#include <u.h>
#include <libc.h>
#include <draw.h>
#include <keyboard.h>
#include <event.h>
Image *c[17];
Rectangle r[16];
int sq[16], score, hues[17] = {DBlack,
	0xfbf305ff, 0xff6403ff, 0xdd0907ff, 0xf20884ff,
	0x8000a5ff, 0x0000d3ff, 0x02abeaff, 0x1fb714ff,
	0x006412ff, 0x562c05ff, 0x90713aff, 0xc0c0c0ff,
	0x808080ff, 0x404040ff, DWhite, DPurpleblue};
void
eresized(int i){
	int d;
	if(i && getwindow(display, Refnone) < 0) sysfatal("Score: %d\ncan't reattach to window", score);
	if(Dx(screen->r) > Dy(screen->r)){
		d = Dy(screen->r);
		r[0].min = Pt(screen->r.min.x + screen->r.max.x - d >> 1, screen->r.min.y);
	}else{
		d = Dx(screen->r);
		r[0].min = Pt(screen->r.min.x, screen->r.min.y + screen->r.max.y - d >> 1);
	}
	d >>= 2;
	r[0].max = Pt(r[0].min.x + d, r[0].min.y + d);
	draw(screen, screen->r, c[0], nil, ZP);
	draw(screen, r[0], c[sq[0]], nil, ZP);
	for(i = 1; i < 16; i++){
		r[i] = rectaddpt(r[0], Pt((i & 3) * d, (i >> 2) * d));
		draw(screen, r[i], c[sq[i]], nil, ZP);
	}
}
void
bye(void){
	int i, n;
	for(n = i = 0; i < 16; i++) if(sq[i] > n) n = sq[i];
	print("Largest Tile: %d\nScore: %d\n", 1 << n, score);
	exits(nil);
}
void
newtile(void)
{
	int i, e, n;
	for(e = i = 0; i < 16; i++) e += !sq[i];
	n = nrand(e);
	while(sq[--i] || n--);
	sq[i] = 1 + (nrand(10) == 0);
	if(e > 1) return;
	for(i = 0; i < 16; i++)
		if(i & 3 && sq[i] == sq[i - 1] || i < 12 && sq[i] == sq[i + 4])
			return;
	bye();
}
int
slide(int *one, int *two, int *three, int *four){
	int m, n, a[4];
	m = n = 0;
	if(*one) a[n++] = *one;
	if(*two) a[n++] = *two;
	if(*three) a[n++] = *three;
	if(*four) a[n++] = *four;
	switch(n){
	case 0:
		break;
	case 1:
		m = *one || *two || *three;
		*one = 0;
		*two = 0;
		*three = 0;
		*four = a[0];
		break;
	case 2:
		m = *one || *two;
		*one = 0;
		*two = 0;
		if(a[0] == a[1]){
			m = 1;
			*three = 0;
			*four = a[0] + 1;
			score += 1 << *four;
		}else{
			*three = a[0];
			*four = a[1];
		}
		break;
	case 3:
		m = *one;
		*one = 0;
		if(a[1] == a[2]){
			m = 1;
			*two = 0;
			*three = a[0];
			*four = a[1] + 1;
			score += 1 << *four;
		}else if(a[0] == a[1]){
			m = 1;
			*two = 0;
			*three = a[1] + 1;
			*four = a[2];
			score += 1 << *three;
		}else{
			*two = a[0];
			*three = a[1];
			*four = a[2];
		}
		break;
	case 4:
		if(a[0] == a[1] && a[2] == a[3]){
			m = 1;
			*one = 0;
			*two = 0;
			*three = a[0] + 1;
			*four = a[2] + 1;
			score += 1 << *three;
			score += 1 << *four;
		}else if(a[2] == a[3]){
			m = 1;
			*one = 0;
			*two = a[0];
			*three = a[1];
			*four = a[2] + 1;
			score += 1 << *four;
		}else if(a[1] == a[2]){
			m = 1;
			*one = 0;
			*two = a[0];
			*three = a[1] + 1;
			score += 1 << *three;
		}else if(a[0] == a[1]){
			m = 1;
			*one = 0;
			*two = a[0] + 1;
			score += 1 << *two;
		}
		break;
	}
	return m;
}
void
main(int, char **argv)
{
	Event e;
	int i;
	if(initdraw(0, 0, argv[0]) < 0) sysfatal("initdraw: %r");
	for(i = 0; i < 17 ; i++)
		if((c[i] = allocimage(display, Rect(0, 0, 1, 1), screen->chan, 1, hues[i])) == nil)
			sysfatal("allocimage: %r");
	einit(Ekeyboard | Emouse);
	srand(truerand());
	newtile();
	newtile();
	eresized(0);
	for(;;)
		if(event(&e) == Ekeyboard){
			switch(e.kbdc){
			default: continue;
			case 'q': case Kdel: bye();
			case Kesc:
				i = open("/dev/wctl", OWRITE);
				if(i >= 0){write(i, "hide\n", 5);close(i);}
				break;
			case Kup:
				if(slide(sq + 12, sq + 8, sq + 4, sq)
				| slide(sq + 13, sq + 9, sq + 5, sq + 1)
				| slide(sq + 14, sq + 10, sq + 6, sq + 2)
				| slide(sq + 15, sq + 11, sq + 7, sq + 3))
					break;
				continue;
			case Kdown:
				if(slide(sq, sq + 4, sq + 8, sq + 12)
				| slide(sq + 1, sq + 5, sq + 9, sq + 13)
				| slide(sq + 2, sq + 6, sq + 10, sq + 14)
				| slide(sq + 3, sq + 7, sq + 11, sq + 15))
					break;
				continue;
			case Kleft:
				if(slide(sq + 3, sq + 2, sq + 1, sq)
				| slide(sq + 7, sq + 6, sq + 5, sq + 4)
				| slide(sq + 11, sq + 10, sq + 9, sq + 8)
				| slide(sq + 15, sq + 14, sq + 13, sq + 12))
					break;
				continue;
			case Kright:
				if(slide(sq, sq + 1, sq + 2, sq + 3)
				| slide(sq + 4, sq + 5, sq + 6, sq + 7)
				| slide(sq + 8, sq + 9, sq + 10, sq + 11)
				| slide(sq + 12, sq + 13, sq + 14, sq + 15))
					break;
				continue;
			}
			newtile();
			for(i = 0; i < 16; i++) draw(screen, r[i], c[sq[i]], nil, ZP);
		}
}