/*
    * ====================================================================
    * 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.impl.io;
  
  import java.io.IOException;
  import java.io.OutputStream;
  import java.nio.ByteBuffer;
  
  import org.apache.hc.core5.util.Args;
  
  /**
   * @since 5.0
   */
  abstract class FrameOutputStream extends OutputStream {
  
      private final OutputStream outputStream;
  
      private final byte[] cache;
      private int cachePosition;
  
      public FrameOutputStream(final int minChunkSize, final OutputStream outputStream) {
          super();
          this.outputStream = Args.notNull(outputStream, "Output stream");
          this.cache = new byte[minChunkSize];
      }
  
      protected abstract void write(final ByteBuffer src, final boolean endStream, final OutputStream outputStream) throws IOException;
  
      private void flushCache(final boolean endStream) throws IOException {
          if (this.cachePosition > 0) {
              write(ByteBuffer.wrap(this.cache, 0, this.cachePosition), endStream, this.outputStream);
              this.cachePosition = 0;
          }
      }
  
      @Override
      public void write(final int b) throws IOException {
          this.cache[this.cachePosition] = (byte) b;
          this.cachePosition++;
          if (this.cachePosition == this.cache.length) {
              flushCache(false);
          }
      }
  
      @Override
      public void write(final byte[] b) throws IOException {
          write(b, 0, b.length);
      }
  
      @Override
      public void write(final byte[] src, final int off, final int len) throws IOException {
          if (len >= this.cache.length - this.cachePosition) {
              flushCache(false);
              write(ByteBuffer.wrap(src, off, len), false, this.outputStream);
          } else {
              System.arraycopy(src, off, cache, this.cachePosition, len);
              this.cachePosition += len;
          }
      }
  
      @Override
      public void flush() throws IOException {
          flushCache(false);
          this.outputStream.flush();
      }
  
      @Override
      public void close() throws IOException {
          if (this.cachePosition > 0) {
              flushCache(true);
          } else {
              write(null, true, this.outputStream);
          }
          flushCache(true);
         this.outputStream.flush();
     }
 
 }