from django.db import transaction
from django.db.models import Q
from rest_framework import status
from rest_framework.authentication import TokenAuthentication
from rest_framework.decorators import action
from rest_framework.parsers import FormParser, JSONParser, MultiPartParser
from rest_framework.permissions import IsAuthenticated
from rest_framework.response import Response
from rest_framework.viewsets import ModelViewSet, ReadOnlyModelViewSet

from apps.account.permissions import IsSuperAdmin
from utils.pagination import StandardResultsSetPagination

from .models import PlaylistItem, Podcast, PodcastCollection, PodcastCategory, PodcastPlaylist
from .serializers_admin import (
    AdminPodcastCategorySerializer,
    AdminPodcastCollectionSerializer,
    AdminPodcastDetailSerializer,
    AdminPodcastListSerializer,
    AdminPodcastPlaylistDetailSerializer,
    AdminPodcastPlaylistItemSerializer,
    AdminPodcastPlaylistListSerializer,
)


class AdminPodcastCategoryViewSet(ReadOnlyModelViewSet):
    serializer_class = AdminPodcastCategorySerializer
    permission_classes = [IsAuthenticated, IsSuperAdmin]
    authentication_classes = [TokenAuthentication]
    pagination_class = None

    def get_queryset(self):
        return PodcastCategory.objects.all().order_by("title")


class AdminPodcastCollectionViewSet(ReadOnlyModelViewSet):
    serializer_class = AdminPodcastCollectionSerializer
    permission_classes = [IsAuthenticated, IsSuperAdmin]
    authentication_classes = [TokenAuthentication]
    pagination_class = None

    def get_queryset(self):
        return PodcastCollection.objects.all().order_by("display_position", "order", "title")


class AdminPodcastViewSet(ModelViewSet):
    permission_classes = [IsAuthenticated, IsSuperAdmin]
    authentication_classes = [TokenAuthentication]
    pagination_class = StandardResultsSetPagination
    parser_classes = (MultiPartParser, FormParser, JSONParser)

    def get_serializer_class(self):
        if self.action == "list":
            return AdminPodcastListSerializer
        return AdminPodcastDetailSerializer

    def get_queryset(self):
        queryset = Podcast.objects.all().prefetch_related("categories", "collections")

        search_query = self.request.query_params.get("search")
        if search_query:
            queryset = queryset.filter(
                Q(title__icontains=search_query)
                | Q(slug__icontains=search_query)
                | Q(description__icontains=search_query)
            )

        status_filter = self.request.query_params.get("status")
        if status_filter in {"true", "false"}:
            queryset = queryset.filter(status=status_filter == "true")

        category_id = self.request.query_params.get("category")
        if category_id and category_id != "all":
            queryset = queryset.filter(categories__id=category_id)

        collection_id = self.request.query_params.get("collection")
        if collection_id and collection_id != "all":
            queryset = queryset.filter(collections__id=collection_id)

        unattached = self.request.query_params.get("unattached")
        if unattached == "true":
            queryset = queryset.filter(playlist_appearances__isnull=True)

        return queryset.distinct().order_by("-created_at")


class AdminPodcastPlaylistViewSet(ModelViewSet):
    permission_classes = [IsAuthenticated, IsSuperAdmin]
    authentication_classes = [TokenAuthentication]
    pagination_class = StandardResultsSetPagination
    parser_classes = (MultiPartParser, FormParser, JSONParser)

    def get_serializer_class(self):
        if self.action == "list":
            return AdminPodcastPlaylistListSerializer
        return AdminPodcastPlaylistDetailSerializer

    def get_queryset(self):
        queryset = PodcastPlaylist.objects.all().prefetch_related("categories", "collections", "playlist_items__podcast")

        search_query = self.request.query_params.get("search")
        if search_query:
            queryset = queryset.filter(
                Q(title__icontains=search_query)
                | Q(slug__icontains=search_query)
                | Q(slogan__icontains=search_query)
                | Q(description__icontains=search_query)
            )

        status_filter = self.request.query_params.get("status")
        if status_filter in {"true", "false"}:
            queryset = queryset.filter(status=status_filter == "true")

        category_id = self.request.query_params.get("category")
        if category_id and category_id != "all":
            queryset = queryset.filter(categories__id=category_id)

        collection_id = self.request.query_params.get("collection")
        if collection_id and collection_id != "all":
            queryset = queryset.filter(collections__id=collection_id)

        return queryset.distinct().order_by("order", "-created_at")

    @action(detail=True, methods=["get", "post"], url_path="items")
    def items(self, request, pk=None):
        playlist = self.get_object()

        if request.method.lower() == "get":
            items = playlist.playlist_items.select_related("podcast").order_by("priority", "id")
            serializer = AdminPodcastPlaylistItemSerializer(items, many=True, context={"request": request})
            return Response(serializer.data)

        serializer = AdminPodcastPlaylistItemSerializer(
            data={
                **request.data,
                "playlist": playlist.id,
                "priority": request.data.get("priority", playlist.playlist_items.count() + 1),
            },
            context={"request": request},
        )
        serializer.is_valid(raise_exception=True)
        serializer.save()
        playlist.total_time = playlist.calculate_total_time()
        playlist.save(update_fields=["total_time"])
        return Response(serializer.data, status=status.HTTP_201_CREATED)

    @action(detail=True, methods=["patch", "delete"], url_path=r"items/(?P<item_id>\d+)")
    def item_detail(self, request, pk=None, item_id=None):
        playlist = self.get_object()
        item = playlist.playlist_items.select_related("podcast").get(pk=item_id)

        if request.method.lower() == "delete":
            item.delete()
            playlist.total_time = playlist.calculate_total_time()
            playlist.save(update_fields=["total_time"])
            return Response(status=status.HTTP_204_NO_CONTENT)

        serializer = AdminPodcastPlaylistItemSerializer(
            item,
            data={**request.data, "playlist": playlist.id},
            partial=True,
            context={"request": request},
        )
        serializer.is_valid(raise_exception=True)
        serializer.save()
        playlist.total_time = playlist.calculate_total_time()
        playlist.save(update_fields=["total_time"])
        return Response(serializer.data)

    @action(detail=True, methods=["post"], url_path="items/reorder")
    def reorder_items(self, request, pk=None):
        playlist = self.get_object()
        item_ids = request.data.get("item_ids", [])
        if not isinstance(item_ids, list):
            return Response({"detail": "item_ids must be a list."}, status=status.HTTP_400_BAD_REQUEST)

        items = list(playlist.playlist_items.filter(id__in=item_ids))
        if len(items) != len(item_ids):
            return Response({"detail": "Some items were not found."}, status=status.HTTP_400_BAD_REQUEST)

        item_map = {item.id: item for item in items}
        with transaction.atomic():
            for index, item_id in enumerate(item_ids, start=1):
                item = item_map[item_id]
                if item.priority != index:
                    item.priority = index
                    item.save(update_fields=["priority"])

        serializer = AdminPodcastPlaylistItemSerializer(
            playlist.playlist_items.select_related("podcast").order_by("priority", "id"),
            many=True,
            context={"request": request},
        )
        return Response(serializer.data)