import java.applet.*;
import java.awt.*;
import java.awt.image.*;
import java.lang.Math;
import java.awt.event.*;
import java.net.*;
import java.util.*;
import java.lang.*;

// use the old event model to be compatible with Java 1.1.5

public class SatWorks extends Applet implements Runnable, ActionListener {
  
  Graphics gb;
  Image buffer;
  Image satImage, laloImage, worldImage;
  RotateGlobe rg;
  String param;
  double longi = 90.;
  double altitude = 20.;
  boolean isRotating = true;
  double ELEVATIONRATIO = 35.38;
  double KMPERPIXEL = 35.;
  double PERIODRATIO = 11.0;
  int R = 180;
  int panelSize;
  double satAng = 0.;
  final double pi2 = .01745329252;
  double declination = 15. * pi2;
  double swathWidth = 20.;
  int ratioMax = 10;  // ratio of sat orbits to earth rotations
  int spotSize = 4;
  int numSpots = 5;
  IncDec adjustRatio, adjustSpotSize, adjustNumSpots, adjustSwathWidth, adjustInclination, adjustAltitude, adjustScanRate;
  Button restart, reset;

  boolean isLeo;
  int xsat, ysat, xsatcutoff;
  int scanRate = 4;

  double resetLongi, resetSatAng, resetAltitude, 
                     resetDeclination, resetSwathWidth;

  int resetRatioMax, resetSpotSize, resetNumSpots, resetScanRate;

  public void init() {

    setLayout(null);
    laloImage = loadImage("latlon2.gif");
    worldImage = loadImage("world2.gif");
    //satImage = loadImage("satellite.jpg");

    isLeo = true;

    if (getParameter("geo") != null) {
      isLeo = false;
      declination = 0.;
      altitude = 0.;
      xsat = -R;
      ysat = R - 2;
      xsatcutoff = R;
    }

    if (getParameter("longitude") != null) {
      longi = Integer.parseInt(getParameter("longitude").trim());
    }

    panelSize = 2 * R + 100;

    rg = new RotateGlobe(laloImage, worldImage,R,isLeo);
    rg.setSwath(declination, swathWidth, spotSize, numSpots);
    rg.setSize(panelSize, panelSize);
    // width=height = 2 * R + 100 (for orbit)
    // applet width = width + 120 for right-side controls

    buffer = createImage(panelSize,panelSize);
    gb = buffer.getGraphics();
    int CWID = 150;

    if (isLeo) {
      adjustInclination = new IncDec(CWID,50,"Inclination = "+ ( (int)Math.round(90.- declination/pi2))+"\u00b0");
      adjustInclination.setLocation(panelSize+10, 10);
      adjustInclination.addActionListener(this);
      add(adjustInclination);

      adjustSwathWidth = new IncDec(CWID,50,"Swath Width = " + ( (int)Math.round(2.1*swathWidth*KMPERPIXEL))+" km");
      adjustSwathWidth.setLocation(panelSize+10, 60+10);
      adjustSwathWidth.addActionListener(this);
      add(adjustSwathWidth);

      adjustAltitude = new IncDec(CWID,50,"Altitude = "+ ( (int)Math.round(altitude*ELEVATIONRATIO)) +" km");
      adjustAltitude.setLocation(panelSize+10, 2*60+10);
      adjustAltitude.addActionListener(this);
      add(adjustAltitude);

      adjustSpotSize = new IncDec(CWID,50,"Spot Size = "+ ( (int)Math.round(spotSize*KMPERPIXEL))+" km");
      adjustSpotSize.setLocation(panelSize+10, 3*60+10);
      adjustSpotSize.addActionListener(this);
      add(adjustSpotSize);

      adjustNumSpots = new IncDec(CWID,50,"Number of Spots = "+numSpots);
      adjustNumSpots.setLocation(panelSize+10, 4*60+10);
      adjustNumSpots.addActionListener(this);
      add(adjustNumSpots);

      adjustRatio = new IncDec(CWID,50,"Period = "+ ( (int)Math.round(60. * PERIODRATIO/ratioMax))+" mins");
      adjustRatio.setLocation(panelSize+10, 5*60+10);
      adjustRatio.addActionListener(this);
      add(adjustRatio);

    } else {

      adjustScanRate = new IncDec(CWID,50,"Scan Rate");
      adjustScanRate.setLocation(panelSize+10, 10);
      adjustScanRate.addActionListener(this);
      add(adjustScanRate);
    }

    restart = new Button("Clear Image");
    restart.setBounds(panelSize+10+CWID/2-90/2, 6*60+30, 90,20);
    restart.addActionListener(this);
    add(restart);

    reset = new Button("Reset");
    reset.setBounds(panelSize+10+CWID/2-90/2, 7*60+10, 90,20);
    reset.addActionListener(this);
    resetSatAng = satAng;
    resetAltitude = altitude;
    resetDeclination = declination;
    resetSwathWidth = swathWidth;
    resetLongi = longi;
    resetSpotSize = spotSize;
    resetNumSpots = numSpots;
    resetRatioMax = ratioMax;
    resetScanRate = scanRate;
    add(reset);

  }

  public void update(Graphics g) { paint(g); }

  public void paint(Graphics g) {
    gb.setColor(Color.black);
    gb.fillRect(0,0,panelSize,panelSize);

    int center = panelSize / 2;

    // offset of 50 lines/pixels for orbit...
    gb.drawImage(rg.getImage(longi),50,50,this);  

    if (isLeo) {
      // increment the satellite position each time this is called
      satAng = satAng + 1.;

      if (satAng >= 180.) satAng = -satAng;

      ysat = (int) Math.round((R+altitude)*Math.cos(satAng*pi2) * 
                                                Math.cos(declination));
      xsat = (int) Math.round(ysat*Math.tan(declination));
      double rr = Math.sqrt((double)ysat*ysat + (double)xsat*xsat);

      if ((Math.abs(rr) < R+4) && satAng < 0.0) {
      } else {
        gb.setColor(Color.black);
        gb.drawRect(center+xsat-2,center-ysat-2,5,5);
        gb.setColor(Color.white);
        gb.drawRect(center+xsat-1,center-ysat-1,3,3);
        if (Math.abs(rr) < R) rg.mapSatellite(xsat,ysat);

      }
    } else {
      xsat = xsat + scanRate;
      if (xsat > xsatcutoff) {
        ysat = ysat - (spotSize - (int)Math.round(spotSize/2. * Math.abs((double)ysat/R)));

        if (ysat < -R) { ysat = R; }

        xsat =(int) -Math.round( (R * Math.cos((double)ysat/R)) );

        xsatcutoff = -xsat;  // when to stop this line
        
      }
      rg.mapSatellite(xsat, ysat);

    }

    gb.setColor(Color.orange);
    g.drawImage(buffer,0,0,this);

  }

  // Listeners
  public void actionPerformed(ActionEvent e) {

    if (e.getSource() == adjustInclination) {
      adjustInclination.enableButtons(true, true);
      if (e.getID() == 0 ) {
        declination = declination+2.*pi2;
        if (declination > 86.*pi2) {
          declination = 86.*pi2;
          adjustInclination.enableButtons(false, true);
        }
      } else if (e.getID() == 1) {
        declination = declination-2.*pi2;
        if (declination < 0.) {
          declination = 0;
          adjustInclination.enableButtons(true, false);
        }

      }
    }

    if (e.getSource() == adjustSwathWidth) {
      adjustSwathWidth.enableButtons(true, true);
      if (e.getID() == 0  ){
        swathWidth = swathWidth - 1.;
        if (swathWidth < 1.) {
          swathWidth = 1.;
          adjustSwathWidth.enableButtons(false, true);
        }
      } else if (e.getID() == 1) {
        swathWidth = swathWidth + 1.;
        if (swathWidth > 50.) {
          swathWidth = 50.;
          adjustSwathWidth.enableButtons(true, false);
        }
      }
    }


    if (e.getSource() == adjustAltitude) {
      adjustAltitude.enableButtons(true, true);
      if (e.getID() == 0  ){
        altitude = altitude - 1.;
        if (altitude < 2.) {
          altitude = 2.;
          adjustAltitude.enableButtons(false, true);
        } else {
          swathWidth = swathWidth - .5;
          if (swathWidth < 1.0) swathWidth = 1.0;
        }

      } else if (e.getID() == 1) {
        altitude = altitude + 1;
        if (altitude > 50.) {
          altitude = 50.;
          adjustAltitude.enableButtons(true, false);
        } else {
          swathWidth = swathWidth + .5;
          if (swathWidth > 50.0) swathWidth = 50.;
        }
      }
      adjustAltitude.setText("Altitude = "+ ( (int)Math.round(altitude*ELEVATIONRATIO)) +" km");
    }


    if (e.getSource() == adjustNumSpots) {
      adjustNumSpots.enableButtons(true, true);
      if (e.getID() == 0  ){
        numSpots = numSpots - 1;
        if (numSpots < 1) {
          numSpots = 1;
          adjustNumSpots.enableButtons(false, true);
        }
      } else if (e.getID() == 1) {
        numSpots = numSpots + 1;
        if (numSpots > 20) {
          numSpots = 20;
          adjustNumSpots.enableButtons(true, false);
        }
      }
    }


    if (e.getSource() == adjustSpotSize) {
      adjustSpotSize.enableButtons(true, true);
      if (e.getID() == 0  ){
        spotSize = spotSize - 1;
        if (spotSize < 1) {
          spotSize = 1;
          adjustSpotSize.enableButtons(false, true);
        }
      } else if (e.getID() == 1) {
        spotSize = spotSize + 1;
        if (spotSize > 10) {
          spotSize = 10;
          adjustSpotSize.enableButtons(true, false);
        }
      }
    }


    if (e.getSource() == adjustRatio) {
      adjustRatio.enableButtons(true, true);
      if (e.getID() == 1  ){
        ratioMax = ratioMax - 1;
        if (ratioMax < 2) {
          ratioMax = 2;
          adjustRatio.enableButtons(true, false);
        }
        
      } else if (e.getID() == 0) {
        ratioMax = ratioMax + 1;
        if (ratioMax > 32) {
          ratioMax = 32;
          adjustRatio.enableButtons(false, true);
        }
      }
    }
     
    if (e.getSource() == adjustScanRate) {
      adjustScanRate.enableButtons(true, true);
      if (e.getID() == 0 ) {
        scanRate = scanRate - 1;
        if (scanRate < 1) {
          scanRate = 1;
          adjustScanRate.enableButtons(false, true);
        }
      } else if (e.getID() == 1) {
        scanRate = scanRate + 1;
        if (scanRate > 20) {
          scanRate = 20;
          adjustScanRate.enableButtons(true, false);
        }

      }
    }



      if (isLeo) {
        adjustAltitude.setText("Altitude = "+ ( (int)Math.round(altitude*ELEVATIONRATIO)) +" km");

        adjustSwathWidth.setText("Swath Width = " + ( (int)Math.round(2.1*swathWidth*KMPERPIXEL))+" km");

        adjustInclination.setText("Inclination = "+ ( (int)Math.round(90.- declination/pi2))+"\u00b0");

        adjustNumSpots.setText("Number of Spots = "+numSpots);

        adjustRatio.setText("Period = "+ ( (int)Math.round(60. * PERIODRATIO/ratioMax))+" mins");

        adjustSpotSize.setText("Spot Size = "+ ( (int)Math.round(spotSize*KMPERPIXEL))+" km");

      } else {

        adjustScanRate.setText("Scan Rate ");
      }

    rg.setSwath(declination, swathWidth, spotSize, numSpots);

    if (e.getSource() == reset) {
      satAng = resetSatAng;
      altitude = resetAltitude;
      declination = resetDeclination;
      swathWidth = resetSwathWidth;
      longi = resetLongi;
      spotSize = resetSpotSize;
      numSpots = resetNumSpots;
      ratioMax = resetRatioMax;

      if (!isLeo) {
        xsat = -R;
        ysat = R;
        declination = 0;
        altitude = 0;
        xsatcutoff = R;
        scanRate = resetScanRate;
      }

      if (isLeo) {

        adjustAltitude.setText("Altitude = "+ ( (int)Math.round(altitude*ELEVATIONRATIO)) +" km");

        adjustSwathWidth.setText("Swath Width = " + ( (int)Math.round(2.1*swathWidth*KMPERPIXEL))+" km");

        adjustInclination.setText("Inclination = "+ ( (int)Math.round(90.- declination/pi2))+"\u00b0");

        adjustNumSpots.setText("Number of Spots = "+numSpots);

        adjustRatio.setText("Period = "+ ( (int)Math.round(60. * PERIODRATIO/ratioMax))+" mins");

        adjustSpotSize.setText("Spot Size = "+ ( (int)Math.round(spotSize*KMPERPIXEL))+" km");

        adjustSpotSize.enableButtons(true, true);
        adjustInclination.enableButtons(true, true);
        adjustSwathWidth.enableButtons(true, true);
        adjustAltitude.enableButtons(true, true);
        adjustNumSpots.enableButtons(true, true);
        adjustRatio.enableButtons(true, true);

      } else {

        adjustScanRate.setText("Scan Rate ");
        adjustScanRate.enableButtons(true, true);

      }

      rg.setSwath(declination, swathWidth, spotSize, numSpots);
      rg.clearImage();
    }



    if (e.getSource() == restart) {
      rg.clearImage();
    }

  }


  // next, handle running a Thread to automatically repaint
  // the display every "refreshRate" milliseconds
  private Thread animator_thread = null;
  private boolean isRunning;
  int refreshRate = 20;
  int ratio = 0;

  public void start() {
    if (animator_thread == null) {
      isRunning = true;
      animator_thread = new Thread(this);
      animator_thread.start();
    }
  }

  public void stop() {
    if ((animator_thread != null) && animator_thread.isAlive()) {
      isRunning = false;
      animator_thread.stop();
    }
    animator_thread = null;
  }

  public void run () {

    while (isRunning) {
      try { Thread.sleep(refreshRate); 
        if (isLeo && isRotating) {
          ratio = ratio + 1;
          if (ratio > ratioMax) {
            longi = longi - .5;
            if (longi < 0.) longi = 360.;
            ratio = 0;
          }
        }
        repaint();
      } catch (Exception re) {
        System.out.println("####  "+re);
      }
    }
  }


  // Utilities for getting images and audio clips from JAR or URL
  public Image loadImage(String name) {
    // first try the URL

    Image img = null;
    URL u = getClass().getResource( (String) name);
    if (u == null) {
      u = getDocumentBase();
      img = getImage(u,name);
    } else {
      img = getImage(u);
    }

		MediaTracker mt = new MediaTracker(this);
		mt.addImage(img, 0);
		try   { mt.waitForAll(); }
		catch ( Exception ex ) {img = null; }
    return img;

  }

}


class RotateGlobe extends Component {
  byte[] pixels, pixWorld, pixHold;
  // now setup for large image (2 x lat/lon of world)
  int LINES=361;
  int ELEMS=721;
  final double pi2 = .01745329252;
  ColorModel cm;
  double centerlon = 0.;
  double declination, swathWidth;
  double factor;
  int spotSize, preferredSpots;
  int R, N;
  int[] line2lat;
  int[][] ele2lon;
  int[] swathX, swathY;
  Image img;
  MemoryImageSource mis = null;
  byte[] pixs;
  double xb, xe, yb, ye, xstep, ystep, lat, lon;
  int z, zz;
  boolean isLeo;

  public RotateGlobe(Image lalo, Image world, int size, boolean leo) {
    isLeo = leo;
    R = size;
    N = 2 * R + 1;
    factor = (double)R/90.;
    line2lat = new int[R+1];
    ele2lon = new int[R+1][R+1];

    try {
      PixelGrabber pg = new PixelGrabber(lalo,0,0,ELEMS,LINES,false);
      pg.grabPixels();
      pixels = (byte[]) pg.getPixels();
      cm = pg.getColorModel();
      int stat = pg.status();

      PixelGrabber pgw = new PixelGrabber(world,0,0,ELEMS,LINES,false);
      pgw.grabPixels();
      pixWorld = (byte[]) pgw.getPixels();
      pixHold = new byte[ELEMS*LINES];

      stat = pgw.status();
      // fix the color for the base map (0=backgnd, 1=map, 2=latlon)
      for (int i=0; i<pixWorld.length; i++) {
        if (pixWorld[i] == 1) pixWorld[i] = (byte) 0x84;
        pixHold[i] = pixWorld[i];
      }
    } catch (Exception e) {
      System.out.println("####  grabbing:"+e);
    }

    pixs = new byte[N * N];

    // compute lats & lons for quadrant 1 only since others
    // can be derived from that...

    for (int y=0; y<R+1; y++) {
       double lat = Math.asin((double)(R-y)/R);
       line2lat[y] = (int)Math.round(factor * lat/pi2);
       for (int x=0; x<R+1; x++) {
         double lon = (double)x/(R*Math.cos(lat));
         if (Math.abs(lon) <= 1.0) {
           ele2lon[x][y] = (int) Math.round(factor * Math.asin(lon)/pi2);
           /*
           if (y == 10 || y == R-10) {
               System.out.println("####   x,y = "+x+"  "+y+" lat="+(lat/pi2)+" lon = "+(lon/pi2));
           }
           */
         } else {
           ele2lon[x][y] = -999;
         }
       }
    }

  }

  public void clearImage() {

    for (int i=0; i<pixWorld.length; i++) {
      pixWorld[i] = pixHold[i];
    }
  }

  public void setSwath(double dec, double sw, int spot, int num) {
    declination = dec;
    swathWidth = sw;
    spotSize = spot;
    preferredSpots = num;
  }



  // uncover the observed satellte data
  public void mapSatellite(int x, int y) {

    xb = x - swathWidth * Math.cos(declination);
    xe = x + swathWidth * Math.cos(declination);
    yb = y + swathWidth * Math.sin(declination);
    ye = y - swathWidth * Math.sin(declination);

    int n = (int) Math.abs(xe - xb);
    if ( Math.abs(ye - yb) > Math.abs(xe -xb) ) n = (int) Math.abs(ye - yb);
    if (n > preferredSpots) n = preferredSpots;

    if ((n > 1)) {
      xstep = (xe - xb)/(n-1);
      ystep = (ye - yb)/(n-1);
    } else {
      xstep = 0;
      ystep = 0;
      xb = x;
      yb = y;
    }

    for (int i=0; i<n; i++) {

      lat = Math.asin((yb + i*ystep)/(double)R);
      lon = (xb + i * xstep)/(R*Math.cos(lat));

      if (Math.abs(lon) > 1.0) continue;

      lon = Math.asin(lon)/pi2 + centerlon;
      lat = lat/pi2;
      if (lon < 0.) lon = 360.+lon;
      if (lon > 360.) lon = lon - 360.;

      z = ELEMS * (int)Math.round(factor * (90-lat)) + (int)Math.round(factor * lon);
      if (spotSize == 1) {
         pixWorld[z] = pixels[z];

      } else {
        
        for (int m=-spotSize/2; m<spotSize/2; m++) {
          for (int j=-spotSize/2; j<spotSize/2; j++) {
            zz = z + (m * ELEMS) + j;
            if (zz >= 0 && zz < (LINES*ELEMS)) pixWorld[zz] = pixels[zz];
          }
        }
      }

    }

  }

  public Image getImage(double longitude) {
    int yi, xi;
    int xp, yp;
    int z = 0;
    centerlon = longitude;
    for (int y=0; y<N; y++) {
      if (y > R) {
        yi = N - 1 -y;
        yp = -1;

      } else {
        yi = y;
        yp = +1;
      }

      for (int x=0; x<N; x++) {
        if (x > R) {
          xi = x - R;
          xp = 1;

        } else { 
          xi = R - x;
          xp = -1;
        }

        if (ele2lon[xi][yi] == -999) {
          pixs[z] = (byte)0;  // should be black

        } else {
          try {
          pixs[z] = pixWorld[
             (((int)(factor * longitude)+xp*ele2lon[xi][yi]) % ELEMS) + 
               (ELEMS * (R - yp*line2lat[yi])) ];

          } catch (Exception e2) {
            //System.out.println("####  yp, yi, l2l = "+yp+"  "+yi+" "+line2lat[yi]);
          }
        }

        z = z + 1;

      }
    }

    if (mis == null) {
      mis = new MemoryImageSource(N,N,cm,pixs,0,N);
      mis.setAnimated(true);
      img = createImage(mis);
    } else {
      mis.newPixels(0,0,N,N,false);
    }

    return img;

  }

}

class IncDec extends Panel implements ActionListener {
  int width, height;
  String text;
  Button plus, minus;
  Label lab;
  ActionListener callMe = null;

  public IncDec(int w, int h, String t) {
    setLayout(new BorderLayout());
    width = w;
    height = h;
    text = t;
    setSize(w,h);
    Font fon = new Font("monospaced",Font.BOLD,12);
    plus = new Button("+");
    plus.setFont(fon);
    plus.addActionListener(this);
    plus.setSize(w/3, w/3);

    minus = new Button("-");
    minus.setFont(fon);
    minus.addActionListener(this);
    minus.setSize(w/3, w/3);

    lab = new Label(text, Label.CENTER);
    Panel p1 = new Panel();
    p1.setLayout(new FlowLayout(FlowLayout.CENTER,10,2));
    p1.add(minus);
    p1.add(plus);
    add("North",p1);
    add("South",lab);
    validate();
  }

  public void enableButtons(boolean m, boolean p) {
    plus.setEnabled(p);
    minus.setEnabled(m);
  }

  public void addActionListener(ActionListener al) {
    callMe = al;
  }

  public void setText(String t) {
    lab.setText(t);
    lab.validate();
  }

  public void actionPerformed(ActionEvent e) {
    if (e.getSource() == minus) {
      if (callMe != null) {
        callMe.actionPerformed(new ActionEvent(this,0,"minus"));
      }

    } else if (e.getSource() == plus) {
      if (callMe != null) {
        callMe.actionPerformed(new ActionEvent(this,1,"plus"));
      }
    }
  }

}