let CONFIG = {
  endpoints: ["http://1.1.1.1", "http://8.8.8.8"],
  numberOfFails: 3,
  httpTimeout: 10,
  toggleTime: 30,                                // Power off duration for modem
  pingTime: 60,                                  // Base ping interval (in seconds)
  jitterRange: 15,                               // ±15s jitter to avoid sync
  rebootCooldown: 15 * 60 * 1000                 // 15 min cooldown between reboots
};

let endpointIdx = 0;
let failCounter = 0;
let pingTimer = null;
let lastRebootTime = 0;

function jitteredPingLoop() {
  let jitter = Math.floor(Math.random() * (2 * CONFIG.jitterRange + 1)) - CONFIG.jitterRange;
  let delay = (CONFIG.pingTime + jitter) * 1000;
  pingTimer = Timer.set(delay, false, pingEndpoints);
}

function pingEndpoints() {
  Shelly.call(
    "http.get",
    { url: CONFIG.endpoints[endpointIdx], timeout: CONFIG.httpTimeout },
    function (response, error_code, error_message) {
      if (error_code === -114 || error_code === -104 || !response || response.code !== 200) {
        print("Modem: Ping failed to", CONFIG.endpoints[endpointIdx]);
        failCounter++;
        endpointIdx = (endpointIdx + 1) % CONFIG.endpoints.length;
      } else {
        failCounter = 0;
      }

      if (failCounter >= CONFIG.numberOfFails) {
        let now = Date.now();
        if ((now - lastRebootTime) > CONFIG.rebootCooldown) {
          print("Modem: Too many failures, rebooting...");
          lastRebootTime = now;
          Timer.clear(pingTimer);
          Shelly.call("Switch.Set", { id: 0, on: false, toggle_after: CONFIG.toggleTime }, function () {});
          return;
        } else {
          print("Modem: Skipping reboot (cooldown active)");
      }

      jitteredPingLoop();
    }
  );
}

print("Modem watchdog started");
jitteredPingLoop();

Shelly.addStatusHandler(function (status) {
  if (status.name !== "switch" || status.id !== 0) return;
  if (typeof status.delta.source === "undefined" || status.delta.source !== "timer") return;
  if (status.delta.output !== true) return;

  print("Modem: Power restored. Waiting 120s before resuming ping checks...");
  Timer.set(120 * 1000, false, jitteredPingLoop);  // Delay restart to allow modem to boot
});