//photon.java
import java.awt.Graphics;
import java.awt.Color;
import java.awt.Point;

class interPoint
{
	public double x,y;
	public interPoint(double x, double y)
	{
		this.x =x;
		this.y = y;
	}
}

public class photon
{
	
	public double length = 0;
	public double y = 0;
	boolean left = false;
	double pos = 0;
	Einstein EIN;
	
	public photon(Einstein EIN)
	{
		this.EIN = EIN;
		left = false;
		pos = 0;
	}
	
	public void setLength(double st)
	{
		length = st;
	}
	
	public double dist(double x1, double y1, double x2, double y2)
	{
		return (Math.sqrt((x1-x2)*(x1-x2) + (y1-y2)*(y1-y2)));
	}
	
	public interPoint intersects(double x1, double y1, double m1,double x2, double y2, double m2)
	{
		double x_int = 0;
		double y_int = 0;
		if (m2 == 0)
		{
			x_int = x2;
		}
		else
		{
			double x_top = (m1*x1 - y1 - m2*x2 + y2);
			double x_bot = (m1 - m2);
			x_int = ( x_top / x_bot );
		}
		y_int = m1*(x_int-x1)+y1;
		return (new interPoint(x_int,y_int));
	}
	
	public void spacedraw(double theTime, double position, double gamma,double theV, int height, Graphics g)
	{
		g.setColor(Color.yellow);
		double L = 2*length;
		if (left)
		{
			for(int loop=0;loop<4;loop++)
			{
				g.drawLine(EIN.space.mapX(position)+(int)(length)-(int)(pos*L)-loop,EIN.space.mapY(0)-(int)(height*.5),EIN.space.mapX(position)+(int)(length)-(int)(pos*L)-loop,EIN.space.mapY(0)+(int)(height*.5));
				//g.drawLine(EIN.space.mapX(position)+(int)(length)-(int)(pos*L-1),EIN.space.mapY(0)-(int)(height*.5),EIN.space.mapX(position)+(int)(length)-(int)((pos*L)-1),EIN.space.mapY(0)+(int)(height*.5));
			}
		}
		else
		{
			for (int loop=0;loop<4;loop++)
			{
				g.drawLine(EIN.space.mapX(position)-(int)(length)+(int)(pos*L)-loop,EIN.space.mapY(0)-(int)(height*.5),EIN.space.mapX(position)-(int)(length)+(int)(pos*L)-loop,EIN.space.mapY(0)+(int)(height*.5));
				//g.drawLine(EIN.space.mapX(position)-(int)(length)+(int)(pos*L)-1,EIN.space.mapY(0)-(int)(height*.5),EIN.space.mapX(position)-(int)(length)+(int)(pos*L)-1,EIN.space.mapY(0)+(int)(height*.5));
			}
		}
					
		/*double v = 0;
		if (theV != 0)
		{
			v = 1/theV;
		}
		double startx = -length;
		double starty = 0;
		double total =0;
		boolean stopped = false;
		double L = 2*length;
		while(total < theTime)
		{
			//Right side first
			interPoint test = intersects(startx,starty,1,length,0,v,g);
			if (theTime > test.y)
			{
				total = test.y;
				startx = test.x;
				starty = test.y;
			}
			else
			{
				//EIN.time.drawLine(startx,starty,startx+(theTime - total),theTime,g);
				g.drawLine(EIN.space.mapX(position)-(int)(length/gamma)+(int)((theTime - total)/(L/gamma)),EIN.space.mapY(0)-(int)(height*.5),EIN.space.mapX(position)-(int)(length/gamma)+(int)((theTime - total)/(L/gamma)),EIN.space.mapY(0)+(int)(height*.5));
				g.drawLine(EIN.space.mapX(position)-(int)(length/gamma)+(int)(((theTime - total)/(L/gamma))-1),EIN.space.mapY(0)-(int)(height*.5),EIN.space.mapX(position)-(int)(length/gamma)+(int)(((theTime - total)/(L/gamma))-1),EIN.space.mapY(0)+(int)(height*.5));
				stopped = true;
				total = theTime;
			}
			//Left side now
			if (!stopped)
			{
				test = intersects(startx,starty,-1,-length,0,v,g);
				g.drawString("I: x "+test.x+" y "+test.y,(int)EIN.time.mapX(0),100);
				if (theTime > test.y)
				{
					total = test.y;
					startx = test.x;
					starty = test.y;
				}
				else
				{
					//EIN.time.drawLine(startx,starty,startx-(theTime - total),theTime,g);
					g.drawLine(EIN.space.mapX(position)+(int)(length/gamma)-(int)((theTime - total)/(L/gamma)),EIN.space.mapY(0)-(int)(height*.5),EIN.space.mapX(position)+(int)(length/gamma)-(int)((theTime - total)/(L/gamma)),EIN.space.mapY(0)+(int)(height*.5));
					g.drawLine(EIN.space.mapX(position)+(int)(length/gamma)-(int)(((theTime - total)/(L/gamma))-1),EIN.space.mapY(0)-(int)(height*.5),EIN.space.mapX(position)+(int)(length/gamma)-(int)(((theTime - total)/(L/gamma))-1),EIN.space.mapY(0)+(int)(height*.5));
					stopped = true;
					total = theTime;
				}
			}
		}*/
		
	}
	
	public void draw(double theTime, double theX, double theV, Graphics g)
	{
		g.setColor(Color.yellow);
		/*double start = -length;
		double ystart = y;
		boolean right = true;
		while (theTime > 0)
		{
			if (right)
			{
				if ((theTime-length) > (theX+length))
				{
					EIN.time.drawLine(start,ystart,(theX+length),(theX+length)
		*/	
		double v = 0;
		if (theV != 0)
		{
			v = 1/theV;
		}
		/*interPoint test = intersects(-length,y,1,length,y,v,g);
		g.drawString("I: x "+test.x+" y "+test.y,(int)EIN.time.mapX(0),50);
		if (theTime > test.y)
		{
			EIN.showStatus("Dist "+dist(test.x,test.y,theX,theTime)+" "+dist(1,-1.5,56,70));
			EIN.time.drawLine(test.x,test.y,test.x-(theTime-test.x-length),theTime,g);
		}*/
		double startx = -length;
		double starty = 0;
		double total =0;
		boolean stopped = false;
		while(total < theTime)
		{
			//Right side first
			interPoint test = intersects(startx,starty,1,length,0,v);
			if (theTime > test.y)
			{
				EIN.time.drawLine(startx,starty,test.x,test.y,g);
				total = test.y;
				startx = test.x;
				starty = test.y;
			}
			else
			{
				EIN.time.drawLine(startx,starty,startx+(theTime - total),theTime,g);
				left = false;
				if ((test.x-startx) != 0)
					pos = (theTime - total)/(test.x-startx);
				else pos = 0;
				stopped = true;
				total = theTime;
			}
			//Left side now
			if (!stopped)
			{
				test = intersects(startx,starty,-1,-length,0,v);
				if (theTime > test.y)
				{
					EIN.time.drawLine(startx,starty,test.x,test.y,g);
					total = test.y;
					startx = test.x;
					starty = test.y;
				}
				else
				{
					EIN.time.drawLine(startx,starty,startx-(theTime - total),theTime,g);
					left = true;
					if ((startx-test.x) != 0)
						pos = (theTime - total)/(startx-test.x);
					else pos = 0;
					stopped = true;
					total = theTime;
				}
			}
		}
		//EIN.showStatus((theTime - total)+" Percent:"+pos);
	}
	
}