using System;
using System.Collections.Generic;
using System.Configuration;
using System.Linq;
using System.Reflection;
using System.Text;
using System.Threading.Tasks;

namespace DH.Commons.Helper
{
    /// <summary>
    /// 配置文件操作工具类（自动定位主程序配置）
    /// </summary>
    public static class SystemConfigHelper
    {
        private static Configuration _mainConfig;
        private static readonly object _lock = new object();

        /// <summary>
        /// 获取主程序配置对象
        /// </summary>
        private static Configuration MainConfiguration
        {
            get
            {
                if (_mainConfig == null)
                {
                    lock (_lock)
                    {
                        if (_mainConfig == null)
                        {
                            // 获取主程序路径
                            string exePath = Assembly.GetEntryAssembly().Location;
                            var configFile = exePath + ".config";

                            // 加载主程序配置
                            var fileMap = new ExeConfigurationFileMap
                            {
                                ExeConfigFilename = configFile
                            };
                            _mainConfig = ConfigurationManager.OpenMappedExeConfiguration(
                                fileMap,
                                ConfigurationUserLevel.None
                            );
                        }
                    }
                }
                return _mainConfig;
            }
        }

        /// <summary>
        /// 检查配置项是否存在
        /// </summary>
        public static bool KeyExists(string key)
        {
            return MainConfiguration.AppSettings.Settings[key] != null;
        }

        /// <summary>
        /// 读取配置项（带类型自动转换）
        /// </summary>
        public static T GetValue<T>(string key, T defaultValue = default)
        {
            try
            {
                var setting = MainConfiguration.AppSettings.Settings[key];
                if (setting == null) return defaultValue;

                return (T)Convert.ChangeType(setting.Value, typeof(T));
            }
            catch
            {
                return defaultValue;
            }
        }

        /// <summary>
        /// 写入配置项（自动保存）
        /// </summary>
        public static void SetValue(string key, object value)
        {
            var settings = MainConfiguration.AppSettings.Settings;
            var stringValue = value?.ToString() ?? string.Empty;

            if (settings[key] == null)
            {
                settings.Add(key, stringValue);
            }
            else
            {
                settings[key].Value = stringValue;
            }

            SaveChanges();
        }

        /// <summary>
        /// 删除指定配置项
        /// </summary>
        public static void RemoveKey(string key)
        {
            if (KeyExists(key))
            {
                MainConfiguration.AppSettings.Settings.Remove(key);
                SaveChanges();
            }
        }

        /// <summary>
        /// 保存配置修改
        /// </summary>
        private static void SaveChanges()
        {
            MainConfiguration.Save(ConfigurationSaveMode.Modified);
            ConfigurationManager.RefreshSection("appSettings");
        }
    }

}