<?php
// fetchOg.php
// Usage: fetchOg.php?url=https://maps.app.goo.gl/...

// Force UTF‑8 output
ini_set('default_charset', 'UTF-8');
mb_internal_encoding("UTF-8");
mb_http_output("UTF-8");

header("Access-Control-Allow-Origin: *");
header("Content-Type: application/json; charset=utf-8");

// Validate input
$target = isset($_GET['url']) ? trim($_GET['url']) : '';
if ($target === '' || !filter_var($target, FILTER_VALIDATE_URL)) {
  http_response_code(400);
  echo json_encode(["error" => "Invalid or missing 'url' parameter"], JSON_UNESCAPED_SLASHES | JSON_UNESCAPED_UNICODE);
  exit;
}

// Try fetching HTML with Facebook UA, fallback to Mozilla UA
$html = fetchHtml($target, "facebookexternalhit/1.1 (+http://www.facebook.com/externalhit_uatext.php)");
if ($html === null) {
  $html = fetchHtml($target, "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/121 Safari/537.36");
}

if ($html === null) {
  http_response_code(502);
  echo json_encode(["error" => "Failed to fetch HTML"], JSON_UNESCAPED_SLASHES | JSON_UNESCAPED_UNICODE);
  exit;
}

// Parse OG tags
$meta = parseOpenGraph($html);

// Fallbacks
if (empty($meta['title'])) {
  $meta['title'] = parseTitleTag($html);
}
if (!isset($meta['description'])) {
  $meta['description'] = null;
}
if (!isset($meta['image'])) {
  $meta['image'] = null;
}

// Normalize image URL
$meta['image'] = absolutizeUrl($meta['image'], $target);

// Output JSON
echo json_encode([
  "title" => $meta['title'],
  "description" => $meta['description'],
  "image" => $meta['image'],
  "url" => $target,
], JSON_UNESCAPED_SLASHES | JSON_UNESCAPED_UNICODE);

/* ----------------------- Helpers ----------------------- */

function fetchHtml($url, $userAgent) {
  $ch = curl_init();
  curl_setopt_array($ch, [
    CURLOPT_URL => $url,
    CURLOPT_RETURNTRANSFER => true,
    CURLOPT_FOLLOWLOCATION => true,
    CURLOPT_MAXREDIRS => 5,
    CURLOPT_TIMEOUT => 12,
    CURLOPT_CONNECTTIMEOUT => 8,
    CURLOPT_SSL_VERIFYPEER => false,
    CURLOPT_SSL_VERIFYHOST => 0,
    CURLOPT_USERAGENT => $userAgent,
    CURLOPT_HTTPHEADER => [
      "Accept: text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8",
      "Accept-Language: en-US,en;q=0.9",
    ],
  ]);
  $html = curl_exec($ch);
  $status = curl_getinfo($ch, CURLINFO_HTTP_CODE);
  curl_close($ch);
  if ($html === false || $status >= 400) return null;
  return $html;
}

function parseOpenGraph($html) {
  libxml_use_internal_errors(true);
  $dom = new DOMDocument();
  $dom->loadHTML('<meta http-equiv="Content-Type" content="text/html; charset=utf-8">' . $html, LIBXML_NOWARNING | LIBXML_NOERROR);
  libxml_clear_errors();

  $result = ["title" => null, "description" => null, "image" => null];
  $xpath = new DOMXPath($dom);

  $result["title"] = getMetaContent($xpath, ['og:title', 'twitter:title']);
  $result["description"] = getMetaContent($xpath, ['og:description', 'twitter:description', 'description']);
  $result["image"] = getMetaContent($xpath, ['og:image', 'twitter:image', 'og:image:url']);

  return $result;
}

function getMetaContent(DOMXPath $xpath, array $keys) {
  foreach ($keys as $key) {
    $query = sprintf('//meta[@property="%s" or @name="%s"]', $key, $key);
    $nodes = $xpath->query($query);
    if ($nodes && $nodes->length > 0) {
      return clean($nodes->item(0)->getAttribute('content'));
    }
  }
  return null;
}

function parseTitleTag($html) {
  if (preg_match('/<title[^>]*>(.*?)<\/title>/is', $html, $match)) {
    return clean($match[1]);
  }
  return null;
}

function clean($s) {
  $s = mb_convert_encoding($s ?? '', 'UTF-8', 'auto');
  $s = html_entity_decode($s, ENT_QUOTES | ENT_HTML5, 'UTF-8');
  $s = preg_replace('/\s+/u', ' ', $s);
  return trim($s);
}

function absolutizeUrl($maybeUrl, $baseUrl) {
  if (!$maybeUrl) return null;
  if (preg_match('#^https?://#i', $maybeUrl)) return $maybeUrl;
  if (strpos($maybeUrl, '//') === 0) {
    $scheme = parse_url($baseUrl, PHP_URL_SCHEME) ?: 'https';
    return $scheme . ':' . $maybeUrl;
  }
  $base = parse_url($baseUrl);
  if (!$base || !isset($base['scheme']) || !isset($base['host'])) return $maybeUrl;
  $scheme = $base['scheme'];
  $host = $base['host'];
  $port = isset($base['port']) ? ':' . $base['port'] : '';
  $path = isset($base['path']) ? $base['path'] : '/';
  $dir = preg_replace('#/[^/]*$#', '/', $path);
  $resolved = ($maybeUrl[0] === '/') ? $maybeUrl : $dir . $maybeUrl;
  return $scheme . '://' . $host . $port . $resolved;
}