/*
    * 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.ObjectUtil;
  import io.netty.util.internal.PlatformDependent;
  
  import java.io.IOException;
  import java.io.InputStream;
  import java.io.OutputStream;
  import java.lang.invoke.VarHandle;
  import java.nio.ByteBuffer;
  import java.nio.ByteOrder;
  import java.nio.channels.ClosedChannelException;
  import java.nio.channels.FileChannel;
  import java.nio.channels.GatheringByteChannel;
  import java.nio.channels.ScatteringByteChannel;
  
  import static io.netty.util.internal.ObjectUtil.checkPositiveOrZero;
  
  /**
   * 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 UnpooledDirectByteBuf extends AbstractReferenceCountedByteBuf {
  
      private final ByteBufAllocator alloc;
  
      CleanableDirectBuffer cleanable;
      ByteBuffer buffer; // accessed by UnpooledUnsafeNoCleanerDirectByteBuf.reallocateDirect()
      private ByteBuffer tmpNioBuf;
      private int capacity;
      private boolean doNotFree;
  
      /**
       * 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 UnpooledDirectByteBuf(ByteBufAllocator alloc, int initialCapacity, int maxCapacity) {
          super(maxCapacity);
          ObjectUtil.checkNotNull(alloc, "alloc");
          checkPositiveOrZero(initialCapacity, "initialCapacity");
          checkPositiveOrZero(maxCapacity, "maxCapacity");
          if (initialCapacity > maxCapacity) {
              throw new IllegalArgumentException(String.format(
                      "initialCapacity(%d) > maxCapacity(%d)", initialCapacity, maxCapacity));
          }
  
          this.alloc = alloc;
          setByteBuffer(allocateDirectBuffer(initialCapacity), false);
      }
  
      /**
       * Creates a new direct buffer by wrapping the specified initial buffer.
       *
       * @param maxCapacity the maximum capacity of the underlying direct buffer
       */
      protected UnpooledDirectByteBuf(ByteBufAllocator alloc, ByteBuffer initialBuffer, int maxCapacity) {
          this(alloc, initialBuffer, maxCapacity, false, true);
      }
  
      UnpooledDirectByteBuf(ByteBufAllocator alloc, ByteBuffer initialBuffer,
              int maxCapacity, boolean doFree, boolean slice) {
          super(maxCapacity);
          ObjectUtil.checkNotNull(alloc, "alloc");
          ObjectUtil.checkNotNull(initialBuffer, "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((slice ? initialBuffer.slice() : initialBuffer).order(ByteOrder.BIG_ENDIAN), false);
         writerIndex(initialCapacity);
     }
 
     /**
      * Allocate a new direct {@link ByteBuffer} with the given initialCapacity.
      * @deprecated Use {@link #allocateDirectBuffer(int)} instead.
      */
     @Deprecated
     protected ByteBuffer allocateDirect(int initialCapacity) {
         return ByteBuffer.allocateDirect(initialCapacity);
     }
 
     /**
      * Free a direct {@link ByteBuffer}
      * @deprecated Use {@link #allocateDirectBuffer(int)} instead.
      */
     @Deprecated
     protected void freeDirect(ByteBuffer buffer) {
         PlatformDependent.freeDirectBuffer(buffer);
     }
 
     protected CleanableDirectBuffer allocateDirectBuffer(int capacity) {
         return PlatformDependent.allocateDirect(capacity);
     }
 
     void setByteBuffer(CleanableDirectBuffer cleanableDirectBuffer, boolean tryFree) {
         if (tryFree) {
             CleanableDirectBuffer oldCleanable = cleanable;
             ByteBuffer oldBuffer = buffer;
             if (oldBuffer != null) {
                 if (doNotFree) {
                     doNotFree = false;
                 } else {
                     if (oldCleanable != null) {
                         oldCleanable.clean();
                     } else {
                         freeDirect(oldBuffer);
                     }
                 }
             }
         }
 
         cleanable = cleanableDirectBuffer;
         buffer = cleanableDirectBuffer.buffer();
         tmpNioBuf = null;
         capacity = buffer.remaining();
     }
 
     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;
         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 oldCapacity = capacity;
         if (newCapacity == oldCapacity) {
             return this;
         }
         int bytesToCopy;
         if (newCapacity > oldCapacity) {
             bytesToCopy = oldCapacity;
         } else {
             trimIndicesToCapacity(newCapacity);
             bytesToCopy = newCapacity;
         }
         ByteBuffer oldBuffer = buffer;
         CleanableDirectBuffer newBuffer = allocateDirectBuffer(newCapacity);
         oldBuffer.position(0).limit(bytesToCopy);
         newBuffer.buffer().position(0).limit(bytesToCopy);
         newBuffer.buffer().put(oldBuffer).clear();
         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() {
         CleanableDirectBuffer cleanable = this.cleanable;
         return cleanable != null && cleanable.hasMemoryAddress();
     }
 
     @Override
     public long memoryAddress() {
         ensureAccessible();
         if (!hasMemoryAddress()) {
             throw new UnsupportedOperationException();
         }
         return cleanable.memoryAddress();
     }
 
     @Override
     public byte getByte(int index) {
         ensureAccessible();
         return _getByte(index);
     }
 
     @Override
     protected byte _getByte(int index) {
         return buffer.get(index);
     }
 
     @Override
     public short getShortLE(int index) {
         ensureAccessible();
         return _getShortLE(index);
     }
 
     @Override
     public short getShort(int index) {
         ensureAccessible();
         return _getShort(index);
     }
 
     @Override
     protected short _getShort(int index) {
         VarHandle varHandle = PlatformDependent.shortBeByteBufferView();
         if (varHandle != null) {
             return (short) varHandle.get(buffer, index);
         }
         return buffer.getShort(index);
     }
 
     @Override
     protected short _getShortLE(int index) {
         VarHandle varHandle = PlatformDependent.shortLeByteBufferView();
         if (varHandle != null) {
             return (short) varHandle.get(buffer, index);
         }
         return ByteBufUtil.swapShort(buffer.getShort(index));
     }
 
     @Override
     public int getUnsignedMedium(int index) {
         ensureAccessible();
         return _getUnsignedMedium(index);
     }
 
     @Override
     protected int _getUnsignedMedium(int index) {
         return (getByte(index) & 0xff)     << 16 |
                (getByte(index + 1) & 0xff) << 8  |
                getByte(index + 2) & 0xff;
     }
 
     @Override
     protected int _getUnsignedMediumLE(int index) {
         return getByte(index) & 0xff             |
                (getByte(index + 1) & 0xff) << 8  |
                (getByte(index + 2) & 0xff) << 16;
     }
 
     @Override
     public int getIntLE(int index) {
         ensureAccessible();
         return _getIntLE(index);
     }
 
     @Override
     public int getInt(int index) {
         ensureAccessible();
         return _getInt(index);
     }
 
     @Override
     protected int _getInt(int index) {
         VarHandle varHandle = PlatformDependent.intBeByteBufferView();
         if (varHandle != null) {
             return (int) varHandle.get(buffer, index);
         }
         return buffer.getInt(index);
     }
 
     @Override
     protected int _getIntLE(int index) {
         VarHandle varHandle = PlatformDependent.intLeByteBufferView();
         if (varHandle != null) {
             return (int) varHandle.get(buffer, index);
         }
         return ByteBufUtil.swapInt(buffer.getInt(index));
     }
 
     @Override
     public long getLongLE(int index) {
         ensureAccessible();
         return _getLongLE(index);
     }
 
     @Override
     public long getLong(int index) {
         ensureAccessible();
         return _getLong(index);
     }
 
     @Override
     protected long _getLong(int index) {
         VarHandle varHandle = PlatformDependent.longBeByteBufferView();
         if (varHandle != null) {
             return (long) varHandle.get(buffer, index);
         }
         return buffer.getLong(index);
     }
 
     @Override
     protected long _getLongLE(int index) {
         VarHandle varHandle = PlatformDependent.longLeByteBufferView();
         if (varHandle != null) {
             return (long) varHandle.get(buffer, index);
         }
         return ByteBufUtil.swapLong(buffer.getLong(index));
     }
 
     @Override
     public ByteBuf getBytes(int index, ByteBuf dst, int dstIndex, int length) {
         checkDstIndex(index, length, dstIndex, dst.capacity());
         if (dst.hasArray()) {
             getBytes(index, dst.array(), dst.arrayOffset() + dstIndex, length);
         } else if (dst.nioBufferCount() > 0) {
             for (ByteBuffer bb: dst.nioBuffers(dstIndex, length)) {
                 int bbLen = bb.remaining();
                 getBytes(index, bb);
                 index += bbLen;
             }
         } else {
             dst.setBytes(dstIndex, this, index, length);
         }
         return this;
     }
 
     @Override
     public ByteBuf getBytes(int index, byte[] dst, int dstIndex, int length) {
         getBytes(index, dst, dstIndex, length, false);
         return this;
     }
 
     void getBytes(int index, byte[] dst, int dstIndex, int length, boolean internal) {
         checkDstIndex(index, length, dstIndex, dst.length);
 
         ByteBuffer tmpBuf;
         if (internal) {
             tmpBuf = internalNioBuffer();
         } else {
             tmpBuf = buffer.duplicate();
         }
         tmpBuf.clear().position(index).limit(index + length);
         tmpBuf.get(dst, dstIndex, length);
     }
 
     @Override
     public ByteBuf readBytes(byte[] dst, int dstIndex, int length) {
         checkReadableBytes(length);
         getBytes(readerIndex, dst, dstIndex, length, true);
         readerIndex += length;
         return this;
     }
 
     @Override
     public ByteBuf getBytes(int index, ByteBuffer dst) {
         getBytes(index, dst, false);
         return this;
     }
 
     void getBytes(int index, ByteBuffer dst, boolean internal) {
         checkIndex(index, dst.remaining());
 
         ByteBuffer tmpBuf;
         if (internal) {
             tmpBuf = internalNioBuffer();
         } else {
             tmpBuf = buffer.duplicate();
         }
         tmpBuf.clear().position(index).limit(index + dst.remaining());
         dst.put(tmpBuf);
     }
 
     @Override
     public ByteBuf readBytes(ByteBuffer dst) {
         int length = dst.remaining();
         checkReadableBytes(length);
         getBytes(readerIndex, dst, true);
         readerIndex += length;
         return this;
     }
 
     @Override
     public ByteBuf setByte(int index, int value) {
         ensureAccessible();
         _setByte(index, value);
         return this;
     }
 
     @Override
     protected void _setByte(int index, int value) {
         buffer.put(index, (byte) value);
     }
 
     @Override
     public ByteBuf setShortLE(int index, int value) {
         ensureAccessible();
         _setShortLE(index, value);
         return this;
     }
 
     @Override
     public ByteBuf setShort(int index, int value) {
         ensureAccessible();
         _setShort(index, value);
         return this;
     }
 
     @Override
     protected void _setShort(int index, int value) {
         VarHandle varHandle = PlatformDependent.shortBeByteBufferView();
         if (varHandle != null) {
             varHandle.set(buffer, index, (short) value);
             return;
         }
         buffer.putShort(index, (short) value);
     }
 
     @Override
     protected void _setShortLE(int index, int value) {
         VarHandle varHandle = PlatformDependent.shortLeByteBufferView();
         if (varHandle != null) {
             varHandle.set(buffer, index, (short) value);
             return;
         }
         buffer.putShort(index, ByteBufUtil.swapShort((short) value));
     }
 
     @Override
     public ByteBuf setMediumLE(int index, int value) {
         ensureAccessible();
         _setMediumLE(index, value);
         return this;
     }
 
     @Override
     public ByteBuf setMedium(int index, int value) {
         ensureAccessible();
         _setMedium(index, value);
         return this;
     }
 
     @Override
     protected void _setMedium(int index, int value) {
         setByte(index, (byte) (value >>> 16));
         setByte(index + 1, (byte) (value >>> 8));
         setByte(index + 2, (byte) value);
     }
 
     @Override
     protected void _setMediumLE(int index, int value) {
         setByte(index, (byte) value);
         setByte(index + 1, (byte) (value >>> 8));
         setByte(index + 2, (byte) (value >>> 16));
     }
 
     @Override
     public ByteBuf setIntLE(int index, int value) {
         ensureAccessible();
         _setIntLE(index, value);
         return this;
     }
 
     @Override
     public ByteBuf setInt(int index, int value) {
         ensureAccessible();
         _setInt(index, value);
         return this;
     }
 
     @Override
     protected void _setInt(int index, int value) {
         VarHandle varHandle = PlatformDependent.intBeByteBufferView();
         if (varHandle != null) {
             varHandle.set(buffer, index, value);
             return;
         }
         buffer.putInt(index, value);
     }
 
     @Override
     protected void _setIntLE(int index, int value) {
         VarHandle varHandle = PlatformDependent.intLeByteBufferView();
         if (varHandle != null) {
             varHandle.set(buffer, index, value);
             return;
         }
         buffer.putInt(index, ByteBufUtil.swapInt(value));
     }
 
     @Override
     public ByteBuf setLong(int index, long value) {
         ensureAccessible();
         _setLong(index, value);
         return this;
     }
 
     @Override
     public ByteBuf setLongLE(int index, long value) {
         ensureAccessible();
         _setLongLE(index, value);
         return this;
     }
 
     @Override
     protected void _setLong(int index, long value) {
         VarHandle varHandle = PlatformDependent.longBeByteBufferView();
         if (varHandle != null) {
             varHandle.set(buffer, index, value);
             return;
         }
         buffer.putLong(index, value);
     }
 
     @Override
     protected void _setLongLE(int index, long value) {
         VarHandle varHandle = PlatformDependent.longLeByteBufferView();
         if (varHandle != null) {
             varHandle.set(buffer, index, value);
             return;
         }
         buffer.putLong(index, ByteBufUtil.swapLong(value));
     }
 
     @Override
     public ByteBuf setBytes(int index, ByteBuf src, int srcIndex, int length) {
         checkSrcIndex(index, length, srcIndex, src.capacity());
         if (src.nioBufferCount() > 0) {
             for (ByteBuffer bb: src.nioBuffers(srcIndex, length)) {
                 int bbLen = bb.remaining();
                 setBytes(index, bb);
                 index += bbLen;
             }
         } else {
             src.getBytes(srcIndex, this, index, length);
         }
         return this;
     }
 
     @Override
     public ByteBuf setBytes(int index, byte[] src, int srcIndex, int length) {
         checkSrcIndex(index, length, srcIndex, src.length);
         ByteBuffer tmpBuf = internalNioBuffer();
         tmpBuf.clear().position(index).limit(index + length);
         tmpBuf.put(src, srcIndex, length);
         return this;
     }
 
     @Override
     public ByteBuf setBytes(int index, ByteBuffer src) {
         ensureAccessible();
         ByteBuffer tmpBuf = internalNioBuffer();
         if (src == tmpBuf) {
             src = src.duplicate();
         }
 
         tmpBuf.clear().position(index).limit(index + src.remaining());
         tmpBuf.put(src);
         return this;
     }
 
     @Override
     public ByteBuf getBytes(int index, OutputStream out, int length) throws IOException {
         getBytes(index, out, length, false);
         return this;
     }
 
     void getBytes(int index, OutputStream out, int length, boolean internal) throws IOException {
         ensureAccessible();
         if (length == 0) {
             return;
         }
         ByteBufUtil.readBytes(alloc(), internal ? internalNioBuffer() : buffer.duplicate(), index, length, out);
     }
 
     @Override
     public ByteBuf readBytes(OutputStream out, int length) throws IOException {
         checkReadableBytes(length);
         getBytes(readerIndex, out, length, true);
         readerIndex += 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 getBytes(int index, FileChannel out, long position, int length) throws IOException {
         return getBytes(index, out, position, length, false);
     }
 
     private int getBytes(int index, FileChannel out, long position, int length, boolean internal) throws IOException {
         ensureAccessible();
         if (length == 0) {
             return 0;
         }
 
         ByteBuffer tmpBuf = internal ? internalNioBuffer() : buffer.duplicate();
         tmpBuf.clear().position(index).limit(index + length);
         return out.write(tmpBuf, position);
     }
 
     @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 readBytes(FileChannel out, long position, int length) throws IOException {
         checkReadableBytes(length);
         int readBytes = getBytes(readerIndex, out, position, length, true);
         readerIndex += readBytes;
         return readBytes;
     }
 
     @Override
     public int setBytes(int index, InputStream in, int length) throws IOException {
         ensureAccessible();
         if (buffer.hasArray()) {
             return in.read(buffer.array(), buffer.arrayOffset() + index, length);
         } else {
             byte[] tmp = ByteBufUtil.threadLocalTempArray(length);
             int readBytes = in.read(tmp, 0, length);
             if (readBytes <= 0) {
                 return readBytes;
             }
             ByteBuffer tmpBuf = internalNioBuffer();
             tmpBuf.clear().position(index);
             tmpBuf.put(tmp, 0, readBytes);
             return readBytes;
         }
     }
 
     @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 setBytes(int index, FileChannel in, long position, int length) throws IOException {
         ensureAccessible();
         ByteBuffer tmpBuf = internalNioBuffer();
         tmpBuf.clear().position(index).limit(index + length);
         try {
             return in.read(tmpBuf, position);
         } 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 final boolean isContiguous() {
         return true;
     }
 
     @Override
     public ByteBuf copy(int index, int length) {
         ensureAccessible();
         ByteBuffer src;
         try {
             src = (ByteBuffer) buffer.duplicate().clear().position(index).limit(index + length);
         } catch (IllegalArgumentException ignored) {
             throw new IndexOutOfBoundsException("Too many bytes to read - Need " + (index + length));
         }
 
         return alloc().directBuffer(length, maxCapacity()).writeBytes(src);
     }
 
     @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) {
             if (cleanable != null) {
                 cleanable.clean();
                 cleanable = null;
             } else {
                 freeDirect(buffer);
             }
         }
     }
 
     @Override
     public ByteBuf unwrap() {
         return null;
     }
 }