class Message {
  final String role; // 'user' or 'assistant'
  final String content;
  final Map? data;
  final DateTime timestamp;
  final bool isIntermediate; // 中间状态标记，替代isLoading

  Message({
    required this.role,
    required this.content,
    required this.timestamp,
    this.data,
    this.isIntermediate = false, // 默认不是中间状态
  });

  // 从JSON构造函数
  factory Message.fromJson(Map<String, dynamic> json) {
    return Message(
      role: json['role'] as String,
      content: json['content'] as String,
      data: json['data'],
      timestamp: DateTime.parse(json['timestamp'] as String),
      isIntermediate: json['isIntermediate'] as bool? ?? false,
    );
  }

  // 转换为JSON
  Map<String, dynamic> toJson() {
    return {
      'role': role,
      'content': content,
      'data': data,
      'timestamp': timestamp.toIso8601String(),
      'isIntermediate': isIntermediate,
    };
  }

  // 创建一个中间状态的消息
  factory Message.intermediate(String role) {
    return Message(
      role: role,
      content: '',
      timestamp: DateTime.now(),
      isIntermediate: true,
    );
  }

  // 复制并修改
  Message copyWith({
    String? role,
    String? content,
    Map? data,
    DateTime? timestamp,
    bool? isIntermediate,
  }) {
    return Message(
      role: role ?? this.role,
      content: content ?? this.content,
      data: data ?? this.data,
      timestamp: timestamp ?? this.timestamp,
      isIntermediate: isIntermediate ?? this.isIntermediate,
    );
  }
}