Add support for directory URIs

Allows the user to assign directory URIs to an RFID tag.
All Tracks in the referenced directory and its sub directories
will be added to the tracklist.

mopidy_pummeluff/actions/tracklist.py

@@ -19,6 +19,23 @@ class Tracklist(Action):
     parameter.
     '''
 
+    @classmethod
+    def _browse_uri(cls, core, uri):
+        '''
+        Searches all tracks in uri (if it is a directory) and sub directories.
+        
+        :param mopidy.core.Core core: The mopidy core instance
+        :param str uri: the URI 
+        '''
+        # try to browse it - maybe it is a directory
+        uris = []
+        for ref in core.library.browse(uri).get():
+            if ref.type == ref.TRACK:
+                uris.append(ref.uri)
+            elif ref.type == ref.DIRECTORY:
+                uris.extend(cls._browse_uri(core, ref.uri))
+
+
     @classmethod
     def execute(cls, core, uri):  # pylint: disable=arguments-differ
         '''
@@ -34,7 +51,16 @@ def execute(cls, core, uri):  # pylint: disable=arguments-differ
         if uri in playlists:
             uris = [item.uri for item in core.playlists.get_items(uri).get()]
         else:
-            uris = [uri]
+            # if uri points to a Directory, we have to call browse to get all
+            # the Tracks. Right now it is not possible to get the type of an
+            # URI. So we just try to browse uri and if it is not a directory
+            # this will return an empty list of uris.
+            uris = cls._browse_uri(core, uri)
+            if not uris:
+                # browse failed
+                uris = [uri]
+
+        LOGGER.info(f'uris: {uris}')
 
         core.tracklist.clear()
         core.tracklist.add(uris=uris)