//
   //  ========================================================================
   //  Copyright (c) 1995-2016 Mort Bay Consulting Pty. Ltd.
   //  ------------------------------------------------------------------------
   //  All rights reserved. This program and the accompanying materials
   //  are made available under the terms of the Eclipse Public License v1.0
   //  and Apache License v2.0 which accompanies this distribution.
   //
   //      The Eclipse Public License is available at
  //      http://www.eclipse.org/legal/epl-v10.html
  //
  //      The Apache License v2.0 is available at
  //      http://www.opensource.org/licenses/apache2.0.php
  //
  //  You may elect to redistribute this code under either of these licenses.
  //  ========================================================================
  //
  
  package org.eclipse.jetty.io;
  
  import java.nio.ByteBuffer;
  import java.util.ArrayList;
  import java.util.List;
  import java.util.Queue;
  import java.util.concurrent.atomic.AtomicInteger;
  
  import org.eclipse.jetty.util.BufferUtil;
  import org.eclipse.jetty.util.ConcurrentArrayQueue;
  
  /**
   * <p>A {@link ByteBuffer} pool.</p>
   * <p>Acquired buffers may be {@link #release(ByteBuffer) released} but they do not need to;
   * if they are released, they may be recycled and reused, otherwise they will be garbage
   * collected as usual.</p>
   */
  public interface ByteBufferPool
  {
      /**
       * <p>Requests a {@link ByteBuffer} of the given size.</p>
       * <p>The returned buffer may have a bigger capacity than the size being
       * requested but it will have the limit set to the given size.</p>
       *
       * @param size   the size of the buffer
       * @param direct whether the buffer must be direct or not
       * @return the requested buffer
       * @see #release(ByteBuffer)
       */
      public ByteBuffer acquire(int size, boolean direct);
  
      /**
       * <p>Returns a {@link ByteBuffer}, usually obtained with {@link #acquire(int, boolean)}
       * (but not necessarily), making it available for recycling and reuse.</p>
       *
       * @param buffer the buffer to return
       * @see #acquire(int, boolean)
       */
      public void release(ByteBuffer buffer);
      
      default ByteBuffer newByteBuffer(int capacity, boolean direct)
      {
          return direct ? BufferUtil.allocateDirect(capacity) : BufferUtil.allocate(capacity);
      }
  
      public static class Lease
      {
          private final ByteBufferPool byteBufferPool;
          private final List<ByteBuffer> buffers;
          private final List<Boolean> recycles;
  
          public Lease(ByteBufferPool byteBufferPool)
          {
              this.byteBufferPool = byteBufferPool;
              this.buffers = new ArrayList<>();
              this.recycles = new ArrayList<>();
          }
  
          public ByteBuffer acquire(int capacity, boolean direct)
          {
              ByteBuffer buffer = byteBufferPool.acquire(capacity, direct);
              BufferUtil.clearToFill(buffer);
              return buffer;
          }
  
          public void append(ByteBuffer buffer, boolean recycle)
          {
              buffers.add(buffer);
              recycles.add(recycle);
          }
  
          public void insert(int index, ByteBuffer buffer, boolean recycle)
          {
              buffers.add(index, buffer);
              recycles.add(index, recycle);
          }
  
          public List<ByteBuffer> getByteBuffers()
          {
              return buffers;
          }
 
         public long getTotalLength()
         {
             long length = 0;
             for (int i = 0; i < buffers.size(); ++i)
                 length += buffers.get(i).remaining();
             return length;
         }
 
         public int getSize()
         {
             return buffers.size();
         }
 
         public void recycle()
         {
             for (int i = 0; i < buffers.size(); ++i)
             {
                 ByteBuffer buffer = buffers.get(i);
                 if (recycles.get(i))
                     byteBufferPool.release(buffer);
             }
             buffers.clear();
             recycles.clear();
         }
     }
 
     
     class Bucket
     {
         private final ByteBufferPool _pool;
         private final int _capacity;
         private final AtomicInteger _space;
         private final Queue<ByteBuffer> _queue= new ConcurrentArrayQueue<>();
 
         public Bucket(ByteBufferPool pool, int bufferSize,int maxSize)
         {
             _pool=pool;
             _capacity=bufferSize;
             _space=maxSize>0?new AtomicInteger(maxSize):null;
         }
     
         public void release(ByteBuffer buffer)
         {
             BufferUtil.clear(buffer);
             if (_space==null)
                 _queue.offer(buffer);
             else if (_space.decrementAndGet()>=0)
                 _queue.offer(buffer);
             else
                 _space.incrementAndGet();
         }
     
         public ByteBuffer acquire(boolean direct)
         {
             ByteBuffer buffer = _queue.poll();
             if (buffer == null) 
                return _pool.newByteBuffer(_capacity,direct);
             if (_space!=null)
                 _space.incrementAndGet();
             return buffer;        
         }
     
         public void clear()
         {
             if (_space==null)
                 _queue.clear();
             else
             {
                 int s=_space.getAndSet(0);
                 while(s-->0)
                 {
                     if (_queue.poll()==null)
                         _space.incrementAndGet();
                 }
             }
         }
         
         boolean isEmpty()
         {
             return _queue.isEmpty();
         }
         
         int size()
         {
             return _queue.size();
         }
         
         @Override
         public String toString()
         {
             return String.format("Bucket@%x{%d,%d}",hashCode(),_capacity,_queue.size());
         }
     }
     
     
 }