/*
    * 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:
    *
    *   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.StringUtil;
  
  import java.io.IOException;
  import java.io.InputStream;
  import java.io.OutputStream;
  import java.nio.ByteBuffer;
  import java.nio.ByteOrder;
  import java.nio.ReadOnlyBufferException;
  import java.nio.channels.GatheringByteChannel;
  import java.nio.channels.ScatteringByteChannel;
  
  
  /**
   * Read-only ByteBuf which wraps a read-only ByteBuffer.
   */
  class ReadOnlyByteBufferBuf extends AbstractReferenceCountedByteBuf {
  
      protected final ByteBuffer buffer;
      private final ByteBufAllocator allocator;
      private ByteBuffer tmpNioBuf;
  
      ReadOnlyByteBufferBuf(ByteBufAllocator allocator, ByteBuffer buffer) {
          super(buffer.remaining());
          if (!buffer.isReadOnly()) {
              throw new IllegalArgumentException("must be a readonly buffer: " + StringUtil.simpleClassName(buffer));
          }
  
          this.allocator = allocator;
          this.buffer = buffer.slice().order(ByteOrder.BIG_ENDIAN);
          writerIndex(this.buffer.limit());
      }
  
      @Override
      protected void deallocate() { }
  
      @Override
      public byte getByte(int index) {
          ensureAccessible();
          return _getByte(index);
      }
  
      @Override
      protected byte _getByte(int index) {
          return buffer.get(index);
      }
  
      @Override
      public short getShort(int index) {
          ensureAccessible();
          return _getShort(index);
      }
  
      @Override
      protected short _getShort(int index) {
          return 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
      public int getInt(int index) {
          ensureAccessible();
          return _getInt(index);
      }
  
      @Override
      protected int _getInt(int index) {
          return buffer.getInt(index);
      }
  
      @Override
     public long getLong(int index) {
         ensureAccessible();
         return _getLong(index);
     }
 
     @Override
     protected long _getLong(int index) {
         return 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) {
         checkDstIndex(index, length, dstIndex, dst.length);
 
         if (dstIndex < 0 || dstIndex > dst.length - length) {
             throw new IndexOutOfBoundsException(String.format(
                     "dstIndex: %d, length: %d (expected: range(0, %d))", dstIndex, length, dst.length));
         }
 
         ByteBuffer tmpBuf = internalNioBuffer();
         tmpBuf.clear().position(index).limit(index + length);
         tmpBuf.get(dst, dstIndex, length);
         return this;
     }
 
     @Override
     public ByteBuf getBytes(int index, ByteBuffer dst) {
         checkIndex(index);
         if (dst == null) {
             throw new NullPointerException("dst");
         }
 
         int bytesToCopy = Math.min(capacity() - index, dst.remaining());
         ByteBuffer tmpBuf = internalNioBuffer();
         tmpBuf.clear().position(index).limit(index + bytesToCopy);
         dst.put(tmpBuf);
         return this;
     }
 
     @Override
     public ByteBuf setByte(int index, int value) {
         throw new ReadOnlyBufferException();
     }
 
     @Override
     protected void _setByte(int index, int value) {
         throw new ReadOnlyBufferException();
     }
 
     @Override
     public ByteBuf setShort(int index, int value) {
         throw new ReadOnlyBufferException();
     }
 
     @Override
     protected void _setShort(int index, int value) {
         throw new ReadOnlyBufferException();
     }
 
     @Override
     public ByteBuf setMedium(int index, int value) {
         throw new ReadOnlyBufferException();
     }
 
     @Override
     protected void _setMedium(int index, int value) {
         throw new ReadOnlyBufferException();
     }
 
     @Override
     public ByteBuf setInt(int index, int value) {
         throw new ReadOnlyBufferException();
     }
 
     @Override
     protected void _setInt(int index, int value) {
         throw new ReadOnlyBufferException();
     }
 
     @Override
     public ByteBuf setLong(int index, long value) {
         throw new ReadOnlyBufferException();
     }
 
     @Override
     protected void _setLong(int index, long value) {
         throw new ReadOnlyBufferException();
     }
 
     @Override
     public int capacity() {
         return maxCapacity();
     }
 
     @Override
     public ByteBuf capacity(int newCapacity) {
         throw new ReadOnlyBufferException();
     }
 
     @Override
     public ByteBufAllocator alloc() {
         return allocator;
     }
 
     @Override
     public ByteOrder order() {
         return ByteOrder.BIG_ENDIAN;
     }
 
     @Override
     public ByteBuf unwrap() {
         return null;
     }
 
     @Override
     public boolean isDirect() {
         return buffer.isDirect();
     }
 
     @Override
     public ByteBuf getBytes(int index, OutputStream out, int length) throws IOException {
         ensureAccessible();
         if (length == 0) {
             return this;
         }
 
         if (buffer.hasArray()) {
             out.write(buffer.array(), index + buffer.arrayOffset(), length);
         } else {
             byte[] tmp = new byte[length];
             ByteBuffer tmpBuf = internalNioBuffer();
             tmpBuf.clear().position(index);
             tmpBuf.get(tmp);
             out.write(tmp);
         }
         return this;
     }
 
     @Override
     public int getBytes(int index, GatheringByteChannel out, int length) throws IOException {
         ensureAccessible();
         if (length == 0) {
             return 0;
         }
 
         ByteBuffer tmpBuf = internalNioBuffer();
         tmpBuf.clear().position(index).limit(index + length);
         return out.write(tmpBuf);
     }
 
     @Override
     public ByteBuf setBytes(int index, ByteBuf src, int srcIndex, int length) {
         throw new ReadOnlyBufferException();
     }
 
     @Override
     public ByteBuf setBytes(int index, byte[] src, int srcIndex, int length) {
         throw new ReadOnlyBufferException();
     }
 
     @Override
     public ByteBuf setBytes(int index, ByteBuffer src) {
         throw new ReadOnlyBufferException();
     }
 
     @Override
     public int setBytes(int index, InputStream in, int length) throws IOException {
         throw new ReadOnlyBufferException();
     }
 
     @Override
     public int setBytes(int index, ScatteringByteChannel in, int length) throws IOException {
         throw new ReadOnlyBufferException();
     }
 
     protected final ByteBuffer internalNioBuffer() {
         ByteBuffer tmpNioBuf = this.tmpNioBuf;
         if (tmpNioBuf == null) {
             this.tmpNioBuf = tmpNioBuf = buffer.duplicate();
         }
         return tmpNioBuf;
     }
 
     @Override
     public ByteBuf copy(int index, int length) {
         ensureAccessible();
         ByteBuffer src;
         try {
             src = (ByteBuffer) internalNioBuffer().clear().position(index).limit(index + length);
         } catch (IllegalArgumentException ignored) {
             throw new IndexOutOfBoundsException("Too many bytes to read - Need " + (index + length));
         }
 
         ByteBuf dst = src.isDirect() ? alloc().directBuffer(length) : alloc().heapBuffer(length);
         dst.writeBytes(src);
         return dst;
     }
 
     @Override
     public int nioBufferCount() {
         return 1;
     }
 
     @Override
     public ByteBuffer[] nioBuffers(int index, int length) {
         return new ByteBuffer[] { nioBuffer(index, length) };
     }
 
     @Override
     public ByteBuffer nioBuffer(int index, int length) {
         return (ByteBuffer) buffer.duplicate().position(index).limit(index + length);
     }
 
     @Override
     public ByteBuffer internalNioBuffer(int index, int length) {
         ensureAccessible();
         return (ByteBuffer) internalNioBuffer().clear().position(index).limit(index + length);
     }
 
     @Override
     public boolean hasArray() {
         return buffer.hasArray();
     }
 
     @Override
     public byte[] array() {
         return buffer.array();
     }
 
     @Override
     public int arrayOffset() {
         return buffer.arrayOffset();
     }
 
     @Override
     public boolean hasMemoryAddress() {
         return false;
     }
 
     @Override
     public long memoryAddress() {
         throw new UnsupportedOperationException();
     }
 }