from rest_framework import status, views, serializers, pagination
from rest_framework.permissions import IsAuthenticated
from rest_framework.response import Response

from basic_info import models as basic_models
from business import services as business_services
from business import models as business_models
from api_v1.views.stock_change_views.mixins import StockChangeViewMixin


class PaymentOrderSerializer(serializers.ModelSerializer):
    supplier_name = serializers.CharField(source='supplier.name', read_only=True)
    operator_name = serializers.CharField(source='operator.name', read_only=True)

    class Meta:
        model = business_models.PaymentOrder
        fields = [
            'id', 'supplier', 'supplier_name', 'payment_date',
            'amount', 'operator', 'operator_name', 'status',
            'remarks', 'created_at', 'updated_at',
        ]
        read_only_fields = ['id', 'supplier_name', 'operator_name', 'status', 'created_at', 'updated_at']


class PaymentOrderPagination(pagination.LimitOffsetPagination):
    default_limit = 20
    max_limit = 100


class PaymentOrderView(StockChangeViewMixin, views.APIView):
    permission_classes = [IsAuthenticated]
    pagination_class = PaymentOrderPagination

    def get(self, request):
        if not self.check_employee_permission(request):
            return self.permission_error_response('无权限访问')
        merchant = request.user.employee.merchant
        queryset = business_models.PaymentOrder.objects.filter(merchant=merchant).select_related(
            'supplier', 'operator'
        ).order_by('-created_at')
        paginator = self.pagination_class()
        page = paginator.paginate_queryset(queryset, request, view=self)
        serializer = PaymentOrderSerializer(page, many=True)
        return paginator.get_paginated_response(serializer.data)

    def post(self, request):
        if not self.check_employee_permission(request):
            return self.permission_error_response('无权限访问')
        merchant = request.user.employee.merchant
        data = request.data or {}
        supplier_id = data.get('supplier')
        payment_date = data.get('payment_date')
        amount = data.get('amount')
        remarks = data.get('remarks', '')

        if not supplier_id:
            return Response({'error': '缺少供应商 ID'}, status=status.HTTP_400_BAD_REQUEST)
        if not payment_date:
            return Response({'error': '缺少 payment_date'}, status=status.HTTP_400_BAD_REQUEST)
        if amount is None:
            return Response({'error': '缺少 amount'}, status=status.HTTP_400_BAD_REQUEST)

        try:
            supplier = basic_models.Supplier.objects.get(id=supplier_id, merchant=merchant)
        except basic_models.Supplier.DoesNotExist:
            return Response({'error': f'供应商 {supplier_id} 不存在'}, status=status.HTTP_400_BAD_REQUEST)

        operator = request.user.employee

        try:
            payment_order = business_services.create_payment_order(
                merchant=merchant,
                supplier=supplier,
                payment_date=payment_date,
                amount=amount,
                operator=operator,
                remarks=remarks,
            )
        except ValueError as exc:
            return Response({'error': str(exc)}, status=status.HTTP_400_BAD_REQUEST)

        return Response(
            {
                'id': payment_order.id,
                'status': payment_order.status,
                'message': '付款单创建成功，等待审批',
            },
            status=status.HTTP_201_CREATED,
        )


class PaymentOrderReviewSerializer(serializers.Serializer):
    action = serializers.ChoiceField(choices=[('approve', '审批通过'), ('cancel', '作废')])


class PaymentOrderReviewView(StockChangeViewMixin, views.APIView):
    permission_classes = [IsAuthenticated]
    ACTION_STATUS_MAP = {
        'approve': business_models.PaymentOrderStatusEnum.APPROVED,
        'cancel': business_models.PaymentOrderStatusEnum.CANCELLED,
    }

    def post(self, request, pk: int):
        if not self.check_employee_permission(request):
            return self.permission_error_response('无权限访问')

        merchant = request.user.employee.merchant
        try:
            payment_order = business_models.PaymentOrder.objects.select_related(
                'supplier', 'operator'
            ).get(id=pk, merchant=merchant)
        except business_models.PaymentOrder.DoesNotExist:
            return self.not_found_response('付款单不存在')

        serializer = PaymentOrderReviewSerializer(data=request.data or {})
        serializer.is_valid(raise_exception=True)
        action = serializer.validated_data['action']
        target_status = self.ACTION_STATUS_MAP[action]

        try:
            business_services.review_payment_order(
                payment_order=payment_order,
                target_status=target_status,
                reviewed_by=request.user,
            )
        except ValueError as exc:
            return Response({'error': str(exc)}, status=status.HTTP_400_BAD_REQUEST)

        refreshed = business_models.PaymentOrder.objects.select_related(
            'supplier', 'operator'
        ).get(id=payment_order.id)
        return Response(PaymentOrderSerializer(refreshed).data, status=status.HTTP_200_OK)