/*
    * 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:
    *
    *   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 io.netty.buffer;
  
  import io.netty.util.internal.PlatformDependent;
  
  import java.io.IOException;
  import java.io.InputStream;
  import java.io.OutputStream;
  import java.nio.ByteBuffer;
  import java.nio.ByteOrder;
  import java.nio.channels.ClosedChannelException;
  import java.nio.channels.GatheringByteChannel;
  import java.nio.channels.ScatteringByteChannel;
  
  /**
   * 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 AbstractReferenceCountedByteBuf {
  
      private final ByteBufAllocator alloc;
  
      private ByteBuffer tmpNioBuf;
      private int capacity;
      private boolean doNotFree;
      ByteBuffer buffer;
      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(maxCapacity);
          if (alloc == null) {
              throw new NullPointerException("alloc");
          }
          if (initialCapacity < 0) {
              throw new IllegalArgumentException("initialCapacity: " + initialCapacity);
          }
          if (maxCapacity < 0) {
              throw new IllegalArgumentException("maxCapacity: " + maxCapacity);
          }
          if (initialCapacity > maxCapacity) {
              throw new IllegalArgumentException(String.format(
                      "initialCapacity(%d) > maxCapacity(%d)", initialCapacity, maxCapacity));
          }
  
          this.alloc = alloc;
          setByteBuffer(allocateDirect(initialCapacity), false);
      }
  
      /**
       * 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 not know if this is an duplicate or
          // an slice. This is done to prevent an IllegalArgumentException when using Java9 as Unsafe.invokeCleaner(...)
          // will check if the given buffer is either an duplicate or slice and in this case throw an
          // IllegalArgumentException.
          //
          // See http://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.
          this(alloc, initialBuffer.slice(), maxCapacity, false);
      }
  
      UnpooledUnsafeDirectByteBuf(ByteBufAllocator alloc, ByteBuffer initialBuffer, int maxCapacity, boolean doFree) {
          super(maxCapacity);
          if (alloc == null) {
              throw new NullPointerException("alloc");
          }
          if (initialBuffer == null) {
              throw new NullPointerException("initialBuffer");
          }
          if (!initialBuffer.isDirect()) {
              throw new IllegalArgumentException("initialBuffer is not a direct buffer.");
          }
          if (initialBuffer.isReadOnly()) {
             throw new IllegalArgumentException("initialBuffer is a read-only buffer.");
         }
 
         int initialCapacity = initialBuffer.remaining();
         if (initialCapacity > maxCapacity) {
             throw new IllegalArgumentException(String.format(
                     "initialCapacity(%d) > maxCapacity(%d)", initialCapacity, maxCapacity));
         }
 
         this.alloc = alloc;
         doNotFree = !doFree;
         setByteBuffer(initialBuffer.order(ByteOrder.BIG_ENDIAN), false);
         writerIndex(initialCapacity);
     }
 
     /**
      * Allocate a new direct {@link ByteBuffer} with the given initialCapacity.
      */
     protected ByteBuffer allocateDirect(int initialCapacity) {
         return ByteBuffer.allocateDirect(initialCapacity);
     }
 
     /**
      * Free a direct {@link ByteBuffer}
      */
     protected void freeDirect(ByteBuffer buffer) {
         PlatformDependent.freeDirectBuffer(buffer);
     }
 
     final void setByteBuffer(ByteBuffer buffer, boolean tryFree) {
         if (tryFree) {
             ByteBuffer oldBuffer = this.buffer;
             if (oldBuffer != null) {
                 if (doNotFree) {
                     doNotFree = false;
                 } else {
                     freeDirect(oldBuffer);
                 }
             }
         }
         this.buffer = buffer;
         memoryAddress = PlatformDependent.directBufferAddress(buffer);
         tmpNioBuf = null;
         capacity = buffer.remaining();
     }
 
     @Override
     public boolean isDirect() {
         return true;
     }
 
     @Override
     public int capacity() {
         return capacity;
     }
 
     @Override
     public ByteBuf capacity(int newCapacity) {
         checkNewCapacity(newCapacity);
 
         int readerIndex = readerIndex();
         int writerIndex = writerIndex();
 
         int oldCapacity = capacity;
         if (newCapacity > oldCapacity) {
             ByteBuffer oldBuffer = buffer;
             ByteBuffer newBuffer = allocateDirect(newCapacity);
             oldBuffer.position(0).limit(oldBuffer.capacity());
             newBuffer.position(0).limit(oldBuffer.capacity());
             newBuffer.put(oldBuffer);
             newBuffer.clear();
             setByteBuffer(newBuffer, true);
         } else if (newCapacity < oldCapacity) {
             ByteBuffer oldBuffer = buffer;
             ByteBuffer newBuffer = allocateDirect(newCapacity);
             if (readerIndex < newCapacity) {
                 if (writerIndex > newCapacity) {
                     writerIndex(writerIndex = newCapacity);
                 }
                 oldBuffer.position(readerIndex).limit(writerIndex);
                 newBuffer.position(readerIndex).limit(writerIndex);
                 newBuffer.put(oldBuffer);
                 newBuffer.clear();
             } else {
                 setIndex(newCapacity, newCapacity);
             }
             setByteBuffer(newBuffer, true);
         }
         return this;
     }
 
     @Override
     public ByteBufAllocator alloc() {
         return alloc;
     }
 
     @Override
     public ByteOrder order() {
         return ByteOrder.BIG_ENDIAN;
     }
 
     @Override
     public boolean hasArray() {
         return false;
     }
 
     @Override
     public byte[] array() {
         throw new UnsupportedOperationException("direct buffer");
     }
 
     @Override
     public int arrayOffset() {
         throw new UnsupportedOperationException("direct buffer");
     }
 
     @Override
     public boolean hasMemoryAddress() {
         return true;
     }
 
     @Override
     public long memoryAddress() {
         ensureAccessible();
         return memoryAddress;
     }
 
     @Override
     protected byte _getByte(int index) {
         return UnsafeByteBufUtil.getByte(addr(index));
     }
 
     @Override
     protected short _getShort(int index) {
         return UnsafeByteBufUtil.getShort(addr(index));
     }
 
     @Override
     protected int _getUnsignedMedium(int index) {
         return UnsafeByteBufUtil.getUnsignedMedium(addr(index));
     }
 
     @Override
     protected int _getInt(int index) {
         return UnsafeByteBufUtil.getInt(addr(index));
     }
 
     @Override
     protected long _getLong(int index) {
         return UnsafeByteBufUtil.getLong(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
     public ByteBuf getBytes(int index, byte[] dst, int dstIndex, int length) {
         UnsafeByteBufUtil.getBytes(this, addr(index), index, dst, dstIndex, length);
         return this;
     }
 
     @Override
     public ByteBuf getBytes(int index, ByteBuffer dst) {
         UnsafeByteBufUtil.getBytes(this, addr(index), index, dst);
         return this;
     }
 
     @Override
     public ByteBuf readBytes(ByteBuffer dst) {
         int length = dst.remaining();
         checkReadableBytes(length);
         getBytes(readerIndex, dst);
         readerIndex += length;
         return this;
     }
 
     @Override
     protected void _setByte(int index, int value) {
         UnsafeByteBufUtil.setByte(addr(index), value);
     }
 
     @Override
     protected void _setShort(int index, int value) {
         UnsafeByteBufUtil.setShort(addr(index), value);
     }
 
     @Override
     protected void _setMedium(int index, int value) {
         UnsafeByteBufUtil.setMedium(addr(index), value);
     }
 
     @Override
     protected void _setInt(int index, int value) {
         UnsafeByteBufUtil.setInt(addr(index), value);
     }
 
     @Override
     protected void _setLong(int index, long value) {
         UnsafeByteBufUtil.setLong(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
     public ByteBuf getBytes(int index, OutputStream out, int length) throws IOException {
         UnsafeByteBufUtil.getBytes(this, addr(index), index, out, length);
         return this;
     }
 
     @Override
     public int getBytes(int index, GatheringByteChannel out, int length) throws IOException {
         return getBytes(index, out, length, false);
     }
 
     private int getBytes(int index, GatheringByteChannel out, int length, boolean internal) throws IOException {
         ensureAccessible();
         if (length == 0) {
             return 0;
         }
 
         ByteBuffer tmpBuf;
         if (internal) {
             tmpBuf = internalNioBuffer();
         } else {
             tmpBuf = buffer.duplicate();
         }
         tmpBuf.clear().position(index).limit(index + length);
         return out.write(tmpBuf);
     }
 
     @Override
     public int readBytes(GatheringByteChannel out, int length) throws IOException {
         checkReadableBytes(length);
         int readBytes = getBytes(readerIndex, out, length, true);
         readerIndex += readBytes;
         return readBytes;
     }
 
     @Override
     public int setBytes(int index, InputStream in, int length) throws IOException {
         return UnsafeByteBufUtil.setBytes(this, addr(index), index, in, length);
     }
 
     @Override
     public int setBytes(int index, ScatteringByteChannel in, int length) throws IOException {
         ensureAccessible();
         ByteBuffer tmpBuf = internalNioBuffer();
         tmpBuf.clear().position(index).limit(index + length);
         try {
             return in.read(tmpBuf);
         } catch (ClosedChannelException ignored) {
             return -1;
         }
     }
 
     @Override
     public int nioBufferCount() {
         return 1;
     }
 
     @Override
     public ByteBuffer[] nioBuffers(int index, int length) {
         return new ByteBuffer[] { nioBuffer(index, length) };
     }
 
     @Override
     public ByteBuf copy(int index, int length) {
         return UnsafeByteBufUtil.copy(this, addr(index), index, length);
     }
 
     @Override
     public ByteBuffer internalNioBuffer(int index, int length) {
         checkIndex(index, length);
         return (ByteBuffer) internalNioBuffer().clear().position(index).limit(index + length);
     }
 
     private ByteBuffer internalNioBuffer() {
         ByteBuffer tmpNioBuf = this.tmpNioBuf;
         if (tmpNioBuf == null) {
             this.tmpNioBuf = tmpNioBuf = buffer.duplicate();
         }
         return tmpNioBuf;
     }
 
     @Override
     public ByteBuffer nioBuffer(int index, int length) {
         checkIndex(index, length);
         return ((ByteBuffer) buffer.duplicate().position(index).limit(index + length)).slice();
     }
 
     @Override
     protected void deallocate() {
         ByteBuffer buffer = this.buffer;
         if (buffer == null) {
             return;
         }
 
         this.buffer = null;
 
         if (!doNotFree) {
             freeDirect(buffer);
         }
     }
 
     @Override
     public ByteBuf unwrap() {
         return null;
     }
 
     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;
     }
 }