raspi_cam_arm/app/main.py

import logging
from contextlib import asynccontextmanager

from fastapi import FastAPI, Request
from fastapi.responses import FileResponse
from fastapi.staticfiles import StaticFiles

from app.api import api_router
from app.api.camera import capture_pair_via_mqtt
from app.services import CameraUnavailableError, get_camera_service
from app.core.config import settings

logging.basicConfig(level=logging.INFO)
logger = logging.getLogger(__name__)

settings.static.ensure_directories()


@asynccontextmanager
async def lifespan(_: FastAPI):
    """
    FastAPI 生命周期管理。

    启动阶段会尝试预热相机，这样第一次请求拍照时更快。
    但这里不会因为相机异常而阻止整个服务启动，
    因为有时你可能还需要先看接口文档、做健康检查或排查环境。
    """
    camera_service = get_camera_service()

    try:
        camera_service.initialize()
        logger.info("树莓派相机预热完成。")
    except CameraUnavailableError as exc:
        logger.warning("相机预热失败，拍照接口暂时不可用：%s", exc)

    try:
        yield
    finally:
        camera_service.close()
        logger.info("相机资源已关闭。")


app = FastAPI(
    title=settings.app.title,
    version=settings.app.version,
    description=settings.app.description,
    lifespan=lifespan,
)

app.include_router(api_router, prefix="/api")
app.mount("/static", StaticFiles(directory=str(settings.static.root_dir)), name="static")


@app.get("/", include_in_schema=False)
def read_root() -> FileResponse:
    return FileResponse(settings.static.index_path)


@app.api_route("/capture-pair", methods=["GET", "POST"], include_in_schema=False)
def capture_pair_alias(request: Request):
    return capture_pair_via_mqtt(request)


@app.get("/health", summary="健康检查")
def health_check() -> dict[str, object]:
    """
    健康检查接口。

    这个接口不强依赖相机真实可用，只返回服务当前状态和相机是否已初始化。
    在部署脚本、容器探针或反向代理检查中都比较实用。
    """
    camera_service = get_camera_service()

    return {
        "status": "ok",
        "camera_initialized": camera_service.is_initialized,
        "app_name": settings.app.title,
        "app_version": settings.app.version,
    }