/* See LICENSE file for copyright and license details. */
#include "common.h"

USAGE("[name] ...");


static volatile sig_atomic_t caught_sigterm = 0;
static volatile sig_atomic_t caught_sigwinch = 1;
static volatile sig_atomic_t caught_sigio = 0;

static int info = 0;
static char path[4096];



static void
sigterm(int signo)
{
	caught_sigterm = 1;
	(void) signo;
}

static void
sigwinch(int signo)
{
	caught_sigwinch = 1;
	(void) signo;
}

static void
sigio(int signo)
{
	caught_sigio = 1;
	(void) signo;
}


static void
writefile(const char *path, char *buf, size_t size)
{
	int fd;
	size_t off = 0;
	ssize_t r;

	fd = open(path, O_WRONLY);
	if (fd < 0) {
		weprintf("write %s:", path);
		return;
	}

	for (;;) {
		r = write(fd, &buf[off], size - off);
		if (r <= 0) {
			if (!r)
				break;
			close(fd);
			weprintf("write %s:", path);
			return;
		}
		off += (size_t)r;
	}

	close(fd);
}


static int
readstrfile(const char *path, char *buf, size_t size)
{
	int fd;
	size_t off = 0, i, j;
	ssize_t r;
	char c;

	fd = open(path, O_RDONLY);
	if (fd < 0)
		return 0;

	for (;;) {
		r = read(fd, &buf[off], size - sizeof("…") - off);
		if (r <= 0) {
			if (!r)
				break;
			close(fd);
			return 0;
		}
		off += (size_t)r;
	}

	off -= (off && buf[off - 1] == '\n');

	if (off == size - sizeof("…")) {
		for (i = 0; i < off;) {
			if ((buf[i] & 0xC0) == 0xC0) {
				j = i;
				c = buf[i];
				do {
					c <<= 1;
					i++;	
				} while ((c & 0x80) && i < off && (buf[i] & 0xC0) == 0x80);
				if (c & 0x80) {
					off = j;
					break;
				}
			} else {
				i += 1;
			}
		}
		memcpy(&buf[off], "…", sizeof("…"));
	} else {
		buf[off] = '\0';
	}

	close(fd);
	return 1;
}

static int
readintfile(const char *path, uintmax_t *valuep)
{
	char buf[256], *end;
	int r;
	r = readstrfile(path, buf, sizeof(buf));
	if (r <= 0)
		return r;
	if (!isdigit(*buf))
		return 0;
	errno = 0;
	*valuep = strtoumax(buf, &end, 10);
	if (errno || *end)
		return 0;
	return 1;
}


static void
adjust_fine(const char *path, uintmax_t max_brightness, uintmax_t *brightnessp, uintmax_t adjustment)
{
	char buf[sizeof(uintmax_t) * 3 + 2];
	uintmax_t brightness = *brightnessp, result;
	int len;

again:

	if (max_brightness) {
		if (adjustment >= max_brightness - brightness)
			brightness = max_brightness;
		else
			brightness += adjustment;
	} else {
		if (brightness < adjustment)
			brightness = 0;
		else
			brightness -= adjustment;
	}

	len = sprintf(buf, "%ju\n", brightness);
	writefile(path, buf, (size_t)len);

	if (readintfile(path, &result)) {
		if (result == *brightnessp && brightness != max_brightness)
			goto again;
		*brightnessp = result;
		/* TODO publish update on bus */
	}
}


static int
show_backlights(int tfd, char **devs, size_t ndevs)
{
	struct winsize winsize;
	char buf[256], c, prev_c = 0, *p, *colour, line[(sizeof("─") - 1) * 64 + 1];
	int width = 0, height = 0, left = 0, namelen = 0, first = 1, len, digits;
	int rearm = 1, redraw = 0, reload = 1, i;
	int have_max = 0, have_current = 0, vis_brightness_at;
	uintmax_t max_brightness = 0, brightness = 0;
	double percent;
	size_t index = 0, k;
	ssize_t r;

	for (k = 0, p = line; k < 64; k++)
		p = stpcpy(p, "—");

	while (!caught_sigterm) {
		if (caught_sigwinch) {
			if (ioctl(STDOUT_FILENO, (unsigned long)TIOCGWINSZ, &winsize) < 0) {
				if (errno == EINTR)
					continue;
				weprintf("ioctl <stdout> TIOCGWINSZ:");
				return -1;
			}
			caught_sigwinch = 0;
			width = winsize.ws_col;
			height = winsize.ws_row;
			if (height > 2)
				height -= 2;
			else
				height = 0;
			if (width > 10) {
				width /= 5;
				if (width < 10)
					width = 10;
			}
			left = (winsize.ws_col - width) / 2;
			redraw = 1;
		}
		if (first) {
			first = 0;
		} else if (caught_sigio) {
			caught_sigio = 0;
			for (;;) {
				/* TODO add support for adjusting with the rat */
				r = read(STDIN_FILENO, &c, 1);
				if (r <= 0) {
					if (!r)
						return 0;
					if (errno == EAGAIN)
						break;
					if (errno == EINTR)
						continue;
					weprintf("read <stdin>:");
					return -1;
				}
				if (c == 'r') {
					rearm = 1;
				} else if (c == 'L' - '@') {
					redraw = 1;
				} else if (c == 'i') {
					info ^= 1;
					redraw = 1;
					stpcpy(p, "/brightness");
				} else if (c == 'q') {
					return 0;
				} else if (c == 'C') {
					if (ndevs > 1) {
						redraw = 1;
						index = (index + 1) % ndevs;
						reload = 1;
						have_current = 0;
					}
				} else if (c == 'D') {
					if (ndevs > 1) {
						redraw = 1;
						if (!index)
							index = ndevs;
						index -= 1;
						reload = 1;
						have_current = 0;
					}
				} else if (c == 'A' && have_max) {
					if (!have_current) {
						stpcpy(p, "/brightness");
						have_current = readintfile(path, &brightness);
					}
					if (have_current && brightness < max_brightness) {
						redraw = 1;
						adjust_fine(path, max_brightness, &brightness, 1);
					}
				} else if (c == 'B' && have_max) {
					if (!have_current) {
						stpcpy(p, "/brightness");
						have_current = readintfile(path, &brightness);
					}
					if (have_current && brightness) {
						redraw = 1;
						adjust_fine(path, 0, &brightness, 1);
					}
				} else if (c == '~' && prev_c == '5' && have_max) {
					if (!have_current) {
						stpcpy(p, "/brightness");
						have_current = readintfile(path, &brightness);
					}
					if (have_current && brightness < max_brightness) {
						redraw = 1;
						adjust_fine(path, max_brightness, &brightness, max_brightness / 10);
					}
				} else if (c == '~' && prev_c == '6' && have_max) {
					if (!have_current) {
						stpcpy(p, "/brightness");
						have_current = readintfile(path, &brightness);
					}
					if (have_current && brightness) {
						redraw = 1;
						adjust_fine(path, 0, &brightness, max_brightness / 10);
					}
				}
				prev_c = c;
			}
		}

		/* Need instead of a sleep at the and to remove artifacts when there is a lot of input */
		if (rearm) {
			if (timerfd_settime(tfd, 0, &(struct itimerspec){{0, 100000000L}, {0, 100000000L}}, NULL)) {
				weprintf("timerfd_settime <timerfd> 0 {0.1s 0.1s} NULL:");
				return -1;
			}
			rearm = 0;
			redraw = 0;
		} else if (redraw) {
			redraw = 0;
		} else {
			if (read(tfd, &(int64_t){0}, sizeof(int64_t)) < 0) {
				if (errno == EINTR)
					continue;
				weprintf("read <timerfd> &(int64_t) sizeof(int64_t):");
				return -1;
			}
		}

		if (reload) {
			reload = 0;
			namelen = strlen(devs[index]);
			p = stpcpy(stpcpy(path, "/sys/class/backlight/"), devs[index]);
			stpcpy(p, "/max_brightness");
			have_max = readintfile(path, &max_brightness);
			stpcpy(p, "/brightness");
		}

		if (info) {
			printf("\033[H\033[1m%s\033[m\033[K\n\033[K", devs[index]);
			stpcpy(p, "/max_brightness");
			if (readstrfile(path, buf, sizeof(buf)))
				printf("\n\033[1mMaximum brightness:\033[m %s\033[K", buf);
			stpcpy(p, "/brightness");
			if (readstrfile(path, buf, sizeof(buf)))
				printf("\n\033[1mBrightness:\033[m         %s\033[K", buf);
			stpcpy(p, "/actual_brightness");
			if (readstrfile(path, buf, sizeof(buf)))
				printf("\n\033[1mActual brightness:\033[m  %s\033[K", buf);
			stpcpy(p, "/bl_power");
			if (readstrfile(path, buf, sizeof(buf)))
				printf("\n\033[1mBacklight power:\033[m    %s\033[K", buf);
			stpcpy(p, "/scale");
			if (readstrfile(path, buf, sizeof(buf)))
				printf("\n\033[1mScale:\033[m              %s\033[K", buf);
			stpcpy(p, "/type");
			if (readstrfile(path, buf, sizeof(buf)))
				printf("\n\033[1mType:\033[m               %s\033[K", buf);
			printf("\033[J");
			fflush(stdout);
			continue;
		}

		have_current = readintfile(path, &brightness);

		printf("\033[H%*.s\033[1m%s\033[m\033[K\n", (winsize.ws_col - namelen) / 2, "", devs[index]);
		if (!have_max || !max_brightness) {
			len = (int)(sizeof("Maximum brightness is unavailable") - 1);
			printf("%*.s%s\033[K\n", (winsize.ws_col - len) / 2, "", "Maximum brightness is unavailable");
		} else if (!have_current) {
			len = (int)(sizeof("Current brightness is unavailable") - 1);
			printf("%*.s%s\033[K\n", (winsize.ws_col - len) / 2, "", "Current brightness is unavailable");
		} else {
			if (width > 2 && height > 12) {
				printf("%*.s┌", left, "");
				for (i = 2; i + 64 < width; i += 64)
					printf("%s", line);
				if (i < width)
					printf("%.*s", (width - i) * ((int)sizeof("─") - 1), line);
				printf("┐\033[K\n");

				vis_brightness_at = (int)((brightness * (uintmax_t)(height - 2) * 2 + 1) / (max_brightness * 2));
				vis_brightness_at = 1 + height - 2 - vis_brightness_at;
				for (i = 2; i < height; i++) {
					colour = (i >= vis_brightness_at) ? "7" : "";
					printf("%*.s│\033[%sm%*.s\033[m│\033[K\n", left, "", colour, width - 2, "");
				}

				printf("%*.s└", left, "");
				for (i = 2; i + 64 < width; i += 64)
					printf("%s", line);
				if (i < width)
					printf("%.*s", (width - i) * ((int)sizeof("─") - 1), line);
				printf("┘\033[K\n");
			}
			digits = max_brightness >= 10000 ? 2 : max_brightness >= 1000 ? 1 : 0;
			percent = 100. * (double)brightness / (double)max_brightness;
			len = snprintf(NULL, 0, "%.*lf%% (%ju of %ju)", digits, percent, brightness, max_brightness);
			printf("%*.s%.*lf%% (%ju of %ju)\033[K", (winsize.ws_col - len) / 2, "",
			       digits, percent, brightness, max_brightness);
		}

		printf("\033[J");
		fflush(stdout);
	}

	return 0;
}


int
main(int argc, char *argv[])
{
	int old_sig = 0, old_flags = -1, tcset = 0, ret, tfd;
	struct f_owner_ex old_owner, new_owner;
	struct termios stty, saved_stty;
	struct sigaction sigact;
	char **devs = NULL, *p;
	size_t ndevs = 0;
	struct dirent *f;
	DIR *dir;

	ARGBEGIN {
	case 'i':
		info = 1;
		break;
	default:
		usage();
	} ARGEND;

	if (!argc) {
		dir = opendir("/sys/class/backlight");
		if (!dir)
			eprintf("opendir /sys/class/backlight:");
		while ((errno = 0, f = readdir(dir))) {
			if (f->d_name[0] == '.')
				continue;
			if (strlen(f->d_name) + 256 > sizeof(path))
				continue;
			p = stpcpy(stpcpy(path, "/sys/class/backlight/"), f->d_name);
			stpcpy(p, "/max_brightness");
			if (access(path, F_OK))
				continue;
			stpcpy(p, "/brightness");
			if (access(path, F_OK))
				continue;
			devs = ereallocn(devs, ndevs + 1, sizeof(*devs), 0);
			devs[ndevs] = strdup(f->d_name);
			if (!devs[ndevs++])
				eprintf("strdup:");
		}
		closedir(dir);
		if (errno)
			eprintf("readdir /sys/class/backlight:");
		if (!ndevs)
			eprintf("no backlight devices found\n");
	} else {
		devs = argv;
		ndevs = (size_t)argc;
	}

	memset(&sigact, 0, sizeof(sigact));

	sigact.sa_handler = sigterm;
	sigaction(SIGTERM, &sigact, NULL);
	sigaction(SIGQUIT, &sigact, NULL);
	sigaction(SIGINT, &sigact, NULL);

	sigact.sa_handler = sigwinch;
	sigaction(SIGWINCH, &sigact, NULL);

	sigact.sa_handler = sigio;
	sigaction(SIGIO, &sigact, NULL);
	sigaction(SIGURG, &sigact, NULL);

	tfd = timerfd_create(CLOCK_MONOTONIC, 0);
	if (tfd < 0)
		eprintf("timerfd_create CLOCK_MONOTONIC 0:");

	if (fcntl(STDIN_FILENO, F_GETOWN_EX, &old_owner))
		eprintf("fcntl <stdin> F_GETOWN_EX:");
	memset(&new_owner, 0, sizeof(new_owner));
	new_owner.type = F_OWNER_PID;
	new_owner.pid = getpid();
	if (fcntl(STDIN_FILENO, F_SETOWN_EX, &new_owner))
		eprintf("fcntl <stdin> F_SETOWN_EX {.type=F_OWNER_PID, .pid=<getpid()>}:");
	old_flags = fcntl(STDIN_FILENO, F_GETFL);
	if (old_flags != -1)
		fcntl(STDIN_FILENO, F_SETFL, old_flags | FASYNC | O_NONBLOCK);
	fcntl(STDIN_FILENO, F_GETSIG, &old_sig);
	if (old_sig)
		fcntl(STDIN_FILENO, F_SETSIG, 0);

	if (!tcgetattr(STDIN_FILENO, &stty)) {
		saved_stty = stty;
		stty.c_lflag &= (tcflag_t)~(ECHO | ICANON);
		tcsetattr(STDIN_FILENO, TCSAFLUSH, &stty);
		tcset = 1;
	}

	fprintf(stdout, "\033[?1049h\033[?25l");

	ret = -show_backlights(tfd, devs, ndevs);

	fprintf(stdout, "\033[?25h\n\033[?1049l");
	fflush(stdout);

	fcntl(STDIN_FILENO, F_SETOWN_EX, &old_owner);
	if (old_flags != -1)
		fcntl(STDIN_FILENO, F_SETFL, old_flags);
	if (old_sig)
		fcntl(STDIN_FILENO, F_SETSIG, old_sig);
	if (tcset)
		tcsetattr(STDIN_FILENO, TCSAFLUSH, &saved_stty);
	close(tfd);
	if (!argc) {
		while (ndevs--)
			free(devs[ndevs]);
		free(devs);
	}

	return ret;
}