import 'dart:convert';

/// 函数服务
/// 仅实现各种功能函数，不包含AI交互逻辑
class FunctionService {
  /// 天气查询工具定义
  /// 返回一个可直接用于tools参数的天气查询工具定义
  static Map<String, dynamic> getWeatherToolDefinition() {
    return {
      'type': 'function',
      'function': {
        'name': 'get_current_weather',
        'description': '获取指定地点的当前天气信息',
        'parameters': {
          'type': 'object',
          'properties': {
            'location': {
              'type': 'string',
              'description': '地理位置，例如：北京市',
            },
            'unit': {
              'type': 'string',
              'description': '温度单位',
              'enum': ['celsius', 'fahrenheit'],
            },
          },
          'required': ['location'],
        },
      },
    };
  }
  
  /// 模拟天气API实现
  /// 返回一个模拟的天气信息，实际应用中应该调用真实的天气API
  static Future<Map<String, dynamic>> getWeatherInfo(Map<String, dynamic> args) async {
    final location = args['location'] ?? '未知地点';
    final unit = args['unit'] ?? 'celsius';
    
    // 在实际应用中，这里应该调用真实的天气API
    return {
      'location': location,
      'temperature': unit == 'celsius' ? '25°C' : '77°F',
      'conditions': '晴转多云',
      'humidity': '55%',
      'wind': '西南风 3级',
      'date': DateTime.now().toString().split(' ')[0],
    };
  }
  
  /// 解析函数调用参数
  /// 从AI响应中提取函数调用参数
  static Map<String, dynamic> parseFunctionCallArguments(Map<String, dynamic> functionCallResponse) {
    if (functionCallResponse['tool_calls'] == null || 
        functionCallResponse['tool_calls'].isEmpty) {
      throw FunctionServiceException('No tool calls found in response');
    }
    
    final toolCall = functionCallResponse['tool_calls'][0];
    if (toolCall['function'] == null || toolCall['function']['arguments'] == null) {
      throw FunctionServiceException('Invalid function call format');
    }
    
    try {
      return json.decode(toolCall['function']['arguments']);
    } catch (e) {
      throw FunctionServiceException('Failed to parse function arguments: $e');
    }
  }
  
  /// 获取函数调用ID和名称
  /// 用于构建工具响应消息
  static Map<String, String> getFunctionCallInfo(Map<String, dynamic> functionCallResponse) {
    if (functionCallResponse['tool_calls'] == null || 
        functionCallResponse['tool_calls'].isEmpty) {
      throw FunctionServiceException('No tool calls found in response');
    }
    
    final toolCall = functionCallResponse['tool_calls'][0];
    if (toolCall['id'] == null || toolCall['function'] == null || toolCall['function']['name'] == null) {
      throw FunctionServiceException('Invalid function call format');
    }
    
    return {
      'id': toolCall['id'],
      'name': toolCall['function']['name'],
    };
  }
}

/// 函数调用服务异常类
class FunctionServiceException implements Exception {
  final String message;
  FunctionServiceException(this.message);
  
  @override
  String toString() => message;
}