package tangentLine;

import java.awt.*;
import java.applet.Applet;
import graphingApplet.*;
import functionParser.*;
import java.util.*;

public class TangentLine extends GraphingApplet{


/////////// SUBCLASS INSTANCE VARIABLES HERE  ////

public TwoPoint[] points; //AN ARRAY TO HOLD THE POINTS ON THE GRAPH OF OUR FUNCTION


double xmin;//Left edge of the graph
double xmax;//Right edge of the graph
double increment; // THE DISTANCE BETWEEN PIXELS ON THE CURRENT SCALE
int pointCount; // THE NUMBER OF PIXELS ACROSS THE GRAPH


double presentX; // X CORDINATE LAST CLICKED ON
double presentY; // Y CORDINATE LAST CLICKED ON
double x_L; //X COORDINATE OF THE LEFT OF THE GRAPH
double x_R; //X COORDINATE OF THE RIGHT OF THE GRAPH
double y_1L; //Y COORDINATE OF TANGENT LINE AT LEFT
double y_1R; //Y COORDINATE OF TANGENT LINE AT RIGHT

double tangentSlope;



boolean clicked = false;


public FunctionEnteringPanel fPanel;
Evaluator eval;





/////////////////////////////////////////////////
	
public void init(){
	super.init();
	
	
	///////////// ADD FUNCTION PANELS //////////
	
	fPanel = new FunctionEnteringPanel(mc,"(2+4*x)/(2+x^2)","x","f");
	fep = new FunctionEnteringPanel[1];
	fep[0] = fPanel;
	
	
	
	////// SET CARD LABELS AND NAMES, INCLUDING NUMBER //////////
	labels =  new String[3];
	labels[0] = "cursor position";
	labels[1] = "graph range controls";
	labels[2] = "slope info";
	
	
	cardNames =  new String[3];
	cardNames[0] = "cursor";
	cardNames[1] = "graph";
	cardNames[2] = "line";
	
	////////////////////////////////////////////
	selector = new CardSelector(cardbox, labels, cardNames, mc);
	
	
	
	cr = new CursorReport(mc);
	
	gp = new GraphParameters(mc,this);
		
	////// GET PROPER SLATE ////
	
	rs = new TangentSlate(mc,"line");
	
	
	cards = new Panel[3];
	
	cards[0] = cr;
	cards[1] = gp;
	cards[2] = rs;
	
	
	////// NOW FOR THE GRAPH...
	
	gc = new GraphCanvas(mc,"graphcanvas");
	//////THIS CREATES A CursorBadge OF THE MATCHING WIDTH
	cbdg = new CursorBadge(mc,(gc.getPreferredSize()).width);
	
	//AND THIS THE CORESPONDING GraphhLocationBadge.
	glbdg = new GraphLocationBadge(mc,(gc.getPreferredSize()).width);
	
	
	//FINALLY, THE COPYRIGHT PANEL:
	copyPanel = 
	new CopyrightPanel("copyright Eric A. Carlen 1996, 1997.  All rights reserved",font);
	
	//AT THIS POINT, STEP(1) IS ALMOST DONE -- THE FOUR KEY ARRAYS ARE READY TO BE USE TO CONSTRUCT
	//top AND bottom.
	
	top = new TopPanel(this);
	bottom = new BottomPanel(mc,fep);
	
	
	//NOW FOR STEP (2):
	add(top);
	add(bottom);
	mc.arrayConversion();//NOTHING THAT CALLS mc (EXCEPT TO SUBSCRIBE) ABOVE HERE...
	gc.updateParameters();//NOTHINNG THAT USES GRAPH PARAMETERS ABOVE HERE...
	selector.showNamedCard("cursor");
	
	//NOW COMES INITIALIZATION OF SUBCLASS INSTANCE VARIABLES 

	eval = mc.getEvaluator("f");
	fPanel.setColor(50,50,255);
	
	//AND THEN FINALY, THE PRELIMINARY COMPUTATIONS.
	
	handleAllData();//THIS HAS TO BE DEFINED BELOW; ABSTRACT IN Super
	
	
	
	}//END OF INIT
	
	public void runNamedMethod(String name, int i,int j){
		Graphics graphics = gc.getGraphics();
		if(name.equals("click")){
		
		mc.writeIntData("clicked",1);
		presentX = gc.pixelToX(i);
		presentY = eval.evaluate(presentX);
		clicked = true;
		mc.writeDoubleData("x_0",presentX);
		mc.writeDoubleData("y_0",presentY);
		tangentSlope = 
		(10000000.0)*(eval.evaluate(presentX+0.0000001) - eval.evaluate(presentX));
		mc.writeDoubleData("tangentSlope",tangentSlope);
		
		
		
		
		mc.updateSubscribers();
		gc.paint(graphics);
		}
		
		}//END OF RUN NAMED METHOD 
		
	
	

	
		
	public void handleAllData(){
		//What we need to do here is to read in the graph size and location,
		//and then to fill in a corresponding array ot TwoPonts, points on the
		//graph of f, so that it is ready to be used by doAllPainting().
		
		 
		//First, initialize the variables holding graph information:
		xmin = mc.readDoubleData("xLeft");
		xmax = xmin + mc.readDoubleData("graphWidth");
		pointCount = mc.readIntData("graphSize");
		increment = (xmax - xmin)/pointCount;
		//And now that we have the size, initialize our array of TwoPoionts.
		points = new TwoPoint[pointCount];
	
		//We need the evaluator before we can fill this in, so call a method
		//of fPanel that prepares its Evaluator:
		try{fPanel.computeGrid();}catch(FunctionParsingException ex)
			{System.out.println("boo-boo");}
		
		//Now fill in the TwoPoints -- the dots to be connected below in the painting.
		for(int i=0;i<pointCount;i++){
		points[i] = new TwoPoint(xmin +i*increment,eval.evaluate(xmin +i*increment));
		}
		
		}
		
	public void doAllPainting(){
		
		Graphics g = gc.getGraphics();
		
		
		//NOW WE DRAW THE CURVE. 
		
		g.setColor(new Color(50,50,255));
		for(int i=0;i<pointCount-1;i++){
		
		//FIRST CLIP THE SEGMENT TO THE GRAPH...
		
		gc.clipSegment(points[i],points[i+1]);
		
		//THEN CHECK TO SEE IF IT IS VERTCAL BEFORE DRAWING IT -- DON'T
		//IF IT IS, SO THAT DISCONTINUITES DO SHOW UP AS SUCH.
		//ANY TIME A SEGMENT JUMPS AN EIGTH OF THE HEIGHT OF THE GRAPH IN
		//A SINGLE PIXEL, IT IS NOT DRAWN.
		
		if(Math.abs(points[i+1].ycoord - points[i].ycoord) < 
		(mc.readDoubleData("graphHeight")/8)){
		g.drawLine(gc.xToPixel(points[i].xcoord),gc.yToPixel(points[i].ycoord),
		gc.xToPixel(points[i+1].xcoord),gc.yToPixel(points[i+1].ycoord));}
		}//END OF FOR
		
		//NOW WE TURNTO if(clicked) TO DRAW IN THE TANGENT LINE.
		
		if(clicked){
        //NOW WE COMPUTE THE ENDPOINTS OF THE TANGENT LINE SEGMENT WE DRAW:
		x_L = mc.readDoubleData("xLeft");
		x_R = x_L  + mc.readDoubleData("graphWidth");
		y_1L = tangentSlope*(x_L - mc.readDoubleData("x_0")) + mc.readDoubleData("y_0");
		y_1R = tangentSlope*(x_R - mc.readDoubleData("x_0")) + mc.readDoubleData("y_0");
		
		g.setColor(Color.green);
		
		
		g.drawLine(gc.xToPixel(x_L),gc.yToPixel(y_1L),gc.xToPixel(x_R),gc.yToPixel(y_1R));
		
		g.setColor(Color.red);
		g.fillOval(gc.xToPixel(mc.readDoubleData("x_0"))-2,gc.yToPixel(mc.readDoubleData("y_0"))-2,4,4);
		}
		
		
		
		
		}//END OF DO ALL PAINTING
		
	public void cleanInput(){
		clicked = false;
		mc.writeIntData("clicked",0);
		}
	
	public void refreshGraphs(){
		gc.repaint();}

}//END OF CLASS