"""FastAPI 入口。"""

from __future__ import annotations

from contextlib import asynccontextmanager
from typing import Any

from fastapi import FastAPI, Request
from fastapi.exceptions import RequestValidationError
from fastapi.middleware.cors import CORSMiddleware
from fastapi.responses import JSONResponse
from sqlalchemy import text
from starlette.exceptions import HTTPException as StarletteHTTPException

from .api import auth, items, knowledge, tickets, workspaces
from .config import get_settings
from .db import SessionFactory, current_app_role, engine
from .errors import AppError, ErrorCode, http_status_for
from .logging_setup import get_logger, request_id_ctx, setup_logging
from .middleware import IdempotencyMiddleware, RequestContextMiddleware, error_body

settings = get_settings()
setup_logging("DEBUG" if settings.env == "dev" else "INFO")
logger = get_logger("app")


@asynccontextmanager
async def lifespan(app: FastAPI):
    settings.validate_runtime()
    logger.info(
        "服务启动",
        extra={"extra_fields": {"env": settings.env, "commit": settings.build_commit}},
    )
    yield
    await engine.dispose()


app = FastAPI(
    title=f"{settings.app_name} API",
    version="0.1.0",
    description="达道Task —— 任务 / 工单 / 知识库，一条流。",
    lifespan=lifespan,
    docs_url="/docs" if settings.env != "prod" else None,
    redoc_url=None,
)

app.add_middleware(
    CORSMiddleware,
    allow_origins=settings.cors_origins,
    allow_credentials=True,
    allow_methods=["*"],
    allow_headers=["*"],
    expose_headers=["X-Request-Id", "X-Idempotent-Replay"],
)
# 后加的中间件先执行：RequestContext 必须最外层
app.add_middleware(IdempotencyMiddleware)
app.add_middleware(RequestContextMiddleware)


# ── 异常处理：对外永远是 {code, message, data, request_id} ──
@app.exception_handler(AppError)
async def handle_app_error(request: Request, exc: AppError) -> JSONResponse:
    return JSONResponse(
        status_code=exc.http_status,
        content=error_body(request_id_ctx.get(), exc.code, exc.message, exc.details),
    )


@app.exception_handler(RequestValidationError)
async def handle_validation(request: Request, exc: RequestValidationError) -> JSONResponse:
    details: list[dict[str, Any]] = [
        {"field": ".".join(str(p) for p in err["loc"][1:]), "msg": err["msg"]}
        for err in exc.errors()
    ]
    return JSONResponse(
        status_code=422,
        content=error_body(
            request_id_ctx.get(), ErrorCode.VALIDATION_FAILED, "参数校验失败", details
        ),
    )


@app.exception_handler(StarletteHTTPException)
async def handle_http(request: Request, exc: StarletteHTTPException) -> JSONResponse:
    code = ErrorCode.NOT_FOUND if exc.status_code == 404 else ErrorCode.BAD_REQUEST
    return JSONResponse(
        status_code=exc.status_code,
        content=error_body(request_id_ctx.get(), code, str(exc.detail)),
    )


@app.exception_handler(Exception)
async def handle_unexpected(request: Request, exc: Exception) -> JSONResponse:
    logger.exception("未处理异常")
    return JSONResponse(
        status_code=http_status_for(ErrorCode.INTERNAL),
        content=error_body(request_id_ctx.get(), ErrorCode.INTERNAL, "服务器内部错误"),
    )


app.include_router(auth.router, prefix=settings.api_prefix)
app.include_router(workspaces.router, prefix=settings.api_prefix)
app.include_router(items.router, prefix=settings.api_prefix)
app.include_router(items.tag_router, prefix=settings.api_prefix)
app.include_router(tickets.router, prefix=settings.api_prefix)
app.include_router(tickets.notify_router, prefix=settings.api_prefix)
app.include_router(knowledge.router, prefix=settings.api_prefix)


@app.get("/health", tags=["运维"], summary="存活探针")
async def health() -> dict:
    db_ok = True
    try:
        async with SessionFactory() as session:
            await session.execute(text("SELECT 1"))
    except Exception:  # noqa: BLE001
        logger.exception("数据库探活失败")
        db_ok = False
    return {"status": "ok" if db_ok else "degraded", "db": db_ok, "env": settings.env}


@app.get("/version", tags=["运维"], summary="构建标记")
async def version() -> dict:
    """部署后必须校验：commit 必须等于 git rev-parse --short HEAD。"""
    role = None
    try:
        async with SessionFactory() as session:
            role = await current_app_role(session)
    except Exception:  # noqa: BLE001
        logger.warning("读取数据库角色失败")

    return {
        "app": settings.app_name,
        "env": settings.env,
        "commit": settings.build_commit,
        "build_time": settings.build_time,
        "api_prefix": settings.api_prefix,
        "db_role": role,
    }