#include "art.h"
Image *color;

/*
 * return the closest point on arc ip to point testp.
 */
Dpoint neararc(Item *ip, Dpoint testp){
	Flt d;
	Dpoint p, cen;
	cen=circumcenter(ip->p[0], ip->p[1], ip->p[2]);
	p=dsub(testp, cen);
	d=dlen(p);
	if(d!=0){
		p=dlerp(cen, p, dist(ip->p[0], cen)/d);
		if(triarea(ip->p[0], p, ip->p[2])*triarea(ip->p[0], ip->p[1], ip->p[2])>0) return p;
	}
	if(dist(testp, ip->p[0])<dist(testp, ip->p[2])) return ip->p[0];
	return ip->p[2];
}

/*
 * given three points, p[0], p[1], p[2] which indicate the points on the circle.
 * p[0] and p[2] makes two end points, and p[1] indicates inner point in the arc
 */
void drawarc(Item *ip, Image *b, Image *color){
	Dpoint cen;
	int alpha, phi, p0, p2;

	if(pldist(ip->p[1], ip->p[0], ip->p[2])<CLOSE){	/* not quite right, but ok */
		line(b, D2P(ip->p[0]), D2P(ip->p[2]), Endsquare, Endsquare, 0, color, ZP);
		if(ip->style&ARROW0)
			line(b, D2P(ip->p[0]), D2P(ip->p[2]), Endsquare, Endarrow, 0, color, ZP);
		if(ip->style&ARROW1)
			line(b, D2P(ip->p[0]), D2P(ip->p[2]), Endarrow, Endsquare, 0, color, ZP);
		return;
	}
	cen=circumcenter(ip->p[0], ip->p[1], ip->p[2]);
	p0 = datan2((ip->p[0].y - cen.y), (ip->p[0].x - cen.x));
	p2 = datan2((ip->p[2].y - cen.y), (ip->p[2].x - cen.x));
	if(p2 > p0) {		/* phi > 0 */
		alpha = p0;
		phi = p2 - p0;
	}else {
		alpha = p2;
		phi = p0 - p2;
	}
	arc(b, D2P(cen), (int)(dist(cen, ip->p[0])*DPI), (int)(dist(cen, ip->p[0])*DPI), 0, color, ZP, alpha, phi);
	if(ip->style&ARROW0) {
		line(b, D2P(cen), D2P(ip->p[0]), Endsquare, Endarrow, 0, color, ZP);
		line(b, D2P(cen), D2P(ip->p[2]), Endsquare, Endarrow, 0, color, ZP);
	}else if(ip->style&ARROW1){
		line(b, D2P(cen), D2P(ip->p[0]), Endarrow, Endsquare, 0, color, ZP);
		line(b, D2P(cen), D2P(ip->p[2]), Endarrow, Endsquare, 0, color, ZP);
	}else{
		line(b, D2P(cen), D2P(ip->p[0]), Endsquare, Endsquare, 0, color, ZP);
		line(b, D2P(cen), D2P(ip->p[2]), Endsquare, Endsquare, 0, color, ZP);
	}
}

void editarc(void){
	Flt l0=dist(arg[0], selection->p[0]);
	Flt l1=dist(arg[0], selection->p[1]);
	Flt l2=dist(arg[0], selection->p[2]);
	if(l0<l1 && l0<l2){
		hotpoint(selection->p[1]);
		hotpoint(selection->p[2]);
		track(movep, 0, selection);
	}
	else if(l1<l2){
		hotpoint(selection->p[0]);
		hotpoint(selection->p[2]);
		track(movep, 1, selection);
	}
	else{
		hotpoint(selection->p[0]);
		hotpoint(selection->p[1]);
		track(movep, 2, selection);
	}
}
void translatearc(Item *ip, Dpoint delta){
	ip->p[0]=dadd(ip->p[0], delta);
	ip->p[1]=dadd(ip->p[1], delta);
	ip->p[2]=dadd(ip->p[2], delta);
}
void deletearc(Item *ip){
}
void writearc(Item *ip, int f){
	fprint(f, "a %.3f %.3f %.3f %.3f %.3f %.3f",
		ip->p[0].x, ip->p[0].y, ip->p[1].x, ip->p[1].y, ip->p[2].x, ip->p[2].y);
	writestyle(f, ip->style);
	fprint(f, "\n");
}
void activatearc(Item *ip){
	hotarc(ip->p[0], ip->p[1], ip->p[2]);
}
int inboxarc(Item *ip, Drectangle r){
	Dpoint i[2];
	return dptinrect(ip->p[0], r)
	    || seginterarc(r.min, Dpt(r.min.x, r.max.y), ip->p[0], ip->p[1], ip->p[2], i)
	    || seginterarc(r.min, Dpt(r.max.x, r.min.y), ip->p[0], ip->p[1], ip->p[2], i)
	    || seginterarc(r.max, Dpt(r.min.x, r.max.y), ip->p[0], ip->p[1], ip->p[2], i)
	    || seginterarc(r.max, Dpt(r.max.x, r.min.y), ip->p[0], ip->p[1], ip->p[2], i);
}
/*
 * This can overestimate the size of the box.
 */
Drectangle bboxarc(Item *ip){
	Drectangle r;
	r.min=dsub(ip->p[0], Dpt(ip->r, ip->r));
	r.max=dadd(ip->p[0], Dpt(ip->r, ip->r));
	return r;
}
Dpoint nearvertarc(Item *ip, Dpoint testp){
	if(dist(ip->p[0], testp)<dist(ip->p[2], testp)) return ip->p[0];
	return ip->p[2];
}
Itemfns arcfns={
	deletearc,
	writearc,
	activatearc,
	neararc,
	drawarc,
	editarc,
	translatearc,
	inboxarc,
	bboxarc,
	nearvertarc,
};
Item *addarc(Item *head, Dpoint p0, Dpoint p1, Dpoint p2){
	return additem(head, ARC, 0., 0, 0, 0, &arcfns, 3, p0, p1, p2);
}