/*
  *
  * Written By: Kenneth C. Baltz
  * Date Completed: 23 Apr 96
  * Description: Graphical display applet of a scanline algorithm
  *              	to locate intersections among arbitrary lines
  * Usage Notes: This algorithm excludes some cases that are remotely
  * 				possible with arbitrary lines. These include:
  *					1) Multiple lines intersecting at the same point
  *					2) Vertical lines (Infinite Slope)
  *					This was written for a class project, so 
  * 				that's why it's not too detailed
  * Filename: Intersect.java
  *	Related Files: 	SketchBoard.java  		// Handles the graphics
  *					InterestingPoint.java	// Data structure
  *					LineList.java			// Manages Scan line
  *					Node.java				// Data structure
  *					point.java				// Data structure
  *					PQ.java					// Priority Queue
  *					line.java               // Data structure
	Last change:  KCB   2 May 96   10:23 am
  */
import java.applet.Applet;
import java.awt.*;
import java.util.*;
import java.io.*;
import java.lang.*;

public class Intersect extends Applet
{
	static final int NUM_LINES = 10;
	static final int MAX_X = 200;
	static final int MAX_Y = 200;
	static final int OFF_X = 10;
	static final int OFF_Y = 10;
	static final boolean rand=true;
	static final boolean DEBUG=false;
	private int RAND_SEED=0;
	private	float scanx=0;
	private int lastx=0;
	private Line select_line=null;


	private InterestingPoint currentIP;
	public int NumIntersects=0;

	/////////////////////////////////////////////////////
	// GUI stuff
	SketchBoard canvas;

	Button step_button;
	Button reset_button;


	Frame displayFrame;
	List list_of_lines;

	Label status_text;
	Label num_intersects;

	TextField rand_text;
	//
	/////////////////////////////////////////////////////

	boolean step;

	private Line [] lines;

	public PQ xtree;
	public LineList ytree;

	public void init()
	{

		this.setLayout(new BorderLayout(15,15));

		canvas = new SketchBoard(lines, scanx, currentIP,select_line,
								MAX_X, MAX_Y, OFF_X, OFF_Y, NUM_LINES);
		canvas.resize(MAX_X + 50,MAX_Y + 50);
		this.add("West",canvas);

		Panel Master_East =new Panel();
		Master_East.setLayout(new BorderLayout(15,15));

		this.add("East",Master_East);

		Panel button_panel = new Panel();
		button_panel.setLayout(new FlowLayout(FlowLayout.CENTER,15,15));
		step_button= new Button("Step");
		button_panel.add( step_button );
		reset_button= new Button("Reset");
		button_panel.add( reset_button );

		Panel list_panel = new Panel();
		list_panel.setLayout(new BorderLayout(1,1));

		Label list_label = new Label("Double Click to highlight lines");
		list_panel.add("North",list_label);
		list_of_lines= new List(NUM_LINES,false);
		list_panel.add("South",list_of_lines );

		this.add("South",button_panel);

		Panel text_panel = new Panel();
		text_panel.setLayout(new BorderLayout(1,1));

		Panel random_panel= new Panel();
		random_panel.setLayout(new BorderLayout(1,1));

		Label l=new Label("Random Seed");
		random_panel.add("North",l);
		rand_text=new TextField("0",3);
		random_panel.add("South",rand_text);


		Panel intersect_panel = new Panel();
		intersect_panel.setLayout(new BorderLayout(15,15));
		num_intersects = new Label("Intersections: "+NumIntersects);
		intersect_panel.add("South",num_intersects);
		status_text = new Label("                   ");
		intersect_panel.add("North",status_text);

		Master_East.add("North", button_panel );
		Master_East.add("West", list_panel );
		text_panel.add("South", random_panel );
		text_panel.add("North", intersect_panel );

		Master_East.add("East", text_panel );

		this.resize(this.minimumSize());

		step_button.disable();

		step=false;
		paint(this.getGraphics());
	} // init()

	private void Reset()
	{
        scanx=0;
		currentIP = null;
        NumIntersects=0;
		num_intersects.setText("Intersections: "+NumIntersects);

		xtree = new PQ(NUM_LINES*3);

//		list_of_lines.clear();
		while(list_of_lines.countItems()>0)
			list_of_lines.delItem(0);

		ytree = new LineList();
	 	lines=new Line[10];

	    if(rand){
			int z=0;
			try
			{
				z=Integer.parseInt(rand_text.getText());
			}
			catch(Exception ex)
			{
				if(ex instanceof NumberFormatException);
					rand_text.setText(Integer.toString(RAND_SEED));
				z=0;
			}
			RAND_SEED=z;

		    Random rand=new Random(RAND_SEED);
		    int x, y;
		    InterestingPoint ip;
//			list_of_lines.clear();

			canvas.select_line=null;
			select_line=null;
		    for ( int i=0;i<NUM_LINES ;i++ )
		    {
			    x=(int)(rand.nextFloat()*MAX_X);
			    y=(int)(rand.nextFloat()*MAX_Y);

			    point p1= new point(x,y);
			    while((x=(int)(rand.nextFloat()*MAX_X))==p1.x);
			    while((y=(int)(rand.nextFloat()*MAX_Y))==p1.y);
			    point p2= new point(x,y);

			    lines[i]= new Line(p1,p2);

			    list_of_lines.addItem(lines[i].toString());

			    // insert the first endpoint
			    ip=new InterestingPoint(lines[i],(p1.x<p2.x));
			    xtree.insert(ip);
			    // insert the second endpoint
			    ip=new InterestingPoint(lines[i],!(p1.x<p2.x));
			    xtree.insert(ip);

			    if(DEBUG) System.out.println("Line["+i+"] = ("+p1.x+","+p1.y+") to ("+p2.x+","+p2.y+")");

		    }
	    } // rand
	    else
	    {
		    lines[0]=new Line(new point(30,25),new point(60,60));
		    lines[1]=new Line(new point(20,50),new point(45,20));
		    lines[2]=new Line(new point(32,70),new point(85,75));
		    lines[3]=new Line(new point(65,50),new point(90,30));
		    lines[4]=new Line(new point(50,30),new point(83,45));

		    InterestingPoint ip;

		    for ( int i=0;i<NUM_LINES ;i++ )
		    {
			    ip=new InterestingPoint(lines[i],true);
			    xtree.insert(ip);
			    // insert the second endpoint
				ip=new InterestingPoint(lines[i],false);
				xtree.insert(ip);
			}
		}// rand
		paint(this.getGraphics());

		step_button.enable();
	}

	protected void go()
	{
		point 	p1, // left point,
				p2;  // right point;

		if(null!=(currentIP=xtree.remove()))
		{
			if(DEBUG) System.out.println("xtree: " + xtree);
			if( currentIP.intersection ) // is this an intersection?
			{
				status_text.setText("Intersection");
				scanx=currentIP.p.x;
				if(DEBUG) System.out.println("scanx = "+scanx);
				if(DEBUG) System.out.println("Dealing with an Intersection at ("+currentIP.p.x+","+currentIP.p.y+")");
				if(DEBUG) System.out.println("with lines "+currentIP.line +" and "+currentIP.line2 );
				NumIntersects++;
				num_intersects.setText("Intersections: "+NumIntersects);
				if(DEBUG) System.out.println("NumIntersects = " + NumIntersects);
				InterestingPoint [] intersections;
				intersections = ytree.Swap(currentIP.line, currentIP.line2);
				if(intersections[0]!=null)
				{
					if(DEBUG) System.out.println("Inserting an intesection at " + intersections[0].p.x);
					if(intersections[0].p.x>scanx)
					    xtree.insert(intersections[0]);

				}
				if(intersections[1]!=null)
				{
					if(DEBUG) System.out.println("Inserting an intesection at " + intersections[1].p.x);
					if(intersections[1].p.x>scanx)
						xtree.insert(intersections[1]);
				}

			}
			else if ( currentIP.left )	// is this IP a left endpoint?
			{
				status_text.setText("Left Endpoint");
				scanx=currentIP.line.p1.x;
				if(DEBUG) System.out.println("scanx = "+scanx);
				if(DEBUG) System.out.println("Dealing with a left endpoint");
				InterestingPoint [] intersections;
				intersections=ytree.Insert(currentIP.line,scanx);
				// could produce 0-2 intersections from inserting a point

				if(intersections[0]!=null)
				{
					if(DEBUG) System.out.println("Inserting an intesection at " + intersections[0].p.x);
					if(intersections[0].p.x>=scanx)
					    xtree.insert(intersections[0]);

				}
				if(intersections[1]!=null)
				{
					if(DEBUG) System.out.println("Inserting an intesection at " + intersections[1].p.x);
					if(intersections[1].p.x>=scanx)
						xtree.insert(intersections[1]);
				}

			}

			else  // if it's a right endpoint
				  // we need to remove it
			{
				status_text.setText("Right Endpoint");
				scanx=currentIP.line.p2.x;
				if(DEBUG) System.out.println("scanx = "+scanx);

				if(DEBUG) System.out.println("Dealing with a right endpoint");

				InterestingPoint p;
				if(null!=(p=ytree.Delete(currentIP.line)))
					// don't want to insert any old intersects
					if(p.p.x>=scanx)
						xtree.insert(p);
			}

		}
		paint(this.getGraphics());
		if(DEBUG) System.out.println("ytree ="+ytree);
		if(DEBUG) System.out.println("xtree: "+xtree);

	} // go

	public void paint(Graphics g)
	{
		canvas.scanx=scanx;
		canvas.lines=lines;
		canvas.currentIP=currentIP;
		canvas.select_line=select_line;
		canvas.paint(canvas.getGraphics());
	}

	public boolean action(Event e, Object arg)
	{
		if(e.target == step_button)
		{
			step=true;
			if(DEBUG) System.out.println("Hit step_button");
			go();
			return true;
		}
		else if(e.target == reset_button)
		{
		    Reset();
			return true;
		}
		else if(e.target == list_of_lines && e.id==Event.ACTION_EVENT )
		{
			int i;
			for( i=0;i<NUM_LINES;i++)
			{
				if( ((String)e.arg).equals(lines[i].toString()) ) break;
			}
			select_line=lines[i];
			if(DEBUG) System.out.println("List line selected :"+i);
			paint(this.getGraphics());
			return true;
		}
		else if(e.target == rand_text)
		{
			if(DEBUG) System.out.println((String)e.arg);
			int x;
			try
			{
				x=Integer.parseInt((String)e.arg);
			}
			catch(Exception ex)
			{
				if(ex instanceof NumberFormatException);
					rand_text.setText(Integer.toString(RAND_SEED));
				x=0;

			}
			RAND_SEED=x;
			Reset();
			return true;
		}
		else return super.action(e, arg);
	}
}