"""Health check router.

A lightweight ``GET /api/health`` endpoint that verifies the application
is running and can serve requests.  Also reports the cached fail2ban liveness
state so monitoring tools and Docker health checks can observe daemon status
without probing the socket directly.
"""

from fastapi import APIRouter, status
from fastapi.responses import JSONResponse

from app.dependencies import ServerStatusDep

router: APIRouter = APIRouter(prefix="/api/v1/health", tags=["Health"])


@router.get("", summary="Application health check")
async def health_check(server_status: ServerStatusDep) -> JSONResponse:
    """Return application and fail2ban status.

    Returns HTTP 200 if fail2ban is online, HTTP 503 if offline.
    Docker health checks interpret 503 as unhealthy and restart the container
    if fail2ban remains unreachable, ensuring the backend only runs when
    fail2ban is available.

    Args:
        server_status: Injected cached server status snapshot.

    Returns:
        HTTP 200 with ``{"status": "ok", "fail2ban": "online"}`` if healthy,
        or HTTP 503 with ``{"status": "unavailable", "fail2ban": "offline"}``
        if fail2ban is unreachable.
    """
    if not server_status.online:
        return JSONResponse(
            status_code=status.HTTP_503_SERVICE_UNAVAILABLE,
            content={"status": "unavailable", "fail2ban": "offline"},
        )

    return JSONResponse(
        status_code=status.HTTP_200_OK,
        content={"status": "ok", "fail2ban": "online"},
    )