from django.db import models
from django.db.models import Exists, OuterRef
from django.utils.timezone import now
from django.utils.translation import gettext_lazy as _, pgettext_lazy
from django_scopes import ScopedManager

from pretix.base.models import LoggedModel
from pretix.base.models.fields import MultiStringField


class CheckinList(LoggedModel):
    event = models.ForeignKey('Event', related_name='checkin_lists', on_delete=models.CASCADE)
    name = models.CharField(max_length=190)
    all_products = models.BooleanField(default=True, verbose_name=_("All products (including newly created ones)"))
    limit_products = models.ManyToManyField('Item', verbose_name=_("Limit to products"), blank=True)
    subevent = models.ForeignKey('SubEvent', null=True, blank=True,
                                 verbose_name=pgettext_lazy('subevent', 'Date'), on_delete=models.CASCADE)
    include_pending = models.BooleanField(verbose_name=pgettext_lazy('checkin', 'Include pending orders'),
                                          default=False,
                                          help_text=_('With this option, people will be able to check in even if the '
                                                      'order have not been paid.'))

    auto_checkin_sales_channels = MultiStringField(
        default=[],
        blank=True,
        verbose_name=_('Sales channels to automatically check in'),
        help_text=_('All items on this check-in list will be automatically marked as checked-in when purchased through '
                    'any of the selected sales channels. This option can be useful when tickets sold at the box office '
                    'are not checked again before entry and should be considered validated directly upon purchase.')
    )

    objects = ScopedManager(organizer='event__organizer')

    class Meta:
        ordering = ('subevent__date_from', 'name')

    @property
    def positions(self):
        from . import OrderPosition, Order

        qs = OrderPosition.objects.filter(
            order__event=self.event,
            order__status__in=[Order.STATUS_PAID, Order.STATUS_PENDING] if self.include_pending else [Order.STATUS_PAID],
            subevent=self.subevent
        )
        if not self.all_products:
            qs = qs.filter(item__in=self.limit_products.values_list('id', flat=True))
        return qs

    @property
    def checkin_count(self):
        return self.event.cache.get_or_set(
            'checkin_list_{}_checkin_count'.format(self.pk),
            lambda: self.positions.annotate(
                checkedin=Exists(Checkin.objects.filter(list_id=self.pk, position=OuterRef('pk')))
            ).filter(
                checkedin=True
            ).count(),
            60
        )

    @property
    def percent(self):
        pc = self.position_count
        return round(self.checkin_count * 100 / pc) if pc else 0

    @property
    def position_count(self):
        return self.event.cache.get_or_set(
            'checkin_list_{}_position_count'.format(self.pk),
            lambda: self.positions.count(),
            60
        )

    def touch(self):
        self.event.cache.delete('checkin_list_{}_position_count'.format(self.pk))
        self.event.cache.delete('checkin_list_{}_checkin_count'.format(self.pk))

    @staticmethod
    def annotate_with_numbers(qs, event):
        # This is only kept for backwards-compatibility reasons. This method used to precompute .position_count
        # and .checkin_count through a huge subquery chain, but was dropped for performance reasons.
        return qs

    def __str__(self):
        return self.name


class Checkin(models.Model):
    """
    A check-in object is created when a person enters the event.
    """
    position = models.ForeignKey('pretixbase.OrderPosition', related_name='checkins', on_delete=models.CASCADE)
    datetime = models.DateTimeField(default=now)
    nonce = models.CharField(max_length=190, null=True, blank=True)
    list = models.ForeignKey(
        'pretixbase.CheckinList', related_name='checkins', on_delete=models.PROTECT,
    )
    auto_checked_in = models.BooleanField(default=False)

    objects = ScopedManager(organizer='position__order__event__organizer')

    class Meta:
        unique_together = (('list', 'position'),)

    def __repr__(self):
        return "<Checkin: pos {} on list '{}' at {}>".format(
            self.position, self.list, self.datetime
        )

    def save(self, **kwargs):
        self.position.order.touch()
        self.list.event.cache.delete('checkin_count')
        self.list.touch()
        super().save(**kwargs)

    def delete(self, **kwargs):
        self.position.order.touch()
        super().delete(**kwargs)
        self.list.touch()