0Pools webhooks

{
  "eventId": "5f2c1b9a4d3e6f7081a2b3c4d5e6f70812a3b4c5d6e7f8091a2b3c4d5e6f7081",
  "type": "pool.transaction.settled",
  "txnId": "txn_3xampl3000000000000",
  "partnerId": "ptnr_3xampl3000000",
  "poolId": "pool_3xampl3000000",
  "side": "on_ramp",
  "status": "settled",
  "fiatAmount": "100.00",
  "cryptoAmount": "99.40",
  "quotedRate": "0.9940",
  "feeBps": 30,
  "spreadBps": 25,
  "engineFillTxId": "fill_3xampl3000000",
  "settledAt": "2026-06-28T12:00:05Z",
  "createdAt": "2026-06-28T12:00:05Z"
}

import crypto from 'node:crypto';

function verifyPoolsWebhook(input: {
  rawBody: string;
  signature: string; // the Gate-Signature header value
  secret: string;
  skewSeconds?: number;
}) {
  const skewSeconds = input.skewSeconds ?? 300;
  const parts = Object.fromEntries(
    input.signature.split(',').map((part) => {
      const [key, value] = part.split('=');
      return [key, value];
    }),
  );

  const timestamp = Number(parts.t);
  if (!Number.isInteger(timestamp)) throw new Error('invalid_signature');

  const now = Math.floor(Date.now() / 1000);
  if (Math.abs(now - timestamp) > skewSeconds) {
    throw new Error('stale_signature');
  }

  const expected = crypto
    .createHmac('sha256', input.secret)
    .update(`${timestamp}.${input.rawBody}`)
    .digest('hex');

  const expectedBuffer = Buffer.from(expected, 'hex');
  const receivedBuffer = Buffer.from(parts.v1 ?? '', 'hex');

  if (
    expectedBuffer.length !== receivedBuffer.length ||
    !crypto.timingSafeEqual(expectedBuffer, receivedBuffer)
  ) {
    throw new Error('signature_mismatch');
  }

  return JSON.parse(input.rawBody);
}

async function handlePoolsEvent(event: { eventId: string; type: string; txnId: string }) {
  const inserted = await eventLog.insertOnce({ eventId: event.eventId, type: event.type });
  if (!inserted) return; // already processed

  await poolTrades.applyTerminalOnce({
    txnId: event.txnId,
    status: event.type.split('.').pop(), // settled | failed | released
    eventId: event.eventId,
  });
}