import java.applet.*;
import java.awt.*;
import java.awt.event.*;
import java.awt.image.*;
import shtick.math.FourierBasis;
import shtick.math.FourierSeries;

//////////////////////////////////////////////////////
//**************************************************//
//*              FourierDemo1 Applet               *//
//*                                                *//
//* Version 1.2.1                                  *//
//* Author: Sean M. Cox                            *//
//* Organization: The Shtick                       *//
//* http://www.smcox.com/                          *//
//*                                                *//
//* Demonstrates, in detail, the use of the        *//
//* Fourier Transform to model periodic functions. *//
//*                                                *//
//**************************************************//
//////////////////////////////////////////////////////

public class FourierDemo extends Applet implements ActionListener{
  private int        harmonics=10;    // How many harmonics deep shall we go
  private static int dataWidth=60;

  private double[] data=new double[dataWidth];
  private double[] sineSeries;
  private double[] cosineSeries;

  private String error="";
  private Button lessButton;
  private Button moreButton;

  private FourierSeries series;
  private FourierBasis  basis;

  public FourierDemo(){
    lessButton= new Button("Less");
    moreButton= new Button("More");
    setLayout(null);
  }

  public void init() {
    add(lessButton);
    add(moreButton);
    lessButton.addActionListener(this);
    moreButton.addActionListener(this);
    lessButton.setBounds(20,140,lessButton.getPreferredSize().width,lessButton.getPreferredSize().height);
    moreButton.setBounds(152,140,moreButton.getPreferredSize().width,moreButton.getPreferredSize().height);

    for (int x=0;x<60; x++) {
      data[x]=Function(.5+x);
    }

    basis = new FourierBasis(dataWidth);
    series = new FourierSeries(data, basis);
    series.translate();
    cosineSeries=series.getCosineSeries();
    sineSeries=series.getSineSeries();
  }

  /**
   * Paint it.
   */
  public void paint(Graphics g) {
    g.setColor(Color.black);
    g.drawString("Function",4,16);
    g.drawRect(0, 20, 61, 80);
    g.drawString("Function with approximation superimposed",10,116);
    g.drawRect(71, 120, 61, 80);
    g.drawString("Fourier Aproximation",118,16);
    g.drawRect(142, 20, 61, 80);
    g.drawString("Number of",63,32);
    g.drawString("Harmonics:"+harmonics,63,44);
    double tally=cosineSeries[0];
    for (int h=1;h<harmonics;h++){
      tally+=cosineSeries[h]*basis.getCosineBasis()[h][0];
    }
    for (int x=1;x<dataWidth; x++){
      g.drawLine(x+1, (int)(data[x-1]+.5)+20, x+2, (int)(data[x]+.5)+20);
      g.drawLine(x+72, (int)(data[x-1]+.5)+120, x+73, (int)(data[x]+.5)+120);
      double tallyNew=(double)cosineSeries[0];
      for (int h=1;h<harmonics;h++){
        tallyNew+=(double)(cosineSeries[h]*basis.getCosineBasis()[h][x]+sineSeries[h]*basis.getSineBasis()[h][x]);
      }
      g.drawLine(x+72, (int)(tally+.5)+120, x+73, (int)(tallyNew+.5)+120);
      g.drawLine(x+143, (int)(tally+.5)+20, x+144, (int)(tallyNew+.5)+20);
      tally=tallyNew;
    }
  }

  public void actionPerformed(ActionEvent ae) {
    if (ae.getActionCommand().equals("Less") & (harmonics>0)){
      harmonics--;
      repaint();
    }
    if (ae.getActionCommand().equals("More") & ((harmonics)<(dataWidth/2))){
      harmonics++;
      repaint();
    }
  }

  private double Function(double x){
    if (x>30) return (double)60;
    return (double)20;
  }

  public String getAppletInfo() {
    return "A fourier series demo by Sean M. Cox";
  }
}