added last.fm chart playlist engine source

spotfm/engine/chart_source.py

@@ -0,0 +1,44 @@
+from fmframework.net.network import Network as FmNet
+from spotframework.net.network import Network as SpotNet
+
+from spotframework.model.uri import Uri
+from spotframework.engine.playlistengine import TrackSource, SourceParameter
+from spotframework.engine.processor.abstract import AbstractProcessor
+
+from spotfm.charts.chart import get_chart_of_spotify_tracks
+
+from typing import List
+import logging
+
+logger = logging.getLogger(__name__)
+
+
+class ChartSource(TrackSource):
+    class Params(SourceParameter):
+        def __init__(self,
+                     chart_range: FmNet.Range,
+                     limit: int = 50,
+                     processors: List[AbstractProcessor] = None):
+            super().__init__(processors=processors, source_type=ChartSource)
+            self.chart_range = chart_range
+            self.limit = limit
+
+    def __init__(self, spotnet: SpotNet, fmnet: SpotNet):
+        super().__init__(net=spotnet)
+        self.fmnet = fmnet
+
+    def load(self):
+        super().load()
+
+    def process(self, params: Params, uris: List[Uri] = None):
+        # TODO add processor support?
+
+        tracks = get_chart_of_spotify_tracks(spotnet=self.net,
+                                             fmnet=self.fmnet,
+                                             period=params.chart_range,
+                                             limit=params.limit)
+
+        if tracks is not None and len(tracks) > 0:
+            return tracks
+        else:
+            logger.error('no tracks returned')