/*
    * This file is part of Waarp Project (named also Waarp or GG).
    *
    *  Copyright (c) 2019, Waarp SAS, and individual contributors by the @author
    *  tags. See the COPYRIGHT.txt in the distribution for a full listing of
    * individual contributors.
    *
    *  All Waarp Project is free software: you can redistribute it and/or
    * modify it under the terms of the GNU General Public License as published by
   * the Free Software Foundation, either version 3 of the License, or (at your
   * option) any later version.
   *
   * Waarp 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 for more details.
   *
   *  You should have received a copy of the GNU General Public License along with
   * Waarp . If not, see <http://www.gnu.org/licenses/>.
   */
  package org.waarp.common.utility;
  
  /**
   *
   */
  public final class Hexa {
    /**
     * HEX_CHARS
     */
    private static final char[] HEX_CHARS = {
        '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'a', 'b', 'c', 'd', 'e',
        'f',
    };
  
    private Hexa() {
    }
  
    public static byte asByte(char a, char b) {
      if (a >= HEX_CHARS[10]) {
        a -= HEX_CHARS[10] - 10;
      } else {
        a -= HEX_CHARS[0];
      }
      if (b >= HEX_CHARS[10]) {
        b -= HEX_CHARS[10] - 10;
      } else {
        b -= HEX_CHARS[0];
      }
      return (byte) ((a << 4) + b);
    }
  
    public static byte[] fromHex(final char[] hex) {
      final int size = hex.length / 2;
      final byte[] bytes = new byte[size];
      for (int i = 0, j = 0; i < size; ) {
        bytes[i++] = asByte(hex[j++], hex[j++]);
      }
      return bytes;
    }
  
    public static byte[] fromHex(final String hex) {
      final char[] chars = hex.toCharArray();
      final int size = chars.length / 2;
      final byte[] bytes = new byte[size];
      for (int i = 0, j = 0; i < size; ) {
        bytes[i++] = asByte(chars[j++], chars[j++]);
      }
      return bytes;
    }
  
    public static char getHighHex(final byte value) {
      return HEX_CHARS[(value & 0xF0) >> 4];
    }
  
    public static char getLowHex(final byte value) {
      return HEX_CHARS[value & 0x0F];
    }
  
    public static String toHex(final byte[] bytes) {
      final int size = bytes.length;
      final int b16size = size * 2;
      final char[] id = new char[b16size];
  
      // split each byte into 4 bit numbers and map to hex characters
      for (int i = 0, j = 0; i < size; i++) {
        id[j++] = HEX_CHARS[(bytes[i] & 0xF0) >> 4];
        id[j++] = HEX_CHARS[bytes[i] & 0x0F];
      }
      return new String(id);
    }
  }