using System;
using System.Collections;
using System.Collections.Generic;

using CB.Config;
using CB.Entity;
using CB.Interface;

namespace CB.Data
{
    public class DatabaseProvider
    {
        private DatabaseProvider() { }
        static DatabaseProvider() { }

        private static Hashtable cacheList = Hashtable.Synchronized(new Hashtable());
        private static object lockObject = new object();

        private static object LoadDbProvider(string typeName, string interfaceId)
        {
            try
            {
                object provider = Activator.CreateInstance(Type.GetType(typeName, false, true), new object[] { interfaceId });
                cacheList.Add(typeName, provider);
                return provider;
            }
            catch (Exception ex)
            {
                throw ex;
            }
        }

        public static T GetDbProvider<T>()
        {
            string interfaceId = typeof(T).Name;
            string keyName = interfaceId;
            var Config = DataProviderConfig.GetConfig(keyName);

            if (null == Config)
                throw new Exception("没有配置接口[" + keyName + "]的实现类！");

            keyName = Config.TypeName;

            object provider = cacheList[keyName];
            if (null == provider)
            {
                lock (lockObject)
                {
                    provider = cacheList[keyName];
                    if (null == provider)
                    {
                        provider = LoadDbProvider(keyName, interfaceId);
                    }
                }
            }
            return (T)provider;
        }

        public static void ResetDbProvider()
        {
            cacheList.Clear();
        }
    }
}