Support reading & writing to STDIN & STDOUT respectively

spotdl/command_line/__main__.py

@@ -1,31 +1,31 @@
 from spotdl.authorize.services import AuthorizeSpotify
 from spotdl import command_line
 
+import sys
+
 def match_arguments(arguments):
     if arguments.tracks:
-        # TODO: Also support reading from stdin for -t parameter
-        # Also supported writing to stdout for all parameters
-        if len(arguments.tracks) > 1:
-            # log.warning("download multiple tracks with optimized list instead")
-            pass
         for track in arguments.tracks:
-            command_line.helpers.download_track(track, arguments)
+            if track == "-":
+                for line in sys.stdin:
+                    command_line.helpers.download_track(line, arguments)
+            else:
+                command_line.helpers.download_track(track, arguments)
     elif arguments.list:
         if arguments.write_m3u:
             youtube_tools.generate_m3u(
                 track_file=arguments.list
             )
         else:
-            command_line.helpers.download_tracks_from_file(
+            list_download = {
+                "sequential": command_line.helpers.download_tracks_from_file,
+                "threaded"  : command_line.helpers.download_tracks_from_file_threaded,
+            }[arguments.processor]
+
+            list_download(
                 arguments.list,
                 arguments,
             )
-            # list_dl = downloader.ListDownloader(
-            #     tracks_file=arguments.list,
-            #     skip_file=arguments.skip,
-            #     write_successful_file=arguments.write_successful,
-            # )
-            # list_dl.download_list()
     elif arguments.playlist:
         spotify_tools.write_playlist(
             playlist_url=arguments.playlist, text_file=arguments.write_to