// netlify/functions/ical-proxy.js
// Proxy server-side pentru iCal Booking.com - ocoleste restrictiile CORS

const https = require('https');
const http = require('http');

exports.handler = async function(event) {
  var url = (event.queryStringParameters || {}).url;

  if (!url) {
    return { statusCode: 400, body: 'Missing url parameter' };
  }

  // Permite doar Booking.com iCal pentru securitate
  if (!url.startsWith('https://ical.booking.com/') &&
      !url.startsWith('http://ical.booking.com/')) {
    return { statusCode: 403, body: 'Only booking.com iCal URLs are allowed' };
  }

  return new Promise(function(resolve) {
    var lib = url.startsWith('https') ? https : http;

    var options = {
      headers: {
        'User-Agent': 'Googlebot/2.1 (+http://www.google.com/bot.html)',
        'Accept': 'text/calendar, text/plain, */*',
        'Accept-Language': 'en-US,en;q=0.9',
        'Cache-Control': 'no-cache'
      }
    };

    var req = lib.get(url, options, function(res) {
      // Urmareste redirecturi
      if (res.statusCode === 301 || res.statusCode === 302) {
        var redirectUrl = res.headers.location;
        if (!redirectUrl) {
          resolve({ statusCode: 502, body: 'Redirect fara Location header' });
          return;
        }
        // Apel recursiv pentru redirect
        var redirectLib = redirectUrl.startsWith('https') ? https : http;
        redirectLib.get(redirectUrl, options, function(res2) {
          var data = [];
          res2.on('data', function(chunk) { data.push(chunk); });
          res2.on('end', function() {
            var body = Buffer.concat(data).toString('utf8');
            resolve({
              statusCode: 200,
              headers: {
                'Content-Type': 'text/calendar; charset=utf-8',
                'Access-Control-Allow-Origin': '*',
                'Cache-Control': 'no-cache, no-store'
              },
              body: body
            });
          });
        }).on('error', function(e) {
          resolve({ statusCode: 500, body: 'Redirect fetch error: ' + e.message });
        });
        return;
      }

      if (res.statusCode !== 200) {
        resolve({
          statusCode: res.statusCode,
          body: 'Booking.com a returnat: ' + res.statusCode
        });
        return;
      }

      var data = [];
      res.on('data', function(chunk) { data.push(chunk); });
      res.on('end', function() {
        var body = Buffer.concat(data).toString('utf8');

        // Verifica daca e un iCal valid
        if (!body.includes('BEGIN:VCALENDAR')) {
          resolve({
            statusCode: 502,
            body: 'Raspuns invalid de la Booking.com: ' + body.slice(0, 200)
          });
          return;
        }

        resolve({
          statusCode: 200,
          headers: {
            'Content-Type': 'text/calendar; charset=utf-8',
            'Access-Control-Allow-Origin': '*',
            'Cache-Control': 'no-cache, no-store'
          },
          body: body
        });
      });
    });

    req.on('error', function(e) {
      resolve({ statusCode: 500, body: 'Eroare conexiune: ' + e.message });
    });

    req.setTimeout(15000, function() {
      req.destroy();
      resolve({ statusCode: 504, body: 'Timeout - Booking.com nu a raspuns in 15s' });
    });
  });
};