cf-worker-telegram.js

// Telegram Bot API base URL
const TELEGRAM_API_BASE = 'https://api.telegram.org';


async function handleRequest(request) {
  const url = new URL(request.url);

  // Reconstruct the Telegram API URL
  const telegramUrl = `${TELEGRAM_API_BASE}${url.pathname}${url.search}`;

  // Create headers for the new request
  const headers = new Headers(request.headers);
  
  // Forward the request to Telegram API
  let body = undefined;
  if (request.method !== 'GET' && request.method !== 'HEAD') {
    try {
      body = await request.arrayBuffer();
    } catch (err) {
      return new Response(`Failed to read request body: ${err.message}`, { status: 400 });
    }
  }

  const proxyReq = new Request(telegramUrl, {
    method: request.method,
    headers: request.headers,
    body,
    redirect: 'follow',
  });

  try {
    const tgRes = await fetch(proxyReq);
    const res = new Response(tgRes.body, tgRes); // Copy response as-is
    res.headers.set('Access-Control-Allow-Origin', '*');
    res.headers.set('Access-Control-Allow-Methods', 'GET, POST, PUT, DELETE, OPTIONS');
    res.headers.set('Access-Control-Allow-Headers', 'Content-Type');
    return res;
  } catch (err) {
    return new Response(`Error proxying request: ${err.message}`, { status: 500 });
  }
}
// Handle OPTIONS requests for CORS
function handleOptions(request) {
  const corsHeaders = {
    'Access-Control-Allow-Origin': '*',
    'Access-Control-Allow-Methods': 'GET, POST, PUT, DELETE, OPTIONS',
    'Access-Control-Allow-Headers': 'Content-Type',
    'Access-Control-Max-Age': '86400',
  };

  return new Response(null, {
    status: 204,
    headers: corsHeaders,
  });
}

// Main event listener for the worker
addEventListener('fetch', event => {
  const request = event.request;
  
  // Handle CORS preflight requests
  if (request.method === 'OPTIONS') {
    event.respondWith(handleOptions(request));
  } else {
    event.respondWith(handleRequest(request));
  }
});