// Checkpoint 4 pendulum class.  Comprehend, answer the questions in the code,
// write your own comments, figure out how to convert it to do part 1, 
// the mass-on-spring code (this requires deleting eight characters) and
// solve the questions on the checkpoint page 
//  Explain the results from the default settings - why doesn't the position
// tend to oscillate about 0, what are the wiggles in the velocity graph, 
// and what is the pendulum doing?
import java.io.*;
import display.*;
import VisualNumerics.math.Sfun;               
import gov.noaa.pmel.sgt.cplab.*;
import java.awt.*;
class DDpend
{
   static BufferedReader keyboard = new BufferedReader(new InputStreamReader(System.in)); 

    public static void main (String argv []) throws IOException
    {
     Vector3 position = new Vector3(0,0,0)  ;
     Vector3 velocity = new Vector3(0,0,0)  ;
     Vector3 acceleration = new Vector3(0,0,0);  
     Vector3 xhat = new Vector3(1,0,0);  
     Vector3 vtemp;
     Vector3 vx;
     Vector3 force;
     boolean catholicPope=true;
     double massive = 1;
     double q = 1;
     double dt =.0023472843;
     int nprint = 1000;
     Vector3 FD = new Vector3(2,0,0); 
     Particle fermion = new Particle(position,velocity,acceleration,massive,q,0.0);
       PrintWriter out;
       out = new PrintWriter(new FileWriter("output.dat"));

       Display panel = new Display("Damped, Driven Pendulum motion");
       panel.setBackground(Color.yellow);
       Input omegaInput= new Input("   Driving Frequency",0.2);
       Input gammaInput= new Input(" Damping coefficient",0.50);
       Input initInput = new Input("Initial displacement",1.0);
       Input velInput = new Input("Initial velocity",10.0);
       Input ampInput  = new Input("   Driving Amplitude",2.0);
       Input kInput    = new Input("     Spring Constant",1.0);
       Input timeInput = new Input("       Time for graph",150.0);
       panel.addInput(omegaInput);
       panel.addInput(gammaInput);
       panel.addInput(initInput);
       panel.addInput(velInput);
       panel.addInput(ampInput);
       panel.addInput(kInput);
       panel.addInput(timeInput);
       SimpleGraph graph = new SimpleGraph("Damped, driven oscillator","Time","seconds",
                                      "Displacement", "Radians");
        graph.showGraph(); 
       SimpleGraph graph1 = new SimpleGraph("Damped, driven oscillator","Time","seconds",
                                      "Angular velocity", "Radians/fs");
        graph1.showGraph(); 
        Color colour = Color.red;
// What does icol do?
        int icol = 1;
	int newSize = 600;
// What does this while loop do?
  while (catholicPope) { 
     panel.waitForButtonPress();
     panel.setSize(panel.getSize().width,newSize);
     double omegaD= omegaInput.getDouble(); 
     double bdamp = -gammaInput.getDouble() ; 
     FD.x= ampInput.getDouble();
     fermion.pos.x = initInput.getDouble();
     fermion.vel.x = velInput.getDouble();
     double kspring = kInput.getDouble();
     double tottime = timeInput.getDouble();
     DataSet data = new DataSet();  
     DataSet data1 = new DataSet();  
     fermion.time = 0.0;
     //  Why are there two loops here? 
     for(int j = 1; j < nprint;j++) {
     for(double itime = 0; itime< tottime/nprint; itime=itime+dt) {
     fermion.pos = Vector3.add(Vector3.add(fermion.pos,
                                         Vector3.multiply(fermion.vel,dt))
                             , Vector3.multiply(fermion.acc,dt*dt/2.0));
     vtemp = Vector3.add(fermion.vel, Vector3.multiply(fermion.acc,dt/2.0));
     force = Vector3.add(Vector3.multiply(xhat,-Math.sin(fermion.pos.x)*kspring),
                       Vector3.multiply(FD,Math.cos(omegaD*fermion.time))); 
     force = Vector3.add(force,  Vector3.multiply(vtemp,bdamp)) ;
     fermion.acc = Vector3.multiply(force,1.0/fermion.mass) ;
     fermion.vel = Vector3.add(vtemp , Vector3.multiply(fermion.acc,dt/2.0));
     fermion.time = fermion.time + dt;
     }     
     data.addPoint(fermion.time,fermion.pos.x);
     data1.addPoint(fermion.time,fermion.vel.x);
        out.println(fermion.time + " " +fermion.pos.x);
  } 
     if(icol==1){ data.setColor(Color.red); data1.setColor(Color.red);}
     else
         {if(icol==2){ data.setColor(Color.blue);data1.setColor(Color.blue);}
     else
         {if(icol==3){ data.setColor(Color.green);data1.setColor(Color.green);}
     else
         {if(icol==4){ data.setColor(Color.orange);data1.setColor(Color.orange);}
     else
         {if(icol==5){ data.setColor(Color.yellow); data1.setColor(Color.yellow); icol=0;}}}}}
     icol = icol+1;
     graph.addData(data); 
     graph1.addData(data1); 
     out.flush();
  }
     out.close(); 
    }}