"""GET /health -- passive health-check endpoint.

Returns a structured snapshot covering service health (process, cycle lag,
queue state) and data health (last compare result, drift traces, dead rows).

HTTP status follows the body's ``status`` field so off-the-shelf monitors that
alert on status code work without parsing JSON:

* ``200`` -- healthy
* ``503`` -- degraded or unhealthy

This keeps "service unreachable" (network/down) distinguishable from "service
up but needs attention" (200 would conflate them).
"""
from __future__ import annotations

from fastapi import APIRouter, Depends, Response

from ..deps import get_checker
from ...health import HealthChecker

router = APIRouter()


@router.get("/health", summary="Sync service health check")
def health(response: Response, checker: HealthChecker = Depends(get_checker)) -> dict:
    snap = checker.snapshot()
    # Map body status to HTTP code for code-based alerting.
    if snap["status"] != "healthy":
        response.status_code = 503
    return snap