/*

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

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 * 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.  Oracle designates this

 * particular file as subject to the "Classpath" exception as provided

 * by Oracle in the LICENSE file that accompanied this code.

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 * 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 Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

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package javax.imageio.plugins.jpeg;

import java.util.Arrays;

/**

 * A class encapsulating a single JPEG Huffman table.

 * Fields are provided for the "standard" tables taken

 * from Annex K of the JPEG specification.

 * These are the tables used as defaults.

 * <p>

 * For more information about the operation of the standard JPEG plug-in,

 * see the <A HREF="../../metadata/doc-files/jpeg_metadata.html">JPEG

 * metadata format specification and usage notes</A>

 */

public class JPEGHuffmanTable {

    /* The data for the publically defined tables, as specified in ITU T.81

     * JPEG specification section K3.3 and used in the IJG library.

     */

    private static final short[] StdDCLuminanceLengths = {

        0x00, 0x01, 0x05, 0x01, 0x01, 0x01, 0x01, 0x01,

        0x01, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,

    };

    private static final short[] StdDCLuminanceValues = {

        0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07,

        0x08, 0x09, 0x0a, 0x0b,

    };

    private static final short[] StdDCChrominanceLengths = {

        0x00, 0x03, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01,

        0x01, 0x01, 0x01, 0x00, 0x00, 0x00, 0x00, 0x00,

    };

    private static final short[] StdDCChrominanceValues = {

        0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07,

        0x08, 0x09, 0x0a, 0x0b,

    };

    private static final short[] StdACLuminanceLengths = {

        0x00, 0x02, 0x01, 0x03, 0x03, 0x02, 0x04, 0x03,

        0x05, 0x05, 0x04, 0x04, 0x00, 0x00, 0x01, 0x7d,

    };

    private static final short[] StdACLuminanceValues = {

        0x01, 0x02, 0x03, 0x00, 0x04, 0x11, 0x05, 0x12,

        0x21, 0x31, 0x41, 0x06, 0x13, 0x51, 0x61, 0x07,

        0x22, 0x71, 0x14, 0x32, 0x81, 0x91, 0xa1, 0x08,

        0x23, 0x42, 0xb1, 0xc1, 0x15, 0x52, 0xd1, 0xf0,

        0x24, 0x33, 0x62, 0x72, 0x82, 0x09, 0x0a, 0x16,

        0x17, 0x18, 0x19, 0x1a, 0x25, 0x26, 0x27, 0x28,

        0x29, 0x2a, 0x34, 0x35, 0x36, 0x37, 0x38, 0x39,

        0x3a, 0x43, 0x44, 0x45, 0x46, 0x47, 0x48, 0x49,

        0x4a, 0x53, 0x54, 0x55, 0x56, 0x57, 0x58, 0x59,

        0x5a, 0x63, 0x64, 0x65, 0x66, 0x67, 0x68, 0x69,

        0x6a, 0x73, 0x74, 0x75, 0x76, 0x77, 0x78, 0x79,

        0x7a, 0x83, 0x84, 0x85, 0x86, 0x87, 0x88, 0x89,

        0x8a, 0x92, 0x93, 0x94, 0x95, 0x96, 0x97, 0x98,

        0x99, 0x9a, 0xa2, 0xa3, 0xa4, 0xa5, 0xa6, 0xa7,

        0xa8, 0xa9, 0xaa, 0xb2, 0xb3, 0xb4, 0xb5, 0xb6,

        0xb7, 0xb8, 0xb9, 0xba, 0xc2, 0xc3, 0xc4, 0xc5,

        0xc6, 0xc7, 0xc8, 0xc9, 0xca, 0xd2, 0xd3, 0xd4,

        0xd5, 0xd6, 0xd7, 0xd8, 0xd9, 0xda, 0xe1, 0xe2,

        0xe3, 0xe4, 0xe5, 0xe6, 0xe7, 0xe8, 0xe9, 0xea,

        0xf1, 0xf2, 0xf3, 0xf4, 0xf5, 0xf6, 0xf7, 0xf8,

        0xf9, 0xfa,

    };

    private static final short[] StdACChrominanceLengths = {

        0x00, 0x02, 0x01, 0x02, 0x04, 0x04, 0x03, 0x04,

        0x07, 0x05, 0x04, 0x04, 0x00, 0x01, 0x02, 0x77,

    };

    private static final short[] StdACChrominanceValues = {

        0x00, 0x01, 0x02, 0x03, 0x11, 0x04, 0x05, 0x21,

        0x31, 0x06, 0x12, 0x41, 0x51, 0x07, 0x61, 0x71,

        0x13, 0x22, 0x32, 0x81, 0x08, 0x14, 0x42, 0x91,

        0xa1, 0xb1, 0xc1, 0x09, 0x23, 0x33, 0x52, 0xf0,

        0x15, 0x62, 0x72, 0xd1, 0x0a, 0x16, 0x24, 0x34,

        0xe1, 0x25, 0xf1, 0x17, 0x18, 0x19, 0x1a, 0x26,

        0x27, 0x28, 0x29, 0x2a, 0x35, 0x36, 0x37, 0x38,

        0x39, 0x3a, 0x43, 0x44, 0x45, 0x46, 0x47, 0x48,

        0x49, 0x4a, 0x53, 0x54, 0x55, 0x56, 0x57, 0x58,

        0x59, 0x5a, 0x63, 0x64, 0x65, 0x66, 0x67, 0x68,

        0x69, 0x6a, 0x73, 0x74, 0x75, 0x76, 0x77, 0x78,

        0x79, 0x7a, 0x82, 0x83, 0x84, 0x85, 0x86, 0x87,

        0x88, 0x89, 0x8a, 0x92, 0x93, 0x94, 0x95, 0x96,

        0x97, 0x98, 0x99, 0x9a, 0xa2, 0xa3, 0xa4, 0xa5,

        0xa6, 0xa7, 0xa8, 0xa9, 0xaa, 0xb2, 0xb3, 0xb4,

        0xb5, 0xb6, 0xb7, 0xb8, 0xb9, 0xba, 0xc2, 0xc3,

        0xc4, 0xc5, 0xc6, 0xc7, 0xc8, 0xc9, 0xca, 0xd2,

        0xd3, 0xd4, 0xd5, 0xd6, 0xd7, 0xd8, 0xd9, 0xda,

        0xe2, 0xe3, 0xe4, 0xe5, 0xe6, 0xe7, 0xe8, 0xe9,

        0xea, 0xf2, 0xf3, 0xf4, 0xf5, 0xf6, 0xf7, 0xf8,

        0xf9, 0xfa,

    };

    /**

     * The standard DC luminance Huffman table.

     */

    public static final JPEGHuffmanTable

        StdDCLuminance = new JPEGHuffmanTable(StdDCLuminanceLengths,

                                              StdDCLuminanceValues, false);

    /**

     * The standard DC chrominance Huffman table.

     */

    public static final JPEGHuffmanTable

        StdDCChrominance = new JPEGHuffmanTable(StdDCChrominanceLengths,

                                                StdDCChrominanceValues, false);

    /**

     * The standard AC luminance Huffman table.

     */

    public static final JPEGHuffmanTable

        StdACLuminance = new JPEGHuffmanTable(StdACLuminanceLengths,

                                              StdACLuminanceValues, false);

    /**

     * The standard AC chrominance Huffman table.

     */

    public static final JPEGHuffmanTable

        StdACChrominance = new JPEGHuffmanTable(StdACChrominanceLengths,

                                                StdACChrominanceValues, false);

    private short[] lengths;

    private short[] values;

    /**

     * Creates a Huffman table and initializes it. The input arrays are copied.

     * The arrays must describe a possible Huffman table.

     * For example, 3 codes cannot be expressed with a single bit.

     *

     * @param lengths an array of {@code short}s where <code>lengths[k]</code>

     * is equal to the number of values with corresponding codes of

     * length <code>k + 1</code> bits.

     * @param values an array of shorts containing the values in

     * order of increasing code length.

     * @throws IllegalArgumentException if <code>lengths</code> or

     * <code>values</code> are null, the length of <code>lengths</code> is

     * greater than 16, the length of <code>values</code> is greater than 256,

     * if any value in <code>lengths</code> or <code>values</code> is less

     * than zero, or if the arrays do not describe a valid Huffman table.

     */

    public JPEGHuffmanTable(short[] lengths, short[] values) {

        if (lengths == null || values == null ||

            lengths.length == 0 || values.length == 0 ||

            lengths.length > 16 || values.length > 256) {

            throw new IllegalArgumentException("Illegal lengths or values");

        }

        for (int i = 0; i<lengths.length; i++) {

            if (lengths[i] < 0) {

                throw new IllegalArgumentException("lengths["+i+"] < 0");

            }

        }

        for (int i = 0; i<values.length; i++) {

            if (values[i] < 0) {

                throw new IllegalArgumentException("values["+i+"] < 0");

            }

        }

        this.lengths = Arrays.copyOf(lengths, lengths.length);

        this.values = Arrays.copyOf(values, values.length);

        validate();

    }

    private void validate() {

        int sumOfLengths = 0;

        for (int i=0; i<lengths.length; i++) {

            sumOfLengths += lengths[i];

        }

        if (sumOfLengths != values.length) {

            throw new IllegalArgumentException("lengths do not correspond " +

                                               "to length of value table");

        }

    }

    /* Internal version which avoids the overhead of copying and checking */

    private JPEGHuffmanTable(short[] lengths, short[] values, boolean copy) {

        if (copy) {

            this.lengths = Arrays.copyOf(lengths, lengths.length);

            this.values = Arrays.copyOf(values, values.length);

        } else {

            this.lengths = lengths;

            this.values = values;

        }

    }

    /**

     * Returns an array of <code>short</code>s containing the number of values

     * for each length in the Huffman table. The returned array is a copy.

     *

     * @return a <code>short</code> array where <code>array[k-1]</code>

     * is equal to the number of values in the table of length <code>k</code>.

     * @see #getValues

     */

    public short[] getLengths() {

        return Arrays.copyOf(lengths, lengths.length);

    }

    /**

     * Returns an array of <code>short</code>s containing the values arranged

     * by increasing length of their corresponding codes.

     * The interpretation of the array is dependent on the values returned

     * from <code>getLengths</code>. The returned array is a copy.

     *

     * @return a <code>short</code> array of values.

     * @see #getLengths

     */

    public short[] getValues() {

        return Arrays.copyOf(values, values.length);

    }

    /**

     * Returns a {@code String} representing this Huffman table.

     * @return a {@code String} representing this Huffman table.

     */

    public String toString() {

        String ls = System.getProperty("line.separator", "\n");

        StringBuilder sb = new StringBuilder("JPEGHuffmanTable");

        sb.append(ls).append("lengths:");

        for (int i=0; i<lengths.length; i++) {

            sb.append(" ").append(lengths[i]);

        }

        sb.append(ls).append("values:");

        for (int i=0; i<values.length; i++) {

            sb.append(" ").append(values[i]);

        }

        return sb.toString();

    }

}