/******************************************************************************
	Copyright 2005-2007 R2@DevFx.NET 
	DevFx.NET is free software; you can redistribute it and/or modify
	it under the terms of the Lesser GNU General Public License as published by
	the Free Software Foundation; either version 2 of the License, or
	(at your option) any later version.

	DevFx.NET 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
	Lesser GNU General Public License for more details.

	You should have received a copy of the Lesser GNU General Public License
	along with this program; if not, write to the Free Software
	Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
/*******************************************************************************/

using System;
using System.Collections.Specialized;
using System.IO;
using System.Text;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Data;
using System.Collections.Generic;
using System.Text.RegularExpressions;

namespace Lskj.DevFx
{
	/// <summary>
	/// 关于WEB项目的一些实用方法
	/// </summary>
	public static class EncodingHelper
	{

		#region Base64 Util

		/// <summary>
		/// 把字符串进行BASE64编码
		/// </summary>
		/// <param name="inputString">原字符串</param>
		/// <param name="encodingName">编码格式名</param>
		/// <returns>编码后的字符串</returns>
		public static string ToBase64(string inputString, string encodingName) {
			return Convert.ToBase64String(Encoding.GetEncoding(encodingName).GetBytes(inputString));
		}

		/// <summary>
		/// 对BASE64字符串进行解码
		/// </summary>
		/// <param name="base64String">待解码的字符串</param>
		/// <param name="encodingName">编码格式名</param>
		/// <returns>解码后的字符串</returns>
		public static string FromBase64(string base64String, string encodingName) {
			return Encoding.GetEncoding(encodingName).GetString(Convert.FromBase64String(base64String));
		}

		#endregion Base64 Util

		#region Hex Util

		private static readonly char[] hexValues = new char[] {'0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'A', 'B', 'C', 'D', 'E', 'F'};

		private static int ConvertHexDigit(char val) {
			if(val <= '9') {
				return (val - '0');
			}
			if(val >= 'a') {
				return ((val - 'a') + '\n');
			}
			return ((val - 'A') + '\n');
		}

		/// <summary>
		/// 把字节数组转换成16进制表示的字符串
		/// </summary>
		/// <param name="sArray">字节数组</param>
		/// <returns>16进制表示的字符串</returns>
		public static string ToHexString(byte[] sArray) {
			if(sArray == null) {
				return null;
			}
			char[] chArray = new char[sArray.Length * 2];
			int i = 0;
			int k = 0;
			while(i < sArray.Length) {
				int t = (sArray[i] & 240) >> 4;
				chArray[k++] = hexValues[t];
				t = sArray[i] & 15;
				chArray[k++] = hexValues[t];
				i++;
			}
			return new string(chArray);
		}

		/// <summary>
		/// 把16进制表示的字符串转换成字节数组
		/// </summary>
		/// <param name="hexString">进制表示的字符串</param>
		/// <returns>字节数组</returns>
		public static byte[] FromHexString(string hexString) {
			byte[] buffer;
			if(hexString == null) {
				throw new ArgumentNullException("hexString");
			}
			bool flag = false;
			int i = 0;
			int hexLength = hexString.Length;
			if(((hexLength >= 2) && (hexString[0] == '0')) && ((hexString[1] == 'x') || (hexString[1] == 'X'))) {
				hexLength = hexString.Length - 2;
				i = 2;
			}
			if(((hexLength % 2) != 0) && ((hexLength % 3) != 2)) {
				throw new ArgumentException("无效的16进制字符串格式");
			}
			if((hexLength >= 3) && (hexString[i + 2] == ' ')) {
				flag = true;
				buffer = new byte[(hexLength / 3) + 1];
			} else {
				buffer = new byte[hexLength / 2];
			}
			for(int k = 0; i < hexString.Length; k++) {
				int h = ConvertHexDigit(hexString[i]);
				int l = ConvertHexDigit(hexString[i + 1]);
				buffer[k] = (byte)(l | (h << 4));
				if(flag) {
					i++;
				}
				i += 2;
			}
			return buffer;
		}

		#endregion Hex Util
        
    }
}