/*
    * Copyright 2013 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.ObjectUtil;
  import io.netty.util.internal.PlatformDependent;
  
  import java.nio.ByteBuffer;
  
  
  /**
   * Read-only ByteBuf which wraps a read-only direct ByteBuffer and use unsafe for best performance.
   */
  final class ReadOnlyUnsafeDirectByteBuf extends ReadOnlyByteBufferBuf {
      private final long memoryAddress;
  
      ReadOnlyUnsafeDirectByteBuf(ByteBufAllocator allocator, ByteBuffer byteBuffer) {
          super(allocator, byteBuffer);
          // Use buffer as the super class will slice the passed in ByteBuffer which means the memoryAddress
          // may be different if the position != 0.
          memoryAddress = PlatformDependent.directBufferAddress(buffer);
      }
  
      @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) {
          checkIndex(index, length);
          ObjectUtil.checkNotNull(dst, "dst");
          if (dstIndex < 0 || dstIndex > dst.capacity() - length) {
              throw new IndexOutOfBoundsException("dstIndex: " + dstIndex);
          }
  
          if (dst.hasMemoryAddress()) {
              PlatformDependent.copyMemory(addr(index), dst.memoryAddress() + dstIndex, length);
          } else if (dst.hasArray()) {
              PlatformDependent.copyMemory(addr(index), dst.array(), dst.arrayOffset() + dstIndex, length);
          } else {
              dst.setBytes(dstIndex, this, index, length);
          }
          return this;
      }
  
      @Override
      public ByteBuf getBytes(int index, byte[] dst, int dstIndex, int length) {
          checkIndex(index, length);
          ObjectUtil.checkNotNull(dst, "dst");
          if (dstIndex < 0 || dstIndex > dst.length - length) {
              throw new IndexOutOfBoundsException(String.format(
                      "dstIndex: %d, length: %d (expected: range(0, %d))", dstIndex, length, dst.length));
          }
  
          if (length != 0) {
              PlatformDependent.copyMemory(addr(index), dst, dstIndex, length);
          }
          return this;
      }
  
      @Override
      public ByteBuf copy(int index, int length) {
          checkIndex(index, length);
          ByteBuf copy = alloc().directBuffer(length, maxCapacity());
         if (length != 0) {
             if (copy.hasMemoryAddress()) {
                 PlatformDependent.copyMemory(addr(index), copy.memoryAddress(), length);
                 copy.setIndex(0, length);
             } else {
                 copy.writeBytes(this, index, length);
             }
         }
         return copy;
     }
 
     @Override
     public boolean hasMemoryAddress() {
         return true;
     }
 
     @Override
     public long memoryAddress() {
         return memoryAddress;
     }
 
     private long addr(int index) {
         return memoryAddress + index;
     }
 }