from __future__ import unicode_literals

import collections
import logging
import random

from mopidy.models import TlTrack

from . import listener


logger = logging.getLogger(__name__)


class TracklistController(object):
    pykka_traversable = True

    def __init__(self, core):
        self.core = core
        self._next_tlid = 0
        self._tl_tracks = []
        self._version = 0

        self._shuffled = []

    ### Properties

    def get_tl_tracks(self):
        return self._tl_tracks[:]

    tl_tracks = property(get_tl_tracks)
    """
    List of :class:`mopidy.models.TlTrack`.

    Read-only.
    """

    def get_tracks(self):
        return [tl_track.track for tl_track in self._tl_tracks]

    tracks = property(get_tracks)
    """
    List of :class:`mopidy.models.Track` in the tracklist.

    Read-only.
    """

    def get_length(self):
        return len(self._tl_tracks)

    length = property(get_length)
    """Length of the tracklist."""

    def get_version(self):
        return self._version

    def _increase_version(self):
        self._version += 1
        self.core.playback.on_tracklist_change()
        self._trigger_tracklist_changed()

    version = property(get_version)
    """
    The tracklist version.

    Read-only. Integer which is increased every time the tracklist is changed.
    Is not reset before Mopidy is restarted.
    """

    def get_consume(self):
        return getattr(self, '_consume', False)

    def set_consume(self, value):
        if self.get_consume() != value:
            self._trigger_options_changed()
        return setattr(self, '_consume', value)

    consume = property(get_consume, set_consume)
    """
    :class:`True`
        Tracks are removed from the playlist when they have been played.
    :class:`False`
        Tracks are not removed from the playlist.
    """

    def get_random(self):
        return getattr(self, '_random', False)

    def set_random(self, value):
        if self.get_random() != value:
            self._trigger_options_changed()
        if value:
            self._shuffled = self.tl_tracks
            random.shuffle(self._shuffled)
        return setattr(self, '_random', value)

    random = property(get_random, set_random)
    """
    :class:`True`
        Tracks are selected at random from the playlist.
    :class:`False`
        Tracks are played in the order of the playlist.
    """

    def get_repeat(self):
        return getattr(self, '_repeat', False)

    def set_repeat(self, value):
        if self.get_repeat() != value:
            self._trigger_options_changed()
        return setattr(self, '_repeat', value)

    repeat = property(get_repeat, set_repeat)
    """
    :class:`True`
        The current playlist is played repeatedly. To repeat a single track,
        select both :attr:`repeat` and :attr:`single`.
    :class:`False`
        The current playlist is played once.
    """

    def get_single(self):
        return getattr(self, '_single', False)

    def set_single(self, value):
        if self.get_single() != value:
            self._trigger_options_changed()
        return setattr(self, '_single', value)

    single = property(get_single, set_single)
    """
    :class:`True`
        Playback is stopped after current song, unless in :attr:`repeat`
        mode.
    :class:`False`
        Playback continues after current song.
    """

    ### Methods

    def index(self, tl_track):
        """
        The position of the given track in the tracklist.

        :param tl_track: the track to find the index of
        :type tl_track: :class:`mopidy.models.TlTrack`
        :rtype: :class:`int` or :class:`None`
        """
        try:
            return self._tl_tracks.index(tl_track)
        except ValueError:
            return None

    def eot_track(self, tl_track):
        """
        The track that will be played after the given track.

        Not necessarily the same track as :meth:`next_track`.

        :param tl_track: the reference track
        :type tl_track: :class:`mopidy.models.TlTrack` or :class:`None`
        :rtype: :class:`mopidy.models.TlTrack` or :class:`None`
        """
        if self.single and self.repeat:
            return tl_track
        elif self.single:
            return None

        # Current difference between next and EOT handling is that EOT needs to
        # handle "single", with that out of the way the rest of the logic is
        # shared.
        return self.next_track(tl_track)

    def next_track(self, tl_track):
        """
        The track that will be played if calling
        :meth:`mopidy.core.PlaybackController.next()`.

        For normal playback this is the next track in the playlist. If repeat
        is enabled the next track can loop around the playlist. When random is
        enabled this should be a random track, all tracks should be played once
        before the list repeats.

        :param tl_track: the reference track
        :type tl_track: :class:`mopidy.models.TlTrack` or :class:`None`
        :rtype: :class:`mopidy.models.TlTrack` or :class:`None`
        """

        if not self.tl_tracks:
            return None

        if self.random and not self._shuffled:
            if self.repeat or not tl_track:
                logger.debug('Shuffling tracks')
                self._shuffled = self.tl_tracks
                random.shuffle(self._shuffled)

        if self.random:
            try:
                return self._shuffled[0]
            except IndexError:
                return None

        if tl_track is None:
            return self.tl_tracks[0]

        next_index = self.index(tl_track) + 1
        if self.repeat:
            next_index %= len(self.tl_tracks)

        try:
            return self.tl_tracks[next_index]
        except IndexError:
            return None

    def previous_track(self, tl_track):
        """
        Returns the track that will be played if calling
        :meth:`mopidy.core.PlaybackController.previous()`.

        For normal playback this is the previous track in the playlist. If
        random and/or consume is enabled it should return the current track
        instead.

        :param tl_track: the reference track
        :type tl_track: :class:`mopidy.models.TlTrack` or :class:`None`
        :rtype: :class:`mopidy.models.TlTrack` or :class:`None`
        """
        if self.repeat or self.consume or self.random:
            return tl_track

        position = self.index(tl_track)

        if position in (None, 0):
            return None

        return self.tl_tracks[position - 1]

    def add(self, tracks=None, at_position=None, uri=None):
        """
        Add the track or list of tracks to the tracklist.

        If ``uri`` is given instead of ``tracks``, the URI is looked up in the
        library and the resulting tracks are added to the tracklist.

        If ``at_position`` is given, the tracks placed at the given position in
        the tracklist. If ``at_position`` is not given, the tracks are appended
        to the end of the tracklist.

        Triggers the :meth:`mopidy.core.CoreListener.tracklist_changed` event.

        :param tracks: tracks to add
        :type tracks: list of :class:`mopidy.models.Track`
        :param at_position: position in tracklist to add track
        :type at_position: int or :class:`None`
        :param uri: URI for tracks to add
        :type uri: string
        :rtype: list of :class:`mopidy.models.TlTrack`
        """
        assert tracks is not None or uri is not None, \
            'tracks or uri must be provided'

        if tracks is None and uri is not None:
            tracks = self.core.library.lookup(uri)

        tl_tracks = []

        for track in tracks:
            tl_track = TlTrack(self._next_tlid, track)
            self._next_tlid += 1
            if at_position is not None:
                self._tl_tracks.insert(at_position, tl_track)
                at_position += 1
            else:
                self._tl_tracks.append(tl_track)
            tl_tracks.append(tl_track)

        if tl_tracks:
            self._increase_version()

        return tl_tracks

    def clear(self):
        """
        Clear the tracklist.

        Triggers the :meth:`mopidy.core.CoreListener.tracklist_changed` event.
        """
        self._tl_tracks = []
        self._increase_version()

    def filter(self, criteria=None, **kwargs):
        """
        Filter the tracklist by the given criterias.

        A criteria consists of a model field to check and a list of values to
        compare it against. If the model field matches one of the values, it
        may be returned.

        Only tracks that matches all the given criterias are returned.

        Examples::

            # Returns tracks with TLIDs 1, 2, 3, or 4 (tracklist ID)
            filter({'tlid': [1, 2, 3, 4]})
            filter(tlid=[1, 2, 3, 4])

            # Returns track with IDs 1, 5, or 7
            filter({'id': [1, 5, 7]})
            filter(id=[1, 5, 7])

            # Returns track with URIs 'xyz' or 'abc'
            filter({'uri': ['xyz', 'abc']})
            filter(uri=['xyz', 'abc'])

            # Returns tracks with ID 1 and URI 'xyz'
            filter({'id': [1], 'uri': ['xyz']})
            filter(id=[1], uri=['xyz'])

            # Returns track with a matching ID (1, 3 or 6) and a matching URI
            # ('xyz' or 'abc')
            filter({'id': [1, 3, 6], 'uri': ['xyz', 'abc']})
            filter(id=[1, 3, 6], uri=['xyz', 'abc'])

        :param criteria: on or more criteria to match by
        :type criteria: dict, of (string, list) pairs
        :rtype: list of :class:`mopidy.models.TlTrack`
        """
        criteria = criteria or kwargs
        matches = self._tl_tracks
        for (key, values) in criteria.iteritems():
            if (not isinstance(values, collections.Iterable)
                    or isinstance(values, basestring)):
                # Fail hard if anyone is using the <0.17 calling style
                raise ValueError('Filter values must be iterable: %r' % values)
            if key == 'tlid':
                matches = filter(lambda ct: ct.tlid in values, matches)
            else:
                matches = filter(
                    lambda ct: getattr(ct.track, key) in values, matches)
        return matches

    def move(self, start, end, to_position):
        """
        Move the tracks in the slice ``[start:end]`` to ``to_position``.

        Triggers the :meth:`mopidy.core.CoreListener.tracklist_changed` event.

        :param start: position of first track to move
        :type start: int
        :param end: position after last track to move
        :type end: int
        :param to_position: new position for the tracks
        :type to_position: int
        """
        if start == end:
            end += 1

        tl_tracks = self._tl_tracks

        assert start < end, 'start must be smaller than end'
        assert start >= 0, 'start must be at least zero'
        assert end <= len(tl_tracks), \
            'end can not be larger than tracklist length'
        assert to_position >= 0, 'to_position must be at least zero'
        assert to_position <= len(tl_tracks), \
            'to_position can not be larger than tracklist length'

        new_tl_tracks = tl_tracks[:start] + tl_tracks[end:]
        for tl_track in tl_tracks[start:end]:
            new_tl_tracks.insert(to_position, tl_track)
            to_position += 1
        self._tl_tracks = new_tl_tracks
        self._increase_version()

    def remove(self, criteria=None, **kwargs):
        """
        Remove the matching tracks from the tracklist.

        Uses :meth:`filter()` to lookup the tracks to remove.

        Triggers the :meth:`mopidy.core.CoreListener.tracklist_changed` event.

        :param criteria: on or more criteria to match by
        :type criteria: dict
        :rtype: list of :class:`mopidy.models.TlTrack` that was removed
        """
        tl_tracks = self.filter(criteria, **kwargs)
        for tl_track in tl_tracks:
            position = self._tl_tracks.index(tl_track)
            del self._tl_tracks[position]
        self._increase_version()
        return tl_tracks

    def shuffle(self, start=None, end=None):
        """
        Shuffles the entire tracklist. If ``start`` and ``end`` is given only
        shuffles the slice ``[start:end]``.

        Triggers the :meth:`mopidy.core.CoreListener.tracklist_changed` event.

        :param start: position of first track to shuffle
        :type start: int or :class:`None`
        :param end: position after last track to shuffle
        :type end: int or :class:`None`
        """
        tl_tracks = self._tl_tracks

        if start is not None and end is not None:
            assert start < end, 'start must be smaller than end'

        if start is not None:
            assert start >= 0, 'start must be at least zero'

        if end is not None:
            assert end <= len(tl_tracks), 'end can not be larger than ' + \
                'tracklist length'

        before = tl_tracks[:start or 0]
        shuffled = tl_tracks[start:end]
        after = tl_tracks[end or len(tl_tracks):]
        random.shuffle(shuffled)
        self._tl_tracks = before + shuffled + after
        self._increase_version()

    def slice(self, start, end):
        """
        Returns a slice of the tracklist, limited by the given start and end
        positions.

        :param start: position of first track to include in slice
        :type start: int
        :param end: position after last track to include in slice
        :type end: int
        :rtype: :class:`mopidy.models.TlTrack`
        """
        return self._tl_tracks[start:end]

    def mark_playing(self, tl_track):
        """Private method used by :class:`mopidy.core.PlaybackController`."""
        if self.random and tl_track in self._shuffled:
            self._shuffled.remove(tl_track)

    def mark_unplayable(self, tl_track):
        """Private method used by :class:`mopidy.core.PlaybackController`."""
        logger.warning('Track is not playable: %s', tl_track.track.uri)
        if self.random and tl_track in self._shuffled:
            self._shuffled.remove(tl_track)

    def mark_played(self, tl_track):
        """Private method used by :class:`mopidy.core.PlaybackController`."""
        if not self.consume:
            return False
        self.remove(tlid=[tl_track.tlid])
        return True

    def _trigger_tracklist_changed(self):
        if self.random:
            self._shuffled = self.tl_tracks
            random.shuffle(self._shuffled)
        else:
            self._shuffled = []

        logger.debug('Triggering event: tracklist_changed()')
        listener.CoreListener.send('tracklist_changed')

    def _trigger_options_changed(self):
        logger.debug('Triggering options changed event')
        listener.CoreListener.send('options_changed')
