/*
    * 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.hadoop.hbase.util;
  
  import java.io.ByteArrayOutputStream;
  import java.io.DataInputStream;
  import java.io.IOException;
  import java.io.InputStream;
  import java.io.OutputStream;
  import java.nio.ByteBuffer;
  
  import org.apache.hadoop.hbase.classification.InterfaceAudience;
  import org.apache.hadoop.hbase.classification.InterfaceStability;
  import org.apache.hadoop.io.IOUtils;
  import org.apache.hadoop.io.WritableUtils;
  
  /**
   * Utility functions for working with byte buffers, such as reading/writing
   * variable-length long numbers.
   */
  @InterfaceAudience.Public
  @InterfaceStability.Evolving
  public final class ByteBufferUtils {
  
    // "Compressed integer" serialization helper constants.
    private final static int VALUE_MASK = 0x7f;
    private final static int NEXT_BIT_SHIFT = 7;
    private final static int NEXT_BIT_MASK = 1 << 7;
  
    private ByteBufferUtils() {
    }
  
    /**
     * Similar to {@link WritableUtils#writeVLong(java.io.DataOutput, long)},
     * but writes to a {@link ByteBuffer}.
     */
    public static void writeVLong(ByteBuffer out, long i) {
      if (i >= -112 && i <= 127) {
        out.put((byte) i);
        return;
      }
  
      int len = -112;
      if (i < 0) {
        i ^= -1L; // take one's complement
        len = -120;
      }
  
      long tmp = i;
      while (tmp != 0) {
        tmp = tmp >> 8;
        len--;
      }
  
      out.put((byte) len);
  
      len = (len < -120) ? -(len + 120) : -(len + 112);
  
      for (int idx = len; idx != 0; idx--) {
        int shiftbits = (idx - 1) * 8;
        long mask = 0xFFL << shiftbits;
        out.put((byte) ((i & mask) >> shiftbits));
      }
    }
  
    /**
     * Similar to {@link WritableUtils#readVLong(DataInput)} but reads from a
     * {@link ByteBuffer}.
     */
    public static long readVLong(ByteBuffer in) {
      byte firstByte = in.get();
      int len = WritableUtils.decodeVIntSize(firstByte);
      if (len == 1) {
        return firstByte;
      }
      long i = 0;
      for (int idx = 0; idx < len-1; idx++) {
        byte b = in.get();
        i = i << 8;
        i = i | (b & 0xFF);
      }
      return (WritableUtils.isNegativeVInt(firstByte) ? (i ^ -1L) : i);
    }
  
  
   /**
    * Put in buffer integer using 7 bit encoding. For each written byte:
    * 7 bits are used to store value
    * 1 bit is used to indicate whether there is next bit.
    * @param value Int to be compressed.
    * @param out Where to put compressed data
    * @return Number of bytes written.
    * @throws IOException on stream error
    */
    public static int putCompressedInt(OutputStream out, final int value)
       throws IOException {
     int i = 0;
     int tmpvalue = value;
     do {
       byte b = (byte) (tmpvalue & VALUE_MASK);
       tmpvalue >>>= NEXT_BIT_SHIFT;
       if (tmpvalue != 0) {
         b |= (byte) NEXT_BIT_MASK;
       }
       out.write(b);
       i++;
     } while (tmpvalue != 0);
     return i;
   }
 
    /**
     * Put in output stream 32 bit integer (Big Endian byte order).
     * @param out Where to put integer.
     * @param value Value of integer.
     * @throws IOException On stream error.
     */
    public static void putInt(OutputStream out, final int value)
        throws IOException {
      for (int i = Bytes.SIZEOF_INT - 1; i >= 0; --i) {
        out.write((byte) (value >>> (i * 8)));
      }
    }
 
   /**
    * Copy the data to the output stream and update position in buffer.
    * @param out the stream to write bytes to
    * @param in the buffer to read bytes from
    * @param length the number of bytes to copy
    */
   public static void moveBufferToStream(OutputStream out, ByteBuffer in,
       int length) throws IOException {
     copyBufferToStream(out, in, in.position(), length);
     skip(in, length);
   }
 
   /**
    * Copy data from a buffer to an output stream. Does not update the position
    * in the buffer.
    * @param out the stream to write bytes to
    * @param in the buffer to read bytes from
    * @param offset the offset in the buffer (from the buffer's array offset)
    *      to start copying bytes from
    * @param length the number of bytes to copy
    */
   public static void copyBufferToStream(OutputStream out, ByteBuffer in,
       int offset, int length) throws IOException {
     if (in.hasArray()) {
       out.write(in.array(), in.arrayOffset() + offset,
           length);
     } else {
       for (int i = 0; i < length; ++i) {
         out.write(in.get(offset + i));
       }
     }
   }
 
   public static int putLong(OutputStream out, final long value,
       final int fitInBytes) throws IOException {
     long tmpValue = value;
     for (int i = 0; i < fitInBytes; ++i) {
       out.write((byte) (tmpValue & 0xff));
       tmpValue >>>= 8;
     }
     return fitInBytes;
   }
 
   /**
    * Check how many bytes are required to store value.
    * @param value Value which size will be tested.
    * @return How many bytes are required to store value.
    */
   public static int longFitsIn(final long value) {
     if (value < 0) {
       return 8;
     }
 
     if (value < (1l << 4 * 8)) {
       // no more than 4 bytes
       if (value < (1l << 2 * 8)) {
         if (value < (1l << 1 * 8)) {
           return 1;
         }
         return 2;
       }
       if (value < (1l << 3 * 8)) {
         return 3;
       }
       return 4;
     }
     // more than 4 bytes
     if (value < (1l << 6 * 8)) {
       if (value < (1l << 5 * 8)) {
         return 5;
       }
       return 6;
     }
     if (value < (1l << 7 * 8)) {
       return 7;
     }
     return 8;
   }
 
   /**
    * Check how many bytes is required to store value.
    * @param value Value which size will be tested.
    * @return How many bytes are required to store value.
    */
   public static int intFitsIn(final int value) {
     if (value < 0) {
       return 4;
     }
 
     if (value < (1 << 2 * 8)) {
       if (value < (1 << 1 * 8)) {
         return 1;
       }
       return 2;
     }
     if (value <= (1 << 3 * 8)) {
       return 3;
     }
     return 4;
   }
 
   /**
    * Read integer from stream coded in 7 bits and increment position.
    * @return the integer that has been read
    * @throws IOException
    */
   public static int readCompressedInt(InputStream input)
       throws IOException {
     int result = 0;
     int i = 0;
     byte b;
     do {
       b = (byte) input.read();
       result += (b & VALUE_MASK) << (NEXT_BIT_SHIFT * i);
       i++;
       if (i > Bytes.SIZEOF_INT + 1) {
         throw new IllegalStateException(
             "Corrupted compressed int (too long: " + (i + 1) + " bytes)");
       }
     } while (0 != (b & NEXT_BIT_MASK));
     return result;
   }
 
   /**
    * Read integer from buffer coded in 7 bits and increment position.
    * @return Read integer.
    */
   public static int readCompressedInt(ByteBuffer buffer) {
     byte b = buffer.get();
     if ((b & NEXT_BIT_MASK) != 0) {
       return (b & VALUE_MASK) + (readCompressedInt(buffer) << NEXT_BIT_SHIFT);
     }
     return b & VALUE_MASK;
   }
 
   /**
    * Read long which was written to fitInBytes bytes and increment position.
    * @param fitInBytes In how many bytes given long is stored.
    * @return The value of parsed long.
    * @throws IOException
    */
   public static long readLong(InputStream in, final int fitInBytes)
       throws IOException {
     long tmpLong = 0;
     for (int i = 0; i < fitInBytes; ++i) {
       tmpLong |= (in.read() & 0xffl) << (8 * i);
     }
     return tmpLong;
   }
 
   /**
    * Read long which was written to fitInBytes bytes and increment position.
    * @param fitInBytes In how many bytes given long is stored.
    * @return The value of parsed long.
    */
   public static long readLong(ByteBuffer in, final int fitInBytes) {
     long tmpLength = 0;
     for (int i = 0; i < fitInBytes; ++i) {
       tmpLength |= (in.get() & 0xffl) << (8l * i);
     }
     return tmpLength;
   }
 
   /**
    * Copy the given number of bytes from the given stream and put it at the
    * current position of the given buffer, updating the position in the buffer.
    * @param out the buffer to write data to
    * @param in the stream to read data from
    * @param length the number of bytes to read/write
    */
   public static void copyFromStreamToBuffer(ByteBuffer out,
       DataInputStream in, int length) throws IOException {
     if (out.hasArray()) {
       in.readFully(out.array(), out.position() + out.arrayOffset(),
           length);
       skip(out, length);
     } else {
       for (int i = 0; i < length; ++i) {
         out.put(in.readByte());
       }
     }
   }
 
   /**
    * Copy from the InputStream to a new heap ByteBuffer until the InputStream is exhausted.
    */
   public static ByteBuffer drainInputStreamToBuffer(InputStream is) throws IOException {
     ByteArrayOutputStream baos = new ByteArrayOutputStream(4096);
     IOUtils.copyBytes(is, baos, 4096, true);
     ByteBuffer buffer = ByteBuffer.wrap(baos.toByteArray());
     buffer.rewind();
     return buffer;
   }
 
   /**
    * Copy from one buffer to another from given offset.
    * <p>
    * Note : This will advance the position marker of {@code out} but not change the position maker
    * for {@code in}
    * @param out destination buffer
    * @param in source buffer
    * @param sourceOffset offset in the source buffer
    * @param length how many bytes to copy
    */
   public static void copyFromBufferToBuffer(ByteBuffer out,
       ByteBuffer in, int sourceOffset, int length) {
     if (in.hasArray() && out.hasArray()) {
       System.arraycopy(in.array(), sourceOffset + in.arrayOffset(),
           out.array(), out.position() +
           out.arrayOffset(), length);
       skip(out, length);
     } else {
       for (int i = 0; i < length; ++i) {
         out.put(in.get(sourceOffset + i));
       }
     }
   }
 
   /**
    * Copy from one buffer to another from given offset. This will be absolute positional copying and
    * won't affect the position of any of the buffers.
    * @param out
    * @param in
    * @param sourceOffset
    * @param destinationOffset
    * @param length
    */
   public static void copyFromBufferToBuffer(ByteBuffer out, ByteBuffer in, int sourceOffset,
       int destinationOffset, int length) {
     if (in.hasArray() && out.hasArray()) {
       System.arraycopy(in.array(), sourceOffset + in.arrayOffset(), out.array(), out.arrayOffset()
           + destinationOffset, length);
     } else {
       for (int i = 0; i < length; ++i) {
         out.put((destinationOffset + i), in.get(sourceOffset + i));
       }
     }
   }
 
   /**
    * Find length of common prefix of two parts in the buffer
    * @param buffer Where parts are located.
    * @param offsetLeft Offset of the first part.
    * @param offsetRight Offset of the second part.
    * @param limit Maximal length of common prefix.
    * @return Length of prefix.
    */
   public static int findCommonPrefix(ByteBuffer buffer, int offsetLeft,
       int offsetRight, int limit) {
     int prefix = 0;
 
     for (; prefix < limit; ++prefix) {
       if (buffer.get(offsetLeft + prefix) != buffer.get(offsetRight + prefix)) {
         break;
       }
     }
 
     return prefix;
   }
 
   /**
    * Find length of common prefix in two arrays.
    * @param left Array to be compared.
    * @param leftOffset Offset in left array.
    * @param leftLength Length of left array.
    * @param right Array to be compared.
    * @param rightOffset Offset in right array.
    * @param rightLength Length of right array.
    */
   public static int findCommonPrefix(
       byte[] left, int leftOffset, int leftLength,
       byte[] right, int rightOffset, int rightLength) {
     int length = Math.min(leftLength, rightLength);
     int result = 0;
 
     while (result < length &&
         left[leftOffset + result] == right[rightOffset + result]) {
       result++;
     }
 
     return result;
   }
 
   /**
    * Check whether two parts in the same buffer are equal.
    * @param buffer In which buffer there are parts
    * @param offsetLeft Beginning of first part.
    * @param lengthLeft Length of the first part.
    * @param offsetRight Beginning of the second part.
    * @param lengthRight Length of the second part.
    * @return True if equal
    */
   public static boolean arePartsEqual(ByteBuffer buffer,
       int offsetLeft, int lengthLeft,
       int offsetRight, int lengthRight) {
     if (lengthLeft != lengthRight) {
       return false;
     }
 
     if (buffer.hasArray()) {
       return 0 == Bytes.compareTo(
           buffer.array(), buffer.arrayOffset() + offsetLeft, lengthLeft,
           buffer.array(), buffer.arrayOffset() + offsetRight, lengthRight);
     }
 
     for (int i = 0; i < lengthRight; ++i) {
       if (buffer.get(offsetLeft + i) != buffer.get(offsetRight + i)) {
         return false;
       }
     }
     return true;
   }
 
   /**
    * Increment position in buffer.
    * @param buffer In this buffer.
    * @param length By that many bytes.
    */
   public static void skip(ByteBuffer buffer, int length) {
     buffer.position(buffer.position() + length);
   }
 
   public static void extendLimit(ByteBuffer buffer, int numBytes) {
     buffer.limit(buffer.limit() + numBytes);
   }
 
   /**
    * Copy the bytes from position to limit into a new byte[] of the exact length and sets the
    * position and limit back to their original values (though not thread safe).
    * @param buffer copy from here
    * @param startPosition put buffer.get(startPosition) into byte[0]
    * @return a new byte[] containing the bytes in the specified range
    */
   public static byte[] toBytes(ByteBuffer buffer, int startPosition) {
     int originalPosition = buffer.position();
     byte[] output = new byte[buffer.limit() - startPosition];
     buffer.position(startPosition);
     buffer.get(output);
     buffer.position(originalPosition);
     return output;
   }
 
   /**
    * Copy the given number of bytes from specified offset into a new byte[]
    * @param buffer
    * @param offset
    * @param length
    * @return a new byte[] containing the bytes in the specified range
    */
   public static byte[] toBytes(ByteBuffer buffer, int offset, int length) {
     byte[] output = new byte[length];
     for (int i = 0; i < length; i++) {
       output[i] = buffer.get(offset + i);
     }
     return output;
   }
 
   public static int compareTo(ByteBuffer buf1, int o1, int len1, ByteBuffer buf2, int o2, int len2) {
     if (buf1.hasArray() && buf2.hasArray()) {
       return Bytes.compareTo(buf1.array(), buf1.arrayOffset() + o1, len1, buf2.array(),
           buf2.arrayOffset() + o2, len2);
     }
     int end1 = o1 + len1;
     int end2 = o2 + len2;
     for (int i = o1, j = o2; i < end1 && j < end2; i++, j++) {
       int a = buf1.get(i) & 0xFF;
       int b = buf2.get(j) & 0xFF;
       if (a != b) {
         return a - b;
       }
     }
     return len1 - len2;
   }
 }