package com.yahoo.labs.samoa.moa.core;

/*
 * #%L
 * SAMOA
 * %%
 * Copyright (C) 2014 - 2015 Apache Software Foundation
 * %%
 * 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
 * 
 *      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.
 * #L%
 */

import java.io.FilterInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.Serializable;

/**
 * Class for monitoring the progress of reading an input stream.
 * 
 * @author Richard Kirkby (rkirkby@cs.waikato.ac.nz)
 * @version $Revision: 7 $
 */
public class InputStreamProgressMonitor extends FilterInputStream implements Serializable {

  /** The number of bytes to read in total */
  protected int inputByteSize;

  /** The number of bytes read so far */
  protected int inputBytesRead;

  public InputStreamProgressMonitor(InputStream in) {
    super(in);
    try {
      this.inputByteSize = in.available();
    } catch (IOException ioe) {
      this.inputByteSize = 0;
    }
    this.inputBytesRead = 0;
  }

  public int getBytesRead() {
    return this.inputBytesRead;
  }

  public int getBytesRemaining() {
    return this.inputByteSize - this.inputBytesRead;
  }

  public double getProgressFraction() {
    return ((double) this.inputBytesRead / (double) this.inputByteSize);
  }

  /*
   * (non-Javadoc)
   * 
   * @see java.io.InputStream#read()
   */
  @Override
  public int read() throws IOException {
    int c = this.in.read();
    if (c > 0) {
      this.inputBytesRead++;
    }
    return c;
  }

  /*
   * (non-Javadoc)
   * 
   * @see java.io.InputStream#read(byte[])
   */
  @Override
  public int read(byte[] b) throws IOException {
    int numread = this.in.read(b);
    if (numread > 0) {
      this.inputBytesRead += numread;
    }
    return numread;
  }

  /*
   * (non-Javadoc)
   * 
   * @see java.io.InputStream#read(byte[], int, int)
   */
  @Override
  public int read(byte[] b, int off, int len) throws IOException {
    int numread = this.in.read(b, off, len);
    if (numread > 0) {
      this.inputBytesRead += numread;
    }
    return numread;
  }

  /*
   * (non-Javadoc)
   * 
   * @see java.io.InputStream#skip(long)
   */
  @Override
  public long skip(long n) throws IOException {
    long numskip = this.in.skip(n);
    if (numskip > 0) {
      this.inputBytesRead += numskip;
    }
    return numskip;
  }

  /*
   * (non-Javadoc)
   * 
   * @see java.io.FilterInputStream#reset()
   */
  @Override
  public synchronized void reset() throws IOException {
    this.in.reset();
    this.inputBytesRead = this.inputByteSize - this.in.available();
  }

}