from fastapi import APIRouter, Depends
from sqlalchemy import func, select, text
from sqlalchemy.orm import Session

from app.config import get_settings
from app.database import get_db
from app.models import Event
from app.services.host_health import count_stale_hosts
from app.version import APP_NAME, APP_VERSION

router = APIRouter(tags=["health"])


def build_health_payload(db: Session) -> dict:
    db_status = "ok"
    try:
        db.execute(text("SELECT 1"))
    except Exception:
        db_status = "error"

    hosts_stale = 0
    last_event_received_at: str | None = None
    if db_status == "ok":
        settings = get_settings()
        hosts_stale = count_stale_hosts(db, settings.sac_heartbeat_stale_minutes)
        last_received = db.scalar(select(func.max(Event.received_at)))
        if last_received is not None:
            last_event_received_at = last_received.isoformat()

    overall = "ok" if db_status == "ok" else "degraded"
    if db_status == "ok" and hosts_stale > 0:
        overall = "degraded"

    return {
        "status": overall,
        "database": db_status,
        "service": "security-alert-center",
        "name": APP_NAME,
        "version": APP_VERSION,
        "hosts_stale": hosts_stale,
        "last_event_received_at": last_event_received_at,
    }


@router.get("/health")
def health(db: Session = Depends(get_db)) -> dict:
    return build_health_payload(db)


@router.get("/healthz")
def healthz(db: Session = Depends(get_db)) -> dict:
    """Kubernetes-style alias; same payload as /health."""
    return build_health_payload(db)