backlight

#!/usr/bin/python3

import math
import os

import argh

PATH = '/sys/class/backlight/intel_backlight'

def read(name):
	with open(os.path.join(PATH, name)) as f:
		return int(f.read())

def write(name, value):
	with open(os.path.join(PATH, name), 'w') as f:
		f.write('{}\n'.format(value))

@argh.arg('percent', nargs='?', default=None)
def main(percent):
	"""Set or get backlight brightness.
	Give a percentage to set, or #N to set to an explicit integer N.
	Give no args to query.
	"""
	if percent and percent.startswith('#'):
		write('brightness', int(percent[1:]))
		return
	maxval = read('max_brightness')
	if percent is None:
		value = read('brightness')
		print("{:.2f}% ({}/{})".format(100. * value / maxval, value, maxval))
	else:
		percent = float(percent)
		value = int(math.ceil(maxval * percent / 100.))
		write('brightness', value)

if __name__ == '__main__':
	argh.dispatch_command(main)