package jp.sourceforge.dvibrowser.dvicore.image.pnm;
/*
 * Copyright (c) 2009, Takeyuki Nagao
 * All rights reserved.
 * 
 * Redistribution and use in source and binary forms, with or
 * without modification, are permitted provided that the
 * following conditions are met:
 * 
 *  * Redistributions of source code must retain the above
 *    copyright notice, this list of conditions and the
 *    following disclaimer.
 *  * Redistributions in binary form must reproduce the above
 *    copyright notice, this list of conditions and the
 *    following disclaimer in the documentation and/or other
 *    materials provided with the distribution.
 *    
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND
 * CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES,
 * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR
 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
 * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
 * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
 * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE
 * USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY
 * OF SUCH DAMAGE.
 */

import java.io.BufferedReader;
import java.io.ByteArrayInputStream;
import java.io.FilterInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;

public abstract class AbstractPnmAsciiFilter
extends FilterInputStream
{
  protected BufferedReader reader;
  protected ByteArrayInputStream byteArrayInput;
  
  public AbstractPnmAsciiFilter(InputStream in) {
    super(in);
    reader = new BufferedReader(new InputStreamReader(in));
  }
  
  protected synchronized void fill() throws IOException
  {
    if (reader == null) {
      throw new IOException("EOF detected while reading the input");
    }
    if (byteArrayInput != null && byteArrayInput.available() > 0) {
      return;
    }
    
    byteArrayInput = new ByteArrayInputStream(fillBuffer());
  }

  protected abstract byte [] fillBuffer() throws IOException;
  
  @Override
  public synchronized int available() throws IOException
  {
    fill();
    return byteArrayInput.available();
  }
  
  @Override
  public synchronized void close() throws IOException
  {
    reader.close();
  }
  
  @Override
  public void mark(int readLimit)
  {
    throw new UnsupportedOperationException("mark is not supported");
  }
  
  @Override
  public void reset()
  {
    throw new UnsupportedOperationException("reset is not supported");
  }
  
  @Override
  public boolean markSupported()
  {
    return false;
  }
  
  @Override
  public synchronized int read() throws IOException
  {
    fill();
    return byteArrayInput.read();
  }

  @Override
  public synchronized int read(byte [] buf, int off, int len) throws IOException
  {
    fill();
    return byteArrayInput.read(buf, off, len);
  }
}
