from enum import IntEnum
import logging
import os

from django.conf import settings as conf
from django.db import models
from django.db.models import Q, Value as V
from django.db.models.functions import Concat
from django.utils import timezone as tz
from django.utils.translation import gettext_lazy as _

from taggit.managers import TaggableManager

from aircox import settings
from .program import Program
from .episode import Episode


logger = logging.getLogger('aircox')


__all__ = ['Sound', 'SoundQuerySet', 'Track']


class SoundQuerySet(models.QuerySet):
    def station(self, station=None, id=None):
        id = station.pk if id is None else id
        return self.filter(program__station__id=id)

    def episode(self, episode=None, id=None):
        id = episode.pk if id is None else id
        return self.filter(episode__id=id)

    def diffusion(self, diffusion=None, id=None):
        id = diffusion.pk if id is None else id
        return self.filter(episode__diffusion__id=id)

    def available(self):
        return self.exclude(type=Sound.TYPE_REMOVED)

    def public(self):
        """ Return sounds available as podcasts """
        return self.filter(is_public=True)

    def downloadable(self):
        """ Return sounds available as podcasts """
        return self.filter(is_downloadable=True)

    def archive(self):
        """ Return sounds that are archives """
        return self.filter(type=Sound.TYPE_ARCHIVE)

    def path(self, paths):
        if isinstance(paths, str):
            return self.filter(file=paths.replace(conf.MEDIA_ROOT + '/', ''))
        return self.filter(file__in=(p.replace(conf.MEDIA_ROOT + '/', '')
                                        for p in paths))

    def playlist(self, archive=True, order_by=True):
        """
        Return files absolute paths as a flat list (exclude sound without path).
        If `order_by` is True, order by path.
        """
        if archive:
            self = self.archive()
        if order_by:
            self = self.order_by('file')
        return [os.path.join(conf.MEDIA_ROOT, file) for file in self.filter(file__isnull=False) \
                   .values_list('file', flat=True)]

    def search(self, query):
        return self.filter(
            Q(name__icontains=query) | Q(file__icontains=query) |
            Q(program__title__icontains=query) |
            Q(episode__title__icontains=query)
        )


class Sound(models.Model):
    """
    A Sound is the representation of a sound file that can be either an excerpt
    or a complete archive of the related diffusion.
    """
    TYPE_OTHER = 0x00
    TYPE_ARCHIVE = 0x01
    TYPE_EXCERPT = 0x02
    TYPE_REMOVED = 0x03
    TYPE_CHOICES = (
        (TYPE_OTHER, _('other')), (TYPE_ARCHIVE, _('archive')),
        (TYPE_EXCERPT, _('excerpt')), (TYPE_REMOVED, _('removed'))
    )

    name = models.CharField(_('name'), max_length=64)
    program = models.ForeignKey(
        Program, models.CASCADE, blank=True, # NOT NULL
        verbose_name=_('program'),
        help_text=_('program related to it'),
        db_index=True,
    )
    episode = models.ForeignKey(
        Episode, models.SET_NULL, blank=True, null=True,
        verbose_name=_('episode'),
        db_index=True,
    )
    type = models.SmallIntegerField(_('type'), choices=TYPE_CHOICES)
    position = models.PositiveSmallIntegerField(
        _('order'), default=0, help_text=_('position in the playlist'),
    )

    def _upload_to(self, filename):
        subdir = AIRCOX_SOUND_ARCHIVES_SUBDIR if self.type == self.TYPE_ARCHIVE else \
                 AIRCOX_SOUND_EXCERPTS_SUBDIR
        return os.path.join(self.program.path, subdir, filename)

    file = models.FileField(
        _('file'), upload_to=_upload_to, max_length=256,
        db_index=True,
    )
    duration = models.TimeField(
        _('duration'),
        blank=True, null=True,
        help_text=_('duration of the sound'),
    )
    mtime = models.DateTimeField(
        _('modification time'),
        blank=True, null=True,
        help_text=_('last modification date and time'),
    )
    is_good_quality = models.BooleanField(
        _('good quality'), help_text=_('sound meets quality requirements'),
        blank=True, null=True
    )
    is_public = models.BooleanField(
        _('public'), help_text=_('whether it is publicly available as podcast'),
        default=False,
    )
    is_downloadable = models.BooleanField(
        _('downloadable'),
        help_text=_('whether it can be publicly downloaded by visitors (sound must be public)'),
        default=False,
    )

    objects = SoundQuerySet.as_manager()

    class Meta:
        verbose_name = _('Sound')
        verbose_name_plural = _('Sounds')

    @property
    def url(self):
        return self.file and self.file.url

    def __str__(self):
        return '/'.join(self.file.path.split('/')[-3:])

    def save(self, check=True, *args, **kwargs):
        if self.episode is not None and self.program is None:
            self.program = self.episode.program
        if check:
            self.check_on_file()
        if not self.is_public:
            self.is_downloadable = False
        self.__check_name()
        super().save(*args, **kwargs)

    # TODO: rename get_file_mtime(self)
    def get_mtime(self):
        """
        Get the last modification date from file
        """
        mtime = os.stat(self.file.path).st_mtime
        mtime = tz.datetime.fromtimestamp(mtime)
        mtime = mtime.replace(microsecond=0)
        return tz.make_aware(mtime, tz.get_current_timezone())

    def file_exists(self):
        """ Return true if the file still exists. """

        return os.path.exists(self.file.path)

    def check_on_file(self):
        """
        Check sound file info again'st self, and update informations if
        needed (do not save). Return True if there was changes.
        """
        if not self.file_exists():
            if self.type == self.TYPE_REMOVED:
                return
            logger.info('sound %s: has been removed', self.file.name)
            self.type = self.TYPE_REMOVED
            return True

        # not anymore removed
        changed = False

        if self.type == self.TYPE_REMOVED and self.program:
            changed = True
            self.type = self.TYPE_ARCHIVE \
                if self.file.name.startswith(self.program.archives_path) else \
                self.TYPE_EXCERPT

        # check mtime -> reset quality if changed (assume file changed)
        mtime = self.get_mtime()

        if self.mtime != mtime:
            self.mtime = mtime
            self.is_good_quality = None
            logger.info('sound %s: m_time has changed. Reset quality info',
                        self.file.name)
            return True

        return changed

    def __check_name(self):
        if not self.name and self.file and self.file.name:
            # FIXME: later, remove date?
            self.name = os.path.basename(self.file.name)
            self.name = os.path.splitext(self.name)[0]
            self.name = self.name.replace('_', ' ')

    def __init__(self, *args, **kwargs):
        super().__init__(*args, **kwargs)
        self.__check_name()


class Track(models.Model):
    """
    Track of a playlist of an object. The position can either be expressed
    as the position in the playlist or as the moment in seconds it started.
    """
    episode = models.ForeignKey(
        Episode, models.CASCADE, blank=True, null=True,
        verbose_name=_('episode'),
    )
    sound = models.ForeignKey(
        Sound, models.CASCADE, blank=True, null=True,
        verbose_name=_('sound'),
    )
    position = models.PositiveSmallIntegerField(
        _('order'), default=0, help_text=_('position in the playlist'),
    )
    timestamp = models.PositiveSmallIntegerField(
        _('timestamp'),
        blank=True, null=True,
        help_text=_('position (in seconds)')
    )
    title = models.CharField(_('title'), max_length=128)
    artist = models.CharField(_('artist'), max_length=128)
    tags = TaggableManager(verbose_name=_('tags'), blank=True,)
    info = models.CharField(
        _('information'),
        max_length=128,
        blank=True, null=True,
        help_text=_('additional informations about this track, such as '
                    'the version, if is it a remix, features, etc.'),
    )

    class Meta:
        verbose_name = _('Track')
        verbose_name_plural = _('Tracks')
        ordering = ('position',)

    def __str__(self):
        return '{self.artist} -- {self.title} -- {self.position}'.format(
               self=self)

    def save(self, *args, **kwargs):
        if (self.sound is None and self.episode is None) or \
                (self.sound is not None and self.episode is not None):
            raise ValueError('sound XOR episode is required')
        super().save(*args, **kwargs)