"""Liveness, readiness and metrics. Mounted at the root, outside ``/api/v1``.

``/healthz`` must never touch a dependency: if it did, a slow database would
make the orchestrator kill healthy processes. ``/readyz`` is the one that checks
dependencies, because a process that cannot reach PostgreSQL should be taken out
of the load-balancer rotation but not restarted.
"""

from __future__ import annotations

from fastapi import APIRouter, Response
from prometheus_client import CONTENT_TYPE_LATEST, generate_latest
from sqlalchemy import text

from packages.shared.config import get_settings
from packages.shared.db import get_session_factory
from packages.shared.errors import AppError, ErrorCode
from packages.shared.logging import get_logger
from packages.shared.observability import REGISTRY
from packages.shared.redis_client import get_redis
from packages.shared.response import ok

router = APIRouter(tags=["ops"])
logger = get_logger(__name__)


@router.get("/healthz", summary="Liveness probe")
async def healthz() -> dict[str, object]:
    settings = get_settings()
    return ok({"status": "ok", "app": settings.app_name, "env": settings.app_env})


@router.get("/readyz", summary="Readiness probe (checks PostgreSQL and Redis)")
async def readyz() -> dict[str, object]:
    checks: dict[str, str] = {}

    try:
        factory = get_session_factory()
        async with factory() as session:
            await session.execute(text("SELECT 1"))
        checks["postgres"] = "ok"
    except Exception as exc:
        checks["postgres"] = f"error: {type(exc).__name__}"

    try:
        await get_redis().ping()
        checks["redis"] = "ok"
    except Exception as exc:
        checks["redis"] = f"error: {type(exc).__name__}"

    if any(v != "ok" for v in checks.values()):
        logger.warning("readiness_failed", checks=checks)
        raise AppError(ErrorCode.UPSTREAM_ERROR, message="依赖未就绪", data={"checks": checks})
    return ok({"status": "ready", "checks": checks})


@router.get("/metrics", summary="Prometheus scrape endpoint", include_in_schema=False)
async def metrics() -> Response:
    return Response(content=generate_latest(REGISTRY), media_type=CONTENT_TYPE_LATEST)