// CoreUtil


using System;
using System.Threading;
using System.Data;
using System.Data.Sql;
using System.Data.SqlClient;
using System.Data.SqlTypes;
using System.Text;
using System.Configuration;
using System.Collections;
using System.Collections.Generic;
using System.Security.Cryptography;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Web.UI.HtmlControls;
using System.IO;
using System.Drawing;
using System.Drawing.Imaging;
using System.Drawing.Drawing2D;
using System.Diagnostics;
using System.Web.Mail;
using System.Net;
using System.Net.Sockets;
using System.Net.NetworkInformation;

namespace CoreUtil
{
	public enum CacheType
	{
		UpdateExpiresWhenAccess = 0,
		DoNotUpdateExpiresWhenAccess = 1,
	}

	public class Cache<TKey, TValue>
	{
		class Entry
		{
			DateTime createdDateTime;
			public DateTime CreatedDateTime
			{
				get { return createdDateTime; }
			}
			DateTime updatedDateTime;
			public DateTime UpdatedDateTime
			{
				get { return updatedDateTime; }
			}
			DateTime lastAccessedDateTime;
			public DateTime LastAccessedDateTime
			{
				get { return lastAccessedDateTime; }
			}

			TKey key;
			public TKey Key
			{
				get
				{
					return key;
				}
			}

			TValue value;
			public TValue Value
			{
				get
				{
					lastAccessedDateTime = Time.NowDateTime;
					return this.value;
				}
				set
				{
					this.value = value;
					updatedDateTime = Time.NowDateTime;
					lastAccessedDateTime = Time.NowDateTime;
				}
			}

			public Entry(TKey key, TValue value)
			{
				this.key = key;
				this.value = value;
				lastAccessedDateTime = updatedDateTime = createdDateTime = Time.NowDateTime;
			}

			public override int GetHashCode()
			{
				return key.GetHashCode();
			}

			public override string ToString()
			{
				return key.ToString() + "," + value.ToString();
			}
		}

		public static readonly TimeSpan DefaultExpireSpan = new TimeSpan(0, 5, 0);
		public const CacheType DefaultCacheType = CacheType.UpdateExpiresWhenAccess;

		TimeSpan expireSpan;
		public TimeSpan ExpireSpan
		{
			get { return expireSpan; }
		}
		CacheType type;
		public CacheType Type
		{
			get { return type; }
		}
		Dictionary<TKey, Entry> list;
		object lockObj;

		public Cache()
		{
			init(DefaultExpireSpan, DefaultCacheType);
		}
		public Cache(CacheType type)
		{
			init(DefaultExpireSpan, type);
		}
		public Cache(TimeSpan expireSpan)
		{
			init(expireSpan, DefaultCacheType);
		}
		public Cache(TimeSpan expireSpan, CacheType type)
		{
			init(expireSpan, type);
		}
		void init(TimeSpan expireSpan, CacheType type)
		{
			this.expireSpan = expireSpan;
			this.type = type;

			list = new Dictionary<TKey, Entry>();
			lockObj = new object();
		}

		public void Add(TKey key, TValue value)
		{
			lock (lockObj)
			{
				Entry e;

				deleteExpired();

				if (list.ContainsKey(key) == false)
				{
					e = new Entry(key, value);

					list.Add(e.Key, e);

					deleteExpired();
				}
				else
				{
					e = list[key];
					e.Value = value;
				}
			}
		}

		public void Delete(TKey key)
		{
			lock (lockObj)
			{
				if (list.ContainsKey(key))
				{
					list.Remove(key);
				}
			}
		}

		public TValue this[TKey key]
		{
			get
			{
				lock (lockObj)
				{
					deleteExpired();

					if (list.ContainsKey(key) == false)
					{
						return default(TValue);
					}

					return list[key].Value;
				}
			}
		}

		static long last_deleted = 0;

		void deleteExpired()
		{
			bool do_delete = false;
			long now = Tick64.Value;
			long delete_interval = expireSpan.Milliseconds / 10;

			lock (lockObj)
			{
				if (last_deleted == 0 || now > (last_deleted + delete_interval))
				{
					last_deleted = now;
					do_delete = true;
				}
			}

			if (do_delete == false)
			{
				return;
			}

			lock (lockObj)
			{
				List<Entry> o = new List<Entry>();
				DateTime expire = Time.NowDateTime - this.expireSpan;

				foreach (Entry e in list.Values)
				{
					if (this.type == CacheType.UpdateExpiresWhenAccess)
					{
						if (e.LastAccessedDateTime < expire)
						{
							o.Add(e);
						}
					}
					else
					{
						if (e.UpdatedDateTime < expire)
						{
							o.Add(e);
						}
					}
				}

				foreach (Entry e in o)
				{
					list.Remove(e.Key);
				}
			}
		}
	}
}

