from rest_framework import serializers, status, permissions
from rest_framework.response import Response
from rest_framework.views import APIView

from stateflow import models as stateflow_models
from stateflow import services as stateflow_services


class BusinessObjectCloneRequestSerializer(serializers.Serializer):
    business_object_id = serializers.IntegerField(min_value=1)
    # 调用方必须显式传入 content_type 与 object_id：
    # - content_type：仅用于校验与源对象一致（不做额外校验）
    # - object_id：克隆后的新业务对象 ID（必须与源对象不同）
    content_type = serializers.IntegerField(min_value=1, allow_null=True)
    object_id = serializers.IntegerField(min_value=1, allow_null=True)


class BusinessObjectCloneView(APIView):
    """
    克隆 BusinessObject（含所有状态流转记录与工艺参数记录）

    POST /api/v2/stateflow/business-objects/clone/

    请求体:
    {
      "business_object_id": 123,
      "content_type": 9,
      "object_id": 456
    }

    返回:
    {
      "business_object_id": 456
    }
    """

    permission_classes = [permissions.IsAuthenticated]

    def post(self, request):
        srz = BusinessObjectCloneRequestSerializer(data=request.data)
        srz.is_valid(raise_exception=True)

        bo_id = srz.validated_data['business_object_id']
        expected_content_type_id = srz.validated_data.get('content_type')
        new_object_id = srz.validated_data.get('object_id')
        try:
            bo = stateflow_models.BusinessObject.objects.get(id=bo_id)
        except stateflow_models.BusinessObject.DoesNotExist:
            return Response({'detail': 'business_object 不存在'}, status=status.HTTP_404_NOT_FOUND)

        try:
            cloned = stateflow_services.clone_business_object(
                bo,
                new_object_id=new_object_id,
                expected_content_type_id=expected_content_type_id,
            )
        except ValueError as e:
            return Response({'detail': str(e)}, status=status.HTTP_400_BAD_REQUEST)

        return Response({'business_object_id': cloned.id})