icc-brightness

#! /usr/bin/env python3
"""Control OLED display brightness by applying ICC color profiles.

icc-brightness brightness max-brightness - set brightness manually
icc-brightness apply - apply brightness from system setting
icc-brightness watch - continuously update to system setting
icc-brightness clean - remove all profiles generated by us
"""

import sys
import os
import subprocess
import time
import fcntl
import signal
import threading
import logging

TEMP_FOLDER = '/tmp'
BACKLIGHT_PATH = '/sys/class/backlight/intel_backlight'
BRIGHTNESS_PATH = os.path.join(BACKLIGHT_PATH, 'brightness')
MAX_BRIGHTNESS_PATH = os.path.join(BACKLIGHT_PATH, 'max_brightness')

CWD = os.path.dirname(__file__)
ICC_BRIGHTNESS_GEN = os.path.join(CWD, 'icc-brightness-gen')

LOCK = threading.Lock()


def clean():
    """Find all profile generated by us and remove them."""
    out = subprocess.check_output(['colormgr', 'get-profiles'])

    object_path = None
    filename = None
    for line in out.decode('utf8').split('\n'):
        if line.startswith('Object Path:'):
            object_path = line.split(':')[1].lstrip()
            continue
        if line.startswith('Filename:'):
            filename = line.split(':')[1].lstrip()
            if filename.find('/brightness_') < 0:
                continue
            logging.info('Removing: %s', filename)
            subprocess.run(['colormgr', 'delete-profile', object_path],
                           check=True)
            subprocess.run(['rm', filename], check=True)


def get_object_path(out):
    object_path = None
    for line in out.decode('utf8').split('\n'):
        if line.startswith('Object Path:'):
            object_path = line.split(':')[1].lstrip()
            break
    return object_path


def find_profile(filename):
    try:
        out = subprocess.check_output(
                ['colormgr', 'find-profile-by-filename', filename])
    except subprocess.CalledProcessError:
        return None
    return get_object_path(out)


def get_device_id():
    out = subprocess.check_output(['colormgr', 'get-devices-by-kind',
                                   'display'])
    return get_object_path(out)


last_icc_filename = None

def icc_brightness(brightness, max_brightness):

    icc_filename = 'brightness_%d_%d.icc' % (brightness, max_brightness)
    logging.debug('Apply profile %s', icc_filename)
    object_path = find_profile(icc_filename)
    if object_path is None:
        icc_filepath = os.path.join(TEMP_FOLDER, icc_filename)
        subprocess.run([ICC_BRIGHTNESS_GEN, icc_filepath,
                        str(brightness), str(max_brightness)], check=True)
        subprocess.check_output(['colormgr', 'import-profile', icc_filepath])
        object_path = find_profile(icc_filename)
        try:
            subprocess.run(['colormgr', 'device-add-profile',
                            get_device_id(), object_path], check=True)
        except subprocess.CalledProcessError as ex:
            logging.warning('Failed to add profile: %s', ex.stdout)

    subprocess.run(['colormgr', 'device-make-profile-default',
                    get_device_id(), object_path], check=True)

    global last_icc_filename
    if last_icc_filename is not None and last_icc_filename != icc_filename:
        object_path = find_profile(last_icc_filename)
        subprocess.run(['colormgr', 'delete-profile', object_path], check=True)
    last_icc_filename = icc_filename


def icc_brightness_apply():
    with open(BRIGHTNESS_PATH) as infile:
        brightness = int(infile.readline())
    with open(MAX_BRIGHTNESS_PATH) as infile:
        max_brightness = int(infile.readline())
    icc_brightness(brightness, max_brightness)


def handler(signum, frame):
    if LOCK.acquire(blocking=False):
        try:
            icc_brightness_apply()
        except subprocess.CalledProcessError as ex:
            logging.exception('Error during call to icc_brightness')
            logging.error(ex.stdout)
        except BaseException:
            logging.exception('Error during call to icc_brightness')
        finally:
            LOCK.release()


def main():
    logging.basicConfig(level=logging.INFO,
                        format='%(levelname)s: %(message)s')

    if len(sys.argv) == 2 and sys.argv[1] == 'clean':
        clean()

    elif len(sys.argv) == 2 and sys.argv[1] == 'apply':
        icc_brightness_apply()

    elif len(sys.argv) == 2 and sys.argv[1] == 'watch':
        try:
            icc_brightness_apply()
        except BaseException:
            logging.exception('device-make-profile-default')
        signal.signal(signal.SIGIO, handler)
        fd = os.open(BACKLIGHT_PATH, os.O_RDONLY)
        fcntl.fcntl(fd, fcntl.F_SETSIG, 0)
        fcntl.fcntl(fd, fcntl.F_NOTIFY, fcntl.DN_MODIFY| fcntl.DN_MULTISHOT)

        while True:
            time.sleep(1000000)

    elif len(sys.argv) == 3:
        brightness = int(sys.argv[1])
        max_brightness = int(sys.argv[2])
        icc_brightness(brightness, max_brightness)

    else:
        print(__doc__)


if __name__ == '__main__':
    main()