from django.urls import re_path
from rest_framework import routers, viewsets, status
from rest_framework.decorators import api_view, permission_classes, action
from rest_framework.response import Response
from rest_framework.permissions import IsAuthenticated
from rest_framework import serializers

from .models import Shipment
from inventory.models import Item
from tickets.models import IssueThread


class ShipmentSerializer(serializers.ModelSerializer):
    related_items = serializers.PrimaryKeyRelatedField(
        many=True, 
        queryset=Item.objects.all(),
        required=False
    )
    related_tickets = serializers.PrimaryKeyRelatedField(
        many=True, 
        queryset=IssueThread.objects.all(),
        required=False
    )
    
    class Meta:
        model = Shipment
        fields = [
            'id', 'public_secret', 'state', 'review_requirement',
            'recipient_name', 'address_supplements', 'street_address',
            'city', 'state_province', 'postal_code', 'country',
            'related_items', 'related_tickets',
            'created_at', 'updated_at', 'shipped_at', 'completed_at'
        ]
        read_only_fields = ['id', 'public_secret', 'created_at', 'updated_at', 'shipped_at', 'completed_at']


class ShipmentViewSet(viewsets.ModelViewSet):
    serializer_class = ShipmentSerializer
    queryset = Shipment.objects.all()
    permission_classes = [IsAuthenticated]

    @action(detail=True, methods=['post'])
    def add_items(self, request, pk=None):
        shipment = self.get_object()
        review_requirement = request.data.get('review_requirement')
        item_ids = request.data.get('item_ids', [])

        try:
            items = Item.objects.filter(id__in=item_ids)
            shipment.related_items.add(*items)
            shipment.add_items(review_requirement)
            return Response(ShipmentSerializer(shipment).data)
        except Exception as e:
            return Response({'error': str(e)}, status=status.HTTP_400_BAD_REQUEST)

    @action(detail=True, methods=['post'])
    def approve(self, request, pk=None):
        shipment = self.get_object()
        try:
            shipment.approve()
            return Response(ShipmentSerializer(shipment).data)
        except Exception as e:
            return Response({'error': str(e)}, status=status.HTTP_400_BAD_REQUEST)

    @action(detail=True, methods=['post'])
    def reject(self, request, pk=None):
        shipment = self.get_object()
        try:
            shipment.reject()
            return Response(ShipmentSerializer(shipment).data)
        except Exception as e:
            return Response({'error': str(e)}, status=status.HTTP_400_BAD_REQUEST)

    @action(detail=True, methods=['post'])
    def mark_shipped(self, request, pk=None):
        shipment = self.get_object()
        try:
            # Validate state transition before attempting to mark as shipped
            if shipment.state != Shipment.READY_FOR_SHIPPING:
                return Response(
                    {'error': f'Invalid state transition: Cannot mark shipment as shipped from {shipment.state} state. Shipment must be in READY_FOR_SHIPPING state.'}, 
                    status=status.HTTP_400_BAD_REQUEST
                )
            shipment.mark_shipped()
            return Response(ShipmentSerializer(shipment).data)
        except Exception as e:
            return Response({'error': str(e)}, status=status.HTTP_400_BAD_REQUEST)

    @action(detail=True, methods=['post'])
    def mark_completed(self, request, pk=None):
        shipment = self.get_object()
        try:
            # Validate state transition before attempting to mark as completed
            if shipment.state != Shipment.SHIPPED:
                return Response(
                    {'error': f'Invalid state transition: Cannot mark shipment as completed from {shipment.state} state. Shipment must be in SHIPPED state.'}, 
                    status=status.HTTP_400_BAD_REQUEST
                )
            shipment.mark_completed()
            return Response(ShipmentSerializer(shipment).data)
        except Exception as e:
            return Response({'error': str(e)}, status=status.HTTP_400_BAD_REQUEST)


router = routers.SimpleRouter()
router.register(r'shipments', ShipmentViewSet, basename='shipments')

urlpatterns = router.urls