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

from apps.books.models import Book, Chapter, ReadingProgress
from apps.books.serializers import (
    BookListSerializer,
    BookSerializer,
    ChapterDetailSerializer,
    ChapterSummarySerializer,
    ReadingProgressSerializer,
)


class BookViewSet(viewsets.ModelViewSet):
    """CRUD for books. Includes nested chapter and progress endpoints."""

    queryset = Book.objects.all().prefetch_related("chapters")
    permission_classes = [IsAuthenticated]
    filter_backends = [DjangoFilterBackend, SearchFilter, OrderingFilter]
    filterset_fields = ["author"]
    search_fields = ["title", "author"]
    ordering_fields = ["title", "author", "created_at"]
    ordering = ["title"]

    def get_serializer_class(self):
        if self.action == "list":
            return BookListSerializer
        return BookSerializer

    @action(detail=True, methods=["get"])
    def chapters(self, request: Request, pk: int | None = None) -> Response:
        """List all chapters for this book (TOC)."""
        book = self.get_object()
        chapters = book.chapters.all().order_by("number")
        serializer = ChapterSummarySerializer(chapters, many=True)
        return Response(serializer.data)

    @action(detail=True, methods=["get"], url_path="chapters/(?P<chapter_number>[0-9]+)")
    def chapter_detail(
        self, request: Request, pk: int | None = None, chapter_number: str | None = None
    ) -> Response:
        """Get a specific chapter with full content."""
        book = self.get_object()
        try:
            chapter = book.chapters.get(number=int(chapter_number))
        except Chapter.DoesNotExist:
            return Response(
                {"detail": "Chapter not found."}, status=status.HTTP_404_NOT_FOUND
            )
        serializer = ChapterDetailSerializer(chapter)
        return Response(serializer.data)

    @action(detail=True, methods=["get", "put"])
    def progress(self, request: Request, pk: int | None = None) -> Response:
        """Get or update reading progress for this book."""
        book = self.get_object()
        progress, created = ReadingProgress.objects.get_or_create(
            user=request.user, book=book
        )

        if request.method == "GET":
            serializer = ReadingProgressSerializer(progress)
            return Response(serializer.data)

        serializer = ReadingProgressSerializer(
            progress, data=request.data, partial=True
        )
        serializer.is_valid(raise_exception=True)
        serializer.save()
        return Response(serializer.data, status=status.HTTP_200_OK)