import json

from django.core.management.base import BaseCommand

from api_v1.external_datetime import parse_external_china_datetime
from printing.models import PrintingOrder


class Command(BaseCommand):
    help = '从 PrintingOrder.external_raw.first_record.KdRiQi 批量回填或修正 kd_riqi'

    def add_arguments(self, parser):
        parser.add_argument('--dry-run', action='store_true', help='只统计不写入')
        parser.add_argument('--batch-size', type=int, default=1000, help='批量处理大小')
        parser.add_argument('--limit', type=int, default=None, help='最多处理多少条候选记录')
        parser.add_argument('--merchant-id', type=int, default=None, help='限定商户ID')
        parser.add_argument('--external-order-id', default=None, help='限定外部订单编号')
        parser.add_argument('--overwrite', action='store_true', help='覆盖已有 kd_riqi，用于修正历史错误值')
        parser.add_argument('--update-outgoing-date', action='store_true', help='同时用 KdRiQi 修正 outgoing_date')

    def handle(self, *args, **options):
        dry_run = bool(options['dry_run'])
        batch_size = max(1, int(options['batch_size'] or 1000))
        limit = options.get('limit')
        overwrite = bool(options['overwrite'])
        update_outgoing_date = bool(options['update_outgoing_date'])

        queryset = PrintingOrder.objects.exclude(external_raw={})
        if not overwrite:
            queryset = queryset.filter(kd_riqi__isnull=True)
        merchant_id = options.get('merchant_id')
        if merchant_id:
            queryset = queryset.filter(merchant_id=merchant_id)

        external_order_id = (options.get('external_order_id') or '').strip()
        if external_order_id:
            queryset = queryset.filter(external_order_id=external_order_id)

        queryset = queryset.order_by('id').only('id', 'external_raw', 'kd_riqi', 'outgoing_date')
        if limit is not None:
            queryset = queryset[: max(0, int(limit))]

        matched = 0
        updated = 0
        skipped_missing = 0
        skipped_invalid = 0
        pending_updates = []
        update_fields = ['kd_riqi']
        if update_outgoing_date:
            update_fields.append('outgoing_date')

        for order in queryset.iterator(chunk_size=batch_size):
            matched += 1
            try:
                first_record = (order.external_raw or {}).get('first_record') or {}
                raw_value = first_record.get('KdRiQi')
            except AttributeError:
                raw_value = None

            if not raw_value:
                skipped_missing += 1
                continue

            parsed = parse_external_china_datetime(raw_value)
            if parsed is None:
                skipped_invalid += 1
                continue

            order.kd_riqi = parsed
            if update_outgoing_date:
                order.outgoing_date = parsed
            updated += 1
            if dry_run:
                continue

            pending_updates.append(order)
            if len(pending_updates) >= batch_size:
                PrintingOrder.objects.bulk_update(pending_updates, update_fields)
                pending_updates = []

        if pending_updates:
            PrintingOrder.objects.bulk_update(pending_updates, update_fields)

        payload = {
            'dry_run': dry_run,
            'matched': matched,
            'updated': 0 if dry_run else updated,
            'would_update': updated if dry_run else 0,
            'skipped_missing': skipped_missing,
            'skipped_invalid': skipped_invalid,
            'overwrite': overwrite,
            'update_outgoing_date': update_outgoing_date,
        }
        self.stdout.write(self.style.SUCCESS(json.dumps(payload, ensure_ascii=False)))