/*
 * ====================================================================
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *   http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 * KIND, either express or implied.  See the License for the
 * specific language governing permissions and limitations
 * under the License.
 * ====================================================================
 *
 * This software consists of voluntary contributions made by many
 * individuals on behalf of the Apache Software Foundation.  For more
 * information on the Apache Software Foundation, please see
 * <http://www.apache.org/>.
 *
 */

package org.apache.hc.core5.http2.hpack;

import org.apache.hc.core5.annotation.Internal;

/**
 * This Huffman codec implementation has been derived from Twitter HPack project
 * (https://github.com/twitter/hpack)
 */
@Internal
public final class Huffman {

    private Huffman() {
        // Do not allow utility class to be instantiated.
    }

    static final int[] CODES = {
            0x1ff8,
            0x7fffd8,
            0xfffffe2,
            0xfffffe3,
            0xfffffe4,
            0xfffffe5,
            0xfffffe6,
            0xfffffe7,
            0xfffffe8,
            0xffffea,
            0x3ffffffc,
            0xfffffe9,
            0xfffffea,
            0x3ffffffd,
            0xfffffeb,
            0xfffffec,
            0xfffffed,
            0xfffffee,
            0xfffffef,
            0xffffff0,
            0xffffff1,
            0xffffff2,
            0x3ffffffe,
            0xffffff3,
            0xffffff4,
            0xffffff5,
            0xffffff6,
            0xffffff7,
            0xffffff8,
            0xffffff9,
            0xffffffa,
            0xffffffb,
            0x14,
            0x3f8,
            0x3f9,
            0xffa,
            0x1ff9,
            0x15,
            0xf8,
            0x7fa,
            0x3fa,
            0x3fb,
            0xf9,
            0x7fb,
            0xfa,
            0x16,
            0x17,
            0x18,
            0x0,
            0x1,
            0x2,
            0x19,
            0x1a,
            0x1b,
            0x1c,
            0x1d,
            0x1e,
            0x1f,
            0x5c,
            0xfb,
            0x7ffc,
            0x20,
            0xffb,
            0x3fc,
            0x1ffa,
            0x21,
            0x5d,
            0x5e,
            0x5f,
            0x60,
            0x61,
            0x62,
            0x63,
            0x64,
            0x65,
            0x66,
            0x67,
            0x68,
            0x69,
            0x6a,
            0x6b,
            0x6c,
            0x6d,
            0x6e,
            0x6f,
            0x70,
            0x71,
            0x72,
            0xfc,
            0x73,
            0xfd,
            0x1ffb,
            0x7fff0,
            0x1ffc,
            0x3ffc,
            0x22,
            0x7ffd,
            0x3,
            0x23,
            0x4,
            0x24,
            0x5,
            0x25,
            0x26,
            0x27,
            0x6,
            0x74,
            0x75,
            0x28,
            0x29,
            0x2a,
            0x7,
            0x2b,
            0x76,
            0x2c,
            0x8,
            0x9,
            0x2d,
            0x77,
            0x78,
            0x79,
            0x7a,
            0x7b,
            0x7ffe,
            0x7fc,
            0x3ffd,
            0x1ffd,
            0xffffffc,
            0xfffe6,
            0x3fffd2,
            0xfffe7,
            0xfffe8,
            0x3fffd3,
            0x3fffd4,
            0x3fffd5,
            0x7fffd9,
            0x3fffd6,
            0x7fffda,
            0x7fffdb,
            0x7fffdc,
            0x7fffdd,
            0x7fffde,
            0xffffeb,
            0x7fffdf,
            0xffffec,
            0xffffed,
            0x3fffd7,
            0x7fffe0,
            0xffffee,
            0x7fffe1,
            0x7fffe2,
            0x7fffe3,
            0x7fffe4,
            0x1fffdc,
            0x3fffd8,
            0x7fffe5,
            0x3fffd9,
            0x7fffe6,
            0x7fffe7,
            0xffffef,
            0x3fffda,
            0x1fffdd,
            0xfffe9,
            0x3fffdb,
            0x3fffdc,
            0x7fffe8,
            0x7fffe9,
            0x1fffde,
            0x7fffea,
            0x3fffdd,
            0x3fffde,
            0xfffff0,
            0x1fffdf,
            0x3fffdf,
            0x7fffeb,
            0x7fffec,
            0x1fffe0,
            0x1fffe1,
            0x3fffe0,
            0x1fffe2,
            0x7fffed,
            0x3fffe1,
            0x7fffee,
            0x7fffef,
            0xfffea,
            0x3fffe2,
            0x3fffe3,
            0x3fffe4,
            0x7ffff0,
            0x3fffe5,
            0x3fffe6,
            0x7ffff1,
            0x3ffffe0,
            0x3ffffe1,
            0xfffeb,
            0x7fff1,
            0x3fffe7,
            0x7ffff2,
            0x3fffe8,
            0x1ffffec,
            0x3ffffe2,
            0x3ffffe3,
            0x3ffffe4,
            0x7ffffde,
            0x7ffffdf,
            0x3ffffe5,
            0xfffff1,
            0x1ffffed,
            0x7fff2,
            0x1fffe3,
            0x3ffffe6,
            0x7ffffe0,
            0x7ffffe1,
            0x3ffffe7,
            0x7ffffe2,
            0xfffff2,
            0x1fffe4,
            0x1fffe5,
            0x3ffffe8,
            0x3ffffe9,
            0xffffffd,
            0x7ffffe3,
            0x7ffffe4,
            0x7ffffe5,
            0xfffec,
            0xfffff3,
            0xfffed,
            0x1fffe6,
            0x3fffe9,
            0x1fffe7,
            0x1fffe8,
            0x7ffff3,
            0x3fffea,
            0x3fffeb,
            0x1ffffee,
            0x1ffffef,
            0xfffff4,
            0xfffff5,
            0x3ffffea,
            0x7ffff4,
            0x3ffffeb,
            0x7ffffe6,
            0x3ffffec,
            0x3ffffed,
            0x7ffffe7,
            0x7ffffe8,
            0x7ffffe9,
            0x7ffffea,
            0x7ffffeb,
            0xffffffe,
            0x7ffffec,
            0x7ffffed,
            0x7ffffee,
            0x7ffffef,
            0x7fffff0,
            0x3ffffee,
            0x3fffffff
    };

    static final byte[] LENGTHS = {
            13, 23, 28, 28, 28, 28, 28, 28, 28, 24, 30, 28, 28, 30, 28, 28,
            28, 28, 28, 28, 28, 28, 30, 28, 28, 28, 28, 28, 28, 28, 28, 28,
            6, 10, 10, 12, 13, 6, 8, 11, 10, 10, 8, 11, 8, 6, 6, 6,
            5, 5, 5, 6, 6, 6, 6, 6, 6, 6, 7, 8, 15, 6, 12, 10,
            13, 6, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7,
            7, 7, 7, 7, 7, 7, 7, 7, 8, 7, 8, 13, 19, 13, 14, 6,
            15, 5, 6, 5, 6, 5, 6, 6, 6, 5, 7, 7, 6, 6, 6, 5,
            6, 7, 6, 5, 5, 6, 7, 7, 7, 7, 7, 15, 11, 14, 13, 28,
            20, 22, 20, 20, 22, 22, 22, 23, 22, 23, 23, 23, 23, 23, 24, 23,
            24, 24, 22, 23, 24, 23, 23, 23, 23, 21, 22, 23, 22, 23, 23, 24,
            22, 21, 20, 22, 22, 23, 23, 21, 23, 22, 22, 24, 21, 22, 23, 23,
            21, 21, 22, 21, 23, 22, 23, 23, 20, 22, 22, 22, 23, 22, 22, 23,
            26, 26, 20, 19, 22, 23, 22, 25, 26, 26, 26, 27, 27, 26, 24, 25,
            19, 21, 26, 27, 27, 26, 27, 24, 21, 21, 26, 26, 28, 27, 27, 27,
            20, 24, 20, 21, 22, 21, 21, 23, 22, 22, 25, 25, 24, 24, 26, 23,
            26, 27, 26, 26, 27, 27, 27, 27, 27, 28, 27, 27, 27, 27, 27, 26,
            30
    };

    static final int EOS = 256;

    static final HuffmanEncoder ENCODER = new HuffmanEncoder(CODES, LENGTHS);

    static final HuffmanDecoder DECODER = new HuffmanDecoder(CODES, LENGTHS);

}