//
//  ========================================================================
//  Copyright (c) 1995-2014 Mort Bay Consulting Pty. Ltd.
//  ------------------------------------------------------------------------
//  All rights reserved. This program and the accompanying materials
//  are made available under the terms of the Eclipse Public License v1.0
//  and Apache License v2.0 which accompanies this distribution.
//
//      The Eclipse Public License is available at
//      http://www.eclipse.org/legal/epl-v10.html
//
//      The Apache License v2.0 is available at
//      http://www.opensource.org/licenses/apache2.0.php
//
//  You may elect to redistribute this code under either of these licenses.
//  ========================================================================
//

package org.eclipse.jetty.util;

import java.io.UnsupportedEncodingException;
import java.nio.charset.Charset;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

/** Fast String Utilities.
 *
 * These string utilities provide both conveniance methods and
 * performance improvements over most standard library versions. The
 * main aim of the optimizations is to avoid object creation unless
 * absolutely required.
 *
 * 
 */
public final class StringUtil
{
	private static final Logger LOG = LoggerFactory.getLogger(StringUtil.class);
	
	public static final String ALL_INTERFACES="0.0.0.0";
	   
	public static final String __ISO_8859_1="ISO-8859-1";
	public final static String __UTF8="UTF-8";
	public final static String __UTF16="UTF-16";
	
	public final static Charset __UTF8_CHARSET;
	public final static Charset __ISO_8859_1_CHARSET;
	
	static
	{
		__UTF8_CHARSET=Charset.forName(__UTF8);
		__ISO_8859_1_CHARSET=Charset.forName(__ISO_8859_1);
	}
	
	private static char[] lowercases = {
		  '\000','\001','\002','\003','\004','\005','\006','\007',
		  '\010','\011','\012','\013','\014','\015','\016','\017',
		  '\020','\021','\022','\023','\024','\025','\026','\027',
		  '\030','\031','\032','\033','\034','\035','\036','\037',
		  '\040','\041','\042','\043','\044','\045','\046','\047',
		  '\050','\051','\052','\053','\054','\055','\056','\057',
		  '\060','\061','\062','\063','\064','\065','\066','\067',
		  '\070','\071','\072','\073','\074','\075','\076','\077',
		  '\100','\141','\142','\143','\144','\145','\146','\147',
		  '\150','\151','\152','\153','\154','\155','\156','\157',
		  '\160','\161','\162','\163','\164','\165','\166','\167',
		  '\170','\171','\172','\133','\134','\135','\136','\137',
		  '\140','\141','\142','\143','\144','\145','\146','\147',
		  '\150','\151','\152','\153','\154','\155','\156','\157',
		  '\160','\161','\162','\163','\164','\165','\166','\167',
		  '\170','\171','\172','\173','\174','\175','\176','\177' };

	/* ------------------------------------------------------------ */
	/**
	 * fast lower case conversion. Only works on ascii (not unicode)
	 * @param s the string to convert
	 * @return a lower case version of s
	 */
	public static String asciiToLowerCase(String s)
	{
		char[] c = null;
		int i=s.length();

		// look for first conversion
		while (i-->0)
		{
			char c1=s.charAt(i);
			if (c1<=127)
			{
				char c2=lowercases[c1];
				if (c1!=c2)
				{
					c=s.toCharArray();
					c[i]=c2;
					break;
				}
			}
		}

		while (i-->0)
		{
			if(c[i]<=127)
				c[i] = lowercases[c[i]];
		}
		
		return c==null?s:new String(c);
	}

	/* ------------------------------------------------------------ */
	/**
	 * replace substrings within string.
	 */
	public static String replace(String s, String sub, String with)
	{
		int c=0;
		int i=s.indexOf(sub,c);
		if (i == -1)
			return s;
	
		StringBuilder buf = new StringBuilder(s.length()+with.length());

		do
		{
			buf.append(s.substring(c,i));
			buf.append(with);
			c=i+sub.length();
		} while ((i=s.indexOf(sub,c))!=-1);

		if (c<s.length())
			buf.append(s.substring(c,s.length()));

		return buf.toString();
		
	}


	/* ------------------------------------------------------------ */
	/**
	 * append hex digit
	 * 
	 */
	public static void append(StringBuilder buf,byte b,int base)
	{
		int bi=0xff&b;
		int c='0'+(bi/base)%base;
		if (c>'9')
			c= 'a'+(c-'0'-10);
		buf.append((char)c);
		c='0'+bi%base;
		if (c>'9')
			c= 'a'+(c-'0'-10);
		buf.append((char)c);
	}
	
	public static void append2digits(StringBuilder buf,int i)
	{
		if (i<100)
		{
			buf.append((char)(i/10+'0'));
			buf.append((char)(i%10+'0'));
		}
	}
	
	public static String toString(byte[] b,int offset,int length,String charset)
	{
		try
		{
			return new String(b,offset,length,charset);
		}
		catch (UnsupportedEncodingException e)
		{
			throw new IllegalArgumentException(e);
		}
	}

	public static boolean isUTF8(String charset)
	{
		return __UTF8.equalsIgnoreCase(charset)||__UTF8Alt.equalsIgnoreCase(charset);
	}


	public static byte[] getBytes(String s)
	{
		try
		{
			return s.getBytes(__ISO_8859_1);
		}
		catch(Exception e)
		{
			LOG.warn("",e);
			return s.getBytes();
		}
	}

}