/*
    * ====================================================================
    * Licensed to the Apache Software Foundation (ASF) under one
    * or more contributor license agreements.  See the NOTICE file
    * distributed with this work for additional information
    * regarding copyright ownership.  The ASF 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.
   * ====================================================================
   *
   * This software consists of voluntary contributions made by many
   * individuals on behalf of the Apache Software Foundation.  For more
   * information on the Apache Software Foundation, please see
   * <http://www.apache.org/>.
   *
   */
  
  package org.apache.hc.core5.http2;
  
  import java.io.IOException;
  import java.nio.ByteBuffer;
  import java.nio.channels.ClosedChannelException;
  import java.nio.channels.WritableByteChannel;
  
  public class WritableByteChannelMock implements WritableByteChannel {
  
      private final int capacityLimit;
  
      private int capacityUsed;
      private ByteBuffer buf;
      private boolean closed;
  
      public WritableByteChannelMock(final int initialSize, final int capacityLimit) {
          this.buf = ByteBuffer.allocate(initialSize);
          this.capacityLimit = capacityLimit;
      }
  
      public WritableByteChannelMock(final int initialSize) {
          this(initialSize, 0);
      }
  
      private void expandCapacity(final int capacity) {
          final ByteBuffer oldbuffer = this.buf;
          this.buf = ByteBuffer.allocate(capacity);
          oldbuffer.flip();
          this.buf.put(oldbuffer);
      }
  
      private void ensureCapacity(final int requiredCapacity) {
          if (requiredCapacity > this.buf.capacity()) {
              expandCapacity(requiredCapacity);
          }
      }
  
      @Override
      public int write(final ByteBuffer src) throws IOException {
          if (this.closed) {
              throw new ClosedChannelException();
          }
          final int len = src.remaining();
          ensureCapacity(this.buf.position() + len);
          if (this.capacityLimit > 0) {
              final int chunk = Math.min(this.capacityLimit - this.capacityUsed, len);
              if (chunk > 0) {
                  final int limit = src.limit();
                  src.limit(src.position() + chunk);
                  this.buf.put(src);
                  src.limit(limit);
                  this.capacityUsed += chunk;
                  return chunk;
              }
              return 0;
          }
          this.buf.put(src);
          return len;
      }
  
      @Override
      public boolean isOpen() {
          return !this.closed;
      }
  
      @Override
      public void close() throws IOException {
          this.closed = true;
      }
  
      public void flush() {
          this.capacityUsed = 0;
     }
 
     public void reset() {
         this.capacityUsed = 0;
         this.buf.clear();
     }
 
     public byte[] toByteArray() {
         final ByteBuffer dup = this.buf.duplicate();
         dup.flip();
         final byte[] bytes = new byte[dup.remaining()];
         dup.get(bytes);
         return bytes;
     }
 
 }