python script to adjust backlight settings

brightness

#!/bin/env python
# this script is specifically geared toward intel_backlight laptop displays
# with a maximum value of 96000. brightness will not set to zero in this script
# to avoid mishaps. it's recommended to whitelist this program in /etc/sudoers:
# Cmnd_Alias                WITHOUTPW = /usr/local/bin/brightness
# Defaults!WITHOUTPW        !authenticate
import os
import sys
import argparse

BRIGHTNESS_FILE = "/sys/class/backlight/intel_backlight/brightness"
# max value of brightness in that file ^
MAX_BRIGHTNESS = 96000


def flags():
    parser = argparse.ArgumentParser()
    parser.add_argument(
        '-p', '--percent',
        help='Prints brightness percent to stdout. Default action.',
        action='store_true'
    )
    parser.add_argument(
        '-v', '--value',
        help='Prints raw brightness value',
        action='store_true'
    )
    parser.add_argument(
        '-s', '--set',
        type=int,
        help='Set brightness to integer percent value between 1 and 100',
    )
    parser.add_argument(
        '-i', '--increment',
        type=int,
        help='Increment brightness by provided percent value up to 100',
    )
    parser.add_argument(
        '-d', '--decrement',
        type=int,
        help='Decrement brightness by provided percent value down to 1',
    )
    return parser.parse_args()


def check_for_root():
    if os.getuid() != 0:
        print("This script must be run as superuser. Exiting.")
        sys.exit(1)


def brightness_value_to_percent(brightness):
    brightness = int(brightness)
    if brightness > MAX_BRIGHTNESS:
        brightness = MAX_BRIGHTNESS
    elif brightness < 1:
        brightness = 1
    return int((brightness / MAX_BRIGHTNESS) * 100)


def percent_to_brightness_value(percent):
    percent = int(percent)
    if percent > 100:
        percent = 100
    elif percent < 1:
        percent = 1
    if percent not in range(1, 101):
        print(f"percent value {brightness} must be between 0 and 100")
        sys.exit(1)
    return int(MAX_BRIGHTNESS * (percent / 100))


def set_brightness_percent(percent):
    new_brightness = percent_to_brightness_value(percent)
    write_brightness_value(new_brightness)
    return percent


def get_brightness_percent():
    current_brightness = get_brightness_value()
    return brightness_value_to_percent(current_brightness)


def get_brightness_value():
    with open(BRIGHTNESS_FILE, 'r') as file:
        brightness = file.read()
    return brightness


def write_brightness_value(brightness):
    with open(BRIGHTNESS_FILE, 'w') as file:
        file.write(str(brightness))


def increment_brightness(percent_interval):
    current_percent = get_brightness_percent()
    new_percent = current_percent + percent_interval
    if new_percent > 100:
        new_percent = 100
    set_brightness_percent(new_percent)
    return new_percent


def decrement_brightness(percent_interval):
    current_percent = get_brightness_percent()
    new_percent = current_percent - percent_interval
    if new_percent < 1:
        new_percent = 1
    set_brightness_percent(new_percent)
    return new_percent


if __name__ == '__main__':
    check_for_root()
    args = flags()
    if not any([args.percent, args.value, args.set, args.increment, args.decrement]):
        args.percent = True

    if args.percent:
        print(get_brightness_percent())
        sys.exit(0)

    if args.value:
        print(get_brightness_value())
        sys.exit(0)

    if args.set:
        print(set_brightness_percent(args.set))
        sys.exit(0)

    if args.increment:
        print(increment_brightness(args.increment))
        sys.exit(0)

    if args.decrement:
        print(decrement_brightness(args.decrement))
        sys.exit(0)