from pprint import pprint

from django.db.models import Aggregate, CharField, Value
from django.db.models import IntegerField, F

from news.models import NewsType
from transfer.models import PageTexts
from transfer.serializers.news import NewsSerializer


class GroupConcat(Aggregate):
    function = 'GROUP_CONCAT'
    template = '%(function)s(%(expressions)s)'

    def __init__(self, expression, **extra):
        output_field = extra.pop('output_field', CharField())
        super().__init__(expression, output_field=output_field, **extra)

    def as_postgresql(self, compiler, connection):
        self.function = 'STRING_AGG'
        return super().as_sql(compiler, connection)


def transfer_news():
    news_type, _ = NewsType.objects.get_or_create(name='News')
    queryset = PageTexts.objects.filter(
        page__type='News',
    ).annotate(
        news_type=Value(news_type.id, output_field=IntegerField()),
        country_code=F('page__site__country_code_2'),
        news_title=F('page__root_title'),
        image=F('page__attachment_suffix_url'),
        template=F('page__template'),
        tags=GroupConcat('page__tags__id'),
    )[:100]

    serialized_data = NewsSerializer(data=list(queryset.values()), many=True)
    if serialized_data.is_valid():
        serialized_data.save()
    else:
        pprint(f'News serializer errors: {serialized_data.errors}')


data_types = {
    'news': [transfer_news]
}