nas-tools/dashboard/frontend/src/lib/opc-ws.js

/**
 * OPC WebSocket Client - Real-time updates
 */

import { getToken } from "./api.js";

let ws = null;
let reconnectTimer = null;
let listeners = new Set();

export function connect() {
  if (ws && ws.readyState === WebSocket.OPEN) {
    return;
  }

  const protocol = window.location.protocol === "https:" ? "wss:" : "ws:";
  const token = getToken();
  const tokenParam = token ? `?token=${encodeURIComponent(token)}` : "";
  const wsUrl = `${protocol}//${window.location.host}/ws/opc${tokenParam}`;

  ws = new WebSocket(wsUrl);

  ws.onopen = () => {
    console.log("OPC WebSocket connected");
    if (reconnectTimer) {
      clearTimeout(reconnectTimer);
      reconnectTimer = null;
    }

    // Send ping every 30 seconds to keep connection alive
    const pingInterval = setInterval(() => {
      if (ws && ws.readyState === WebSocket.OPEN) {
        ws.send("ping");
      } else {
        clearInterval(pingInterval);
      }
    }, 30000);
  };

  ws.onmessage = (event) => {
    try {
      const message = JSON.parse(event.data);
      notifyListeners(message);
    } catch (e) {
      console.error("Failed to parse WebSocket message:", e);
    }
  };

  ws.onerror = (error) => {
    console.error("WebSocket error:", error);
  };

  ws.onclose = () => {
    console.log("OPC WebSocket disconnected");
    ws = null;

    // Reconnect after 5 seconds
    reconnectTimer = setTimeout(() => {
      console.log("Reconnecting WebSocket...");
      connect();
    }, 5000);
  };
}

export function disconnect() {
  if (ws) {
    ws.close();
    ws = null;
  }
  if (reconnectTimer) {
    clearTimeout(reconnectTimer);
    reconnectTimer = null;
  }
}

export function subscribe(callback) {
  listeners.add(callback);
  return () => listeners.delete(callback);
}

function notifyListeners(message) {
  listeners.forEach((callback) => {
    try {
      callback(message);
    } catch (e) {
      console.error("Listener error:", e);
    }
  });
}