/*
 * Copyright (C) 2013 University of Dundee & Open Microscopy Environment.
 * All rights reserved.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License along
 * with this program; if not, write to the Free Software Foundation, Inc.,
 * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
 */

package ome.formats.importer.util;

import org.apache.commons.lang.time.StopWatch;

/**
 * Class implementing the {@link TimeEstimator} interface. Uses the Exponential
 * Moving Average equation to provide an estimate of the remaining upload time
 * of binary data. A correction factor is used for minimal overestimation.
 *
 * @author Blazej Pindelski, bpindelski at dundee.ac.uk
 * @since 5.0
 */
public class ProportionalTimeEstimatorImpl implements TimeEstimator {

    private long imageContainerSize = 0, timeLeft = 0;

    private long totalBytes = 0;

    private long totalTime = 0;

    private StopWatch sw;

    /**
     * Creates a new object of this class with a defined internal buffer size.
     *
     * @param imageContainerSize
     *            The total size in bytes of the data container for which upload
     *            time is being estimated.
     */
    public ProportionalTimeEstimatorImpl(long imageContainerSize) {
        sw = new StopWatch();
        this.imageContainerSize = imageContainerSize;
    }

    /**
     * @see TimeEstimator#start()
     */
    public void start() {
        sw.reset();
        sw.start();
    }

    /**
     * @see TimeEstimator#stop()
     */
    public void stop() {
        sw.stop();
        totalTime += sw.getTime();
    }

    /**
     * @see TimeEstimator#stop(long)
     */
    public void stop(long uploadedBytes) {
        sw.stop();
        totalTime += sw.getTime();
        totalBytes += uploadedBytes;
        imageContainerSize -= uploadedBytes;

        if (totalTime > 0) {
            float averageBps = totalBytes / ((float) totalTime / 1000);
            timeLeft = (long) Math
                    .ceil((imageContainerSize / averageBps) * 1000);
        }
    }

    /**
     * @see TimeEstimator#getUploadTimeLeft()
     */
    public long getUploadTimeLeft() {
        return timeLeft;
    }

}