content: /*
   * 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.
   */
  
  package org.apache.commons.codec.binary;
  
  import java.io.UnsupportedEncodingException;
  
  import org.apache.commons.codec.BinaryDecoder;
  import org.apache.commons.codec.BinaryEncoder;
  import org.apache.commons.codec.CharEncoding;
  import org.apache.commons.codec.DecoderException;
  import org.apache.commons.codec.EncoderException;
  
  /**
   * Converts hexadecimal Strings. The charset used for certain operation can be set, the default is set in
   * {@link #DEFAULT_CHARSET_NAME}
   * 
   * @since 1.1
   * @author Apache Software Foundation
   * @version $Id: Hex.java 1080701 2011-03-11 17:52:27Z ggregory $
   */
  public class Hex implements BinaryEncoder, BinaryDecoder {
  
      /**
       * Default charset name is {@link CharEncoding#UTF_8}
       * 
       * @since 1.4
       */
      public static final String DEFAULT_CHARSET_NAME = CharEncoding.UTF_8;
  
      /**
       * Used to build output as Hex
       */
      private static final char[] DIGITS_LOWER = {'0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'a', 'b', 'c', 'd', 'e', 'f'};
  
      /**
       * Used to build output as Hex
       */
      private static final char[] DIGITS_UPPER = {'0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'A', 'B', 'C', 'D', 'E', 'F'};
  
      /**
       * Converts an array of characters representing hexadecimal values into an array of bytes of those same values. The
       * returned array will be half the length of the passed array, as it takes two characters to represent any given
       * byte. An exception is thrown if the passed char array has an odd number of elements.
       * 
       * @param data
       *            An array of characters containing hexadecimal digits
       * @return A byte array containing binary data decoded from the supplied char array.
       * @throws DecoderException
       *             Thrown if an odd number or illegal of characters is supplied
       */
      public static byte[] decodeHex(char[] data) throws DecoderException {
  
          int len = data.length;
  
          if ((len & 0x01) != 0) {
              throw new DecoderException("Odd number of characters.");
          }
  
          byte[] out = new byte[len >> 1];
  
          // two characters form the hex value.
          for (int i = 0, j = 0; j < len; i++) {
              int f = toDigit(data[j], j) << 4;
              j++;
              f = f | toDigit(data[j], j);
              j++;
              out[i] = (byte) (f & 0xFF);
          }
  
          return out;
      }
  
      /**
       * Converts an array of bytes into an array of characters representing the hexadecimal values of each byte in order.
       * The returned array will be double the length of the passed array, as it takes two characters to represent any
       * given byte.
       * 
       * @param data
       *            a byte[] to convert to Hex characters
       * @return A char[] containing hexadecimal characters
       */
      public static char[] encodeHex(byte[] data) {
          return encodeHex(data, true);
      }
  
      /**
       * Converts an array of bytes into an array of characters representing the hexadecimal values of each byte in order.
       * The returned array will be double the length of the passed array, as it takes two characters to represent any
       * given byte.
       * 
       * @param data
       *            a byte[] to convert to Hex characters
       * @param toLowerCase
       *            <code>true</code> converts to lowercase, <code>false</code> to uppercase
       * @return A char[] containing hexadecimal characters
       * @since 1.4
       */
      public static char[] encodeHex(byte[] data, boolean toLowerCase) {
          return encodeHex(data, toLowerCase ? DIGITS_LOWER : DIGITS_UPPER);
      }
  
      /**
       * Converts an array of bytes into an array of characters representing the hexadecimal values of each byte in order.
       * The returned array will be double the length of the passed array, as it takes two characters to represent any
       * given byte.
       * 
       * @param data
       *            a byte[] to convert to Hex characters
       * @param toDigits
       *            the output alphabet
       * @return A char[] containing hexadecimal characters
       * @since 1.4
       */
      protected static char[] encodeHex(byte[] data, char[] toDigits) {
          int l = data.length;
          char[] out = new char[l << 1];
          // two characters form the hex value.
          for (int i = 0, j = 0; i < l; i++) {
              out[j++] = toDigits[(0xF0 & data[i]) >>> 4];
              out[j++] = toDigits[0x0F & data[i]];
          }
          return out;
      }
  
      /**
       * Converts an array of bytes into a String representing the hexadecimal values of each byte in order. The returned
       * String will be double the length of the passed array, as it takes two characters to represent any given byte.
       * 
       * @param data
       *            a byte[] to convert to Hex characters
       * @return A String containing hexadecimal characters
       * @since 1.4
       */
      public static String encodeHexString(byte[] data) {
          return new String(encodeHex(data));
      }
  
      /**
       * Converts a hexadecimal character to an integer.
       * 
       * @param ch
       *            A character to convert to an integer digit
       * @param index
       *            The index of the character in the source
       * @return An integer
       * @throws DecoderException
       *             Thrown if ch is an illegal hex character
       */
      protected static int toDigit(char ch, int index) throws DecoderException {
          int digit = Character.digit(ch, 16);
          if (digit == -1) {
              throw new DecoderException("Illegal hexadecimal character " + ch + " at index " + index);
          }
          return digit;
      }
  
      private final String charsetName;
  
      /**
       * Creates a new codec with the default charset name {@link #DEFAULT_CHARSET_NAME}
       */
      public Hex() {
          // use default encoding
          this.charsetName = DEFAULT_CHARSET_NAME;
      }
  
      /**
       * Creates a new codec with the given charset name.
       * 
       * @param csName
       *            the charset name.
       * @since 1.4
       */
      public Hex(String csName) {
          this.charsetName = csName;
      }
  
      /**
       * Converts an array of character bytes representing hexadecimal values into an array of bytes of those same values.
       * The returned array will be half the length of the passed array, as it takes two characters to represent any given
       * byte. An exception is thrown if the passed char array has an odd number of elements.
       * 
       * @param array
       *            An array of character bytes containing hexadecimal digits
       * @return A byte array containing binary data decoded from the supplied byte array (representing characters).
       * @throws DecoderException
       *             Thrown if an odd number of characters is supplied to this function
       * @see #decodeHex(char[])
       */
      public byte[] decode(byte[] array) throws DecoderException {
          try {
              return decodeHex(new String(array, getCharsetName()).toCharArray());
          } catch (UnsupportedEncodingException e) {
              throw new DecoderException(e.getMessage(), e);
          }
      }
  
      /**
       * Converts a String or an array of character bytes representing hexadecimal values into an array of bytes of those
       * same values. The returned array will be half the length of the passed String or array, as it takes two characters
       * to represent any given byte. An exception is thrown if the passed char array has an odd number of elements.
       * 
       * @param object
       *            A String or, an array of character bytes containing hexadecimal digits
       * @return A byte array containing binary data decoded from the supplied byte array (representing characters).
       * @throws DecoderException
       *             Thrown if an odd number of characters is supplied to this function or the object is not a String or
       *             char[]
       * @see #decodeHex(char[])
       */
      public Object decode(Object object) throws DecoderException {
          try {
              char[] charArray = object instanceof String ? ((String) object).toCharArray() : (char[]) object;
              return decodeHex(charArray);
          } catch (ClassCastException e) {
              throw new DecoderException(e.getMessage(), e);
          }
      }
  
      /**
       * Converts an array of bytes into an array of bytes for the characters representing the hexadecimal values of each
       * byte in order. The returned array will be double the length of the passed array, as it takes two characters to
       * represent any given byte.
       * <p>
       * The conversion from hexadecimal characters to the returned bytes is performed with the charset named by
       * {@link #getCharsetName()}.
       * </p>
       * 
       * @param array
       *            a byte[] to convert to Hex characters
       * @return A byte[] containing the bytes of the hexadecimal characters
       * @throws IllegalStateException
       *             if the charsetName is invalid. This API throws {@link IllegalStateException} instead of
       *             {@link UnsupportedEncodingException} for backward compatibility.
       * @see #encodeHex(byte[])
       */
      public byte[] encode(byte[] array) {
          return StringUtils.getBytesUnchecked(encodeHexString(array), getCharsetName());
      }
  
      /**
       * Converts a String or an array of bytes into an array of characters representing the hexadecimal values of each
       * byte in order. The returned array will be double the length of the passed String or array, as it takes two
       * characters to represent any given byte.
       * <p>
       * The conversion from hexadecimal characters to bytes to be encoded to performed with the charset named by
       * {@link #getCharsetName()}.
       * </p>
       * 
       * @param object
       *            a String, or byte[] to convert to Hex characters
       * @return A char[] containing hexadecimal characters
       * @throws EncoderException
       *             Thrown if the given object is not a String or byte[]
       * @see #encodeHex(byte[])
       */
      public Object encode(Object object) throws EncoderException {
          try {
              byte[] byteArray = object instanceof String ? ((String) object).getBytes(getCharsetName()) : (byte[]) object;
              return encodeHex(byteArray);
          } catch (ClassCastException e) {
              throw new EncoderException(e.getMessage(), e);
          } catch (UnsupportedEncodingException e) {
              throw new EncoderException(e.getMessage(), e);
          }
      }
  
      /**
       * Gets the charset name.
       * 
       * @return the charset name.
       * @since 1.4
       */
      public String getCharsetName() {
          return this.charsetName;
      }
  
      /**
       * Returns a string representation of the object, which includes the charset name.
       * 
       * @return a string representation of the object.
       */
      public String toString() {
          return super.toString() + "[charsetName=" + this.charsetName + "]";
      }
  }
  