/*
 * $RCSfile: TIFFLZWUtil.java,v $
 *
 * 
 * Copyright (c) 2005 Sun Microsystems, Inc. All  Rights Reserved.
 * 
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met: 
 * 
 * - Redistribution of source code must retain the above copyright 
 *   notice, this  list of conditions and the following disclaimer.
 * 
 * - Redistribution in binary form must reproduce the above copyright
 *   notice, this list of conditions and the following disclaimer in 
 *   the documentation and/or other materials provided with the
 *   distribution.
 * 
 * Neither the name of Sun Microsystems, Inc. or the names of 
 * contributors may be used to endorse or promote products derived 
 * from this software without specific prior written permission.
 * 
 * This software is provided "AS IS," without a warranty of any 
 * kind. ALL EXPRESS OR IMPLIED CONDITIONS, REPRESENTATIONS AND 
 * WARRANTIES, INCLUDING ANY IMPLIED WARRANTY OF MERCHANTABILITY, 
 * FITNESS FOR A PARTICULAR PURPOSE OR NON-INFRINGEMENT, ARE HEREBY
 * EXCLUDED. SUN MIDROSYSTEMS, INC. ("SUN") AND ITS LICENSORS SHALL 
 * NOT BE LIABLE FOR ANY DAMAGES SUFFERED BY LICENSEE AS A RESULT OF 
 * USING, MODIFYING OR DISTRIBUTING THIS SOFTWARE OR ITS
 * DERIVATIVES. IN NO EVENT WILL SUN OR ITS LICENSORS BE LIABLE FOR 
 * ANY LOST REVENUE, PROFIT OR DATA, OR FOR DIRECT, INDIRECT, SPECIAL,
 * CONSEQUENTIAL, INCIDENTAL OR PUNITIVE DAMAGES, HOWEVER CAUSED AND
 * REGARDLESS OF THE THEORY OF LIABILITY, ARISING OUT OF THE USE OF OR
 * INABILITY TO USE THIS SOFTWARE, EVEN IF SUN HAS BEEN ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGES. 
 * 
 * You acknowledge that this software is not designed or intended for 
 * use in the design, construction, operation or maintenance of any 
 * nuclear facility. 
 *
 * $Revision: 1.1 $
 * $Date: 2005/02/11 05:01:48 $
 * $State: Exp $
 */
package com.github.jaiimageio.impl.plugins.tiff;

import java.io.IOException;

import javax.imageio.IIOException;

public class TIFFLZWUtil {

    private static final boolean debug = false;

    public TIFFLZWUtil() {
    }

    byte[] srcData;
    int srcIndex;

    byte[] dstData;
    int dstIndex = 0;

    byte stringTable[][];
    int tableIndex, bitsToGet = 9;

    int predictor, samplesPerPixel;
    int nextData = 0;
    int nextBits = 0;

    private static final int andTable[] = {
        511, 
        1023,
        2047,
        4095
    };

    public byte[] decode(byte[] data, int predictor, int samplesPerPixel,
                         int width, int height) throws IOException {
        if (data[0] == (byte)0x00 && data[1] == (byte)0x01) {
            throw new IIOException("TIFF 5.0-style LZW compression is not supported!");
        }

        this.srcData = data;
        this.srcIndex = 0;
        this.nextData = 0;
        this.nextBits = 0;

        this.dstData = new byte[8192];
        this.dstIndex = 0;

        initializeStringTable();

        int code, oldCode = 0;
        byte[] string;

        while ((code = getNextCode()) != 257) {
            if (code == 256) {
                initializeStringTable();
                code = getNextCode();
                if (code == 257) {
                    break;
                }

                writeString(stringTable[code]);
                oldCode = code;
            } else {
                if (code < tableIndex) {
                    string = stringTable[code];

                    writeString(string);
                    addStringToTable(stringTable[oldCode], string[0]); 
                    oldCode = code;
                } else {
                    string = stringTable[oldCode];
                    string = composeString(string, string[0]);
                    writeString(string);
                    addStringToTable(string);
                    oldCode = code;
                }
            }
        }

        if (predictor == 2) {
            
            int count;
            for (int j = 0; j < height; j++) {
                
                count = samplesPerPixel * (j * width + 1);
                
                for (int i = samplesPerPixel; i < width * samplesPerPixel; i++) {
                    
                    dstData[count] += dstData[count - samplesPerPixel];
                    count++;
                }
            }
        }

        byte[] newDstData = new byte[dstIndex];
        System.arraycopy(dstData, 0, newDstData, 0, dstIndex);
        return newDstData;
    }

    /**
     * Initialize the string table.
     */
    public void initializeStringTable() {
        stringTable = new byte[4096][];
        
        for (int i = 0; i < 256; i++) {
            stringTable[i] = new byte[1];
            stringTable[i][0] = (byte)i;
        }
        
        tableIndex = 258;
        bitsToGet = 9;
    }

    private void ensureCapacity(int bytesToAdd) {
        if (dstIndex + bytesToAdd > dstData.length) {
            byte[] newDstData = new byte[Math.max((int)(dstData.length*1.2f),
                                                  dstIndex + bytesToAdd)];
            System.arraycopy(dstData, 0, newDstData, 0, dstData.length);
            dstData = newDstData;
        }
    }

    /**
     * Write out the string just uncompressed.
     */
    public void writeString(byte string[]) {
        ensureCapacity(string.length);
        for (int i = 0; i < string.length; i++) {
            dstData[dstIndex++] = string[i];
        }
    }
    
    /**
     * Add a new string to the string table.
     */
    public void addStringToTable(byte oldString[], byte newString) {
        int length = oldString.length;
        byte string[] = new byte[length + 1];
        System.arraycopy(oldString, 0, string, 0, length);
        string[length] = newString;
        
        // Add this new String to the table
        stringTable[tableIndex++] = string;
        
        if (tableIndex == 511) {
            bitsToGet = 10;
        } else if (tableIndex == 1023) {
            bitsToGet = 11;
        } else if (tableIndex == 2047) {
            bitsToGet = 12;
        } 
    }

    /**
     * Add a new string to the string table.
     */
    public void addStringToTable(byte string[]) {
        // Add this new String to the table
        stringTable[tableIndex++] = string;
        
        if (tableIndex == 511) {
            bitsToGet = 10;
        } else if (tableIndex == 1023) {
            bitsToGet = 11;
        } else if (tableIndex == 2047) {
            bitsToGet = 12;
        } 
    }

    /**
     * Append <code>newString</code> to the end of <code>oldString</code>.
     */
    public byte[] composeString(byte oldString[], byte newString) {
        int length = oldString.length;
        byte string[] = new byte[length + 1];
        System.arraycopy(oldString, 0, string, 0, length);
        string[length] = newString;

        return string;
    }

    // Returns the next 9, 10, 11 or 12 bits
    public int getNextCode() {
        // Attempt to get the next code. The exception is caught to make
        // this robust to cases wherein the EndOfInformation code has been
        // omitted from a strip. Examples of such cases have been observed
        // in practice.

        try {
            nextData = (nextData << 8) | (srcData[srcIndex++] & 0xff);
            nextBits += 8;

            if (nextBits < bitsToGet) {
                nextData = (nextData << 8) | (srcData[srcIndex++] & 0xff);
                nextBits += 8;
            }

            int code =
                (nextData >> (nextBits - bitsToGet)) & andTable[bitsToGet - 9];
            nextBits -= bitsToGet;

            return code;
        } catch (ArrayIndexOutOfBoundsException e) {
            // Strip not terminated as expected: return EndOfInformation code.
            return 257;
        }
    }
}