/*
    * Copyright 2012 The Netty Project
    *
    * The Netty Project 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:
    *
    *   https://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 io.netty.buffer;
  
  import io.netty.util.internal.CleanableDirectBuffer;
  import io.netty.util.internal.PlatformDependent;
  import io.netty.util.internal.UnstableApi;
  
  import java.io.IOException;
  import java.io.InputStream;
  import java.io.OutputStream;
  import java.nio.ByteBuffer;
  
  /**
   * A NIO {@link ByteBuffer} based buffer. It is recommended to use
   * {@link UnpooledByteBufAllocator#directBuffer(int, int)}, {@link Unpooled#directBuffer(int)} and
   * {@link Unpooled#wrappedBuffer(ByteBuffer)} instead of calling the constructor explicitly.}
   */
  public class UnpooledUnsafeDirectByteBuf extends UnpooledDirectByteBuf {
  
      private static final boolean USE_VAR_HANDLE = PlatformDependent.useVarHandleForMultiByteAccess();
  
      long memoryAddress;
  
      /**
       * Creates a new direct buffer.
       *
       * @param initialCapacity the initial capacity of the underlying direct buffer
       * @param maxCapacity     the maximum capacity of the underlying direct buffer
       */
      public UnpooledUnsafeDirectByteBuf(ByteBufAllocator alloc, int initialCapacity, int maxCapacity) {
          super(alloc, initialCapacity, maxCapacity);
      }
  
      UnpooledUnsafeDirectByteBuf(ByteBufAllocator alloc, int initialCapacity, int maxCapacity,
                                  boolean permitExpensiveClean) {
          super(alloc, initialCapacity, maxCapacity, permitExpensiveClean);
      }
  
      /**
       * Creates a new direct buffer by wrapping the specified initial buffer.
       *
       * @param maxCapacity the maximum capacity of the underlying direct buffer
       */
      protected UnpooledUnsafeDirectByteBuf(ByteBufAllocator alloc, ByteBuffer initialBuffer, int maxCapacity) {
          // We never try to free the buffer if it was provided by the end-user as we don't know if this is a duplicate or
          // a slice. This is done to prevent an IllegalArgumentException when using Java9 as Unsafe.invokeCleaner(...)
          // will check if the given buffer is either a duplicate or slice and in this case throw an
          // IllegalArgumentException.
          //
          // See https://hg.openjdk.java.net/jdk9/hs-demo/jdk/file/0d2ab72ba600/src/jdk.unsupported/share/classes/
          // sun/misc/Unsafe.java#l1250
          //
          // We also call slice() explicitly here to preserve behaviour with previous netty releases.
          super(alloc, initialBuffer, maxCapacity, /* doFree = */ false, /* slice = */ true);
      }
  
      /**
       * Creates a new direct ByteBuf by wrapping the specified initial buffer.
       * Allows subclasses to control if initialBuffer.slice() should be invoked.
       *
       *  Attention: this is a dangerous API and should only be used by someone
       *  who really knows the possible consequences.
       *  It allows to disable a protective slicing for the provided ByteBuffer instance
       *  and can cause sharing of this ByteBuffer instance between several UnpooledUnsafeDirectByteBuf objects,
       *  as a result modifications would be racy and unsafe.
       *
       * @param slice true means slice() should be called for the provided initialBuffer
       * @param maxCapacity the maximum capacity of the underlying direct buffer
       */
      @UnstableApi
      protected UnpooledUnsafeDirectByteBuf(ByteBufAllocator alloc, boolean slice,
                                            ByteBuffer initialBuffer, int maxCapacity) {
          super(alloc, initialBuffer, maxCapacity, /* doFree = */ false, slice);
      }
  
      UnpooledUnsafeDirectByteBuf(ByteBufAllocator alloc, ByteBuffer initialBuffer, int maxCapacity, boolean doFree) {
          super(alloc, initialBuffer, maxCapacity, doFree, false);
      }
  
      @Override
      final void setByteBuffer(ByteBuffer buffer, boolean tryFree) {
          super.setByteBuffer(buffer, tryFree);
          memoryAddress = PlatformDependent.directBufferAddress(buffer);
      }
  
     @Override
     final void setByteBuffer(CleanableDirectBuffer cleanableDirectBuffer, boolean tryFree) {
         super.setByteBuffer(cleanableDirectBuffer, tryFree);
         memoryAddress = PlatformDependent.directBufferAddress(cleanableDirectBuffer.buffer());
     }
 
     @Override
     public boolean hasMemoryAddress() {
         return true;
     }
 
     @Override
     public long memoryAddress() {
         ensureAccessible();
         return memoryAddress;
     }
 
     @Override
     public byte getByte(int index) {
         checkIndex(index);
         return _getByte(index);
     }
 
     @Override
     protected byte _getByte(int index) {
         return UnsafeByteBufUtil.getByte(addr(index));
     }
 
     @Override
     public short getShort(int index) {
         checkIndex(index, 2);
         return _getShort(index);
     }
 
     @Override
     protected short _getShort(int index) {
         if (USE_VAR_HANDLE) {
             return VarHandleByteBufferAccess.getShortBE(buffer, index);
         }
         return UnsafeByteBufUtil.getShort(addr(index));
     }
 
     @Override
     protected short _getShortLE(int index) {
         if (USE_VAR_HANDLE) {
             return VarHandleByteBufferAccess.getShortLE(buffer, index);
         }
         return UnsafeByteBufUtil.getShortLE(addr(index));
     }
 
     @Override
     public int getUnsignedMedium(int index) {
         checkIndex(index, 3);
         return _getUnsignedMedium(index);
     }
 
     @Override
     protected int _getUnsignedMedium(int index) {
         return UnsafeByteBufUtil.getUnsignedMedium(addr(index));
     }
 
     @Override
     protected int _getUnsignedMediumLE(int index) {
         return UnsafeByteBufUtil.getUnsignedMediumLE(addr(index));
     }
 
     @Override
     public int getInt(int index) {
         checkIndex(index, 4);
         return _getInt(index);
     }
 
     @Override
     protected int _getInt(int index) {
         if (USE_VAR_HANDLE) {
             return VarHandleByteBufferAccess.getIntBE(buffer, index);
         }
         return UnsafeByteBufUtil.getInt(addr(index));
     }
 
     @Override
     protected int _getIntLE(int index) {
         if (USE_VAR_HANDLE) {
             return VarHandleByteBufferAccess.getIntLE(buffer, index);
         }
         return UnsafeByteBufUtil.getIntLE(addr(index));
     }
 
     @Override
     public long getLong(int index) {
         checkIndex(index, 8);
         return _getLong(index);
     }
 
     @Override
     protected long _getLong(int index) {
         if (USE_VAR_HANDLE) {
             return VarHandleByteBufferAccess.getLongBE(buffer, index);
         }
         return UnsafeByteBufUtil.getLong(addr(index));
     }
 
     @Override
     protected long _getLongLE(int index) {
         if (USE_VAR_HANDLE) {
             return VarHandleByteBufferAccess.getLongLE(buffer, index);
         }
         return UnsafeByteBufUtil.getLongLE(addr(index));
     }
 
     @Override
     public ByteBuf getBytes(int index, ByteBuf dst, int dstIndex, int length) {
         UnsafeByteBufUtil.getBytes(this, addr(index), index, dst, dstIndex, length);
         return this;
     }
 
     @Override
     void getBytes(int index, byte[] dst, int dstIndex, int length, boolean internal) {
         UnsafeByteBufUtil.getBytes(this, addr(index), index, dst, dstIndex, length);
     }
 
     @Override
     void getBytes(int index, ByteBuffer dst, boolean internal) {
         UnsafeByteBufUtil.getBytes(this, addr(index), index, dst);
     }
 
     @Override
     public ByteBuf setByte(int index, int value) {
         checkIndex(index);
         _setByte(index, value);
         return this;
     }
 
     @Override
     protected void _setByte(int index, int value) {
         UnsafeByteBufUtil.setByte(addr(index), value);
     }
 
     @Override
     public ByteBuf setShort(int index, int value) {
         checkIndex(index, 2);
         _setShort(index, value);
         return this;
     }
 
     @Override
     protected void _setShort(int index, int value) {
         if (USE_VAR_HANDLE) {
             VarHandleByteBufferAccess.setShortBE(buffer, index, value);
             return;
         }
         UnsafeByteBufUtil.setShort(addr(index), value);
     }
 
     @Override
     protected void _setShortLE(int index, int value) {
         if (USE_VAR_HANDLE) {
             VarHandleByteBufferAccess.setShortLE(buffer, index, value);
             return;
         }
         UnsafeByteBufUtil.setShortLE(addr(index), value);
     }
 
     @Override
     public ByteBuf setMedium(int index, int value) {
         checkIndex(index, 3);
         _setMedium(index, value);
         return this;
     }
 
     @Override
     protected void _setMedium(int index, int value) {
         UnsafeByteBufUtil.setMedium(addr(index), value);
     }
 
     @Override
     protected void _setMediumLE(int index, int value) {
         UnsafeByteBufUtil.setMediumLE(addr(index), value);
     }
 
     @Override
     public ByteBuf setInt(int index, int value) {
         checkIndex(index, 4);
         _setInt(index, value);
         return this;
     }
 
     @Override
     protected void _setInt(int index, int value) {
         if (USE_VAR_HANDLE) {
             VarHandleByteBufferAccess.setIntBE(buffer, index, value);
             return;
         }
         UnsafeByteBufUtil.setInt(addr(index), value);
     }
 
     @Override
     protected void _setIntLE(int index, int value) {
         if (USE_VAR_HANDLE) {
             VarHandleByteBufferAccess.setIntLE(buffer, index, value);
             return;
         }
         UnsafeByteBufUtil.setIntLE(addr(index), value);
     }
 
     @Override
     public ByteBuf setLong(int index, long value) {
         checkIndex(index, 8);
         _setLong(index, value);
         return this;
     }
 
     @Override
     protected void _setLong(int index, long value) {
         if (USE_VAR_HANDLE) {
             VarHandleByteBufferAccess.setLongBE(buffer, index, value);
             return;
         }
         UnsafeByteBufUtil.setLong(addr(index), value);
     }
 
     @Override
     protected void _setLongLE(int index, long value) {
         if (USE_VAR_HANDLE) {
             VarHandleByteBufferAccess.setLongLE(buffer, index, value);
             return;
         }
         UnsafeByteBufUtil.setLongLE(addr(index), value);
     }
 
     @Override
     public ByteBuf setBytes(int index, ByteBuf src, int srcIndex, int length) {
         UnsafeByteBufUtil.setBytes(this, addr(index), index, src, srcIndex, length);
         return this;
     }
 
     @Override
     public ByteBuf setBytes(int index, byte[] src, int srcIndex, int length) {
         UnsafeByteBufUtil.setBytes(this, addr(index), index, src, srcIndex, length);
         return this;
     }
 
     @Override
     public ByteBuf setBytes(int index, ByteBuffer src) {
         UnsafeByteBufUtil.setBytes(this, addr(index), index, src);
         return this;
     }
 
     @Override
     void getBytes(int index, OutputStream out, int length, boolean internal) throws IOException {
         UnsafeByteBufUtil.getBytes(this, addr(index), index, out, length);
     }
 
     @Override
     public int setBytes(int index, InputStream in, int length) throws IOException {
         return UnsafeByteBufUtil.setBytes(this, addr(index), index, in, length);
     }
 
     @Override
     public ByteBuf copy(int index, int length) {
         return UnsafeByteBufUtil.copy(this, addr(index), index, length);
     }
 
     final long addr(int index) {
         return memoryAddress + index;
     }
 
     @Override
     protected SwappedByteBuf newSwappedByteBuf() {
         if (PlatformDependent.isUnaligned()) {
             // Only use if unaligned access is supported otherwise there is no gain.
             return new UnsafeDirectSwappedByteBuf(this);
         }
         return super.newSwappedByteBuf();
     }
 
     @Override
     public ByteBuf setZero(int index, int length) {
         checkIndex(index, length);
         UnsafeByteBufUtil.setZero(addr(index), length);
         return this;
     }
 
     @Override
     public ByteBuf writeZero(int length) {
         ensureWritable(length);
         int wIndex = writerIndex;
         UnsafeByteBufUtil.setZero(addr(wIndex), length);
         writerIndex = wIndex + length;
         return this;
     }
 }