music: re-add missing file

app/src/main/java/org/oxycblt/auxio/music/external/ExternalPlaylistManager.kt

@@ -0,0 +1,90 @@
+/*
+ * Copyright (c) 2023 Auxio Project
+ * ExternalPlaylistManager.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.external
+
+import android.content.Context
+import android.net.Uri
+import dagger.hilt.android.qualifiers.ApplicationContext
+import org.oxycblt.auxio.music.Playlist
+import javax.inject.Inject
+import org.oxycblt.auxio.music.fs.DocumentPathFactory
+import org.oxycblt.auxio.music.fs.Path
+import org.oxycblt.auxio.music.fs.contentResolverSafe
+import org.oxycblt.auxio.util.logE
+
+/**
+ * Generic playlist file importing abstraction.
+ *
+ * @see ImportedPlaylist
+ * @see M3U
+ * @author Alexander Capehart (OxygenCobalt)
+ */
+interface ExternalPlaylistManager {
+    suspend fun import(uri: Uri): ImportedPlaylist?
+    suspend fun export(playlist: Playlist, uri: Uri): Boolean
+}
+
+/**
+ * A playlist that has been imported.
+ *
+ * @property name The name of the playlist. May be null if not provided.
+ * @property paths The paths of the files in the playlist.
+ * @see ExternalPlaylistManager
+ * @see M3U
+ */
+data class ImportedPlaylist(val name: String?, val paths: List<Path>)
+
+class ExternalPlaylistManagerImpl
+@Inject
+constructor(
+    @ApplicationContext private val context: Context,
+    private val documentPathFactory: DocumentPathFactory,
+    private val m3u: M3U
+) : ExternalPlaylistManager {
+    override suspend fun import(uri: Uri): ImportedPlaylist? {
+        val filePath = documentPathFactory.unpackDocumentUri(uri) ?: return null
+
+        return try {
+            context.contentResolverSafe.openInputStream(uri)?.use {
+                return m3u.read(it, filePath.directory)
+            }
+        } catch (e: Exception) {
+            logE("Failed to import playlist: $e")
+            null
+        }
+    }
+
+    override suspend fun export(playlist: Playlist, uri: Uri): Boolean {
+        val filePath = documentPathFactory.unpackDocumentUri(uri) ?: return false
+        return try {
+            val outputStream = context.contentResolverSafe.openOutputStream(uri)
+            if (outputStream == null) {
+                logE("Failed to export playlist: Could not open output stream")
+                return false
+            }
+            outputStream.use {
+                m3u.write(playlist, it, filePath.directory)
+                true
+            }
+        } catch (e: Exception) {
+            logE("Failed to export playlist: $e")
+            false
+        }
+    }
+}