from django.contrib.postgres.fields import JSONField
from django.contrib.postgres.fields.jsonb import KeyTextTransform
from django.db import models
from django.utils.translation import gettext_lazy as _

from utils.models import ProjectBaseMixin, BaseAttributes


class NewsType(models.Model):
    """NewsType model."""
    name = models.CharField(_('name'), max_length=250)


class NewsManager(models.Manager):
    """Manager for model News"""

    def annotate_localized_fields(self, locale):
        """Return queryset by locale"""
        prefix = 'trans'

        # Prepare fields to localization (only JSONField can be localized)
        fields = [field.name for field in self.model._meta.fields if isinstance(field, JSONField)]

        # Check filters to check if field has localization
        filters = {f'{field}__has_key': locale for field in fields}
        # Filter QuerySet by prepared filters
        queryset = self.filter(**filters)

        # Prepare field for annotator
        localized_fields = {f'{field}_{prefix}': KeyTextTransform(f'{locale}', field) for field in fields}

        # Annotate them
        for _ in fields:
            queryset = queryset.annotate(**localized_fields)
        return queryset


class NewsQuerySet(models.QuerySet):
    """QuerySet for model News"""
    def by_type(self, news_type):
        """Filter News by type"""
        return self.filter(news_type__name=news_type)


class News(BaseAttributes):
    """News model."""
    news_type = models.ForeignKey(
        NewsType, verbose_name=_('news type'), on_delete=models.CASCADE)

    title = JSONField(
        _('title'), null=True, blank=True,
        default=None, help_text='{"en":"some text"}')
    subtitle = JSONField(
        _('subtitle'), null=True, blank=True,
        default=None, help_text='{"en":"some text"}'
    )
    description = JSONField(
        _('subtitle'), null=True, blank=True,
        default=None, help_text='{"en":"some text"}'
    )
    start = models.DateTimeField(_('start'))
    end = models.DateTimeField(_('end'))
    playlist = models.IntegerField(_('playlist'))
    address = models.ForeignKey(
        'location.Address', verbose_name=_('address'), blank=True,
        null=True, default=None, on_delete=models.CASCADE)
    # TODO: metadata_keys - описание ключей для динамического построения полей метаданных
    # TODO: metadata_values - Описание значений для динамических полей из MetadataKeys

    objects = NewsManager.from_queryset(NewsQuerySet)()

    class Meta:
        verbose_name = _('news')
        verbose_name_plural = _('news')

    def __str__(self):
        return f'news: {self.id}'