app/main.py

from contextlib import asynccontextmanager
import asyncio
from typing import Any, Dict

from fastapi.responses import JSONResponse

from fastapi import FastAPI

from app.api.routes import router as api_router
from app.core.openai_client import openai_client
from app.db.mongo import close_mongo_connection, connect_to_mongo, get_client


@asynccontextmanager
async def lifespan(_: FastAPI):
    await connect_to_mongo()
    try:
        yield
    finally:
        await close_mongo_connection()


app = FastAPI(
    title="Auto Categorizer API",
    version="1.0.0",
    lifespan=lifespan,
)

app.include_router(api_router, prefix="/api/v1")


@app.get("/health", tags=["Health"])
async def health_check() -> JSONResponse | Dict[str, Any]:
    checks: Dict[str, bool] = {"mongo": False, "openai": False}
    errors: Dict[str, str] = {}

    # Run checks with conservative timeouts to avoid hanging the health endpoint.
    mongo_ok, mongo_err = await _run_check(_check_mongo)
    checks["mongo"] = mongo_ok
    if mongo_err:
        errors["mongo"] = mongo_err

    openai_ok, openai_err = await _run_check(_check_openai)
    checks["openai"] = openai_ok
    if openai_err:
        errors["openai"] = openai_err

    if errors:
        return JSONResponse(status_code=503, content={"status": "unhealthy", "checks": checks, "errors": errors})

    return {"status": "healthy", "checks": checks}


async def _run_check(fn, timeout: float = 5.0) -> tuple[bool, str | None]:
    try:
        await asyncio.wait_for(fn(), timeout=timeout)
        return True, None
    except Exception as exc:  # pragma: no cover - defensive
        return False, str(exc)


async def _check_mongo() -> None:
    await connect_to_mongo()
    client = get_client()
    await client.admin.command("ping")


async def _check_openai() -> None:
    await openai_client.models.list()