Change and reload redshift brightness in Linux

redshift_bright.py

#!/usr/bin/env python

import argparse
import pathlib
import re
import subprocess
from typing import List


def read_config(config_path: str) -> List[str]:
    config_lines: List[str] = []
    try:
        with pathlib.Path(config_path).expanduser().open(mode='r') as conf:
            config_lines = conf.readlines()
    except FileNotFoundError:
        pass
    finally:
        return config_lines


def write_config(config_path: str, config_lines: List[str]) -> None:
    with pathlib.Path(config_path).expanduser().open(mode='w') as conf:
        conf.writelines(config_lines)


def modify_brightness_value(brightness: float, operation: str) -> float:
    new_brightness: float
    if operation == 'increase':
        new_brightness = brightness + 0.1
        if new_brightness > 1.0:
            new_brightness = 1.0
    else:
        new_brightness = brightness - 0.1
        if new_brightness < 0.1:
            new_brightness = 0.1

    return new_brightness


def change_config(config_lines: List[str], op: str) -> List[str]:
    line_re = re.compile(r'(^brightness\s*=\s*)')
    value_re = re.compile(r'(\d+\.\d+|\d+)')
    brightness: float = 0.5
    new_config: List[str] = []
    for line in config_lines:
        if re.search(line_re, line):
            read_value = re.search(value_re, line)
            if read_value:
                brightness = float(read_value.groups()[0])
            new_brightness: float = modify_brightness_value(brightness, op)
            line = 'brightness={:.1f}\n'.format(new_brightness)
        new_config.append(line)

    return new_config


def main(config_path: str, operation: str) -> None:
    config_lines = read_config(config_path)
    if not config_lines:
        return
    new_config = change_config(config_lines, operation)
    write_config(config_path, new_config)
    return


if __name__ == '__main__':
    config_path: str = '~/.config/redshift/redshift.conf'

    cli_parser = argparse.ArgumentParser(
        description='Modify Redshift brightness.',
    )

    cmd_group = cli_parser.add_mutually_exclusive_group(required='True')
    cmd_group.add_argument(
        '--inc',
        help='Increase brightness by 0.1.',
        action='store_true'
    )
    cmd_group.add_argument(
        '--dec',
        help='Decrease brightness by 0.1.',
        action='store_true'
    )

    args = cli_parser.parse_args()
    if args.increase:
        operation = 'inc'
    else:
        operation = 'dec'

    main(config_path, operation)

    subprocess.Popen(
        'killall -KILL redshift && nohup redshift > /dev/null && disown %1',
        shell=True
    )