/*
 * Copyright 2004-2005 The Apache Software Foundation
 * 
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 * 
 * http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

using System;

namespace Lucene.Net.Analysis
{
	
	/// <summary> A filter that replaces accented characters in the ISO Latin 1 character set 
	/// (ISO-8859-1) by their unaccented equivalent. The case will not be altered.
	/// <p>
	/// For instance, '&agrave;' will be replaced by 'a'.
	/// <p>
	/// </summary>
	public class ISOLatin1AccentFilter : TokenFilter
	{
		public ISOLatin1AccentFilter(TokenStream input) : base(input)
		{
		}
		
		public override Token Next()
		{
			Token t = input.Next();
			if (t == null)
				return null;
			// Return a token with filtered characters.
			return new Token(RemoveAccents(t.TermText()), t.StartOffset(), t.EndOffset(), t.Type());
		}
		
		/// <summary> To replace accented characters in a String by unaccented equivalents.</summary>
		public static System.String RemoveAccents(System.String input)
		{
			System.Text.StringBuilder output = new System.Text.StringBuilder();
			for (int i = 0; i < input.Length; i++)
			{
                long val = input[i];

				switch (input[i])
				{
					
					case '\u00C0':  // À
					case '\u00C1':  // Ã?
					case '\u00C2':  // Â
					case '\u00C3':  // Ã
					case '\u00C4':  // Ä
					case '\u00C5':  // Ã…
						output.Append("A");
						break;
					
					case '\u00C6':  // Æ
						output.Append("AE");
						break;
					
					case '\u00C7':  // Ç
						output.Append("C");
						break;
					
					case '\u00C8':  // È
					case '\u00C9':  // É
					case '\u00CA':  // Ê
					case '\u00CB':  // Ë
						output.Append("E");
						break;
					
					case '\u00CC':  // Ì
					case '\u00CD':  // Ã?
					case '\u00CE':  // ÃŽ
					case '\u00CF':  // Ã?
						output.Append("I");
						break;
					
					case '\u00D0':  // Ã?
						output.Append("D");
						break;
					
					case '\u00D1':  // Ñ
						output.Append("N");
						break;
					
					case '\u00D2':  // Ã’
					case '\u00D3':  // Ó
					case '\u00D4':  // Ô
					case '\u00D5':  // Õ
					case '\u00D6':  // Ö
					case '\u00D8':  // Ø
						output.Append("O");
						break;
					
					case '\u0152':  // Å’
						output.Append("OE");
						break;
					
					case '\u00DE':  // Þ
						output.Append("TH");
						break;
					
					case '\u00D9':  // Ù
					case '\u00DA':  // Ú
					case '\u00DB':  // Û
					case '\u00DC':  // Ü
						output.Append("U");
						break;
					
					case '\u00DD':  // Ã?
					case '\u0178':  // Ÿ
						output.Append("Y");
						break;
					
					case '\u00E0':  // à
					case '\u00E1':  // á
					case '\u00E2':  // â
					case '\u00E3':  // ã
					case '\u00E4':  // ä
					case '\u00E5':  // å
						output.Append("a");
						break;
					
					case '\u00E6':  // æ
						output.Append("ae");
						break;
					
					case '\u00E7':  // ç
						output.Append("c");
						break;
					
					case '\u00E8':  // è
					case '\u00E9':  // é
					case '\u00EA':  // ê
					case '\u00EB':  // ë
						output.Append("e");
						break;
					
					case '\u00EC':  // ì
					case '\u00ED':  // í
					case '\u00EE':  // î
					case '\u00EF':  // ï
						output.Append("i");
						break;
					
					case '\u00F0':  // ð
						output.Append("d");
						break;
					
					case '\u00F1':  // ñ
						output.Append("n");
						break;
					
					case '\u00F2':  // ò
					case '\u00F3':  // ó
					case '\u00F4':  // ô
					case '\u00F5':  // õ
					case '\u00F6':  // ö
					case '\u00F8':  // ø
						output.Append("o");
						break;
					
					case '\u0153':  // Å“
						output.Append("oe");
						break;
					
					case '\u00DF':  // ß
						output.Append("ss");
						break;
					
					case '\u00FE':  // þ
						output.Append("th");
						break;
					
					case '\u00F9':  // ù
					case '\u00FA':  // ú
					case '\u00FB':  // û
					case '\u00FC':  // ü
						output.Append("u");
						break;
					
					case '\u00FD':  // ý
					case '\u00FF':  // ÿ
						output.Append("y");
						break;
					
					default: 
						output.Append(input[i]);
						break;
					
				}
			}
			return output.ToString();
		}
	}
}