"""A dummy audio actor for use in tests.

This class implements the audio API in the simplest way possible. It is used in
tests of the core and backends.
"""

from __future__ import absolute_import, unicode_literals

import pykka

from mopidy import audio


def create_proxy(config=None, mixer=None):
    return DummyAudio.start(config, mixer).proxy()


# TODO: reset position on track change?
class DummyAudio(pykka.ThreadingActor):

    def __init__(self, config=None, mixer=None):
        super(DummyAudio, self).__init__()
        self.state = audio.PlaybackState.STOPPED
        self._volume = 0
        self._position = 0
        self._callback = None
        self._uri = None
        self._stream_changed = False
        self._tags = {}
        self._bad_uris = set()

    def set_uri(self, uri):
        assert self._uri is None, 'prepare change not called before set'
        self._tags = {}
        self._uri = uri
        self._stream_changed = True

    def set_appsrc(self, *args, **kwargs):
        pass

    def emit_data(self, buffer_):
        pass

    def emit_end_of_stream(self):
        pass

    def get_position(self):
        return self._position

    def set_position(self, position):
        self._position = position
        audio.AudioListener.send('position_changed', position=position)
        return True

    def start_playback(self):
        return self._change_state(audio.PlaybackState.PLAYING)

    def pause_playback(self):
        return self._change_state(audio.PlaybackState.PAUSED)

    def prepare_change(self):
        self._uri = None
        return True

    def stop_playback(self):
        return self._change_state(audio.PlaybackState.STOPPED)

    def get_volume(self):
        return self._volume

    def set_volume(self, volume):
        self._volume = volume
        return True

    def set_metadata(self, track):
        pass

    def get_current_tags(self):
        return self._tags

    def set_about_to_finish_callback(self, callback):
        self._callback = callback

    def enable_sync_handler(self):
        pass

    def wait_for_state_change(self):
        pass

    def _change_state(self, new_state):
        if not self._uri:
            return False

        if new_state == audio.PlaybackState.STOPPED and self._uri:
            self._stream_changed = True
            self._uri = None

        if self._uri is not None:
            audio.AudioListener.send('position_changed', position=0)

        if self._stream_changed:
            self._stream_changed = False
            audio.AudioListener.send('stream_changed', uri=self._uri)

        old_state, self.state = self.state, new_state
        audio.AudioListener.send(
            'state_changed',
            old_state=old_state, new_state=new_state, target_state=None)

        if new_state == audio.PlaybackState.PLAYING:
            self._tags['audio-codec'] = [u'fake info...']
            audio.AudioListener.send('tags_changed', tags=['audio-codec'])

        return self._uri not in self._bad_uris

    def trigger_fake_playback_failure(self, uri):
        self._bad_uris.add(uri)

    def trigger_fake_tags_changed(self, tags):
        self._tags.update(tags)
        audio.AudioListener.send('tags_changed', tags=self._tags.keys())

    def get_about_to_finish_callback(self):
        # This needs to be called from outside the actor or we lock up.
        def wrapper():
            if self._callback:
                self.prepare_change()
                self._callback()

            if not self._uri or not self._callback:
                self._tags = {}
                audio.AudioListener.send('reached_end_of_stream')
            else:
                audio.AudioListener.send('position_changed', position=0)
                audio.AudioListener.send('stream_changed', uri=self._uri)

        return wrapper

@@ -880,33 +880,36 @@
       self._
-tags = %7B%7D
+position = 0
 %0A        sel
@@ -952,24 +952,48 @@
 anged = True
+%0A        self._tags = %7B%7D
 %0A%0A    def se

Make DummyAudio reset position when URI changes