from django.db import models
from django.db.models import Q, Max
from django.conf import settings
from songs.models import Song


class Playlist(models.Model):
    def __str__(self):
        return 'Playlist #' + str(self.id)


class PlaylistSong(models.Model):
    playlist = models.ForeignKey(
        Playlist,
        on_delete=models.SET_NULL,
        blank=True,
        null=True
    )
    song = models.ForeignKey(
        Song,
        on_delete=models.SET_NULL,
        blank=True,
        null=True
    )
    user = models.ForeignKey(
        settings.AUTH_USER_MODEL,
        on_delete=models.SET_NULL,
        blank=True,
        null=True
    )

    # 0: Queued.
    # 1: Playing.
    # 2: Played.
    # 3: Cancelled.
    state = models.IntegerField(default=0)

    order = models.IntegerField()

    def move_up(self):
        other_song = PlaylistSong.objects.filter(playlist=self.playlist, order__lt=self.order)\
            .order_by('-order').first()
        self.switch_order(other_song)

    def move_down(self):
        other_song = PlaylistSong.objects.filter(playlist=self.playlist, order__gt=self.order).order_by('order').first()
        self.switch_order(other_song)

    def switch_order(self, other_song):
        old_order = self.order
        self.order = other_song.order
        self.save()
        other_song.order = old_order
        other_song.save()

    def __str__(self):
        return 'Playlist #' + str(self.playlist_id) + ': ' + str(self.song)


class Queue(models.Model):
    class Meta:
        permissions = (
            ('can_skip', 'Can skip the currently playing song'),
            ('can_move', 'Can move all songs in the queue'),
            ('can_cancel', 'Can cancel all songs in the queue'),
        )

    name = models.TextField()
    playlist = models.ForeignKey(
        Playlist,
        on_delete=models.SET_NULL,
        blank=True,
        null=True,
    )
    random_playlist = models.ForeignKey(
        Playlist,
        on_delete=models.SET_NULL,
        blank=True,
        null=True,
        related_name='random_playlist_set'
    )
    started_at = models.DateTimeField(blank=True, null=True)
    songs = None
    player_token = models.TextField(blank=True, null=True)

    def get_songs(self):
        if self.songs is None:
            self.fill_random_queue()
            self.songs = PlaylistSong.objects\
                .filter(Q(playlist=self.playlist_id) | Q(playlist_id=self.random_playlist_id),
                        Q(state=0) | Q(state=1))\
                .order_by('-state', 'playlist_id', 'order')\
                .select_related('song', 'user')
        return self.songs

    def current_song(self):
        songs = self.get_songs()
        if len(songs) < 1:
            return None
        song = songs[0]
        if song.state != 1:
            song.state = 1
            song.save()
        return song

    def queue(self):
        songs = self.get_songs()
        if len(songs) < 2:
            return []
        return songs[1:]

    def request(self, song, user):
        order = PlaylistSong.objects.filter(playlist=self.playlist).aggregate(Max('order'))['order__max']
        if order is None:
            order = 0
        order += 1
        playlist_song = PlaylistSong(playlist=self.playlist, song=song, user=user, order=order)
        playlist_song.save()

    def fill_random_queue(self):
        song_count = PlaylistSong.objects.filter(playlist_id=self.random_playlist_id, state=0).count()
        while song_count < 5:
            order = PlaylistSong.objects.filter(playlist_id=self.random_playlist_id)\
                .aggregate(Max('order'))['order__max']
            if order is None:
                order = 0
            order += 1
            song = Song.objects.filter(deleted=False).order_by('?').first()
            if song is None:
                return
            playlist_song = PlaylistSong(playlist=self.random_playlist,
                                         song=song,
                                         user=None, order=order)
            playlist_song.save()
            song_count += 1

    def __str__(self):
        return self.name