"""AI Knowledge Link — FastAPI 应用工厂。

Phase 1-3: 配置校验、日志、异常处理器、健康检查、lifespan 资源管理、认证路由。
后续 Phase 逐步挂载：knowledge-bases、documents、public /k/ 路由。
"""

from contextlib import asynccontextmanager
from pathlib import Path

from fastapi import FastAPI
from fastapi.middleware.cors import CORSMiddleware

from app.api.auth import router as auth_router
from app.api.categories import router as cat_router
from app.api.documents import router as doc_router
from app.api.health import router as health_router
from app.api.knowledge_bases import router as kb_router
from app.api.recycle_bin import router as recycle_router
from app.public.routes import router as public_router
from app.core.config import get_settings
from app.core.db import dispose_engine, get_session_factory
from app.core.errors import LinkExpiredError, register_exception_handlers
from app.core.logging import get_logger, setup_logging

logger = get_logger(__name__)


def _seed_free_plan() -> None:
    """启动时确保 free plan 存在（幂等）。"""
    from app.repositories.plan_repo import PlanRepository

    factory = get_session_factory()
    with factory() as session:
        repo = PlanRepository(session)
        plan = repo.get_by_code("free")
        if plan is None:
            repo.get_or_create_free()
            session.commit()
            logger.info("Seeded free plan (100MB / 20MB-per-file)")
        else:
            logger.debug("Free plan already exists (id=%s)", plan.id)


def _cleanup_access_logs() -> int:
    """清理超过保留期的访问日志。返回删除条数。"""
    from datetime import datetime, timedelta

    from sqlalchemy import delete

    from app.core.config import get_settings
    from app.models.access_log import AccessLog

    settings = get_settings()
    retention = settings.access_log_retention_days
    if retention <= 0:
        return 0

    cutoff = (datetime.now() - timedelta(days=retention)).strftime("%Y-%m-%d %H:%M:%S")
    factory = get_session_factory()
    with factory() as session:
        result = session.execute(delete(AccessLog).where(AccessLog.accessed_at < cutoff))
        session.commit()
        count = result.rowcount or 0
        if count:
            logger.info("已清理 %d 条过期访问日志（保留 %d 天）", count, retention)
        return count


async def _periodic_cleanup() -> None:
    """每小时执行一次数据清理：访问日志 + 回收站过期内容。"""
    import asyncio

    while True:
        await asyncio.sleep(3600)
        try:
            await asyncio.to_thread(_cleanup_access_logs)
        except Exception:  # noqa: BLE001
            logger.exception("定期清理访问日志失败")
        try:
            await asyncio.to_thread(_purge_recycle_bin)
        except Exception:  # noqa: BLE001
            logger.exception("定期清理回收站失败")


def _purge_recycle_bin() -> int:
    """彻底删除回收站中超过保留期的内容。"""
    from app.services.recycle_bin_service import RecycleBinService

    factory = get_session_factory()
    with factory() as session:
        return RecycleBinService(session).purge_expired()


@asynccontextmanager
async def lifespan(app: FastAPI):
    settings = get_settings()
    setup_logging()

    # 确保 data 目录存在
    data_dir = settings.storage_root_path
    data_dir.mkdir(parents=True, exist_ok=True)
    logger.info("Starting backend (env=%s, data=%s)", settings.environment, data_dir)

    # Seed：确保 free plan 存在
    _seed_free_plan()

    # 启动时清理过期数据：访问日志 + 回收站（不阻塞启动）
    import asyncio

    cleanup_task = asyncio.create_task(_periodic_cleanup())
    try:
        await asyncio.wait_for(asyncio.to_thread(_cleanup_access_logs), timeout=15)
    except Exception:  # noqa: BLE001
        logger.warning("启动时清理访问日志未完成（首次部署属正常）")
    try:
        await asyncio.wait_for(asyncio.to_thread(_purge_recycle_bin), timeout=15)
    except Exception:  # noqa: BLE001
        logger.warning("启动时清理回收站未完成（首次部署属正常）")

    yield

    cleanup_task.cancel()
    dispose_engine()
    logger.info("Backend shutdown complete")


def create_app() -> FastAPI:
    settings = get_settings()
    app = FastAPI(
        title="AI Knowledge Link",
        version="0.1.0",
        lifespan=lifespan,
        docs_url="/api/docs" if not settings.is_production else None,
        openapi_url="/api/openapi.json" if not settings.is_production else None,
    )

    # CORS（开发期允许 Vite dev server）
    app.add_middleware(
        CORSMiddleware,
        allow_origins=[settings.frontend_origin],
        allow_credentials=True,
        allow_methods=["GET", "POST", "PUT", "PATCH", "DELETE", "OPTIONS"],
        allow_headers=["Content-Type", "X-Requested-With"],
    )

    register_exception_handlers(app)

    # 链接过期：HTML 返回友好失效页，JSON/MD/TXT 返回对应格式（HTTP 410）
    from app.public.routes import link_expired_handler

    app.add_exception_handler(LinkExpiredError, link_expired_handler)

    # 路由挂载
    app.include_router(health_router, prefix="/api", tags=["health"])
    app.include_router(auth_router, prefix="/api", tags=["auth"])
    app.include_router(kb_router, prefix="/api", tags=["knowledge-bases"])
    app.include_router(doc_router, prefix="/api", tags=["documents"])
    app.include_router(cat_router, prefix="/api", tags=["categories"])
    app.include_router(recycle_router, prefix="/api", tags=["recycle-bin"])
    app.include_router(public_router, tags=["public"])

    return app


app = create_app()