/* 
 * Copyright 1998-1999 Sun Microsystems, Inc.  All Rights Reserved.
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This code is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 only, as
 * published by the Free Software Foundation.
 *
 * This code 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 General Public License
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
 * CA 95054 USA or visit www.sun.com if you need additional information or
 * have any questions.
 */

/*
 */

import java.io.*;
import java.rmi.server.*;
import java.net.*;

public class Compress {

    interface CompressConstants {
	// constants for 6-bit code values
	static final int NOP  = 0;	// no operation: used to pad words on flush()
	static final int RAW  = 1;	// introduces raw byte format
	static final int BASE = 2;	// base for codes found in lookup table
	static final String codeTable =
	    "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ ,.!?\"'()";
    }
    
    public static class CompressRMIClientSocketFactory 
	implements java.rmi.server.RMIClientSocketFactory, Serializable {

	public Socket createSocket(String host, int port) 
	    throws IOException {
	    
	    return ((Socket) new CompressSocket(host, port));
	}
    }

    public static class CompressRMIServerSocketFactory 
	implements RMIServerSocketFactory, 
		   Serializable {
	
	public ServerSocket createServerSocket(int port) 
	    throws IOException {

	    return ((ServerSocket) new CompressServerSocket(port));
	}
    }
    
    public static class CompressSocket extends Socket {
	private InputStream in;
	private OutputStream out;
	public CompressSocket() { super(); }
	public CompressSocket(String host, int port) throws IOException {
	    super(host, port);
	}
	public InputStream getInputStream() throws IOException {
	    if (in == null) {
		in = new CompressInputStream(super.getInputStream());
	    }
	    return in;
        }
	public OutputStream getOutputStream() throws IOException {
	    if (out == null) {
		out = new CompressOutputStream(super.getOutputStream());
	    }
	    return out;
	}
    }

    public static class CompressServerSocket extends ServerSocket {
	public CompressServerSocket(int port) throws IOException {
	    super(port);
	}
	public Socket accept() throws IOException {
	    Socket s = new CompressSocket();
	    implAccept(s);
	    return s;
	}
    }

    public static class CompressInputStream extends FilterInputStream
	implements CompressConstants
    {
	
	public CompressInputStream(InputStream in) {
	    super(in);
	}
	
	// buffer of unpacked 6-bit codes from last 32-word read
	int buf[] = new int[5];
	
	// position of next code to read in buffer (5 == end of buffer)
	int bufPos = 5;
	
	public int read() throws IOException {
	    try {
		int code;
		do {
		    code = readCode();
		} while (code == NOP);	// ignore NOP codes
		
		if (code >= BASE)
		    return codeTable.charAt(code - BASE);
		else if (code == RAW) {
		    int high = readCode();
		    int low = readCode();
		    return (high << 4) | low;
		} else
		    throw new IOException("unknown compression code: " + code);
	    } catch (EOFException e) {
		return -1;
	    }
	}
	
	public int read(byte b[], int off, int len) throws IOException {
	    if (len <= 0) {
		return 0;
	    }
	    
	    int c = read();
	    if (c == -1) {
		return -1;
	    }
	    b[off] = (byte)c;
	    
	    int i = 1;
	    /*****
		  try {
		  for (; i < len ; i++) {
		  c = read();
		  if (c == -1) {
		  break;
		  }
		  if (b != null) {
		  b[off + i] = (byte)c;
		  }
		  }
		  } catch (IOException ee) {
		  }
	    *****/
	    return i;
	}
	
	private int readCode() throws IOException {
	    if (bufPos == 5) {
		int b1 = in.read();
		int b2 = in.read();
		int b3 = in.read();
		int b4 = in.read();
		if ((b1 | b2 | b3 | b4) < 0)
		    throw new EOFException();
		int pack = (b1 << 24) | (b2 << 16) | (b3 << 8) | b4;
		buf[0] = (pack >>> 24) & 0x3F;
		buf[1] = (pack >>> 18) & 0x3F;
		buf[2] = (pack >>> 12) & 0x3F;
		buf[3] = (pack >>>  6) & 0x3F;
		buf[4] = (pack >>>  0) & 0x3F;
		bufPos = 0;
	    }
	    return buf[bufPos++];
	}
    }

    public static class CompressOutputStream extends FilterOutputStream
	implements CompressConstants
    {
	
	public CompressOutputStream(OutputStream out) {
	    super(out);
	}
	
	// buffer of 6-bit codes to pack into next 32-bit word
	int buf[] = new int[5];
	
	// number of valid codes pending in buffer
	int bufPos = 0;
	
	public void write(int b) throws IOException {
	    b &= 0xFF;			// force argument to a byte
	    
	    int pos = codeTable.indexOf((char)b);
	    if (pos != -1)
		writeCode(BASE + pos);
	    else {
		writeCode(RAW);
		writeCode(b >> 4);
		writeCode(b & 0xF);
	    }
	}
	
	public void write(byte b[], int off, int len) throws IOException {
	    /*
	     * This is quite an inefficient implementation, 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]);
	}
	
	public void flush() throws IOException {
	    while (bufPos > 0)
		writeCode(NOP);
	}
	
	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;
	    }
	}
    }
}