parseLinkHeader function

List<LinkEntry> parseLinkHeader(String header)

Parses an HTTP Link header value into a list of LinkEntry.

Handles:

• Multiple links separated by ,
• Attributes separated by ;
• Quoted and unquoted attribute values
• Multiple Link header values joined with ,

Example input: <https://hub.example.com>; rel="mercure", <https://example.com/foo>; rel="self"

Implementation

List<LinkEntry> parseLinkHeader(String header) {
  final entries = <LinkEntry>[];

  // Split on commas that are NOT inside angle brackets
  final linkStrings = _splitLinks(header);

  for (final linkStr in linkStrings) {
    final trimmed = linkStr.trim();
    if (trimmed.isEmpty) continue;

    // Extract URL from angle brackets
    final urlMatch = RegExp(r'<([^>]*)>').firstMatch(trimmed);
    if (urlMatch == null) continue;

    final url = urlMatch.group(1)!;
    final rest = trimmed.substring(urlMatch.end);

    // Parse attributes
    final attributes = <String, String>{};
    final attrPattern =
        RegExp(r';\s*(\w[\w.-]*)(?:\s*=\s*(?:"([^"]*)"|([^\s;,]*)))?');
    for (final match in attrPattern.allMatches(rest)) {
      final key = match.group(1)!.toLowerCase();
      final value = match.group(2) ?? match.group(3) ?? '';
      attributes[key] = value;
    }

    entries.add(LinkEntry(
      url: url,
      rel: attributes['rel'],
      attributes: attributes,
    ));
  }

  return entries;
}