/*
 * BSD Zero Clause License
 *
 * Copyright (c) 2022 Thomas Voss
 *
 * Permission to use, copy, modify, and/or distribute this software for any
 * purpose with or without fee is hereby granted.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES WITH
 * REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
 * AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT,
 * INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
 * LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR
 * OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
 * PERFORMANCE OF THIS SOFTWARE.
 */

#include <fcntl.h>
#include <stdio.h>
#include <unistd.h>

#include "lux.h"

int
luxmax(lux_t *disp)
{
	/* The maximum brightness shouldn't change, so we can cache it in the
	 * struct.
	 */
	if (disp->__max != -1)
		return disp->__max;

	int fd = openat(disp->__dirfd, "max_brightness", O_RDONLY);
	if (fd == -1)
		return -1;
	FILE *stream = fdopen(fd, "r");
	if (stream == NULL) {
		close(fd);
		return -1;
	}

	fscanf(stream, "%d", &disp->__max);
	fclose(stream);
	return disp->__max;
}