using System;
using System.Collections.Generic;
using System.Configuration;
using System.Web;
using System.Web.Configuration;
using Zhaizj.Framework.Utils;

namespace Zhaizj.Framework.Config.DotNetConfig
{
	/// <summary>
	/// 配置组（依赖 .NET的配置架构）
	/// </summary>
	/// <remarks>
	///		<code>
	///			&lt;configSections&gt;
	///				&lt;sectionGroup name="KEB.devfx" type="KEB.DevFx.Config.DotNetConfig.GroupHandler, KEB.DevFx.BaseFx"&gt;
	///					&lt;section name="mail" type="KEB.DevFx.Utils.Mail.Config.SectionHandler, KEB.DevFx.BaseFx" /&gt;
	///					......
	///				&lt;/sectionGroup&gt;
	///			&lt;/configSections&gt;
	/// 
	///			......
	/// 
	///			&lt;KEB.devfx&gt;
	///				&lt;mail&gt;
	///					&lt;smtpSetting server="" port="" userName="" password="" /&gt;
	///				&lt;/mail&gt;
	///			&lt;/KEB.devfx&gt;
	///			......
	/// </code>
	/// </remarks>
	public class GroupHandler : ConfigurationSectionGroup
	{
		private static GroupHandler instance;
		private static bool isInit;
		private static bool isWebApp;
		private static Dictionary<Type, ConfigurationSection> sectionCache;
		private static readonly object lockObject = new object();

		private static void Init(bool throwOnError) {
			if (isInit) {
				return;
			}
			Configuration config;
			if (HttpContext.Current != null) {
				isWebApp = true;
				config = WebConfigurationManager.OpenWebConfiguration(HttpContext.Current.Request.ApplicationPath);
			} else {
				isWebApp = false;
				config = ConfigurationManager.OpenExeConfiguration(ConfigurationUserLevel.None);
			}
			foreach (string key in config.SectionGroups.Keys) {
				ConfigurationSectionGroup csg = config.SectionGroups[key];
				if(csg == null || string.IsNullOrEmpty(csg.Type)) {
					continue;
				}
				Type csgType = TypeHelper.CreateType(csg.Type, false);
				if (csgType == typeof(GroupHandler)) {
					break;
				}
			}

			sectionCache = new Dictionary<Type, ConfigurationSection>();

			if (instance == null) {
				isInit = true;
				if (throwOnError) {
					throw new Exception("配置组未正确配置");
				}
				return;
			}

			foreach (ConfigurationSection section in instance.Sections) {
				string sectionTypeName = section.SectionInformation.Type;
				string sectionName = section.SectionInformation.SectionName;
				Type sectionType = TypeHelper.CreateType(sectionTypeName, false);
				object objectSection;
				if (isWebApp) {
					objectSection = WebConfigurationManager.GetSection(sectionName);
				} else {
					objectSection = ConfigurationManager.GetSection(sectionName);
				}
				if (objectSection != null) {
					sectionCache.Add(sectionType, (ConfigurationSection)objectSection);
				}
			}

			isInit = true;
		}

		/// <summary>
		/// 当前配置组的实例（单件）
		/// </summary>
		public static GroupHandler Instance {
			get { return instance; }
		}

		/// <summary>
		/// 获取配置节（泛型）
		/// </summary>
		/// <typeparam name="T">配置节类型</typeparam>
		/// <returns>配置节</returns>
		public static T GetSection<T>() where T : ConfigurationSection {
			return GetSection<T>(true);
		}

		/// <summary>
		/// 获取配置节（泛型）
		/// </summary>
		/// <typeparam name="T">配置节类型</typeparam>
		/// <param name="throwOnError">如果配置组未配置是否抛出异常</param>
		/// <returns>配置节</returns>
		public static T GetSection<T>(bool throwOnError) where T : ConfigurationSection {
			if (!isInit) {
				lock (lockObject) {
					if (!isInit) {
						Init(throwOnError);
					}
				}
			}

			Type type = typeof(T);
			ConfigurationSection sectionObject;
			sectionCache.TryGetValue(type, out sectionObject);
			return sectionObject as T;
		}

		/// <summary>
		/// 构造方法
		/// </summary>
		protected GroupHandler() {
			instance = this;
		}
	}
}