Обработка вебхуков и slash-команд Slack на serverless

import { createHmac, timingSafeEqual } from 'node:crypto';

export async function handler(event) {
  const body = event.body ?? '';
  const timestamp = event.headers['x-slack-request-timestamp'] ?? '';
  if (Math.abs(Date.now() / 1000 - Number(timestamp)) > 300) {
    return { statusCode: 400, body: 'stale request' };
  }
  const sigBase = `v0:${timestamp}:${body}`;
  const expected = 'v0=' + createHmac('sha256', process.env.SLACK_SIGNING_SECRET).update(sigBase).digest('hex');
  const received = event.headers['x-slack-signature'] ?? '';
  if (expected.length !== received.length ||
      !timingSafeEqual(Buffer.from(expected), Buffer.from(received))) {
    return { statusCode: 401, body: 'invalid signature' };
  }
  const params = Object.fromEntries(new URLSearchParams(body));
  await global.durable.startNew('slack-command', undefined, {
    command: params.command,
    text: params.text,
    userId: params.user_id,
    channelId: params.channel_id,
    responseUrl: params.response_url,
  });
  return { statusCode: 200, body: '' };
}

export async function handler(event) {
  const { command, text, userId, responseUrl } = event.payload ?? {};
  const result = await processCommand(command, text, userId);
  await fetch(responseUrl, {
    method: 'POST',
    headers: { 'Content-Type': 'application/json' },
    body: JSON.stringify({
      response_type: 'in_channel',
      blocks: [{ type: 'section', text: { type: 'mrkdwn', text: result } }],
    }),
  });
  return { command, userId, result };
}