最佳實踐

const WebSocket = require("ws");

const apiKey = process.env.TICKDB_API_KEY;
const universe = process.env.TICKDB_UNIVERSE;
if (!apiKey) throw new Error("Set TICKDB_API_KEY first");
if (universe && !["CN_Stock", "HK_Stock", "US_Stock"].includes(universe)) {
  throw new Error("Invalid TICKDB_UNIVERSE");
}

let attempts = 0;
let stopped = false;
const RECONNECT_STAGES = new Map([
  [1_000, 3],        // 等待 1 秒，最多 3 次
  [5_000, 3],        // 等待 5 秒，最多 3 次
  [30_000, Infinity] // 此後每次等待 30 秒
]);

function reconnectDelay(attempt) {
  for (const [delayMs, count] of RECONNECT_STAGES) {
    if (attempt <= count) return delayMs;
    attempt -= count;
  }
}

function connect() {
  const url = new URL("wss://api.tickdb.ai/v1/realtime");
  url.searchParams.set("api_key", apiKey);
  const ws = new WebSocket(url, { perMessageDeflate: true });
  let heartbeat;
  let pongTimeout;

  ws.on("unexpected-response", (_request, response) => {
    if ([401, 403].includes(response.statusCode)) stopped = true;
    console.error("WebSocket handshake failed:", response.statusCode);
    response.resume();
    ws.terminate();
  });

  ws.on("open", () => {
    attempts = 0;
    if (universe && !ws.extensions.includes("permessage-deflate")) {
      stopped = true;
      console.error("Full-market subscriptions require permessage-deflate");
      ws.close();
      return;
    }

    const subscription = universe
      ? { cmd: "subscribe", data: { universes: [universe], channels: ["ticker"] } }
      : { cmd: "subscribe", data: { channel: "ticker", symbols: ["BTCUSDT"] } };
    ws.send(JSON.stringify(subscription)); // 每次重連後重新訂閱

    heartbeat = setInterval(() => {
      if (ws.readyState !== WebSocket.OPEN || pongTimeout) return;
      ws.send(JSON.stringify({ cmd: "ping" }));
      pongTimeout = setTimeout(() => ws.terminate(), 20_000);
    }, 60_000);
  });

  ws.on("message", (raw) => {
    let message;
    try { message = JSON.parse(raw.toString()); }
    catch { return; }

    for (const item of Array.isArray(message) ? message : [message]) {
      if (item.cmd === "pong") {
        clearTimeout(pongTimeout);
        pongTimeout = undefined;
      } else if (item.cmd === "ticker") {
        console.log(item.data.symbol, item.data.last_price);
      } else if (item.cmd === "error") {
        console.error("Subscription error:", item.code, item.message);
        if (["2008", "4005"].includes(String(item.code))) {
          stopped = true;
          ws.close();
        }
      }
    }
  });

  ws.on("error", (error) => console.error("WebSocket error:", error.message));
  ws.on("close", () => {
    clearInterval(heartbeat);
    clearTimeout(pongTimeout);
    if (stopped) return;

    setTimeout(connect, reconnectDelay(++attempts));
  });
}

connect();