#include <u.h>
#include <libc.h>
#include <bio.h>
#include <thread.h>
#include <draw.h>
#include <memdraw.h>
#include <mouse.h>
#include <keyboard.h>
#include <geometry.h>

typedef Point Triangle[3];


Memimage *fb;
Memimage *red, *green, *blue;
Channel *drawc;

void resized(void);
uvlong nanosec(void);

void *
emalloc(ulong n)
{
	void *p;

	p = malloc(n);
	if(p == nil)
		sysfatal("malloc: %r");
	setmalloctag(p, getcallerpc(&n));
	return p;
}

void *
erealloc(void *p, ulong n)
{
	void *np;

	np = realloc(p, n);
	if(np == nil){
		if(n == 0)
			return nil;
		sysfatal("realloc: %r");
	}
	if(p == nil)
		setmalloctag(np, getcallerpc(&p));
	else
		setrealloctag(np, getcallerpc(&p));
	return np;
}

Image *
eallocimage(Display *d, Rectangle r, ulong chan, int repl, ulong col)
{
	Image *i;

	i = allocimage(d, r, chan, repl, col);
	if(i == nil)
		sysfatal("allocimage: %r");
	return i;
}

Memimage *
eallocmemimage(Rectangle r, ulong chan)
{
	Memimage *i;

	i = allocmemimage(r, chan);
	if(i == nil)
		sysfatal("allocmemimage: %r");
	memfillcolor(i, DTransparent);
	return i;
}

int
min(int a, int b)
{
	return a < b? a: b;
}

int
max(int a, int b)
{
	return a > b? a: b;
}

Memimage *
rgb(ulong c)
{
	Memimage *i;

	i = eallocmemimage(Rect(0,0,1,1), screen->chan);
	i->flags |= Frepl;
	i->clipr = Rect(-1e6, -1e6, 1e6, 1e6);
	memfillcolor(i, c);
	return i;
}

void
pixel(Memimage *dst, Point p, Memimage *src)
{
	Rectangle r;

	if(dst == nil || src == nil)
		return;

	r = rectaddpt(Rect(0,0,1,1), p);

	memimagedraw(dst, rectaddpt(r, dst->r.min), src, ZP, nil, ZP, SoverD);
}

void
swap(int *a, int *b)
{
	int t;

	t = *a;
	*a = *b;
	*b = t;
}

void
bresenham(Memimage *dst, Point p0, Point p1, Memimage *src)
{
	int steep = 0, Δe, e, Δy;
	Point p, dp;

	/* transpose the points */
	if(abs(p0.x-p1.x) < abs(p0.y-p1.y)){
		steep = 1;
		swap(&p0.x, &p0.y);
		swap(&p1.x, &p1.y);
	}

	/* make them left-to-right */
	if(p0.x > p1.x){
		swap(&p0.x, &p1.x);
		swap(&p0.y, &p1.y);
	}

	dp = subpt(p1, p0);
	Δe = 2*abs(dp.y);
	e = 0;
	Δy = p1.y > p0.y? 1: -1;

	for(p = p0; p.x <= p1.x; p.x++){
		if(steep) swap(&p.x, &p.y);
		pixel(dst, p, src);
		if(steep) swap(&p.x, &p.y);

		e += Δe;
		if(e > dp.x){
			p.y += Δy;
			e -= 2*dp.x;
		}
	}
}

int
ycoordsort(void *a, void *b)
{
	return ((Point*)a)->y - ((Point*)b)->y;
}

void
triangle(Memimage *dst, Point p0, Point p1, Point p2, Memimage *src)
{
	Triangle t;

	t[0] = p0;
	t[1] = p1;
	t[2] = p2;

	qsort(t, nelem(t), sizeof(Point), ycoordsort);

	bresenham(dst, t[0], t[1], src);
	bresenham(dst, t[1], t[2], src);
	bresenham(dst, t[2], t[0], green);
}

void
filltriangle(Memimage *dst, Point p0, Point p1, Point p2, Memimage *src)
{
	int y;
	double m₀₂, m₀₁, m₁₂;
	Point dp₀₂, dp₀₁, dp₁₂;
	Triangle t;

	t[0] = p0;
	t[1] = p1;
	t[2] = p2;

	qsort(t, nelem(t), sizeof(Point), ycoordsort);

	dp₀₂ = subpt(t[2], t[0]);
	m₀₂ = (double)dp₀₂.x/dp₀₂.y;
	dp₀₁ = subpt(t[1], t[0]);
	m₀₁ = (double)dp₀₁.x/dp₀₁.y;
	dp₁₂ = subpt(t[2], t[1]);
	m₁₂ = (double)dp₁₂.x/dp₁₂.y;

	/* first half */
	for(y = t[0].y; y <= t[1].y; y++)
		bresenham(dst, Pt(t[0].x + (y-t[0].y)*m₀₂,y), Pt(t[0].x + (y-t[0].y)*m₀₁,y), src);
	/* second half */
	for(; y <= t[2].y; y++)
		bresenham(dst, Pt(t[0].x + (y-t[0].y)*m₀₂,y), Pt(t[1].x + (y-t[1].y)*m₁₂,y), src);
}

void
shade(Memimage *dst, Memimage *(*shader)(Point))
{
	Point p;
	Memimage *c;

	p = ZP;
	for(; p.y < Dy(dst->r); p.y++)
		for(p.x = 0; p.x < Dx(dst->r); p.x++)
			if((c = shader(p)) != nil)
				pixel(dst, p, c);
}

Memimage *
triangleshader(Point p)
{
	Triangle2 t;
	Rectangle bbox;
	Point3 bc;

	t.p0 = Pt2(240,200,1);
	t.p1 = Pt2(400,40,1);
	t.p2 = Pt2(240,40,1);

	bbox = Rect(
		min(min(t.p0.x, t.p1.x), t.p2.x),
		min(min(t.p0.y, t.p1.y), t.p2.y),
		max(max(t.p0.x, t.p1.x), t.p2.x),
		max(max(t.p0.y, t.p1.y), t.p2.y)
	);
	if(!ptinrect(p, bbox))
		return nil;

	bc = barycoords(t, Pt2(p.x,p.y,1));
	if(bc.x < 0 || bc.y < 0 || bc.z < 0)
		return nil;
	return red;
}

void
redraw(void)
{
	lockdisplay(display);
	draw(screen, screen->r, display->black, nil, ZP);
	loadimage(screen, screen->r, byteaddr(fb, fb->r.min), bytesperline(fb->r, fb->depth)*Dy(fb->r));
	flushimage(display, 1);
	unlockdisplay(display);
}

void
rmb(Mousectl *, Keyboardctl *)
{
}

void
lmb(Mousectl *, Keyboardctl *)
{
}

void
mouse(Mousectl *mc, Keyboardctl *kc)
{
	if((mc->buttons&1) != 0)
		lmb(mc, kc);
	if((mc->buttons&4) != 0)
		rmb(mc, kc);
}

void
key(Rune r)
{
	switch(r){
	case Kdel:
	case 'q':
		threadexitsall(nil);
	}
}

void
usage(void)
{
	fprint(2, "usage: %s\n", argv0);
	exits("usage");
}

void
threadmain(int argc, char *argv[])
{
	Mousectl *mc;
	Keyboardctl *kc;
	Rune r;
	uvlong t0, t1;

	GEOMfmtinstall();
	ARGBEGIN{
	default: usage();
	}ARGEND;
	if(argc > 0)
		usage();

	if(newwindow(nil) < 0)
		sysfatal("newwindow: %r");
	if(initdraw(nil, nil, nil) < 0)
		sysfatal("initdraw: %r");
	if(memimageinit() != 0)
		sysfatal("memimageinit: %r");
	if((mc = initmouse(nil, screen)) == nil)
		sysfatal("initmouse: %r");
	if((kc = initkeyboard(nil)) == nil)
		sysfatal("initkeyboard: %r");

	fb = eallocmemimage(screen->r, screen->chan);
	red = rgb(DRed);
	green = rgb(DGreen);
	blue = rgb(DBlue);

	bresenham(fb, Pt(40,40), Pt(300,300), red);
	bresenham(fb, Pt(80,80), Pt(100,200), red);
	bresenham(fb, Pt(80,80), Pt(200,100), red);

	filltriangle(fb, Pt(30,10), Pt(45, 45), Pt(5, 100), blue);
	triangle(fb, Pt(30,10), Pt(45, 45), Pt(5, 100), red);
	filltriangle(fb, Pt(300,120), Pt(200,350), Pt(50, 210), blue);
	triangle(fb, Pt(300,120), Pt(200,350), Pt(50, 210), red);
	filltriangle(fb, Pt(400,230), Pt(450,180), Pt(150, 320), blue);
	triangle(fb, Pt(400,230), Pt(450,180), Pt(150, 320), red);

	t0 = nanosec();
	shade(fb, triangleshader);
	t1 = nanosec();
	fprint(2, "shader took %lludns\n", t1-t0);

	drawc = chancreate(sizeof(void*), 1);

	display->locking = 1;
	unlockdisplay(display);
	nbsend(drawc, nil);

	for(;;){
		enum { MOUSE, RESIZE, KEYBOARD, DRAW };
		Alt a[] = {
			{mc->c, &mc->Mouse, CHANRCV},
			{mc->resizec, nil, CHANRCV},
			{kc->c, &r, CHANRCV},
			{drawc, nil, CHANRCV},
			{nil, nil, CHANEND}
		};

		switch(alt(a)){
		case MOUSE:
			mouse(mc, kc);
			break;
		case RESIZE:
			resized();
			break;
		case KEYBOARD:
			key(r);
			break;
		case DRAW:
			redraw();
			break;
		}
	}
}

void
resized(void)
{
	lockdisplay(display);
	if(getwindow(display, Refnone) < 0)
		sysfatal("couldn't resize");
	unlockdisplay(display);
	nbsend(drawc, nil);
}