExtractor.from(context, volumeManager)
+
+    @Provides
+    fun contentPathResolver(@ApplicationContext context: Context, volumeManager: VolumeManager) = ContentPathResolver.from(context, volumeManager)
 }

app/src/main/java/org/oxycblt/auxio/music/import/ImportModule.kt

@@ -0,0 +1,32 @@
+/*
+ * Copyright (c) 2023 Auxio Project
+ * ForeignModule.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.import
+
+import dagger.Binds
+import dagger.Module
+import dagger.hilt.InstallIn
+import dagger.hilt.components.SingletonComponent
+
+@Module
+@InstallIn(SingletonComponent::class)
+interface ImportModule {
+    @Binds fun playlistImporter(playlistImporter: PlaylistImporterImpl): PlaylistImporter
+
+    @Binds fun m3u(m3u: M3UImpl): M3U
+}

app/src/main/java/org/oxycblt/auxio/music/import/M3U.kt

@@ -0,0 +1,73 @@
+/*
+ * Copyright (c) 2023 Auxio Project
+ * M3U.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.import
+
+import org.oxycblt.auxio.music.fs.Components
+import java.io.BufferedReader
+import java.io.InputStream
+import java.io.InputStreamReader
+import org.oxycblt.auxio.music.fs.Path
+import org.oxycblt.auxio.util.logW
+import javax.inject.Inject
+
+interface M3U {
+    fun read(stream: InputStream, workingDirectory: Path): List<Path>?
+}
+
+class M3UImpl @Inject constructor() : M3U {
+    override fun read(stream: InputStream, workingDirectory: Path): List<Path>? {
+        val reader = BufferedReader(InputStreamReader(stream))
+        val media = mutableListOf<Path>()
+
+        consumeFile@ while (true) {
+            collectMetadata@ while (true) {
+                val line = reader.readLine() ?: break@consumeFile
+                if (!line.startsWith("#")) {
+                    break@collectMetadata
+                }
+            }
+
+            val path = reader.readLine()
+            if (path == null) {
+                logW("Expected a path, instead got an EOF")
+                break@consumeFile
+            }
+
+            val relativeComponents = Components.parse(path)
+            val absoluteComponents =
+                resolveRelativePath(relativeComponents, workingDirectory.components)
+
+            media.add(Path(workingDirectory.volume, absoluteComponents))
+        }
+
+        return media.ifEmpty { null }
+    }
+
+    private fun resolveRelativePath(relative: Components, workingDirectory: Components): Components {
+        var components = workingDirectory
+        for (component in relative.components) {
+            when (component) {
+                ".." -> components = components.parent()
+                "." -> {}
+                else -> components = components.child(component)
+            }
+        }
+        return components
+    }
+}

app/src/main/java/org/oxycblt/auxio/music/import/PlaylistImporter.kt

@@ -0,0 +1,33 @@
+package org.oxycblt.auxio.music.import
+
+import android.content.ContentResolver
+import android.content.Context
+import android.net.Uri
+import dagger.hilt.android.qualifiers.ApplicationContext
+import org.oxycblt.auxio.music.Playlist
+import org.oxycblt.auxio.music.Song
+import org.oxycblt.auxio.music.device.DeviceLibrary
+import org.oxycblt.auxio.music.fs.ContentPathResolver
+import org.oxycblt.auxio.music.fs.Path
+import org.oxycblt.auxio.music.fs.contentResolverSafe
+import javax.inject.Inject
+
+interface PlaylistImporter {
+    suspend fun import(uri: Uri): ImportedPlaylist?
+}
+
+data class ImportedPlaylist(val name: String?, val paths: List<Path>)
+
+class PlaylistImporterImpl @Inject constructor(
+    @ApplicationContext private val contentResolver: ContentResolver,
+    private val contentPathResolver: ContentPathResolver,
+    private val m3u: M3U
+) : PlaylistImporter {
+    override suspend fun import(uri: Uri): ImportedPlaylist? {
+        val workingDirectory = contentPathResolver.resolve(uri) ?: return null
+        return contentResolver.openInputStream(uri)?.use {
+            val paths = m3u.read(it, workingDirectory) ?: return null
+            return ImportedPlaylist(null, paths)
+        }
+    }
+}