from rest_framework import viewsets, filters
from rest_framework.authentication import TokenAuthentication
from django_filters.rest_framework import DjangoFilterBackend
from rest_framework.pagination import PageNumberPagination
from rest_framework.permissions import IsAuthenticated

from api.logger.mixins import LoggingMixin
from core.permissions import require_permission, user_has_permission, IsInternalService
from mixins.filtrado_organizacion import OrganizacionFiltradaMixin
from .models import Task
from .serializers import TaskSerializer
from .filters import TaskFilter


class TaskPagination(PageNumberPagination):
    page_size = 10
    page_size_query_param = 'page_size'
    max_page_size = 100


class TaskViewSet(LoggingMixin, viewsets.ModelViewSet, OrganizacionFiltradaMixin):
    # Task se relaciona con pedimento, que tiene contribuyente
    campo_contribuyente = 'pedimento__contribuyente'

    queryset = Task.objects.select_related('pedimento', 'servicio').all()
    serializer_class = TaskSerializer
    filter_backends = [DjangoFilterBackend, filters.OrderingFilter]
    filterset_class = TaskFilter
    pagination_class = TaskPagination
    ordering_fields = ['timestamp']
    ordering = ['-timestamp']

    my_tags = ['tasks']

    def get_permissions(self):
        # Escritura: exclusivo para microservicio interno (Token + superuser)
        # Lectura: usuarios con pedimentos.view via JWT
        if self.action in ('create', 'update', 'partial_update', 'destroy'):
            return [IsAuthenticated(), IsInternalService()]
        return [IsAuthenticated(), require_permission('pedimentos.view')()]

    def get_queryset(self):
        user = self.request.user
        # Service account (Token + superuser): sin filtro de org, accede a todas las tasks
        if user.is_superuser and isinstance(
            getattr(self.request, 'successful_authenticator', None), TokenAuthentication
        ):
            return Task.objects.select_related('pedimento', 'servicio').all()
        if not user_has_permission(user, 'pedimentos.view'):
            return Task.objects.none()
        return self.get_queryset_filtrado_por_organizacion()


from rest_framework.views import APIView
from rest_framework.response import Response
from rest_framework import status
from celery.result import AsyncResult


class TaskStatusView(APIView):
    permission_classes = [IsAuthenticated, require_permission('pedimentos.view')]

    # Mapeo de status del microservicio → estados estándar
    _STATUS_MAP = {
        'failed':     'FAILURE',
        'completed':  'SUCCESS',
        'processing': 'STARTED',
        'submitted':  'PENDING',
        'pending':    'PENDING',
    }

    def get(self, request, task_id):
        """
        Consulta el estado de una tarea.

        Fuente de verdad: registro Django Task (actualizado por el microservicio vía PUT).
        Celery AsyncResult se usa como complemento para tareas de auditoría masiva (SUCCESS)
        y como fallback cuando la tarea no está en la BD todavía.

        Estados posibles:
          PENDING  — en cola o aún no registrada
          STARTED  — worker ejecutando
          SUCCESS  — completada sin errores
          FAILURE  — terminó con error
          RETRY    — el worker la está reintentando
        """
        try:
            # Prioridad 1: Django Task record (fuente de verdad del microservicio)
            try:
                django_task = Task.objects.get(task_id=task_id)
                effective_state = self._STATUS_MAP.get(
                    django_task.status.lower(), django_task.status.upper()
                )
                is_terminal = effective_state in ('SUCCESS', 'FAILURE')

                response_data = {
                    'task_id': task_id,
                    'status': effective_state,
                    'ready': is_terminal,
                    'successful': (effective_state == 'SUCCESS') if is_terminal else None,
                    'message': django_task.message,
                }

                if effective_state == 'FAILURE':
                    response_data['error'] = django_task.message

                elif effective_state == 'SUCCESS':
                    # Para auditoría masiva, intentar enriquecer con resultado de Celery
                    try:
                        celery_result = AsyncResult(task_id)
                        if celery_result.ready() and celery_result.successful():
                            result = celery_result.result
                            response_data['result'] = result
                            if isinstance(result, dict) and 'total_pedimentos' in result:
                                total = result.get('total_pedimentos', 0)
                                completados = result.get('completados', 0)
                                con_pendientes = result.get('con_pendientes', 0)
                                con_errores = result.get('con_errores', 0)
                                if con_pendientes == 0 and con_errores == 0:
                                    response_data['mensaje'] = f'Auditoría completa — {completados}/{total} pedimentos sin pendientes'
                                else:
                                    partes = []
                                    if con_pendientes:
                                        partes.append(f'{con_pendientes} con documentos pendientes')
                                    if con_errores:
                                        partes.append(f'{con_errores} con error')
                                    response_data['mensaje'] = f'{completados}/{total} pedimentos completos — {", ".join(partes)}'
                    except Exception:
                        pass

                return Response(response_data, status=status.HTTP_200_OK)

            except Task.DoesNotExist:
                pass

            # Prioridad 2: Celery AsyncResult (tarea aún no registrada en BD)
            task_result = AsyncResult(task_id)
            state = task_result.state

            response_data = {
                'task_id': task_id,
                'status': state,
                'ready': task_result.ready(),
                'successful': task_result.successful() if task_result.ready() else None,
            }

            if state == 'SUCCESS':
                result = task_result.result
                response_data['result'] = result
                if isinstance(result, dict) and 'total_pedimentos' in result:
                    total = result.get('total_pedimentos', 0)
                    completados = result.get('completados', 0)
                    con_pendientes = result.get('con_pendientes', 0)
                    con_errores = result.get('con_errores', 0)
                    if con_pendientes == 0 and con_errores == 0:
                        response_data['mensaje'] = f'Auditoría completa — {completados}/{total} pedimentos sin pendientes'
                    else:
                        partes = []
                        if con_pendientes:
                            partes.append(f'{con_pendientes} con documentos pendientes')
                        if con_errores:
                            partes.append(f'{con_errores} con error')
                        response_data['mensaje'] = f'{completados}/{total} pedimentos completos — {", ".join(partes)}'

            elif state == 'FAILURE':
                response_data['error'] = str(task_result.info)

            elif state == 'STARTED':
                response_data['info'] = str(task_result.info) if task_result.info else None

            return Response(response_data, status=status.HTTP_200_OK)

        except Exception as e:
            return Response(
                {'error': f'Error al consultar tarea: {str(e)}'},
                status=status.HTTP_500_INTERNAL_SERVER_ERROR
            )