using System;
using System.Collections;
using System.Collections.Generic;
using System.Configuration;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Web;
using System.Web.Caching;

namespace Cache.WebCache
{
    /// <summary>
    /// 默认的.net WebCache接口实现
    /// </summary>
    public class WebCache 
    {
        protected static volatile System.Web.Caching.Cache webCache = HttpRuntime.Cache;

        /// <summary>
        /// 判断值是否存在..
        /// </summary>
        /// <param name="key"></param>
        /// <returns></returns>
        public bool IsExist(string key)
        {
            if (string.IsNullOrEmpty(key))
                return false;
            return webCache[key] != null;
        }

        /// <summary>
        /// 写入某个Cache
        /// </summary>
        /// <param name="key">键</param>
        /// <param name="o">对像</param>
        public void AddObject<T>(string key, T o, int t = 0)
        {
            if (String.IsNullOrEmpty(key) || o == null)
                return;
            if (t == 0)
                t = int.Parse(ConfigurationManager.AppSettings["OutTime"]);
            CacheItemRemovedCallback callBack = new CacheItemRemovedCallback(onRemove);
            webCache.Insert(key, o, null, System.DateTime.Now.AddMinutes(t), System.Web.Caching.Cache.NoSlidingExpiration, System.Web.Caching.CacheItemPriority.High, callBack);
        }

        /// <summary>
        /// 取某个key对应的object值
        /// </summary>
        /// <param name="key">键</param>
        /// <returns></returns>
        public T GetObject<T>(string key)
        {
            if (!String.IsNullOrEmpty(key))
                return (T)webCache.Get(key);

            return default(T);
        }

        /// <summary>
        /// 移出某个Cache
        /// </summary>
        /// <param name="key">键</param>
        public void RemoveObject(string key)
        {
            if (!String.IsNullOrEmpty(key))
                webCache.Remove(key);
        }

        /// <summary>
        /// 批量移出类型key的对像
        /// </summary>
        /// <param name="key"></param>
        public void RemoveObjectByRegex(string pattern)
        {
            if (!string.IsNullOrEmpty(pattern))
            {
                IDictionaryEnumerator enu = webCache.GetEnumerator();
                while (enu.MoveNext())
                {
                    string key = enu.Key.ToString();
                    if (key.IndexOf(pattern, StringComparison.CurrentCultureIgnoreCase) != -1)
                    {
                        RemoveObject(key);
                    }
                }
            }
        }

        /// <summary>
        /// 移出所有Cache
        /// </summary>
        public void RemoveAll()
        {
            IDictionaryEnumerator enu = webCache.GetEnumerator();
            while (enu.MoveNext())
            {
                RemoveObject(enu.Key.ToString());
            }
        }


        public void onRemove(string key, object val, CacheItemRemovedReason reason)
        {
            switch (reason)
            {
                case CacheItemRemovedReason.DependencyChanged:
                    //更新缓存映射表
                    break;
                case CacheItemRemovedReason.Expired:
                    //更新缓存映射表
                    break;
                case CacheItemRemovedReason.Removed:
                    break;
                case CacheItemRemovedReason.Underused:
                    break;
                default:
                    break;
            }
        }

        /// <summary>
        /// 返回所有键值
        /// </summary>
        /// <returns></returns>
        public List<string> GetKeys()
        {
            List<string> list = new List<string>();
            IDictionaryEnumerator enu = webCache.GetEnumerator();
            while (enu.MoveNext())
            {
                list.Add(enu.Key.ToString());
            }

            return list;
        }
    }
}