/*

  * 

  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS HEADER.

  * 

  * Copyright 2007-2008 Sun Microsystems, Inc. All rights reserved.

  * 

  * The contents of this file are subject to the terms of either the GNU

  * General Public License Version 2 only ("GPL") or the Common Development

  * and Distribution License("CDDL") (collectively, the "License").  You

  * may not use this file except in compliance with the License. You can obtain

  * a copy of the License at https://glassfish.dev.java.net/public/CDDL+GPL.html

  * or glassfish/bootstrap/legal/LICENSE.txt.  See the License for the specific

  * language governing permissions and limitations under the License.

  * 

  * When distributing the software, include this License Header Notice in each

  * file and include the License file at glassfish/bootstrap/legal/LICENSE.txt.

  * Sun designates this particular file as subject to the "Classpath" exception

  * as provided by Sun in the GPL Version 2 section of the License file that

  * accompanied this code.  If applicable, add the following below the License

  * Header, with the fields enclosed by brackets [] replaced by your own

  * identifying information: "Portions Copyrighted [year]

  * [name of copyright owner]"

  * 

  * Contributor(s):

  * 

  * If you wish your version of this file to be governed by only the CDDL or

  * only the GPL Version 2, indicate your decision by adding "[Contributor]

  * elects to include this software in this distribution under the [CDDL or GPL

  * Version 2] license."  If you don't indicate a single choice of license, a

  * recipient has the option to distribute your version of this file under

  * either the CDDL, the GPL Version 2 or to extend the choice of license to

  * its licensees as provided above.  However, if you add GPL Version 2 code

  * and therefore, elected the GPL Version 2 license, then the option applies

  * only if the new code is made subject to such option by the copyright

  * holder.

  *

  */

 package com.sun.grizzly.util;

 import java.io.IOException;

 import java.nio.ByteBuffer;

 import java.nio.channels.ReadableByteChannel;

 import java.nio.channels.SelectableChannel;

 import java.nio.channels.SelectionKey;

 import java.nio.channels.Selector;

 /**

  * Class contains set of useful operations commonly used in the framework

  * 

  * @author Alexey Stashok

  * @author Jean-Francois Arcand

  */

 public class Utils {

      /**

      * Character translation tables.

      */

     private static final byte[] toLower = new byte[256];

     /**

      * Initialize character translation and type tables.

      */

     static {

         for (int i = 0; i < 256; i++) {

             toLower[i] = (byte)i;

         }

         for (int lc = 'a'; lc <= 'z'; lc++) {

             int uc = lc + 'A' - 'a';

             toLower[uc] = (byte)lc;

         }

     }

     /**

      * Method reads data from {@link SelectableChannel} to 

      * {@link ByteBuffer}. If data is not immediately available - channel

      *  will be reregistered on temporary {@link Selector} and wait maximum

      * readTimeout milliseconds for data.

      * 

      * @param channel {@link SelectableChannel} to read data from

      * @param byteBuffer {@link ByteBuffer} to store read data to

      * @param readTimeout maximum time in millis operation will wait for 

      * incoming data

      * 

      * @return number of bytes were read

      * @throws <code>IOException</code> if any error was occured during read

      */

     public static int readWithTemporarySelector(SelectableChannel channel,

             ByteBuffer byteBuffer, long readTimeout) throws IOException {

         int count = 1;

         int byteRead = 0;

         int preReadInputBBPos = byteBuffer.position();

         Selector readSelector = null;

         SelectionKey tmpKey = null;

         try {

             ReadableByteChannel readableChannel = (ReadableByteChannel) channel;

             while (count > 0){

                 count = readableChannel.read(byteBuffer);

                 if ( count > -1 )

                     byteRead += count;

                 else

                     byteRead = count;

             }            

             if (byteRead == 0 && byteBuffer.position() == preReadInputBBPos) {

                 readSelector = SelectorFactory.getSelector();

                 if ( readSelector == null ){

                     return 0;

                 }

                 count = 1;

                 tmpKey = channel.register(readSelector, SelectionKey.OP_READ);

                 tmpKey.interestOps(tmpKey.interestOps() | SelectionKey.OP_READ);

                 int code = readSelector.select(readTimeout);

                 tmpKey.interestOps(

                     tmpKey.interestOps() & (~SelectionKey.OP_READ));

                 if ( code == 0 ){

                     return 0; // Return on the main Selector and try again.

                 }

                 while (count > 0){

                     count = readableChannel.read(byteBuffer);

                     if ( count > -1 )

                         byteRead += count;

                     else

                         byteRead = count;                    

                 }

             } else if (byteRead == 0 && byteBuffer.position() != preReadInputBBPos) {

                 byteRead += (byteBuffer.position() - preReadInputBBPos);

             }

         } finally {

             if (tmpKey != null)

                 tmpKey.cancel();

             if ( readSelector != null) {

                 // Bug 6403933

                 SelectorFactory.selectNowAndReturnSelector(readSelector);

             }

         }

         return byteRead;

     } 

     /** 

      * Return the bytes contained between the startByte and the endByte. The ByteBuffer

      * will be left in the state it was before invoking that method, meaning 

      * its position and limit will be the same.

      * 

      * @param byteBuffer The bytes. 

      * @param startByte the first byte to look for

      * @param endByte the second byte to look for

      * @return The byte[] contained between startByte and endByte

      */

     public static byte[] extractBytes(ByteBuffer byteBuffer, 

             byte startByte, byte endByte) throws IOException{   

         int curPosition = byteBuffer.position();

         int curLimit = byteBuffer.limit();

         if (byteBuffer.position() == 0){

             throw new IllegalStateException("Invalid state");

         }

         byteBuffer.position(0);

         byteBuffer.limit(curPosition);

         int state =0;

         int start =0;

         int end = 0;  

         try {                         

             byte c;            

             // Rule b - try to determine the context-root

             while(byteBuffer.hasRemaining()) {

                 c = byteBuffer.get();

                 switch(state) {

                     case 0: // Search for first ' '

                         if (c == startByte){

                             state = 1;

                             start = byteBuffer.position();

                         }

                         break;

                     case 1: 

                         if (c == endByte){

                             end = byteBuffer.position();

                             byte[] bytes = new byte[end - start];

                             byteBuffer.position(start);

                             byteBuffer.limit(end);

                             byteBuffer.get(bytes);

                             return bytes;

                         }

                         break;

                     default:

                         throw new IllegalArgumentException("Unexpected state");

                 }      

             }

             throw new IllegalStateException("Unexpected state");

         } finally {     

             byteBuffer.limit(curLimit);

             byteBuffer.position(curPosition);                               

         }       

     } 

     /**

      * Specialized utility method: find a sequence of lower case bytes inside

      * a ByteBuffer.

      */

     public static int findBytes(ByteBuffer byteBuffer, byte[] b) {

         int curPosition = byteBuffer.position();

         int curLimit = byteBuffer.limit();

         if (byteBuffer.position() == 0){

             throw new IllegalStateException("Invalid state");

         }

         byteBuffer.position(0);

         byteBuffer.limit(curPosition);

         try {                         

             byte first = b[0];

             int start = 0;

             int end = curPosition;

             // Look for first char 

             int srcEnd = b.length;

             for (int i = start; i <= (end - srcEnd); i++) {

                 if ((toLower[byteBuffer.get(i) & 0xff] & 0xff) != first) continue;

                 // found first char, now look for a match

                 int myPos = i+1;

                 for (int srcPos = 1; srcPos < srcEnd; ) {

                         if ((toLower[byteBuffer.get(myPos++) & 0xff] & 0xff) != b[srcPos++])

                     break;

                         if (srcPos == srcEnd) return i - start; // found it

                 }

             }

             return -1;

         } finally {

             byteBuffer.limit(curLimit);

             byteBuffer.position(curPosition);                

         }

     }

 }