content: /*
   * Copyright 2014-2025 Real Logic Limited.
   *
   * Licensed 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 org.agrona.io;
  
  import org.agrona.DirectBuffer;
  
  import java.io.InputStream;
  
  /**
   * An {@link InputStream} that wraps a {@link DirectBuffer}.
   */
  public class DirectBufferInputStream extends InputStream
  {
      private DirectBuffer buffer;
      private int offset;
      private int length;
      private int position;
  
      /**
       * Default constructor.
       */
      public DirectBufferInputStream()
      {
      }
  
      /**
       * Wrap given {@link DirectBuffer}.
       *
       * @param buffer to wrap.
       */
      @SuppressWarnings("this-escape")
      public DirectBufferInputStream(final DirectBuffer buffer)
      {
          wrap(buffer, 0, buffer.capacity());
      }
  
      /**
       * Wrap given {@link DirectBuffer}.
       *
       * @param buffer to wrap.
       * @param offset into the buffer.
       * @param length in bytes.
       */
      @SuppressWarnings("this-escape")
      public DirectBufferInputStream(final DirectBuffer buffer, final int offset, final int length)
      {
          wrap(buffer, offset, length);
      }
  
      /**
       * Wrap given {@link DirectBuffer}.
       *
       * @param buffer to wrap.
       */
      public void wrap(final DirectBuffer buffer)
      {
          wrap(buffer, 0, buffer.capacity());
      }
  
      /**
       * Wrap given {@link DirectBuffer}.
       *
       * @param buffer to wrap.
       * @param offset into the buffer.
       * @param length in bytes.
       */
      public void wrap(final DirectBuffer buffer, final int offset, final int length)
      {
          if (null == buffer)
          {
              throw new NullPointerException("buffer cannot be null");
          }
  
          this.buffer = buffer;
          this.offset = offset;
          this.length = length;
          this.position = 0;
      }
  
      /**
       * The offset within the underlying buffer at which to start.
       *
       * @return offset within the underlying buffer at which to start.
       */
      public int offset()
      {
          return offset;
      }
  
      /**
       * The length of the underlying buffer to use.
       *
       * @return length of the underlying buffer to use.
       */
      public int length()
      {
          return length;
      }
  
      /**
       * The underlying buffer being wrapped.
       *
       * @return the underlying buffer being wrapped.
       */
      public DirectBuffer buffer()
      {
          return buffer;
      }
  
      /**
       * {@inheritDoc}
       */
      public boolean markSupported()
      {
          return false;
      }
  
      /**
       * {@inheritDoc}
       */
      public int available()
      {
          return length - position;
      }
  
      /**
       * {@inheritDoc}
       */
      public long skip(final long n)
      {
          final int skipped = (int)Math.min(n, available());
          position += skipped;
  
          return skipped;
      }
  
      /**
       * {@inheritDoc}
       */
      public int read()
      {
          int b = -1;
          if (position < length)
          {
              b = buffer.getByte(offset + position) & 0xFF;
              ++position;
          }
  
          return b;
      }
  
      /**
       * {@inheritDoc}
       */
      public int read(final byte[] dstBytes, final int dstOffset, final int length)
      {
          int bytesRead = -1;
  
          if (position < this.length)
          {
              bytesRead = Math.min(length, available());
              buffer.getBytes(offset + position, dstBytes, dstOffset, bytesRead);
              position += bytesRead;
          }
  
          return bytesRead;
      }
  
      /**
       * {@inheritDoc}
       */
      public void close()
      {
      }
  }
  