/*-
 * SPDX-License-Identifier: BSD-2-Clause
 *
 * Copyright (c) 2020 Emmanuel Vadot <manu@FreeBSD.org>
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

#include <sys/types.h>
#include <sys/ioctl.h>
#include <stdbool.h>
#include <sys/capsicum.h>
#include <sys/backlight.h>

#include <err.h>
#include <errno.h>
#include <fcntl.h>
#include <limits.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <capsicum_helpers.h>

#define BACKLIGHT_QUERY                 0x0001
#define BACKLIGHT_SET_BRIGHTNESS        0x0002
#define BACKLIGHT_INCR                  0x0004
#define BACKLIGHT_DECR                  0x0008
#define BACKLIGHT_INFO                  0x0010

static char device_name[PATH_MAX] = "/dev/backlight/backlight0";

static void
set_device_name(const char *name)
{

        if (name[0] == '/')
                strlcpy(device_name, name, sizeof(device_name));
        else
                snprintf(device_name, sizeof(device_name), "/dev/backlight/%s", name);
}

static void
usage(void)
{
        fprintf(stderr, "Usage:\n");
        fprintf(stderr, "\tbacklight [-q] [-f device]\n");
        fprintf(stderr, "\tbacklight [-q] [-f device] -i\n");
        fprintf(stderr, "\tbacklight [-f device] value\n");
        fprintf(stderr, "\tbacklight [-f device] incr|+ value\n");
        fprintf(stderr, "\tbacklight [-f device] decr|- value\n");
        exit(1);
}

static const char *
backlight_type_to_string(enum backlight_info_type type)
{
        switch (type) {
        case BACKLIGHT_TYPE_PANEL:
                return ("Panel");
        case BACKLIGHT_TYPE_KEYBOARD:
                return ("Keyboard");
        }

        return ("Unknown");
}

int
main(int argc, char *argv[])
{
        struct backlight_props props;
        struct backlight_info info;
        int fd;
        int action, ch;
        cap_rights_t right_ioctl;
        const unsigned long backlight_ioctls[] = {
                BACKLIGHTGETSTATUS,
                BACKLIGHTUPDATESTATUS,
                BACKLIGHTGETINFO};
        long percent = -1;
        const char *percent_error;
        uint32_t i;
        bool quiet = false;

        action = BACKLIGHT_QUERY;
        fd = -1;

        while ((ch = getopt(argc, argv, "f:qhi")) != -1) {
                switch (ch) {
                case 'q':
                        quiet = true;
                        break;
                case 'f':
                        set_device_name(optarg);
                        break;
                case 'i':
                        action = BACKLIGHT_INFO;
                        break;
                case 'h':
                        usage();
                        break;
                }
        }

        argc -= optind;
        argv += optind;
        if (argc != 0) {
                if (strcmp("incr", argv[0]) == 0 ||
                    strcmp("+", argv[0]) == 0) {
                        action = BACKLIGHT_INCR;
                        argc -= 1;
                        argv += 1;
                }
                else if (strcmp("decr", argv[0]) == 0 ||
                    strcmp("-", argv[0]) == 0) {
                        action = BACKLIGHT_DECR;
                        argc -= 1;
                        argv += 1;
                } else
                        action = BACKLIGHT_SET_BRIGHTNESS;

                if (argc == 1) {
                        /* ignore a trailing % for user friendlyness */
                        if (strlen(argv[0]) > 0 &&
                            argv[0][strlen(argv[0]) - 1] == '%')
                                argv[0][strlen(argv[0]) - 1] = '\0';
                        percent = strtonum(argv[0], 0, 100, &percent_error);
                        if (percent_error)
                                errx(1, "Cannot parse brightness level %s: %s",
                                    argv[0],
                                    percent_error);
                }
        }

        if ((fd = open(device_name, O_RDWR)) == -1)
                errx(1, "cannot open %s: %s",
                    device_name, strerror(errno));

        if (caph_limit_stdio() < 0)
                errx(1, "can't limit stdio rights");
        caph_cache_catpages();
        cap_rights_init(&right_ioctl, CAP_IOCTL);
        if (caph_rights_limit(fd, &right_ioctl) < 0)
                errx(1, "cap_right_limit() failed");
        if (caph_ioctls_limit(fd, backlight_ioctls, nitems(backlight_ioctls)) < 0)
                errx(1, "caph_ioctls_limit() failed");
        if (caph_enter() < 0)
                errx(1, "failed to enter capability mode");

        switch (action) {
        case BACKLIGHT_QUERY:
                if (ioctl(fd, BACKLIGHTGETSTATUS, &props) == -1)
                        errx(1, "Cannot query the backlight device");
                if (quiet)
                        printf("%u\n", props.brightness);
                else {
                        printf("brightness: %d\n", props.brightness);
                        if (props.nlevels != 0) {
                                printf("levels:");
                                for (i = 0; i < props.nlevels; i++)
                                        printf(" %d", props.levels[i]);
                                printf("\n");
                        }
                }
                break;
        case BACKLIGHT_SET_BRIGHTNESS:
                if (percent == -1)
                        usage();
                props.brightness = percent;
                if (ioctl(fd, BACKLIGHTUPDATESTATUS, &props) == -1)
                        errx(1, "Cannot update the backlight device");
                break;
        case BACKLIGHT_INCR:
        case BACKLIGHT_DECR:
                if (percent == 0)
                        /* Avoid any ioctl if we don't have anything to do */
                        break;
                if (ioctl(fd, BACKLIGHTGETSTATUS, &props) == -1)
                        errx(1, "Cannot query the backlight device");
                percent = percent == -1 ? 10 : percent;
                percent = action == BACKLIGHT_INCR ? percent : -percent;
                props.brightness += percent;
                if ((int)props.brightness < 0)
                        props.brightness = 0;
                if (props.brightness > 100)
                        props.brightness = 100;
                if (ioctl(fd, BACKLIGHTUPDATESTATUS, &props) == -1)
                        errx(1, "Cannot update the backlight device");
                break;
        case BACKLIGHT_INFO:
                if (ioctl(fd, BACKLIGHTGETINFO, &info) == -1)
                        errx(1, "Cannot query the backlight device");
                if (quiet == false) {
                        printf("Backlight name: %s\n", info.name);
                        printf("Backlight hardware type: %s\n", backlight_type_to_string(info.type));
                } else {
                        printf("%s\n", info.name);
                        printf("%s\n", backlight_type_to_string(info.type));
                }
                break;
        }

        close(fd);
        return (0);
}