from django.db import transaction

from apps.authentication.models import City
from apps.herd.models import Rancher, Herd


class HerdRancherSyncService:

    @classmethod
    def bulk_sync(cls, queryset, batch_size=1000):
        """
        optimized bulk sync for large datasets
        """

        city_map = {
            name.strip(): id
            for id, name in City.objects.all().values_list('id', 'name')
        }

        rancher_map = {
            r.national_code: r
            for r in Rancher.objects.filter(
                national_code__in=queryset.values_list(
                    'rancher_national_code', flat=True
                )
            ).only('id', 'national_code')
        }

        new_ranchers = []
        new_herds = []

        existing_herds = set(
            Herd.objects.filter(
                rancher__national_code__in=queryset.values_list(
                    'rancher_national_code', flat=True
                )
            ).values_list(
                'rancher__national_code', 'code'
            )
        )

        seen_in_batch = set()

        for temp in queryset.iterator(chunk_size=batch_size):

            rancher = rancher_map.get(temp.rancher_national_code)

            if not rancher:
                rancher = Rancher(
                    first_name=temp.rancher_name,
                    mobile=temp.mobile,
                    national_code=temp.rancher_national_code,
                    rancher_type='N',
                    city_id=city_map.get(temp.city.strip()),
                    province_id=30
                )
                new_ranchers.append(rancher)
                rancher_map[temp.rancher_national_code] = rancher

            herd_key = (temp.rancher_national_code, temp.herd_code)

            if herd_key in existing_herds:
                continue

            if herd_key in seen_in_batch:
                continue

            seen_in_batch.add(herd_key)

            new_herds.append({
                "rancher_code": temp.rancher_national_code,
                "herd": Herd(
                    name=temp.herd_name,
                    code=temp.herd_code,
                    epidemiologic=temp.epidemiologic,
                    latitude=temp.latitude,
                    longitude=temp.longitude,
                    postal=temp.postal_code,
                    unit_unique_id=temp.unit_unique_id,
                    city_id=city_map.get(temp.city.strip()),
                    province_id=30
                )
            }
            )

        with transaction.atomic():
            Rancher.objects.bulk_create(
                new_ranchers,
                ignore_conflicts=True,
                batch_size=batch_size
            )

            # refresh ranchers with ids
            rancher_map = {
                r.national_code: r
                for r in Rancher.objects.filter(
                    national_code__in=rancher_map.keys()
                )
            }

            final_herds = []

            for item in new_herds:
                rancher = rancher_map.get(item["rancher_code"])

                if not rancher:
                    continue

                herd = item["herd"]
                herd.rancher = rancher
                final_herds.append(herd)

            Herd.objects.bulk_create(
                final_herds,
                ignore_conflicts=True,
                batch_size=batch_size
            )