// CoreUtil
// 
// Copyright (C) 2012-2014 Daiyuu Nobori. All Rights Reserved.
// Copyright (C) 2012-2014 SoftEther VPN Project at University of Tsukuba. All Rights Reserved.
// Comments: Tetsuo Sugiyama, Ph.D.
// 
// This program is free software; you can redistribute it and/or
// modify it under the terms of the GNU General Public License
// version 2 as published by the Free Software Foundation.
// 
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU General Public License for more details.
// 
// You should have received a copy of the GNU General Public License version 2
// along with this program; if not, write to the Free Software
// Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
// 
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
// EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
// MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
// IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
// CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
// TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
// SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
// 
// THE LICENSE AGREEMENT IS ATTACHED ON THE SOURCE-CODE PACKAGE
// AS "LICENSE.TXT" FILE. READ THE TEXT FILE IN ADVANCE TO USE THE SOFTWARE.
// 
// 
// THIS SOFTWARE IS DEVELOPED IN JAPAN, AND DISTRIBUTED FROM JAPAN,
// UNDER JAPANESE LAWS. YOU MUST AGREE IN ADVANCE TO USE, COPY, MODIFY,
// MERGE, PUBLISH, DISTRIBUTE, SUBLICENSE, AND/OR SELL COPIES OF THIS
// SOFTWARE, THAT ANY JURIDICAL DISPUTES WHICH ARE CONCERNED TO THIS
// SOFTWARE OR ITS CONTENTS, AGAINST US (SOFTETHER PROJECT, SOFTETHER
// CORPORATION, DAIYUU NOBORI OR OTHER SUPPLIERS), OR ANY JURIDICAL
// DISPUTES AGAINST US WHICH ARE CAUSED BY ANY KIND OF USING, COPYING,
// MODIFYING, MERGING, PUBLISHING, DISTRIBUTING, SUBLICENSING, AND/OR
// SELLING COPIES OF THIS SOFTWARE SHALL BE REGARDED AS BE CONSTRUED AND
// CONTROLLED BY JAPANESE LAWS, AND YOU MUST FURTHER CONSENT TO
// EXCLUSIVE JURISDICTION AND VENUE IN THE COURTS SITTING IN TOKYO,
// JAPAN. YOU MUST WAIVE ALL DEFENSES OF LACK OF PERSONAL JURISDICTION
// AND FORUM NON CONVENIENS. PROCESS MAY BE SERVED ON EITHER PARTY IN
// THE MANNER AUTHORIZED BY APPLICABLE LAW OR COURT RULE.
// 
// USE ONLY IN JAPAN. DO NOT USE IT IN OTHER COUNTRIES. IMPORTING THIS
// SOFTWARE INTO OTHER COUNTRIES IS AT YOUR OWN RISK. SOME COUNTRIES
// PROHIBIT ENCRYPTED COMMUNICATIONS. USING THIS SOFTWARE IN OTHER
// COUNTRIES MIGHT BE RESTRICTED.
// 
// 
// SOURCE CODE CONTRIBUTION
// ------------------------
// 
// Your contribution to SoftEther VPN Project is much appreciated.
// Please send patches to us through GitHub.
// Read the SoftEther VPN Patch Acceptance Policy in advance:
// http://www.softether.org/5-download/src/9.patch
// 
// 
// DEAR SECURITY EXPERTS
// ---------------------
// 
// If you find a bug or a security vulnerability please kindly inform us
// about the problem immediately so that we can fix the security problem
// to protect a lot of users around the world as soon as possible.
// 
// Our e-mail address for security reports is:
// softether-vpn-security [at] softether.org
// 
// Please note that the above e-mail address is not a technical support
// inquiry address. If you need technical assistance, please visit
// http://www.softether.org/ and ask your question on the users forum.
// 
// Thank you for your cooperation.
// 
// 
// NO MEMORY OR RESOURCE LEAKS
// ---------------------------
// 
// The memory-leaks and resource-leaks verification under the stress
// test has been passed before release this source code.


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_inveral = expireSpan.Milliseconds / 10;

			lock (lockObj)
			{
				if (last_deleted == 0 || now > (last_deleted + delete_inveral))
				{
					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);
				}
			}
		}
	}
}


// Developed by SoftEther VPN Project at University of Tsukuba in Japan.
// Department of Computer Science has dozens of overly-enthusiastic geeks.
// Join us: http://www.tsukuba.ac.jp/english/admission/
