# -*- coding: utf-8 -*-
"""FastAPI 应用工厂。

设计（strangler 迁移）：
- 已迁移的路由挂在 `/api/v1` 前缀下，与遗留 Flask 的同名路由（根路径）并存，
  便于逐端点比对响应契约（.zcode/refactor/parity.py）。
- `serve_flask_fallback=True` 时，把未迁移的遗留 Flask 应用整体挂到根路径兜底，
  实现「新端点走 FastAPI、其余走 Flask」的单进程双框架运行；迁移完成后删掉该开关。

注意（默认关闭的原因）：Flask fallback 会在 FastAPI 进程内 import main，
进而初始化 MusicAPIService / 打开 SQLite —— 与生产既有的 waitress 进程是
两套独立进程语义。生产切换前需按计划把状态与任务模型统一（见迁移计划阶段 C），
当前仅用于开发期联调。
"""

from contextlib import asynccontextmanager
from pathlib import Path

from fastapi import FastAPI
from fastapi.staticfiles import StaticFiles

from core.config import APP_VERSION
from core.security import init_secret_key
from web.errors import install_error_handlers
from web.middleware import ResponseHygieneMiddleware
from web.routers import account as account_router
from web.routers import admin as admin_router
from web.routers import auth as auth_router
from web.routers import auth_status as auth_status_router
from web.routers import delivery as delivery_router
from web.routers import index as index_router
from web.routers import music as music_router
from web.routers import podcast as podcast_router
from web.routers import site as site_router
from web.routers import stream as stream_router
from web.routers import system as system_router
from web.routers import tasks as tasks_router
from web.routers import user as user_router


@asynccontextmanager
async def _lifespan(app: FastAPI):
    """应用生命周期：关闭时释放 aiohttp 连接池（含按事件循环隔离的 session）。"""
    yield
    try:
        from core import aiohttp_compat, http_client

        await http_client.client.close()
        await aiohttp_compat.close()
    except Exception:
        pass


def _init_audio_secret() -> None:
    """注入音频签名密钥（与 Flask 同源，令两栈 token 互认）。"""
    try:
        import auth_system

        init_secret_key(auth_system.get_secret_key())
    except Exception:
        pass


def create_app(serve_flask_fallback: bool = False) -> FastAPI:
    """创建 FastAPI 应用。"""
    _init_audio_secret()

    app = FastAPI(
        title='云村小助手API服务',
        version=APP_VERSION,
        docs_url='/api/v1/docs',
        redoc_url=None,
        openapi_url='/api/v1/openapi.json',
        lifespan=_lifespan,
    )

    # 响应侧统一处理：安全头 + 音频直链签名保护 + 版本指纹抹除
    app.add_middleware(ResponseHygieneMiddleware)

    # 静态资源（/static/site_auth.js 等）——与 Flask static_folder 同目录
    _static_dir = Path(__file__).resolve().parent.parent / 'static'
    if _static_dir.is_dir():
        app.mount('/static', StaticFiles(directory=str(_static_dir)), name='static')

    # 已迁移路由：统一挂 /api/v1（迁移期与 Flask 根路径并存，便于对比）
    app.include_router(system_router.router, prefix='/api/v1', tags=['system'])
    app.include_router(site_router.router, prefix='/api/v1', tags=['site'])
    app.include_router(music_router.router, prefix='/api/v1', tags=['music'])
    app.include_router(account_router.router, prefix='/api/v1', tags=['account'])
    app.include_router(podcast_router.router, prefix='/api/v1', tags=['podcast'])
    app.include_router(tasks_router.router, prefix='/api/v1', tags=['tasks'])
    app.include_router(delivery_router.router, prefix='/api/v1', tags=['delivery'])
    app.include_router(stream_router.router, prefix='/api/v1', tags=['stream'])
    app.include_router(auth_status_router.router, prefix='/api/v1', tags=['auth'])
    app.include_router(auth_router.router, prefix='/api/v1', tags=['auth'])
    app.include_router(user_router.router, prefix='/api/v1', tags=['user'])
    app.include_router(admin_router.router, prefix='/api/v1', tags=['admin'])
    # 首页与静态资源（迁移完成形态；fallback 模式下同路径也能由 Flask 提供）
    app.include_router(index_router.router, tags=['index'])

    install_error_handlers(app)

    if serve_flask_fallback:
        _mount_flask_fallback(app)

    return app


def _mount_flask_fallback(app: FastAPI) -> None:
    """把遗留 Flask WSGI 应用挂到根路径，兜底未迁移的路由。"""
    from starlette.middleware.wsgi import WSGIMiddleware

    import main as legacy_flask

    app.mount('/', WSGIMiddleware(legacy_flask.app))