/*
 * JBoss, Home of Professional Open Source.
 * Copyright 2008, Red Hat Middleware LLC, and individual contributors
 * as indicated by the @author tags. See the copyright.txt file in the
 * distribution for a full listing of individual contributors.
 *
 * This is free software; you can redistribute it and/or modify it
 * under the terms of the GNU Lesser General Public License as
 * published by the Free Software Foundation; either version 2.1 of
 * the License, or (at your option) any later version.
 *
 * This software is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this software; if not, write to the Free
 * Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
 * 02110-1301 USA, or see the FSF site: http://www.fsf.org.
 */
package org.jboss.test.invokers.ejb;

import java.io.*;
 
class CompressionOutputStream extends FilterOutputStream
    implements CompressionConstants
{

    /*
     * Constructor calls constructor of superclass.
     */
    public CompressionOutputStream(OutputStream out) {
        super(out);
    }
 
    /* 
     * Buffer of 6-bit codes to pack into next 32-bit word
     * Five 6-bit codes fit into 4 words. 
     */
    int buf[] = new int[5];
 
    /*
     * Index of valid codes waiting in buf. 
     */
    int bufPos = 0;
 

    /*  
     * This method writes one byte to the socket stream. 
     */ 
    public void write(int b) throws IOException {
        // force argument to one byte
        b &= 0xFF;  

        // Look up pos in codeTable to get its encoding. 
        int pos = codeTable.indexOf((char)b);

        if (pos != -1){
            // If pos is in the codeTable, write BASE + pos into buf. 
            // By adding BASE to pos, we know that the characters in
            // the codeTable will always have a code between 2 and 63
            // inclusive. This allows us to use RAW (RAW is equal to
            // 1) to signify that the next two groups of 6-bits are 
            // necessary for decompression of the next character.
	    
            writeCode(BASE + pos);
        } else {
            // Otherwise, write RAW into buf to signify that the
            // Character is being sent in 12 bits.
            writeCode(RAW);

            // Write the last 4 bits of b into the buf.
            writeCode(b >> 4);

            // Truncate b to contain data in only the first 4 bits, 
            // and write the first 4 bits of b into buf.
            writeCode(b & 0xF);
        }
    }
 
    /* 
     * This method writes up to len bytes to the socket stream. 
     */
    public void write(byte b[], int off, int len) throws IOException {
        /*
         * This implementation is quite inefficient because it has to
         * call the other write method for every byte in the array.  It
         * could be optimized for performance by doing all the processing
         * in this method.
         */
        for (int i = 0; i < len; i++)
            write(b[off + i]);
    }
 

   /* 
    * Clears buffer of all data (zeroes it out). 
    */ 
  public void flush() throws IOException {
    while (bufPos > 0)
      writeCode(NOP);
  }
 
    /* 
     * This method actually puts the data into the output stream after
     * packing the data from all 5 bytes in buf into one word.
     * Remember, each byte has, at most, 6 significant bits.
     */
    private void writeCode(int c) throws IOException {
        buf[bufPos++] = c;
        if (bufPos == 5) {      // write next word when we have 5 codes
            int pack = (buf[0] << 24) | (buf[1] << 18) | (buf[2] << 12) |
                       (buf[3] << 6) | buf[4];
            out.write((pack >>> 24) & 0xFF);
            out.write((pack >>> 16) & 0xFF);
            out.write((pack >>> 8)  & 0xFF);
            out.write((pack >>> 0)  & 0xFF);
            bufPos = 0;
        }
    }
}
