ViewModels: Delegate medialibrary callbacks

Make a delegate to remove Medialibrary callbacks management from viewmodels

vlc-android/src/org/videolan/vlc/viewmodels/CallBackDelegate.kt

+/*
+ *****************************************************************************
+ * CallBackDelegate.kt
+ *****************************************************************************
+ * Copyright © 2019 VLC authors and VideoLAN
+ *
+ * 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 2 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, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston MA 02110-1301, USA.
+ *****************************************************************************/
+
+package org.videolan.vlc.viewmodels
+
+import kotlinx.coroutines.CoroutineScope
+import kotlinx.coroutines.channels.SendChannel
+import org.videolan.medialibrary.interfaces.AbstractMedialibrary
+import org.videolan.tools.conflatedActor
+
+interface ICallBackHandler : AbstractMedialibrary.OnMedialibraryReadyListener,
+        AbstractMedialibrary.OnDeviceChangeListener,
+        AbstractMedialibrary.MediaCb,
+        AbstractMedialibrary.ArtistsCb,
+        AbstractMedialibrary.AlbumsCb,
+        AbstractMedialibrary.GenresCb,
+        AbstractMedialibrary.PlaylistsCb
+{
+    val medialibrary : AbstractMedialibrary
+
+    fun CoroutineScope.registerCallBacks(refresh: () -> Unit)
+    fun releaseCallbacks()
+    fun watchMedia()
+    fun watchArtists()
+    fun watchAlbums()
+    fun watchGenres()
+    fun watchPlaylists()
+
+    override fun onMedialibraryReady()
+    override fun onMedialibraryIdle()
+    override fun onDeviceChange()
+    override fun onMediaAdded()
+    override fun onMediaModified()
+    override fun onMediaDeleted()
+    override fun onArtistsAdded()
+    override fun onArtistsModified()
+    override fun onArtistsDeleted()
+    override fun onAlbumsAdded()
+    override fun onAlbumsModified()
+    override fun onAlbumsDeleted()
+    override fun onGenresAdded()
+    override fun onGenresModified()
+    override fun onGenresDeleted()
+    override fun onPlaylistsAdded()
+    override fun onPlaylistsModified()
+    override fun onPlaylistsDeleted()
+}
+
+class CallBackDelegate : ICallBackHandler {
+
+    override val medialibrary = AbstractMedialibrary.getInstance()
+    private lateinit var refreshActor: SendChannel<Unit>
+
+    private var mediaCb = false
+    private var artistsCb = false
+    private var albumsCb = false
+    private var genresCb = false
+    private var playlistsCb = false
+
+    override fun CoroutineScope.registerCallBacks(refresh: () -> Unit) {
+        refreshActor = conflatedActor { refresh() }
+        medialibrary.addOnMedialibraryReadyListener(this@CallBackDelegate)
+        medialibrary.addOnDeviceChangeListener(this@CallBackDelegate)
+    }
+
+    override fun watchMedia() {
+        medialibrary.addMediaCb(this)
+        mediaCb = true
+    }
+
+    override fun watchArtists() {
+        medialibrary.addArtistsCb(this)
+        artistsCb = true
+    }
+
+    override fun watchAlbums() {
+        medialibrary.addAlbumsCb(this)
+        albumsCb = true
+    }
+
+    override fun watchGenres() {
+        medialibrary.addGenreCb(this)
+        genresCb = true
+    }
+
+    override fun watchPlaylists() {
+        medialibrary.addPlaylistCb(this)
+        playlistsCb = true
+    }
+
+    override fun releaseCallbacks() {
+        medialibrary.removeOnMedialibraryReadyListener(this)
+        medialibrary.removeOnDeviceChangeListener(this)
+        if (mediaCb) medialibrary.removeMediaCb(this)
+        if (artistsCb) medialibrary.removeArtistsCb(this)
+        if (albumsCb) medialibrary.removeAlbumsCb(this)
+        if (genresCb) medialibrary.removeGenreCb(this)
+        if (playlistsCb) medialibrary.removePlaylistCb(this)
+        refreshActor.close()
+
+    }
+
+    override fun onMedialibraryReady() { refreshActor.offer(Unit) }
+
+    override fun onMedialibraryIdle() { refreshActor.offer(Unit) }
+
+    override fun onDeviceChange() { refreshActor.offer(Unit) }
+
+    override fun onMediaAdded() { refreshActor.offer(Unit) }
+
+    override fun onMediaModified() { refreshActor.offer(Unit) }
+
+    override fun onMediaDeleted() { refreshActor.offer(Unit) }
+
+    override fun onArtistsAdded() { refreshActor.offer(Unit) }
+
+    override fun onArtistsModified() { refreshActor.offer(Unit) }
+
+    override fun onArtistsDeleted() { refreshActor.offer(Unit) }
+
+    override fun onAlbumsAdded() { refreshActor.offer(Unit) }
+
+    override fun onAlbumsModified() { refreshActor.offer(Unit) }
+
+    override fun onAlbumsDeleted() { refreshActor.offer(Unit) }
+
+    override fun onGenresAdded() { refreshActor.offer(Unit) }
+
+    override fun onGenresModified() { refreshActor.offer(Unit) }
+
+    override fun onGenresDeleted() { refreshActor.offer(Unit) }
+
+    override fun onPlaylistsAdded() { refreshActor.offer(Unit) }
+
+    override fun onPlaylistsModified() { refreshActor.offer(Unit) }
+
+    override fun onPlaylistsDeleted() { refreshActor.offer(Unit) }
+}