/**
 * Zulip Gateway Supervisor — external watchdog process.
 *
 * Monitors the router health endpoint every 30s. If 3 consecutive checks fail,
 * restarts the abiba-zulip PM2 process gracefully.
 *
 * This is the pattern Hermes uses: an external supervisor that can recover
 * the gateway even when the gateway process itself is hung (not just crashed).
 *
 * Deployed via PM2 as a separate process in ecosystem.config.cjs.
 */

const HEALTH_URL = "http://127.0.0.1:9200/health";
const CHECK_INTERVAL_MS = 30_000;
const MAX_FAILURES = 3;
const RESTART_GRACE_MS = 15_000;

let failures = 0;

async function check() {
  try {
    const res = await fetch(HEALTH_URL, {
      signal: AbortSignal.timeout(5000),
    });

    if (res.ok) {
      const data = await res.json();

      if (data.status === "ok" && data.zulip?.connected) {
        if (failures > 0) {
          console.log(`[watchdog] Router recovered after ${failures} failure(s)`);
        }
        failures = 0;
        // Silent health log every 10 checks (~5 min) for monitoring
        if (Math.random() < 0.1) {
          console.log(`[watchdog] Router healthy (uptime: ${Math.round(process.uptime())}s)`);
        }
        return;
      }

      // Connected but degraded
      console.warn(`[watchdog] Router degraded: status=${data.status}, connected=${data.zulip?.connected}`);
      failures++;
    } else {
      console.warn(`[watchdog] Health check returned ${res.status}`);
      failures++;
    }
  } catch (err) {
    failures++;
    console.warn(`[watchdog] Health check ${failures}/${MAX_FAILURES}: ${err.message}`);
  }

  if (failures >= MAX_FAILURES) {
    console.error(`[watchdog] ${MAX_FAILURES} consecutive failures — restarting abiba-zulip`);

    const { execSync } = await import("node:child_process");
    try {
      execSync("pm2 restart abiba-zulip", { timeout: 30000, encoding: "utf-8" });
      console.log("[watchdog] Restart command sent successfully");
    } catch (e) {
      console.error(`[watchdog] Restart failed: ${e.message}`);

      // Fallback: try resurrect if restart fails (process may be deleted)
      try {
        execSync("pm2 resurrect", { timeout: 30000 });
        console.log("[watchdog] PM2 resurrected (fallback)");
      } catch (e2) {
        console.error(`[watchdog] Resurrect also failed: ${e2.message}`);
      }
    }

    failures = 0;
    // Wait for restart to fully initialize before checking again
    await new Promise((r) => setTimeout(r, RESTART_GRACE_MS));
  }
}

console.log("[watchdog] Zulip gateway supervisor started");
console.log(`[watchdog] Monitoring ${HEALTH_URL} every ${CHECK_INTERVAL_MS / 1000}s`);
console.log(`[watchdog] Max failures before restart: ${MAX_FAILURES}`);

// Immediate first check, then periodic
check();
setInterval(check, CHECK_INTERVAL_MS);