/*
    java lab: phase transitions
 */

import java.awt.*;
import java.applet.*;

public class phase extends Applet implements Runnable{
    public MediaTracker tracker;
	public Image offScreenImage;
	public Image theBox, theHeater;
	public boolean copyRight = false, auto = false, makePlot = false;
	public char cr = '\n';
	Thread moveThread;
	private static final int MOVEPAUSE = 1000;
	public boolean myGo = false;
		
	public double dQdt = 0;  		// heating rate in kW
	public int xh = 0, yh = 302;	// coordinates for rate plot radio button
	public int numMeas = 0;		// number of temperature measurements
	public double heat = 0.0;		// total heat inserted
	public double mass;			// total mass of water in kg, set in init()
	public double temper = -50.0;	// current temperature that's displayed

	public double measuredT[] = new double[5000];	// temperature mesurements
	public double measuredQ[] = new double[5000];	// corresp. Q measurements

	public long t1, t1old;
	

	public void start()  {
		if(myGo) {
			if(moveThread == null){
				moveThread = new Thread(this);
				moveThread.start();
			}
		}
	}
	
	public void stop()  {
		if(moveThread != null){
			moveThread.stop();
			try {
				moveThread.join();
			}
			catch (InterruptedException e) { }
		}
		moveThread=null;
	}
		
	public void run() {
		while (true){
			try {
				moveThread.sleep(MOVEPAUSE);
			}catch(InterruptedException e) {
			}
			repaint();
		}
	}
	
	public void init() {
		super.init();		
		// load the background image
		tracker= new MediaTracker(this);
		theBox = this.getImage(getCodeBase(),"bg.jpg");
		tracker.addImage(theBox,0);
		try {
	    	tracker.waitForID(0);
		} catch (InterruptedException e) {
		}
		theHeater = this.getImage(getCodeBase(),"heat.jpg");
		tracker.addImage(theHeater,0);
		try {
	    	tracker.waitForID(0);
		} catch (InterruptedException e) {
		}
		
		offScreenImage = createImage(400,350);
		
		// set the total mass of the water randomly between 0.1 and 0.3 kg
		mass = 0.1 + 0.2*Math.random();

		//{{INIT_CONTROLS
		setLayout(null);
		resize(550,350);
		textArea1 = new java.awt.TextArea();
		textArea1.reshape(400,0,150,350);
		textArea1.setFont(new Font("Helvetica", Font.PLAIN, 10));
		add(textArea1);
		//}}
	}

	public void update(Graphics g){
		Graphics offg = offScreenImage.getGraphics();
		paint(offg);
		g.drawImage(offScreenImage, 0, 0, this);
	}

	public void paint(Graphics g){
		g.setColor(Color.white);
		g.fillRect(0,0,500,350);
		if (makePlot) {
			int x0 = 70;
			int y0 = 300;
			myGo = false;
			g.setColor(Color.black);
			g.drawRect(x0,y0-250,250,250);
			// scale in the plot:  1 pixel = 4 kJ, 1 pixel = 1°C
			// 0°C is at y0-50,  0 kJ is at x0
			g.setFont(new Font("Helvetica", Font.BOLD, 12));
			g.drawString("200",x0-30,y0-250);
			g.drawString("150",x0-30,y0-200);
			g.drawString("100",x0-30,y0-150);
			g.drawString(" 50",x0-30,y0-100);
			g.drawString("  0",x0-30,y0- 50);
			g.drawString("-50",x0-30,y0    );
			g.drawString("T (°C)",20,y0-280);
			g.drawString("  0",x0-10,y0+20);
			g.drawString("200",x0+40,y0+20);
			g.drawString("400",x0+90,y0+20);
			g.drawString("600",x0+140,y0+20);
			g.drawString("800",x0+190,y0+20);
			g.drawString("1000",x0+240,y0+20);
			g.drawString("Q (kJ)",x0+120,y0+40);
			g.setColor(Color.gray);
			g.drawLine(x0,y0-200,x0+250,y0-200);
			g.drawLine(x0,y0-150,x0+250,y0-150);
			g.drawLine(x0,y0-100,x0+250,y0-100);
			g.drawLine(x0,y0- 50,x0+250,y0- 50);
			g.drawLine(x0+ 50,y0-250,x0+ 50,y0);
			g.drawLine(x0+100,y0-250,x0+100,y0);
			g.drawLine(x0+150,y0-250,x0+150,y0);
			g.drawLine(x0+200,y0-250,x0+200,y0);
			g.setColor(Color.green);
			for (int i=1; i<=numMeas; i++) {
				int xPlot = x0 + (int)(measuredQ[i] / 4.0);
				int yPlot =	y0 - 50 - (int)(measuredT[i]);
				g.fillOval(xPlot-1,yPlot-1,3,3);
			}

		} else {
			g.drawImage(theBox,0,0,theBox.getWidth(this),theBox.getHeight(this),this);
			if (dQdt > 0) {
				// heating rate radio button:
				g.setColor(Color.red);
				g.fillOval(xh,yh,7,7);
				if (myGo) {
					g.drawImage(theHeater,168,218,theHeater.getWidth(this),theHeater.getHeight(this),this);
		            t1 = System.currentTimeMillis();
					if (t1 - t1old > 1000) {
						heat = heat + dQdt;
						t1old = t1;				
						// Here we put in the equation of state for water to calculate the
						// temperature from the total heat put in.  Remember, we start at -50°C
						// Specific heats:
						//		c-ice = 2.22 kJ/kg K; c-water = 4.19 kJ/kg K; c-steam = 2.01 kJ/kg K
						// Latent heats:
						//		L-freezing = 333 kJ/kg;  L-boiling = 2263 kJ/kg
						temper = -50.0;
						double heatToMelt  = 2.22 * (0-temper) * mass;
						double heatToWater = heatToMelt + 333.0*mass;
						double heatToBoil  = heatToWater + 100.0 * 4.19 * mass;
						double heatToSteam = heatToBoil + 2263.0 * mass;
						if (heat < heatToMelt) {
							// still ice
							temper = temper + heat / (2.22 * mass);
						} else if (heat < heatToWater) {
							// ice-water mixture
							temper = 0;
						} else if (heat < heatToBoil) {
							// only water
							temper = (heat - heatToWater) / (4.19 * mass);
						} else if (heat < heatToSteam) {
							// steam-water mixture
							temper = 100.0;
						} else {
							temper = 100.0 + (heat - heatToSteam) / (2.01 * mass);
						}
										
						// now add some temperature fluctuation and display:
						if (!auto) {
							temper = temper + (1.-2.*Math.random())*dQdt;  // assume simple linear error proportional to heating rate
						}
				
						// automatic operation:
						if (auto) {
							// display total mass:
							g.drawString(""+outString(""+mass,5)+" kg",133,83);
							// record a measurement:
							numMeas ++;
							measuredT[numMeas] = temper;
							measuredQ[numMeas] = heat + (0.5-Math.random())*dQdt;
						}
					
						// display the measurements in the text area:
						String derText = " Q (kJ)  T (°C)";
						for (int i=1; i<=numMeas; i++) {
							String ys = outString(""+measuredQ[i],5)+", "+outString(""+measuredT[i],5);
							derText = derText+cr+ys;
						}
						textArea1.setText(derText);
					}
				}
			}
			// output total heat:
			g.setColor(Color.yellow);
			g.setFont(new Font("Helvetica", Font.BOLD, 18));
			g.drawString(""+outString(""+heat,5)+" kJ",180,334);
			// paint temperature bar
			g.setColor(Color.green);
			int ytop = (int)(300.0 - (temper+50.0)*251.0/200.0);
			g.fillRect(323,ytop,16,300-ytop);
			g.setColor(Color.red);
			g.drawLine(323,ytop,339,ytop);
		}
		
		// copyright notice:
		if (copyRight) {
			g.setColor(Color.green);
			g.fillRect(100,100,240,70);
			g.setColor(Color.white);
			g.setFont(new Font("Helvetica", Font.PLAIN, 18));
			g.drawString("This applet was written by:",110,120);
			g.drawString("Wolfgang Bauer",110,140);
			g.drawString("Copyright: WB 1999",110,160);
		}

		// automatic switch-off condition
		if (temper > 170 || numMeas > 4998) {
			g.setColor(Color.blue);
			if (!makePlot) {
				g.setFont(new Font("Helvetica", Font.BOLD, 18));
				g.drawString("End of run,",8,250);
				g.drawString("maximum T reached",8,270);
			}
			myGo = false;
			stop();
		}

	}

	public boolean handleEvent(Event event) {
		if (event.id == Event.KEY_PRESS){
			String thePressedKey = ""+(char)event.key;
			if (thePressedKey.equalsIgnoreCase("w")) {
				copyRight = !copyRight;
	            repaint();
			}
			if (thePressedKey.equalsIgnoreCase("a")) {
				auto = !auto;
	            repaint();
			}
		}
		if (event.target == this && event.id == Event.MOUSE_UP) {
			phase_MouseUp(event);
			return true;
		}
		return super.handleEvent(event);
	}

	//{{DECLARE_CONTROLS
	java.awt.TextArea textArea1;
	//}}

	public String outString(String inString, int l){    // returns the first l chars of string
		int ls = (int)Math.min(inString.length(),l);
		return inString.substring(0,ls);
	}
	
	void phase_MouseUp(Event event) {
		int xx = event.x;
		int yy = event.y;
		if (xx < 77 && yy > 68 && yy < 98 && !makePlot) {
			// plot button pushed
			dQdt = 0;
			myGo = false;
			makePlot = true;
			stop();
		} else {
			makePlot = false;
		}
		//select heating rate
		if (yy > 299 && yy < 315) {
			if (xx > 63 && xx < 79) {
				dQdt = 8.0;
				xh = 67;
			}
			if (xx > 108 && xx < 124) {
				dQdt = 4.0;
				xh = 112;
			}
			if (xx > 153 && xx < 169) {
				dQdt = 2.0;
				xh = 157;
			}
			if (xx > 198 && xx < 214) {
				dQdt = 1.0;
				xh = 202;
			}
			if (xx > 243 && xx < 269) {
				dQdt = 0.5;
				xh = 247;
			}
		}
		if (xx > 320 && xx < 343 && yy < 311 && yy > 11) {
			// here we have a measurement of the temperature
			// temperature is measured by clicking the mouse
			numMeas ++;
			measuredT[numMeas] = -50.0 + (300.0-yy)*200.0/251.0;
			// heat is measured adding random fluctuations proportional to heaitng rate
			measuredQ[numMeas] = heat + (0.5-Math.random())*dQdt;
		}
		if (xx < 77 && yy < 34) {
			// start button pushed
			heat = 0.0;
			temper = -50.0;
			numMeas = 0;
			myGo = true;
			start();
		}
		if (xx < 77 && yy > 36 && yy < 66) {
			// stop button pushed
			dQdt = 0;
			myGo = false;
			stop();
		}
		repaint();
	}

}