abstract class TlToken {
  static Iterable<TlToken> tokenize(String file) sync* {
    var lastWasNone = false;
    for (final untrimmedLine in file.split(RegExp(r'[\r\n]'))) {
      final line = untrimmedLine.trim();
      if (line.isEmpty) {
        if (!lastWasNone) {
          yield TlTokenNone();
          lastWasNone = true;
        }
        continue;
      }
      else {
        lastWasNone = false;
        if (line.startsWith('//')) {
          // Comment
          if (!line.contains('@')) {
            yield TlTokenCommentLine(line);
            continue;
          }
          // Skip to first @tag
          final interestLine = line.substring(line.indexOf('@'));
          for (final unTrimmedTaggedChunk in interestLine.split('@')) {
            final taggedChunk = unTrimmedTaggedChunk.trim();
            if (taggedChunk.isEmpty) {
              continue;
            }
            final firstWs = taggedChunk.indexOf(RegExp(r'\s'));
            final tagName = taggedChunk.substring(0, firstWs);
            final tagValue = taggedChunk.substring(firstWs).trim();
            yield TlTokenCommentTag(name: tagName, value: tagValue);
          }
        }
        else if (line == '---functions---') {
          yield TlTokenFunctionsDelimiter();
        }
        else {
          // class
          // Split by space
          final chunksIt = line.split(RegExp(r'\s+')).iterator;
          // First is name
          chunksIt.moveNext();
          final name = chunksIt.current;
          // Then there are parameters until =
          final parameters = <TlTokenClassParam>[];
          do {
            chunksIt.moveNext();
            if (chunksIt.current == '=') {
              break;
            }
            // Params are defined as name:type
            // Ignore oddities
            if (!chunksIt.current.contains(':')) {
              continue;
            }
            final splitted = chunksIt.current.split(':');
            parameters.add(TlTokenClassParam(
              name: splitted[0], 
              type: splitted[1]
            ));
          } while (true);
          // Finally, there is the base type (abstract class)
          chunksIt.moveNext();
          String removeSemicolon(String input) {
            while (input.codeUnits.last == ';'.codeUnits[0]) {
              input = input.substring(0, input.length - 1);
            }
            return input;
          }
          final baseType = removeSemicolon(chunksIt.current);

          yield TlTokenClassTag(
            name: name, 
            parameters: parameters, 
            baseType: baseType,
          );
        }
      }
    }
  }
}
class TlTokenFunctionsDelimiter extends TlToken {
  @override
  String toString() {
    return 'TlToken: ---functions---';
  }
}
class TlTokenNone extends TlToken {
  @override
  String toString() {
    return 'TlToken.';
  }
}
class TlTokenCommentLine extends TlToken {
  /// The content of the comment including the leading slashes
  final String content;
  TlTokenCommentLine(this.content);

  @override
  String toString() {
    return 'TlToken: //$content';
  }
}
class TlTokenCommentTag extends TlToken {
  /// The name of the tag, excluding the ampersand: description
  final String name;
  /// The value of the tag: Provides ...
  final String value;

  TlTokenCommentTag({required this.name, required this.value});

  @override
  String toString() {
    return 'TlToken: //@$name $value';
  }
}
class TlTokenClassTag extends TlToken {
  /// The name of the class
  final String name;
  final List<TlTokenClassParam> parameters;
  final String baseType;
  TlTokenClassTag({required this.name, required this.parameters, required this.baseType});

  @override
  String toString() {
    final params = parameters.join(', ');
    return 'TlToken: $name($params) = $baseType';
  }
}
class TlTokenClassParam {
  final String name;
  final String type;
  TlTokenClassParam({required this.name, required this.type});

  @override
  String toString() {
    return '$name:$type';
  }
}