from django.shortcuts import get_object_or_404

from rest_framework import status
from rest_framework.viewsets import ModelViewSet
from rest_framework.response import Response
from rest_framework.permissions import IsAuthenticated
from rest_framework.decorators import action
from rest_framework.filters import SearchFilter, OrderingFilter
from django_filters.rest_framework import DjangoFilterBackend

from core.paginations.limit_offset import CustomLimitOffsetPagination

from apps.workspaces.models import Workspace
from apps.clients.models import Client
from apps.projects.models import Project
from apps.projects.api.serializers import (
    ProjectSerializer, ProjectCreateSerializer, ProjectUpdateSerializer,
)
from apps.projects.api.permissions import IsProjectMember, IsProjectManager
from apps.projects.services.projects import (
    create_project,
    update_project,
    toggle_project_archive
)
from apps.workspaces.services import (
    PROJECTS_ARCHIVE,
    PROJECTS_CREATE,
    PROJECTS_DELETE,
    PROJECTS_EDIT,
    can_delete_workspace_object,
    has_workspace_capability,
)


class ProjectViewSet(ModelViewSet):
    """
    API endpoints for managing projects.
    """
    pagination_class = CustomLimitOffsetPagination
    
    filter_backends = [DjangoFilterBackend, SearchFilter, OrderingFilter]
    filterset_fields = ["workspace", "client", "is_archived"]
    search_fields = ["name", "description"]
    ordering_fields = ["name", "created_at", "updated_at"]
    ordering = ["-updated_at", "-created_at"]

    def get_permissions(self):
        """
        Instantiates and returns the list of permissions that this view requires.
        - Workspace-authorized users can update, delete, or archive.
        - Workspace members can retrieve/view.
        - Any authenticated user can list their workspace projects or attempt to create.
        """
        if self.action in ["update", "partial_update", "destroy", "archive"]:
            permission_classes = [IsAuthenticated, IsProjectManager]
        elif self.action in ["retrieve"]:
            permission_classes = [IsAuthenticated, IsProjectMember]
        else:
            permission_classes = [IsAuthenticated]
            
        return [permission() for permission in permission_classes]

    def get_queryset(self):
        """
        Returns active projects in workspaces where the current user is an active member.
        """
        if getattr(self, "swagger_fake_view", False) or not self.request.user.is_authenticated:
            return Project.objects.none()

        queryset = Project.objects.filter(
            workspace__memberships__user=self.request.user,
            workspace__memberships__is_active=True,
            is_deleted=False
        ).distinct()

        client_ids = [client_id for client_id in self.request.query_params.getlist("clients") if client_id]
        if client_ids:
            queryset = queryset.filter(client_id__in=client_ids)

        return queryset

    def get_serializer_class(self):
        """
        Selects the appropriate serializer based on the request action.
        """
        if self.action == "create":
            return ProjectCreateSerializer
        elif self.action in ["update", "partial_update"]:
            return ProjectUpdateSerializer
        return ProjectSerializer

    def create(self, request, *args, **kwargs):
        """
        Creates a new project using the project service layer.
        """
        serializer = self.get_serializer(data=request.data)
        serializer.is_valid(raise_exception=True)

        workspace = get_object_or_404(Workspace, id=serializer.validated_data["workspace"], is_deleted=False)
        if not has_workspace_capability(request.user, workspace, PROJECTS_CREATE):
            return Response(
                {"detail": "You do not have permission to create projects in this workspace."},
                status=status.HTTP_403_FORBIDDEN,
            )
        client_id = serializer.validated_data.get("client")
        client = get_object_or_404(Client, id=client_id, is_deleted=False) if client_id else None

        project = create_project(
            user=request.user,
            workspace=workspace,
            name=serializer.validated_data["name"],
            client=client,
            description=serializer.validated_data.get("description", ""),
            color=serializer.validated_data.get("color", "")
        )
        
        output_serializer = ProjectSerializer(project)
        return Response(output_serializer.data, status=status.HTTP_201_CREATED)

    def update(self, request, *args, **kwargs):
        """
        Updates an existing project using the project service layer.
        """
        partial = kwargs.pop("partial", False)
        project = self.get_object()
        
        serializer = self.get_serializer(data=request.data, partial=partial)
        serializer.is_valid(raise_exception=True)

        updated_project = update_project(
            project=project,
            **serializer.validated_data
        )
        
        output_serializer = ProjectSerializer(updated_project)
        return Response(output_serializer.data, status=status.HTTP_200_OK)

    def destroy(self, request, *args, **kwargs):
        """
        Soft deletes a project.
        """
        project = self.get_object()
        if not can_delete_workspace_object(request.user, project, PROJECTS_DELETE):
            return Response(
                {"detail": "You do not have permission to delete this project."},
                status=status.HTTP_403_FORBIDDEN,
            )
        project.is_deleted = True
        project.save(update_fields=["is_deleted", "updated_at"])
        return Response(status=status.HTTP_204_NO_CONTENT)

    @action(detail=True, methods=["post"])
    def archive(self, request, pk=None):
        """
        Custom endpoint to toggle the archive status of a project.
        """
        project = self.get_object()
        updated_project = toggle_project_archive(project)
        
        output_serializer = ProjectSerializer(updated_project)
        return Response(output_serializer.data, status=status.HTTP_200_OK)