using System;
using System.Text;

namespace FairyGUI.Utils
{
	/// <summary>
	/// 
	/// </summary>
	public class XMLUtils
	{
		public static string DecodeString(string aSource)
		{
			int len = aSource.Length;
			StringBuilder sb = new StringBuilder();
			int pos1 = 0, pos2 = 0;

			while (true)
			{
				pos2 = aSource.IndexOf('&', pos1);
				if (pos2 == -1)
				{
					sb.Append(aSource.Substring(pos1));
					break;
				}
				sb.Append(aSource.Substring(pos1, pos2 - pos1));

				pos1 = pos2 + 1;
				pos2 = pos1;
				int end = Math.Min(len, pos2 + 10);
				for (; pos2 < end; pos2++)
				{
					if (aSource[pos2] == ';')
						break;
				}
				if (pos2 < end && pos2 > pos1)
				{
					string entity = aSource.Substring(pos1, pos2 - pos1);
					int u = 0;
					if (entity[0] == '#')
					{
						if (entity.Length > 1)
						{
							if (entity[1] == 'x')
								u = Convert.ToInt16(entity.Substring(2), 16);
							else
								u = Convert.ToInt16(entity.Substring(1));
							sb.Append((char)u);
							pos1 = pos2 + 1;
						}
						else
							sb.Append('&');
					}
					else
					{
						switch (entity)
						{
							case "amp":
								u = 38;
								break;

							case "apos":
								u = 39;
								break;

							case "gt":
								u = 62;
								break;

							case "lt":
								u = 60;
								break;

							case "nbsp":
								u = 32;
								break;

							case "quot":
								u = 34;
								break;
						}
						if (u > 0)
						{
							sb.Append((char)u);
							pos1 = pos2 + 1;
						}
						else
							sb.Append('&');
					}
				}
				else
				{
					sb.Append('&');
				}
			}

			return sb.ToString();
		}

		public static string EncodeString(string str)
		{
			if (str == null || str.Length == 0)
				return "";
			else
				return str.Replace("&", "&amp;").Replace("<", "&lt;").Replace(">", "&gt;").Replace("'", "&apos;");
		}
	}
}