// grafana's events. The tool runtime imports this once the broker is bound. It watches unified
// alerting and announces when an alert instance starts firing.
//
// Emits (novox/hq ADR 0041/0042):
//   module.grafana.alert.firing   — an alert instance entered the Alerting state
//
// A Grafana with no alerting configured simply never has a firing alert, so this observes nothing
// and emits nothing — no error, no noise.

import { emit } from "@novox/mesh-sdk/events";
import { GrafanaClient, type GrafanaAlert } from "./client.js";

// Constructed lazily so an unconfigured node (no auth) loads this entrypoint without crashing the
// events host — it simply watches nothing.
let grafana: GrafanaClient | undefined;
try {
  grafana = GrafanaClient.fromEnv();
} catch (err) {
  console.log(`[grafana] not configured, not watching alerts: ${err}`);
}

// Firing alerts, by diffing the set currently in the Alerting state. Primed silently on the first
// look so alerts already firing when this started are not announced as freshly firing.
const firing = new Set<string>();
let primed = false;

const alertKey = (a: GrafanaAlert): string =>
  `${a.name}:${Object.entries(a.labels).sort().map(([k, v]) => `${k}=${v}`).join(",")}`;

async function pollAlerts(client: GrafanaClient): Promise<void> {
  const now = new Set<string>();
  const byKey = new Map<string, GrafanaAlert>();
  for (const a of await client.listAlerts()) {
    if (a.state.toLowerCase() !== "alerting") continue;
    const key = alertKey(a);
    now.add(key);
    byKey.set(key, a);
  }
  if (primed) {
    for (const key of now) {
      if (!firing.has(key)) {
        const a = byKey.get(key)!;
        await emit("module.grafana.alert.firing", { name: a.name, labels: a.labels, activeAt: a.activeAt });
      }
    }
  }
  firing.clear();
  for (const key of now) firing.add(key);
  primed = true;
}

if (grafana) {
  const client = grafana;
  const run = (): void => void pollAlerts(client).catch((err) => console.error(`[grafana] ${err}`));
  setInterval(run, 30_000);
  run();
  console.log("[grafana] watching for firing alerts");
}