getPreviewData function

Implementation

Future<PreviewData> getPreviewData(
  String text, {
  String? proxy,
  Duration? requestTimeout,
  String? userAgent,
}) async {
  const previewData = PreviewData();

  String? previewDataDescription;
  PreviewDataImage? previewDataImage;
  String? previewDataTitle;
  String? previewDataUrl;

  try {
    final emailRegexp = RegExp(regexEmail, caseSensitive: false);
    final textWithoutEmails = text
        .replaceAllMapped(
          emailRegexp,
          (match) => '',
        )
        .trim();
    if (textWithoutEmails.isEmpty) return previewData;

    final urlRegexp = RegExp(regexLink, caseSensitive: false);
    final matches = urlRegexp.allMatches(textWithoutEmails);
    if (matches.isEmpty) return previewData;

    var url = textWithoutEmails.substring(
      matches.first.start,
      matches.first.end,
    );

    if (!url.toLowerCase().startsWith('http')) {
      url = 'https://$url';
    }
    previewDataUrl = _calculateUrl(url, proxy);
    final uri = Uri.parse(previewDataUrl);
    final response = await http.get(uri, headers: {
      'User-Agent': userAgent ?? 'WhatsApp/2',
    }).timeout(requestTimeout ?? const Duration(seconds: 5));
    final document = parser.parse(utf8.decode(response.bodyBytes));

    final imageRegexp = RegExp(regexImageContentType);

    if (imageRegexp.hasMatch(response.headers['content-type'] ?? '')) {
      final imageSize = await _getImageSize(previewDataUrl);
      previewDataImage = PreviewDataImage(
        height: imageSize.height,
        url: previewDataUrl,
        width: imageSize.width,
      );
      return PreviewData(
        image: previewDataImage,
        link: previewDataUrl,
      );
    }

    if (!_hasUTF8Charset(document)) {
      return previewData;
    }

    final title = _getTitle(document);
    if (title != null) {
      previewDataTitle = title.trim();
    }

    final description = _getDescription(document);
    if (description != null) {
      previewDataDescription = description.trim();
    }

    final imageUrls = _getImageUrls(document, url);

    Size imageSize;
    String imageUrl;

    if (imageUrls.isNotEmpty) {
      imageUrl = imageUrls.length == 1
          ? _calculateUrl(imageUrls[0], proxy)
          : await _getBiggestImageUrl(imageUrls, proxy);

      imageSize = await _getImageSize(imageUrl);
      previewDataImage = PreviewDataImage(
        height: imageSize.height,
        url: imageUrl,
        width: imageSize.width,
      );
    }
    return PreviewData(
      description: previewDataDescription,
      image: previewDataImage,
      link: previewDataUrl,
      title: previewDataTitle,
    );
  } catch (e) {
    return PreviewData(
      description: previewDataDescription,
      image: previewDataImage,
      link: previewDataUrl,
      title: previewDataTitle,
    );
  }
}