HeadlessTaskMonitor.java

/**
 *
 */
package com.rgi.suite.cli;

import com.rgi.common.TaskMonitor;

import java.util.logging.Level;
import java.util.logging.Logger;
import java.util.stream.IntStream;

/**
 * TaskMonitor for headless operation, outputs progress bar to the command line for tracking status.
 *
 * @author matthew.moran
 */
public class HeadlessTaskMonitor implements TaskMonitor
{

	public static final int PROGRESS_BAR_LENGTH = 25;
	private int maximum;
	private int step = 1;
	private       int    last;
	private final Logger logger;

	HeadlessTaskMonitor(final Logger logger)
	{
		this.logger = logger;
	}

	@Override
	public void setMaximum(final int maximum)
	{
		this.maximum = maximum;
		if(maximum >= HeadlessTaskMonitor.PROGRESS_BAR_LENGTH)
		{
			this.step = maximum / HeadlessTaskMonitor.PROGRESS_BAR_LENGTH;
		}
	}

	@SuppressWarnings("NumericCastThatLosesPrecision")
	@Override
	public void setProgress(final int value)
	{
		final int percent = value * 100 / this.maximum;
		if(value > this.last + this.step)
		{
			final StringBuilder builder = new StringBuilder("[");
			//25 works well with console progress bars, the value is fairly arbitrary though.
			IntStream.rangeClosed(1, HeadlessTaskMonitor.PROGRESS_BAR_LENGTH).forEach(index -> {
				if(index < percent / 4)
				{
					builder.append('=');
				}
				else if(index == percent / 4)
				{
					builder.append('>');
				}
				else
				{
					builder.append(' ');
				}
			});
			builder.append(String.format("]  - %d / %d ", value, this.maximum));
			// return carriage and write over progress bar.
			//noinspection HardcodedLineSeparator,UseOfSystemOutOrSystemErr
			System.out.print("\r" + builder);
			this.last = value;
		}
		if(value == this.maximum)
		{
			this.logger.log(Level.INFO,
							String.format("\rGenerated %d/%d tiles successfully!", value, this.maximum));
			//noinspection HardcodedLineSeparator,UseOfSystemOutOrSystemErr
			System.out.println(String.format("\r[=========================] %d / %d", value, this.maximum));
			System.exit(0);

		}

	}

}