"""
故事模块视图 - App端
"""
from django.db.models import Count
from rest_framework import viewsets
from rest_framework.decorators import action
from rest_framework.permissions import IsAuthenticated
from drf_spectacular.utils import extend_schema

from utils.response import success, error
from utils.exceptions import ErrorCode
from apps.admins.authentication import AppJWTAuthentication
from .models import StoryShelf, Story
from .serializers import (
    StoryShelfSerializer,
    CreateShelfSerializer,
    StoryListSerializer,
    GenerateStorySerializer,
)


@extend_schema(tags=['故事'])
class StoryViewSet(viewsets.ViewSet):
    """故事视图集（App端）"""

    authentication_classes = [AppJWTAuthentication]
    permission_classes = [IsAuthenticated]

    def list(self, request):
        """
        获取故事列表
        GET /api/v1/stories/?shelf_id=1&page=1&page_size=20
        """
        queryset = Story.objects.filter(user=request.user)

        shelf_id = request.query_params.get('shelf_id')
        if shelf_id:
            queryset = queryset.filter(shelf_id=shelf_id)

        # 分页
        page = int(request.query_params.get('page', 1))
        page_size = int(request.query_params.get('page_size', 20))
        start = (page - 1) * page_size
        total = queryset.count()
        items = queryset[start:start + page_size]

        return success(data={
            'total': total,
            'items': StoryListSerializer(items, many=True).data,
        })

    def destroy(self, request, pk=None):
        """
        删除故事
        DELETE /api/v1/stories/{id}/
        """
        try:
            story = Story.objects.get(id=pk, user=request.user)
        except Story.DoesNotExist:
            return error(code=ErrorCode.STORY_NOT_FOUND, message='故事不存在')
        story.delete()
        return success(message='删除成功')

    @action(detail=False, methods=['post'], url_path='generate')
    def generate(self, request):
        """
        生成故事 (SSE 流式 - 占位)
        POST /api/v1/stories/generate/
        """
        serializer = GenerateStorySerializer(data=request.data)
        if not serializer.is_valid():
            return error(message=str(serializer.errors))

        # TODO: 接入 LLM API 实现 SSE 流式生成
        shelf_id = serializer.validated_data.get('shelf_id')
        shelf = None
        if shelf_id:
            try:
                shelf = StoryShelf.objects.get(id=shelf_id, user=request.user)
            except StoryShelf.DoesNotExist:
                return error(code=ErrorCode.SHELF_NOT_FOUND, message='书架不存在')

        story = Story.objects.create(
            user=request.user,
            shelf=shelf,
            title='生成中...',
            content='',
            generation_mode=serializer.validated_data.get('mode', 'random'),
            prompt=serializer.validated_data.get('prompt', ''),
        )

        return success(data={
            'id': story.id,
            'message': '故事生成功能待接入 LLM API',
        })


@extend_schema(tags=['故事'])
class ShelfViewSet(viewsets.ViewSet):
    """书架视图集（App端）"""

    authentication_classes = [AppJWTAuthentication]
    permission_classes = [IsAuthenticated]

    def list(self, request):
        """
        书架列表
        GET /api/v1/stories/shelves/
        """
        shelves = StoryShelf.objects.filter(
            user=request.user
        ).annotate(story_count=Count('stories'))
        return success(data=StoryShelfSerializer(shelves, many=True).data)

    def create(self, request):
        """
        创建书架
        POST /api/v1/stories/shelves/
        """
        serializer = CreateShelfSerializer(data=request.data)
        if not serializer.is_valid():
            return error(message=str(serializer.errors))

        shelf = StoryShelf.objects.create(
            user=request.user,
            name=serializer.validated_data['name'],
        )
        return success(data=StoryShelfSerializer(shelf).data, message='创建成功')

    def destroy(self, request, pk=None):
        """
        删除书架（故事保留，shelf_id 置 null）
        DELETE /api/v1/stories/shelves/{id}/
        """
        try:
            shelf = StoryShelf.objects.get(id=pk, user=request.user)
        except StoryShelf.DoesNotExist:
            return error(code=ErrorCode.SHELF_NOT_FOUND, message='书架不存在')

        Story.objects.filter(shelf=shelf).update(shelf=None)
        shelf.delete()
        return success(message='删除成功')