from rest_framework.serializers import ModelSerializer

AVAILABLE_CONFIGS_FIELD = ('fields', 'read_only_fields', 'exclude', 'write_only_fields')


class BaseModelSerializer(ModelSerializer):
    """
      Clase abstracta serializadora donde se pueden configurar campos para cada acciones genéricas de 
      las vistas ModelViewSet que provee DjangoRestFramework y acciones personalizadas
      Serializer Ex:
        class OrderSerializer(BaseModelSerializer):
            class Meta:
                model = Order
                fields = "__all__"
                fields_config = {
                  "create": { 
                    "exclude": ("total",)
                  },
                  "update": { 
                    "fields": ("id", "total", "status", "delivery", "products"),
                    "read_only_fields": ("id", "total", "status")
                  },
                  "change_status":{ # Custom action
                    "fields": ("status",)
                  }
                }
        View Ex:
            class OrderModelViewSet(ModelViewSet):
                serializer = OrderSerializer
                queryset = Order.objects.all()
                
                @detail_route(methods=['patch'])
                def change_status(self, request, *args, **kwargs):
                    # Ejecutar logica de cambio de estado de una orden
                    # O simplemente dejar que django rest lo haga por defecto devolviendo el update
                    # El serializador se encarga de permitir modificar ciertos atributos de acuerdo a la firma del metodo
                    return super(OrderModelViewSet, self).update(request, *args, **kwargs)
    """
    def __init__(self, *args, **kwargs):
        if kwargs.get('context'):
            action = kwargs['context']['view'].action

            fields_config = getattr(self.Meta, 'fields_config')

            if fields_config and fields_config.get(action):
                custom_fields_by_action = fields_config.get(action)
                
                if custom_fields_by_action.get('exclude') and getattr(self.Meta, 'fields', False):
                    delattr(self.Meta, 'fields')
                elif custom_fields_by_action.get('fields') and getattr(self.Meta, 'exclude', False):
                    delattr(self.Meta, 'exclude')
                    
                for key, value in custom_fields_by_action.items():
                    assert key in AVAILABLE_CONFIGS_FIELD, "The %s can't support" % key
                    setattr(self.Meta, key, value)

        super(BaseModelSerializer, self).__init__(*args, **kwargs)

    class Meta:
        abstract = True