How to Build Real-Time Lottery Draw Notifications & Webhooks

{
  "event": "draw.results.published",
  "event_id": "evt_powerball_20260801_9911",
  "timestamp": "2026-08-01T23:05:12Z",
  "data": {
    "game_id": "powerball",
    "game_name": "Powerball",
    "draw_date": "2026-08-01",
    "winning_numbers": [12, 34, 45, 56, 67],
    "powerball": 10,
    "multiplier": "2x",
    "estimated_jackpot": "$1,200,000,000",
    "next_draw_date": "2026-08-03",
    "next_jackpot_estimate": "$1,350,000,000"
  }
}

const express = require("express");
const crypto = require("crypto");
const fetch = require("node-fetch");

const app = express();
// Note: Use raw body buffer for signature calculation
app.use(express.json({
  verify: (req, res, buf) => {
    req.rawBody = buf;
  }
}));

const WEBHOOK_SECRET = process.env.LOTTERY_WEBHOOK_SECRET;
const TELEGRAM_BOT_TOKEN = process.env.TELEGRAM_BOT_TOKEN;
const TELEGRAM_CHAT_ID = process.env.TELEGRAM_CHAT_ID;
const DISCORD_WEBHOOK_URL = process.env.DISCORD_WEBHOOK_URL;

// Helper: Verify HMAC-SHA256 signature
function verifySignature(req) {
  const signature = req.headers["x-lottery-signature"];
  if (!signature || !WEBHOOK_SECRET) return false;

  const expectedSignature = crypto
    .createHmac("sha256", WEBHOOK_SECRET)
    .update(req.rawBody)
    .digest("hex");

  return crypto.timingSafeEqual(
    Buffer.from(signature),
    Buffer.from(expectedSignature)
  );
}

// Push to Telegram Channel
async function sendTelegramAlert(data) {
  if (!TELEGRAM_BOT_TOKEN || !TELEGRAM_CHAT_ID) return;

  const message = `🚨 *NEW ${data.game_name.toUpperCase()} DRAW RESULT* 🚨\n\n` +
    `📅 *Draw Date:* ${data.draw_date}\n` +
    `🎱 *Numbers:* ${data.winning_numbers.join(", ")}\n` +
    `🔴 *Powerball:* ${data.powerball}\n` +
    `⚡ *Multiplier:* ${data.multiplier}\n` +
    `💰 *Jackpot:* ${data.estimated_jackpot}\n\n` +
    `➡️ *Next Jackpot:* ${data.next_jackpot_estimate} (${data.next_draw_date})`;

  await fetch(`https://api.telegram.org/bot${TELEGRAM_BOT_TOKEN}/sendMessage`, {
    method: "POST",
    headers: { "Content-Type": "application/json" },
    body: JSON.stringify({
      chat_id: TELEGRAM_CHAT_ID,
      text: message,
      parse_mode: "Markdown",
    }),
  });
}

// Push to Discord Channel
async function sendDiscordAlert(data) {
  if (!DISCORD_WEBHOOK_URL) return;

  const payload = {
    embeds: [
      {
        title: `🎉 ${data.game_name} Winning Numbers Released!`,
        color: 65535, // Neon Cyan
        fields: [
          { name: "Draw Date", value: data.draw_date, inline: true },
          { name: "Winning Numbers", value: data.winning_numbers.join(" - "), inline: false },
          { name: "Bonus Ball", value: String(data.powerball), inline: true },
          { name: "Multiplier", value: data.multiplier, inline: true },
          { name: "Current Jackpot", value: data.estimated_jackpot, inline: true },
        ],
        footer: { text: "Powered by US Lottery API" },
        timestamp: new Date().toISOString(),
      },
    ],
  };

  await fetch(DISCORD_WEBHOOK_URL, {
    method: "POST",
    headers: { "Content-Type": "application/json" },
    body: JSON.stringify(payload),
  });
}

// Webhook HTTP Receiver Route
app.post("/api/webhooks/lottery", async (req, res) => {
  if (!verifySignature(req)) {
    console.warn("Unauthorized webhook attempt - HMAC signature mismatch!");
    return res.status(401).json({ status: "error", message: "Invalid signature" });
  }

  const { event, data } = req.body;
  console.log(`Received Webhook Event: ${event} for ${data.game_name}`);

  if (event === "draw.results.published") {
    // Send alerts concurrently
    await Promise.allSettled([
      sendTelegramAlert(data),
      sendDiscordAlert(data)
    ]);
  }

  // Always respond 200 OK within 5 seconds to acknowledge receipt
  return res.status(200).json({ status: "success", message: "Event processed" });
});

app.listen(3000, () => console.log("Webhook receiver listening on port 3000"));