from django.shortcuts import get_object_or_404
from django.db import transaction

from rest_framework import generics, views, parsers, filters
from rest_framework.response import Response

from django_filters.rest_framework.backends import DjangoFilterBackend

from core.apps.accounts.permissions.permissions import HasRolePermission
from core.apps.finance.models import Expence, DeletedExpence
from core.apps.finance.serializers import expence as serializers
from core.apps.finance.filters.expence import ExpenceFilter
from core.apps.counterparty.models import Counterparty


class ExpenceCreateApiView(generics.GenericAPIView):
    serializer_class = serializers.ExpenceCreateSerializer
    queryset = Expence.objects.select_related(
        'cash_transaction', 'payment_type', 'project_folder', 'project',
        'counterparty', 'expence_type', 'user'
    )
    permission_classes = [HasRolePermission]
    parser_classes = [parsers.FormParser, parsers.MultiPartParser]

    def post(self, request):
        serializer = self.serializer_class(data=request.data, context={'user': request.user})
        if serializer.is_valid(raise_exception=True):
            serializer.save()
            return Response(
                {
                    'success': True,
                    'message': 'Expence created'
                },
                status=201
            )
        return Response(
            {
                'success': False,
                'message': 'Expence create failed',
                'error': serializer.errors
            },
            status=400
        )


class ExpenceListApiView(generics.GenericAPIView):
    serializer_class = serializers.ExpenceListSerializer
    queryset = Expence.objects.select_related(
        'cash_transaction', 'payment_type', 'project_folder', 'project',
        'counterparty', 'expence_type',
    ).exclude(is_deleted=True)
    permission_classes = [HasRolePermission]
    filter_backends = [DjangoFilterBackend, filters.SearchFilter]
    filterset_class = ExpenceFilter
    search_fields = [
        'cash_transaction__name', 'payment_type__name', 'project_folder__name', 'project__name', 'counterparty__name', 'expence_type__name', 'user__full_name'
    ]

    def get(self, request):
        cash_transaction_ids = request.query_params.getlist('cash_transaction')
        status = request.query_params.get('status')
        if cash_transaction_ids:
            self.queryset = self.queryset.filter(cash_transaction__in=cash_transaction_ids).distinct()
        if status:
            self.queryset = self.queryset.filter(status=status).distinct()
        page = self.paginate_queryset(self.filter_queryset(self.queryset))
        if page is not None:
            serializer = self.serializer_class(page, many=True)
            return self.get_paginated_response(serializer.data)
        
    

class CounterpartyExpenceListApiView(generics.GenericAPIView):
    permission_classes = [HasRolePermission]
    queryset = Expence.objects.select_related(
        'cash_transaction', 'payment_type', 'project_folder', 'project', 'counterparty', 'expence_type',
        'user'
    ).exclude(counterparty__isnull=True).distinct()
    serializer_class = serializers.ExpenceListSerializer

    def get(self, request, counterparty_id):
        counterparty = get_object_or_404(Counterparty, id=counterparty_id)
        page = self.paginate_queryset(self.queryset.filter(counterparty=counterparty))
        if page is not None:
            ser = self.serializer_class(page, many=True)
            return self.get_paginated_response(ser.data)
    

class ChangeExpenceStatusApiView(views.APIView):
    permission_classes = [HasRolePermission]

    def post(self, request, id):
        expence = get_object_or_404(Expence, id=id)
        status = request.data.get('status', None)
        if status is None:
            return Response(
                {
                    'success': False,
                    'message': 'status field is required, choices PENDING, CANCELLED, CONFIRMED'
                },
                status=400
            )
        expence.status = status
        expence.save()
        return Response(
            {
                'success': True, 
                'message': 'expence status successfully updated',
            },
            status=200
        )
    

class ExpenceDeleteApiView(generics.GenericAPIView):
    serializer_class = serializers.ExpenceDeleteSerializer
    queryset = Expence.objects.all()
    permission_classes = [HasRolePermission]

    def post(self, request, id):
        expence = get_object_or_404(Expence, id=id, is_deleted=False)
        serializer = self.serializer_class(data=request.data)
        
        if serializer.is_valid(raise_exception=True):
            with transaction.atomic():
                comment = serializer.validated_data.get('comment')
                currency = expence.currency.lower()
                
                DeletedExpence.objects.create(
                    expence=expence,
                    comment=comment,
                    user=request.user,
                )
                
                cash_transaction = expence.cash_transaction
                payment_type = expence.payment_type
                counterparty = expence.counterparty
                
                if currency == 'uzs':
                    cash_transaction.expence_balance_uzs -= expence.price  
                    cash_transaction.total_balance_uzs = (
                        cash_transaction.income_balance_uzs - cash_transaction.expence_balance_uzs
                    )
                    payment_type.total_uzs += expence.price
                    
                    if counterparty and hasattr(counterparty, 'balance'):
                        counterparty.balance.balance_uzs -= expence.price
                        counterparty.balance.save()
                
                elif currency == 'usd':
                    cash_transaction.expence_balance_usd -= expence.price 
                    cash_transaction.total_balance_usd = (
                        cash_transaction.income_balance_usd - cash_transaction.expence_balance_usd
                    )
                    payment_type.total_usd += expence.price 
                    
                    if counterparty and hasattr(counterparty, 'balance'):
                        counterparty.balance.balance_usd -= expence.price
                        counterparty.balance.save()
                
                expence.is_deleted = True
                
                cash_transaction.save()
                payment_type.save()
                expence.save()
                
                return Response(
                    {
                        'success': True,
                        'message': "Expence o'chirildi",
                        'data': {
                            'expence_id': expence.id,
                            'price': expence.price,
                            'currency': expence.currency
                        }
                    },
                    status=200
                )
    

class ExpenceUpdateApiView(generics.GenericAPIView):
    serializer_class = serializers.ExpenceUpdateSerializer
    queryset = Expence.objects.all()
    permission_classes = [HasRolePermission]

    def patch(self, request, id):
        expence = get_object_or_404(Expence, id=id)
        serializer = self.serializer_class(data=request.data, instance=expence)
        if serializer.is_valid(raise_exception=True):
            serializer.save()
            return Response(
                {
                    'success': True,
                    'message': 'Expence updated'
                }, status=200
            )
        return Response(
            {
                'success': False,
                'message': serializer.errors,
            }, status=400
        )