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

enum {
	Etick = 256,
};

int	pids[2];
int	pause;

vlong	bufoff;
vlong	minoff;
vlong	maxoff;
vlong	curoff;

void
eresized(int new)
{
	Rectangle r1, r2;
	char buf[32];

	if(new && getwindow(display, Refnone) < 0)
		fprint(2,"can't reattach to window");

	r1 = screen->r;
	r2 = r1;
	if((maxoff - minoff) <= 0)
		r1.max.x = r1.min.x + Dx(r2);
	else
		r1.max.x = r1.min.x + ((vlong)Dx(r2) * (curoff - minoff)) / (maxoff - minoff);
	r2.min.x = r1.max.x;
	draw(screen, r1, display->black, nil, ZP);
	draw(screen, r2, display->white, nil, ZP);
	if(pause){
		strcpy(buf, "pause");

		r2.min = ZP;
		r2.max = stringsize(display->defaultfont, buf);
		r1 = rectsubpt(screen->r, screen->r.min);
		r2 = rectaddpt(r2, subpt(divpt(r1.max, 2), divpt(r2.max, 2)));
		r2 = rectaddpt(r2, screen->r.min);
		r1 = insetrect(r2, -4);
		draw(screen, r1, display->white, nil, ZP);
		border(screen, insetrect(r1, 1), 2, display->black, ZP);
		string(screen, r2.min, display->black, ZP, display->defaultfont, buf);
	}

	flushimage(display, 1);
}

void
usage(void)
{
	fprint(2, "usage: %s [-s | -b buffer]\n", argv0);
	exits("usage");
}

void
killpids(void)
{
	int pid, i;

	pid = getpid();
	for(i=0; i<nelem(pids); i++){
		if(pids[i] <= 0 || pids[i] == pid)
			continue;
		postnote(PNPROC, pids[i], "kill");
		sleep(1);
	}
}

void
main(int argc, char *argv[])
{
	char buf[1024];
	int stream, fd, pid, n;
	vlong o;

	fd = 0;
	stream = 0;

	ARGBEGIN {
	case 'b':
		bufoff = atoll(EARGF(usage()));
		bufoff *= 1024;
		bufoff &= ~0xFLL;
		if(bufoff < 0)
			usage();
	case 's':
		stream = 1;
		break;
	default:
		usage();
	} ARGEND;

	if(stream){
		snprint(buf, sizeof(buf), "/tmp/aseek.%d.tmp", getpid());
		if((fd = create(buf, ORDWR|ORCLOSE, 0600)) < 0)
			sysfatal("create: %r");
		if((pid = rfork(RFMEM|RFPROC)) < 0)
			sysfatal("rfork: %r");
		if(pid == 0){
			for(;;){
				n = sizeof(buf);
				o = maxoff;
				if(bufoff != 0){
					if(((o + n) - curoff) > bufoff){
						sleep(200);
						continue;
					}
					o %= bufoff;
					if((o + n) > bufoff)
						n = bufoff - o;
				}
				if((n = read(0, buf, n)) <= 0)
					break;
				if(pwrite(fd, buf, n, o) != n)
					break;
				maxoff += n;
				if(bufoff != 0 && maxoff > bufoff)
					minoff += n;
			}
			_exits(0);
		}
		pids[0] = pid;
	} else
		maxoff = seek(0, 0, 2);

	atexit(killpids);
	if(initdraw(0, 0, "seeker") < 0)
		sysfatal("initdraw: %r");
	einit(Emouse|Ekeyboard);
	etimer(Etick, 1000);
	eresized(0);

	if((pid = rfork(RFMEM|RFPROC)) < 0)
		sysfatal("rfork: %r");

	if(pid == 0){
		for(;;){
			n = 0;
			if(!pause){
				if(!stream)
					maxoff = seek(fd, 0, 2);
				n = sizeof(buf);
				o = curoff;
				if(o < minoff)
					o = minoff;
				if(o >= maxoff)
					n = 0;
				else if((o + n) > maxoff)
					n = maxoff - o;
				if(bufoff != 0){
					o %= bufoff;
					if((o + n) > bufoff)
						n = bufoff - o;
				}
				if(n > 0)
					n = pread(fd, buf, n, o);
			}
			if(n <= 0){
				sleep(200);
				continue;
			}
			if(write(1, buf, n) != n)
				break;
			curoff += n;
		}
	} else {
		Event e;
		Mouse m;

		pids[1] = pid;
		memset(&m, 0, sizeof(m));
		for(;;){
			n = eread(Emouse|Ekeyboard|Etick, &e);
			if(n == Emouse){
				m=e.mouse;
				if(m.buttons != 0){
					o = m.xy.x - screen->r.min.x;
					if(o < 0) o = 0LL;
					o *= (maxoff - minoff);
					o /= Dx(screen->r);
					o &= ~0xFLL;
					curoff = minoff + o;
					eresized(0);
				}
			} else if(n == Ekeyboard){
				if(e.kbdc == Kdel || e.kbdc == 'q')
					break;
				else if(e.kbdc == ' '){
					pause = !pause;
					eresized(0);
				}
			} else if(n == Etick){
				if(m.buttons == 0)
					eresized(0);
			} else
				break;
		}
	}
	exits(0);
}