/*
 * Copyright (C) 2011 Citrix Systems, Inc.  All rights reserved.
 * 
 * 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.
 */
package com.cloud.bridge.util;

import java.io.IOException;
import java.io.InputStream;

/**
 * @author Kelven, John Zucker
 * Provide converters for regexp (case independent tokens)
 * Also provide upper case or lower case (default) converters for byte array b[] to hex String
 */
public class StringHelper {
	public static final String EMPTY_STRING = "";

	private static final char[] hexCharsUpperCase = { '0','1','2','3','4','5','6','7','8','9','A','B','C','D','E','F' }; 
	
	private static final char[] hexCharsLowerCase = { '0','1','2','3','4','5','6','7','8','9','a','b','c','d','e','f' };

   /* Convert byte array b[] into an uppercase hex string
   */
	public static String toHexStringUpperCase(byte[] b) {
		StringBuffer sb = new StringBuffer();
		for (int i = 0; i < b.length; i++) {
			sb.append(hexCharsUpperCase[ (int)(((int)b[i] >> 4) & 0x0f)]);
			sb.append(hexCharsUpperCase[ (int)(((int)b[i]) & 0x0f)]);
		}
	    return sb.toString(); 
	}
	
	/* Convert byte array b[] into a lowercase (default) hex string
	 */
	public static String toHexString(byte[] b) {
		StringBuffer sb = new StringBuffer();
		for (int i = 0; i < b.length; i++) {
			sb.append(hexCharsLowerCase[ (int)(((int)b[i] >> 4) & 0x0f)]);
			sb.append(hexCharsLowerCase[ (int)(((int)b[i]) & 0x0f)]);
		}
	    return sb.toString(); 
	}
	
	public static String substringInBetween(String name, 
		String prefix, String delimiter) {
		
		int startPos = 0;
		if(prefix != null)
			startPos = prefix.length() + 1;
		
		int endPos = name.indexOf(delimiter, startPos);
		if(endPos > 0)
			return name.substring(startPos, endPos);
		
		return null;
	}
	
	public static String stringFromStream(InputStream is) throws IOException {
		StringBuffer sb = new StringBuffer();
	    byte[] b = new byte[4096];
	    int n;
	    while((n = is.read(b)) != -1) {
	        sb.append(new String(b, 0, n));
	    }
	    return sb.toString();
	}
	
	/**
	 * Convert the string into a regex to allow easy matching.  In both S3 and EC2 regex strings
	 * are used for matching.  We must remember to quote all special regex characters that appear 
	 * in the string.
	 */
	public static String toRegex(String param) 
	{
		StringBuffer regex = new StringBuffer();
		for( int i=0; i < param.length(); i++ ) 
		{
			char next = param.charAt( i );
			     if ('*'  == next) regex.append( ".+"   );   // -> multi-character match wild card
			else if ('?'  == next) regex.append( "."    );   // -> single-character match wild card
			else if ('.'  == next) regex.append( "\\."  );   // all of these are special regex characters we are quoting
			else if ('+'  == next) regex.append( "\\+"  );   
			else if ('$'  == next) regex.append( "\\$"  );   
			else if ('\\' == next) regex.append( "\\\\" );  
			else if ('['  == next) regex.append( "\\["  );   
			else if (']'  == next) regex.append( "\\]"  );   
			else if ('{'  == next) regex.append( "\\{"  );   
			else if ('}'  == next) regex.append( "\\}"  );   
			else if ('('  == next) regex.append( "\\("  );   
			else if (')'  == next) regex.append( "\\)"  );   
			else if ('&'  == next) regex.append( "\\&"  );   
			else if ('^'  == next) regex.append( "\\^"  );   
			else if ('-'  == next) regex.append( "\\-"  );   
			else if ('|'  == next) regex.append( "\\|"  );   
			else regex.append( next );
		}
		
		return regex.toString();
	}
}