using System;
using System.Collections.Generic;

public class ConfigCache
{
    // 单例实例
    private static ConfigCache _instance;
    public static ConfigCache Instance
    {
        get
        {
            _instance ??= new ConfigCache();
            return _instance;
        }
    }

    // 私有构造函数，防止外部实例化
    private ConfigCache() 
    {
        _configDictionary = new Dictionary<string, string>();
    }

    // 用于存储配置的字典
    private readonly Dictionary<string, string> _configDictionary;

    /// <summary>
    /// 设置配置项
    /// </summary>
    /// <param name="key">配置的键</param>
    /// <param name="value">配置的值</param>
    public void SetConfig(string key, string value)
    {
        if (string.IsNullOrEmpty(key))
        {
            Console.WriteLine("键不能为空！");
            return;
        }

        if (_configDictionary.ContainsKey(key))
        {
            _configDictionary[key] = value; // 如果键已存在，更新值
            Console.WriteLine($"配置已更新：{key} = {value}");
        }
        else
        {
            _configDictionary.Add(key, value); // 如果键不存在，添加新项
            Console.WriteLine($"配置已添加：{key} = {value}");
        }
    }

    /// <summary>
    /// 获取配置项
    /// </summary>
    /// <param name="key">配置的键</param>
    /// <returns>配置的值，如果键不存在返回 null</returns>
    public string GetConfig(string key)
    {
        if (string.IsNullOrEmpty(key))
        {
            Console.WriteLine("键不能为空！");
            return null;
        }

        if (_configDictionary.TryGetValue(key, out string value))
        {
            Console.WriteLine($"读取到配置：{key} = {value}");
            return value;
        }
        else
        {
            Console.WriteLine($"配置项不存在：{key}");
            return null;
        }
    }

    /// <summary>
    /// 删除配置项
    /// </summary>
    /// <param name="key">配置的键</param>
    public void RemoveConfig(string key)
    {
        if (string.IsNullOrEmpty(key))
        {
            Console.WriteLine("键不能为空！");
            return;
        }

        if (_configDictionary.Remove(key))
        {
            Console.WriteLine($"配置已删除：{key}");
        }
        else
        {
            Console.WriteLine($"配置项不存在，无法删除：{key}");
        }
    }

    /// <summary>
    /// 清空所有配置
    /// </summary>
    public void ClearConfigs()
    {
        _configDictionary.Clear();
        Console.WriteLine("所有配置已清空！");
    }
}