"""Private and company-wide reusable task board templates."""

from django.db.models import Q
from rest_framework import status, viewsets
from rest_framework.decorators import action
from rest_framework.exceptions import PermissionDenied
from rest_framework.permissions import IsAuthenticated
from rest_framework.response import Response

from tasks.models import TaskBoardTemplate
from tasks.realtime import send_task_board_update
from tasks.templates import create_board_from_template

from ..serializers.boards import TaskBoardSerializer
from ..serializers.templates import (
    TaskBoardTemplateInstantiateSerializer,
    TaskBoardTemplateSerializer,
)


class TaskBoardTemplateViewSet(viewsets.ModelViewSet):
    permission_classes = [IsAuthenticated]
    serializer_class = TaskBoardTemplateSerializer

    def get_queryset(self):
        return (
            TaskBoardTemplate.objects.filter(
                Q(is_shared=True) | Q(created_by=self.request.user)
            )
            .select_related("created_by")
            .distinct()
        )

    def get_object(self):
        template = super().get_object()
        if self.action in {"update", "partial_update", "destroy"}:
            self._require_owner(template)
        return template

    def perform_create(self, serializer):
        serializer.save(created_by=self.request.user)

    def _require_owner(self, template):
        if template.created_by_id != self.request.user.pk:
            raise PermissionDenied("Изменять шаблон может только его автор.")

    def perform_update(self, serializer):
        self._require_owner(serializer.instance)
        serializer.save()

    def perform_destroy(self, instance):
        self._require_owner(instance)
        instance.delete()

    @action(detail=True, methods=["post"], url_path="instantiate")
    def instantiate(self, request, pk=None):
        template = self.get_object()
        serializer = TaskBoardTemplateInstantiateSerializer(data=request.data)
        serializer.is_valid(raise_exception=True)
        name = serializer.validated_data.get("name") or template.name
        board = create_board_from_template(template, owner=request.user, name=name)
        send_task_board_update(board, "created", "board", board.id)
        return Response(
            TaskBoardSerializer(board, context={"request": request}).data,
            status=status.HTTP_201_CREATED,
        )