#include <u.h>
#include <libc.h>
#include <draw.h>
#include <event.h>

#define RAD (PI * 2)
#define DEG (PI / 180.0)

Image *bg,*fg;

int frametime;
double spr;
int wings;
double wingrads;
double turns;

vlong starttime;

void
usage(void)
{
	fprint(2,"usage: %s [-f framerate] [-r rpm] [-w wings] [-t turns]\n", argv0);
	exits("usage");
}

Point
SPt(int x, int y)
{
	return addpt(Pt(x, y), screen->r.min);
}

Rectangle
SRect(int x0, int y0, int x1, int y1)
{
	return rectaddpt(Rect(x0, y0, x1, y1), screen->r.min);
}

Point
imagecenter(Image* img)
{
	return divpt(addpt(img->r.min, img->r.max), 2);
}

double
imageradius(Image* img)
{
	Point dims;
	dims = divpt(subpt(img->r.max, img->r.min), 2);
	return 1.4 + sqrt(dims.x*dims.x + dims.y*dims.y);
}

Point
vecpt(double radians, double radius)
{
	double x,y;
	x = sin(radians) * radius;
	y = cos(radians) * radius;

	return Pt(x + 1, y + 1);
}

void
drawframe(double ts)
{
	double radians, radius, spiralrads, spiralx, spiraly;
	uint numpoints, iradius;
	int i, j, k;
	Point center;
	Point *wingpoints;

	radians = fmod(ts / spr, spr) * RAD;
	radius = imageradius(screen) * 1.4;
	iradius = radius + 1;
	center = imagecenter(screen);

	numpoints = iradius + iradius;
	wingpoints = malloc(sizeof(Point) * numpoints);
	wingpoints[0] = center;
	wingpoints[numpoints - 1] = center;

	draw(screen, screen->r, bg, nil, SPt(0, 0));

	for(i = 0; i < wings; i++){
		for(j = 0; j < iradius; j++){
			spiralrads = (double)j / (double)iradius * turns * RAD;
			spiralx = sin(radians + spiralrads) * j;
			spiraly = cos(radians + spiralrads) * j;
			k = j;
			wingpoints[k] = addpt(center, Pt(spiralx, spiraly));
		}

		radians += wingrads;

		for(j = 0; j < iradius; j++){
			spiralrads = (double)(iradius - j) / (double)iradius * turns * RAD;
			spiralx = sin(radians + spiralrads) * (iradius - j);
			spiraly = cos(radians + spiralrads) * (iradius - j);
			// weird syntax issue
			k = j + iradius;
			wingpoints[k] = addpt(center, Pt(spiralx, spiraly));
		}

		fillpoly(screen, wingpoints, numpoints, ~0, fg, Pt(0,0));

		radians += wingrads;
	}

	free(wingpoints);
}

double
ftime(void)
{
	return ((double)(nsec() - starttime)) / 1000000000.0;
}

void
eresized(int new)
{
	if(new && getwindow(display, Refnone) < 0)
		fprint(2,"can't reattach to window\n");
	drawframe(ftime());
}

void
main(int argc, char* argv[])
{
	int timer,etype;
	Event e;

	frametime = 1.0 / 30.0 * 1000;
	wings = 3;
	spr = 2;
	turns = 1.0 / 6.0;

	ARGBEGIN{
	case 'f':
		frametime = 1.0 / atof(EARGF(usage())) * 1000;
		break;
	case 'r':
		spr = 1.0 / (atof(EARGF(usage())) / 60.0);
		break;
	case 'w':
		wings = atoi(EARGF(usage()));
		break;
	case 't':
		turns = atof(EARGF(usage()));
		break;
	default:
		usage();
	}ARGEND

	fprint(2,"turns: %f\n", turns);

	if(wings < 1) wings = 1;
	wingrads = PI / (double) wings;

	if(initdraw(nil, nil, "spiral") < 0)
		sysfatal("initdraw: %r");

	fg = allocimage(display, Rect(0,0, 1,1), GREY1, 1, DBlack);
	if(!fg)
		sysfatal("couldn't allocimage!");

	bg = allocimage(display, Rect(0,0, 1,1), GREY1, 1, DWhite);
	if(!bg)
		sysfatal("couldn't allocimage!");

	starttime = nsec();

	einit(Emouse);
	timer = etimer(0, frametime);

	for(;;){
		etype = event(&e);

		if (etype == timer)
			drawframe(ftime());
	}
}