/* OpenLogViewer
    *
    * Copyright 2011
    *
    * This file is part of the OpenLogViewer project.
    *
    * OpenLogViewer software 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 3 of the License, or
   * (at your option) any later version.
   *
   * OpenLogViewer software 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 any OpenLogViewer software.  If not, see http://www.gnu.org/licenses/
   *
   * I ask that if you make any changes to this file you fork the code on github.com!
   *
   */
  package org.diyefi.openlogviewer;
  
  import java.awt.Dimension;
  import java.awt.FlowLayout;
  import java.awt.event.ActionEvent;
  import java.awt.event.ActionListener;
  import java.text.DecimalFormat;
  import java.text.DecimalFormatSymbols;
  import java.text.NumberFormat;
  import java.util.ResourceBundle;
  
  import javax.swing.JLabel;
  import javax.swing.JPanel;
  import javax.swing.Timer;
  
  public class FramesPerSecondPanel extends JPanel implements ActionListener {
  	private static final long serialVersionUID = 1L;
  	private static final int PREFERRED_WIDTH = 80;
  	private static final int PPREFERRED_HEIGHT = 16;
  	private static final int TIMER_RATE = 250; // milliseconds - changes display/update speed
  	private static final double MILLISECONDS_PER_SECOND = 1000d;
  
  	private static final char ZERO = '0';
  	private static final char DS = DecimalFormatSymbols.getInstance().getDecimalSeparator();
  	private static final char TS = DecimalFormatSymbols.getInstance().getGroupingSeparator();
  	private static final String FORMAT = "#" + TS + "##0" + DS + ZERO;
  
  	private static final DecimalFormat DF = (DecimalFormat) NumberFormat.getNumberInstance();
  	static {
  		DF.applyLocalizedPattern(FORMAT);
  	}
  
  	private static long frameCount;
  	private static long thePast;
  	private static long currentTime;
  	private static long previousCount;
  
  	private final String framesPerSecond;
  
  	private final JLabel output;
  	private final Timer sampleTimer;
  
  	private Double fps;
  
  	public FramesPerSecondPanel(final ResourceBundle labels) {
  		setName("fpsPanel");
  		setPreferredSize(new Dimension(PREFERRED_WIDTH, PPREFERRED_HEIGHT));
  		setLayout(new FlowLayout(FlowLayout.LEFT, 0, 0));
  
  		framesPerSecond = labels.getString(Text.FRAMES_PER_SECOND);
  		final String defaultFpsLabel = framesPerSecond + ZERO + DS + ZERO;
  		output = new JLabel(defaultFpsLabel);
  		output.setVerticalTextPosition(JLabel.CENTER);
  		output.setHorizontalTextPosition(JLabel.CENTER);
  		this.add(output);
  
  		// Start timer after objects that it operates on exist...
  		sampleTimer = new Timer(TIMER_RATE, this);
  		sampleTimer.setInitialDelay(0);
  		sampleTimer.start();
  		currentTime = System.currentTimeMillis();
  		thePast = currentTime;
  	}
  
  	public static void increaseFrameCount() {
  		currentTime = System.currentTimeMillis();
  		frameCount++;
  	}
  
  	@Override
  	public final void actionPerformed(final ActionEvent e) {
  		if (e.getSource().equals(sampleTimer)) {
  			final long sampleWindow = currentTime - thePast;
  			final long sampleCount = frameCount - previousCount;
  			if (sampleWindow == 0L) { // Avoid division by zero
  				fps = 0d;
  			} else {
 				fps = ((double) sampleCount / (double) sampleWindow) * MILLISECONDS_PER_SECOND;
 			}
 			output.setText(framesPerSecond + DF.format(fps));
 			previousCount = frameCount;
 			thePast = currentTime;
 		}
 	}
 
 }