/*
 * Edge.java
 *
 * Created on December 3, 2003, 12:49 AM
 */

/**
 *
 * @author  linyuan
 */
public class Edge extends Selectable {
    
    Vertex u;
    
    Vertex v;
    
    /** Creates a new instance of Edge */
    public Edge() {
    }
    
    public Edge(Vertex u, Vertex v){
     this.u=u;
     this.v=v;
    }
    double distance(int x, int y) {
        double a, b, c;
        a=(u.x-x)*(u.x-x)+(u.y-y)*(u.y-y)+0.0;
        b=(v.x-x)*(v.x-x)+(v.y-y)*(v.y-y)+0.0;
        c=(u.x-v.x)*(u.x-v.x)+(u.y-v.y)*(u.y-v.y)+0.0;
        if(a>=b+c) return Math.sqrt((double) b);
        if(b>=a+c) return Math.sqrt((double) a);
        return Math.sqrt(b-(c+b-a)*(c+b-a)/4.0/c);
    }
    
    public void draw(java.awt.Graphics g){
        if(isSelected()) g.setColor(selectedColor);
        else g.setColor(color);
        g.drawLine(u.x,u.y,v.x,v.y);

	//draw end arrow
	int r = 3; //thickness of vertex
	int s = 5; //thickness of line
	double ax = u.x+0.5;
	double ay = u.y+0.5;
	double length=Math.sqrt((v.x-u.x)*(v.x-u.x)+(v.y-u.y)*(v.y-u.y));
	if (length==0) return;
	double sin = (v.y-u.y)/length;
	double cos = (v.x-u.x)/length ;
	double px = length-(r+1);
	double py = 0;
	double ly = s;
	double lx = length-(r+s+s);
	double rx = lx;
	double ry = -ly;
	double mx = length-(r+s+s/2);
	double my = 0;
	double tx; double ty;
	tx = px*cos-py*sin;
	ty = px*sin+py*cos;
	px = tx; py = ty;
	tx = lx*cos-ly*sin;
	ty = lx*sin+ly*cos;
	lx = tx; ly = ty;
	tx = rx*cos-ry*sin;
	ty = rx*sin+ry*cos;
	rx = tx; ry = ty;
	tx = mx*cos-my*sin;
	ty = mx*sin+my*cos;
	mx = tx; my = ty;
	px+=ax; py+=ay;
	mx+=ax; my+=ay;
	lx+=ax; ly+=ay;
	rx+=ax; ry+=ay;
	int[] xvals=new int[4];
        int[] yvals=new int[4];
	xvals[0]=(int)px;
	xvals[1]=(int)lx;
	xvals[2]=(int)mx;
	xvals[3]=(int)rx;
	yvals[0]=(int)py;
	yvals[1]=(int)ly;
	yvals[2]=(int)my;
	yvals[3]=(int)ry;
	g.fillPolygon(xvals,yvals,4);
    }
}