"""
库存红冲（对冲）占位视图
"""

from rest_framework import status, views, serializers
from rest_framework.response import Response
from rest_framework.permissions import IsAuthenticated
from drf_spectacular.utils import extend_schema, OpenApiResponse

from stock import models as stock_models, services as stock_services

from .mixins import StockChangeViewMixin


class StockChangeOffsetSerializer(serializers.Serializer):
    """红冲请求体验证"""

    reason = serializers.CharField(max_length=255, allow_blank=False)
    items = serializers.ListField(
        child=serializers.DictField(),
        required=False,
        allow_empty=True,
    )
    request_id = serializers.CharField(required=False, allow_blank=True)
    extra_meta = serializers.JSONField(required=False)


class OffsetStockChangeView(StockChangeViewMixin, views.APIView):
    """针对既有出入库记录发起红冲的占位接口"""

    permission_classes = [IsAuthenticated]

    @extend_schema(
        tags=['库存红冲'],
        summary='发起库存红冲（占位）',
        description=(
            '对指定库存变动记录创建红冲请求。当前仅提供占位实现，'
            '会返回 501 Not Implemented，待库存红冲逻辑完善后启用。'
        ),
        request=StockChangeOffsetSerializer,
        responses={
            201: OpenApiResponse(
                description='红冲成功（未来实现后返回）'
            ),
            400: OpenApiResponse(description='参数或业务校验失败'),
            403: OpenApiResponse(description='无权访问对应出入库记录'),
            404: OpenApiResponse(description='库存变动记录不存在'),
            501: OpenApiResponse(description='功能占位，尚未实现'),
        },
    )
    def post(self, request, record_id: int):
        if not self.check_employee_permission(request):
            return self.permission_error_response('无权限访问')

        merchant = request.user.employee.merchant

        try:
            stock_change_record = stock_models.StockChangeRecord.objects.select_related(
                'merchant', 'warehouse'
            ).get(id=record_id)
        except stock_models.StockChangeRecord.DoesNotExist:
            return self.not_found_response(f'库存变动记录ID {record_id} 不存在')

        if stock_change_record.merchant_id != merchant.id:
            return self.permission_error_response('无权访问该库存变动记录')

        if not self.validate_warehouse_visibility(stock_change_record.warehouse_id, request):
            return self.permission_error_response('该库存变动记录的仓库对当前用户不可见')

        serializer = StockChangeOffsetSerializer(data=request.data or {})
        serializer.is_valid(raise_exception=True)
        payload = serializer.validated_data

        service = stock_services.StockFlowService(merchant=merchant, created_by=request.user)

        try:
            offset_record, details, detail_count = service.offset_stock_change(
                source_record_id=stock_change_record.id,
                reason=payload['reason'],
                items=payload.get('items'),
                request_id=payload.get('request_id'),
                extra_meta=payload.get('extra_meta'),
            )
        except NotImplementedError as exc:
            return Response(
                {
                    'error': 'stock_offset_not_ready',
                    'message': str(exc),
                    'record_id': stock_change_record.id,
                },
                status=status.HTTP_501_NOT_IMPLEMENTED,
            )
        except ValueError as exc:
            return Response({'error': str(exc)}, status=status.HTTP_400_BAD_REQUEST)

        response_data = {
            'status': 'success',
            'message': '红冲记录已创建',
            'stock_change_record': self.build_record_data(offset_record),
            'details': [self.build_detail_data(detail) for detail in details],
            'created_details_count': detail_count,
        }
        return Response(response_data, status=status.HTTP_201_CREATED)