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.cassandra.cql3.functions.types.utils;
  
  import java.lang.reflect.Constructor;
  import java.nio.ByteBuffer;
  import java.util.Arrays;
  
  /**
   * Simple utility methods to make working with bytes (blob) easier.
   */
  public final class Bytes
  {
  
      private Bytes()
      {
      }
  
      private static final byte[] charToByte = new byte[256];
      private static final char[] byteToChar = new char[16];
  
      static
      {
          for (char c = 0; c < charToByte.length; ++c)
          {
              if (c >= '0' && c <= '9') charToByte[c] = (byte) (c - '0');
              else if (c >= 'A' && c <= 'F') charToByte[c] = (byte) (c - 'A' + 10);
              else if (c >= 'a' && c <= 'f') charToByte[c] = (byte) (c - 'a' + 10);
              else charToByte[c] = (byte) -1;
          }
  
          for (int i = 0; i < 16; ++i)
          {
              byteToChar[i] = Integer.toHexString(i).charAt(0);
          }
      }
  
      /*
       * We use reflexion to get access to a String protected constructor
       * (if available) so we can build avoid copy when creating hex strings.
       * That's stolen from Cassandra's code.
       */
      private static final Constructor<String> stringConstructor;
  
      static
      {
          Constructor<String> c;
          try
          {
              c = String.class.getDeclaredConstructor(int.class, int.class, char[].class);
              c.setAccessible(true);
          }
          catch (Exception e)
          {
              c = null;
          }
          stringConstructor = c;
      }
  
      private static String wrapCharArray(char[] c)
      {
          if (c == null) return null;
  
          String s = null;
          if (stringConstructor != null)
          {
              try
              {
                  s = stringConstructor.newInstance(0, c.length, c);
              }
              catch (Exception e)
              {
                  // Swallowing as we'll just use a copying constructor
              }
          }
          return s == null ? new String(c) : s;
      }
  
      /**
       * Converts a blob to its CQL hex string representation.
       *
       * <p>A CQL blob string representation consist of the hexadecimal representation of the blob bytes
       * prefixed by "0x".
       *
       * @param bytes the blob/bytes to convert to a string.
       * @return the CQL string representation of {@code bytes}. If {@code bytes} is {@code null}, this
       * method returns {@code null}.
       */
      public static String toHexString(ByteBuffer bytes)
      {
          if (bytes == null) return null;
  
          if (bytes.remaining() == 0) return "0x";
  
          char[] array = new char[2 * (bytes.remaining() + 1)];
          array[0] = '0';
          array[1] = 'x';
          return toRawHexString(bytes, array, 2);
      }
  
      /**
       * Converts a blob to its CQL hex string representation.
       *
       * <p>A CQL blob string representation consist of the hexadecimal representation of the blob bytes
       * prefixed by "0x".
       *
       * @param byteArray the blob/bytes array to convert to a string.
       * @return the CQL string representation of {@code bytes}. If {@code bytes} is {@code null}, this
       * method returns {@code null}.
       */
      public static String toHexString(byte[] byteArray)
      {
          return toHexString(ByteBuffer.wrap(byteArray));
      }
  
      /**
       * Parse an hex string representing a CQL blob.
       *
       * <p>The input should be a valid representation of a CQL blob, i.e. it must start by "0x"
       * followed by the hexadecimal representation of the blob bytes.
       *
       * @param str the CQL blob string representation to parse.
       * @return the bytes corresponding to {@code str}. If {@code str} is {@code null}, this method
       * returns {@code null}.
       * @throws IllegalArgumentException if {@code str} is not a valid CQL blob string.
       */
      public static ByteBuffer fromHexString(String str)
      {
          if ((str.length() & 1) == 1)
              throw new IllegalArgumentException(
              "A CQL blob string must have an even length (since one byte is always 2 hexadecimal character)");
  
          if (str.charAt(0) != '0' || str.charAt(1) != 'x')
              throw new IllegalArgumentException("A CQL blob string must start with \"0x\"");
  
          return ByteBuffer.wrap(fromRawHexString(str, 2));
      }
  
      /**
       * Extract the content of the provided {@code ByteBuffer} as a byte array.
       *
       * <p>This method work with any type of {@code ByteBuffer} (direct and non-direct ones), but when
       * the {@code ByteBuffer} is backed by an array, this method will try to avoid copy when possible.
       * As a consequence, changes to the returned byte array may or may not reflect into the initial
       * {@code ByteBuffer}.
       *
       * @param bytes the buffer whose content to extract.
       * @return a byte array with the content of {@code bytes}. That array may be the array backing
       * {@code bytes} if this can avoid a copy.
       */
      public static byte[] getArray(ByteBuffer bytes)
      {
          int length = bytes.remaining();
  
          if (bytes.hasArray())
          {
              int boff = bytes.arrayOffset() + bytes.position();
              if (boff == 0 && length == bytes.array().length) return bytes.array();
              else return Arrays.copyOfRange(bytes.array(), boff, boff + length);
          }
          // else, DirectByteBuffer.get() is the fastest route
          byte[] array = new byte[length];
          bytes.duplicate().get(array);
          return array;
      }
  
      private static String toRawHexString(ByteBuffer bytes, char[] array, int offset)
      {
          int size = bytes.remaining();
          int bytesOffset = bytes.position();
          assert array.length >= offset + 2 * size;
          for (int i = 0; i < size; i++)
          {
              int bint = bytes.get(i + bytesOffset);
              array[offset + i * 2] = byteToChar[(bint & 0xf0) >> 4];
              array[offset + 1 + i * 2] = byteToChar[bint & 0x0f];
          }
          return wrapCharArray(array);
      }
  
      /**
       * Converts a CQL hex string representation into a byte array.
       *
       * <p>A CQL blob string representation consist of the hexadecimal representation of the blob
       * bytes.
       *
       * @param str       the string converted in hex representation.
       * @param strOffset he offset for starting the string conversion
       * @return the byte array which the String was representing.
       */
      private static byte[] fromRawHexString(String str, int strOffset)
      {
          byte[] bytes = new byte[(str.length() - strOffset) / 2];
          for (int i = 0; i < bytes.length; i++)
          {
              byte halfByte1 = charToByte[str.charAt(strOffset + i * 2)];
              byte halfByte2 = charToByte[str.charAt(strOffset + i * 2 + 1)];
              if (halfByte1 == -1 || halfByte2 == -1)
                  throw new IllegalArgumentException("Non-hex characters in " + str);
              bytes[i] = (byte) ((halfByte1 << 4) | halfByte2);
          }
          return bytes;
      }
  }
  