feat(subsonic): support public playlists

When multiple people share the same instance, they might want to share
their playlists between them.

This allows people to mark playlists as public, and to listen to public
playlists from other people. Listeners will also know who owns the
playlist, to help avoid confusion and make this feature a bit nicer.

Subsonic restrict updating playlists only to owners, this honors that
behavior, but adding flexibility could be achieved easily.

server/ctrlsubsonic/handlers_playlist.go

@@ -23,6 +23,8 @@ func playlistRender(c *Controller, playlist *db.Playlist) *spec.Playlist {
 		Comment:   playlist.Comment,
 		Created:   playlist.CreatedAt,
 		SongCount: playlist.TrackCount,
+		Public:    playlist.IsPublic,
+		Owner:     user.Name,
 	}
 
 	trackIDs := playlist.GetItems()
@@ -48,7 +50,7 @@ func playlistRender(c *Controller, playlist *db.Playlist) *spec.Playlist {
 func (c *Controller) ServeGetPlaylists(r *http.Request) *spec.Response {
 	user := r.Context().Value(CtxUser).(*db.User)
 	var playlists []*db.Playlist
-	c.DB.Where("user_id=?", user.ID).Find(&playlists)
+	c.DB.Where("user_id=?", user.ID).Or("is_public=?", true).Find(&playlists)
 	sub := spec.NewResponse()
 	sub.Playlists = &spec.Playlists{
 		List: make([]*spec.Playlist, len(playlists)),
@@ -90,6 +92,9 @@ func (c *Controller) ServeCreatePlaylist(r *http.Request) *spec.Response {
 		FirstOrCreate(&playlist)
 
 		// update meta info
+	if playlist.UserID != 0 && playlist.UserID != user.ID {
+		return spec.NewResponse()
+	}
 	playlist.UserID = user.ID
 	if val, err := params.Get("name"); err == nil {
 		playlist.Name = val
@@ -123,6 +128,9 @@ func (c *Controller) ServeUpdatePlaylist(r *http.Request) *spec.Response {
 		FirstOrCreate(&playlist)
 
 		// update meta info
+	if playlist.UserID != 0 && playlist.UserID != user.ID {
+		return spec.NewResponse()
+	}
 	playlist.UserID = user.ID
 	if val, err := params.Get("name"); err == nil {
 		playlist.Name = val
@@ -130,6 +138,9 @@ func (c *Controller) ServeUpdatePlaylist(r *http.Request) *spec.Response {
 	if val, err := params.Get("comment"); err == nil {
 		playlist.Comment = val
 	}
+	if val, err := params.GetBool("public"); err == nil {
+		playlist.IsPublic = val
+	}
 	trackIDs := playlist.GetItems()
 
 	// delete items

server/db/migrations.go

@@ -40,6 +40,7 @@ func (db *DB) Migrate(ctx MigrationContext) error {
 		construct(ctx, "202201042236", migrateArtistGuessedFolder),
 		construct(ctx, "202202092013", migrateArtistCover),
 		construct(ctx, "202202121809", migrateAlbumRootDirAgain),
+		construct(ctx, "202202241218", migratePublicPlaylist),
 	}
 
 	return gormigrate.
@@ -327,3 +328,7 @@ func migrateArtistCover(tx *gorm.DB, ctx MigrationContext) error {
 func migrateAlbumRootDirAgain(tx *gorm.DB, ctx MigrationContext) error {
 	return migrateAlbumRootDir(tx, ctx)
 }
+
+func migratePublicPlaylist(tx *gorm.DB, ctx MigrationContext) error {
+	return tx.AutoMigrate(Playlist{}).Error
+}

server/db/model.go

@@ -247,6 +247,7 @@ type Playlist struct {
 	Comment    string
 	TrackCount int
 	Items      string
+	IsPublic   bool `sql:"default: null"`
 }
 
 func (p *Playlist) GetItems() []int {