redshift-hue.py

import ConfigParser
import datetime
import logging
import os
import time

from phue import Bridge
from Pysolar.solar import GetAltitude
from xdg.BaseDirectory import xdg_config_home


log_format = '%(asctime)s %(levelname)-5.5s [%(name)s] %(message)s'
logging.basicConfig(format=log_format, level=logging.INFO)
log = logging.getLogger('redshift-hue')

config_defaults = {
    'temp-day': '5500',
    'temp-night': '3500',
    'brightness': '1.0',
    'dimmable-lights': '1',
    'color-lights': '1',
}
config = ConfigParser.ConfigParser(config_defaults)
config.read([
    os.path.join(xdg_config_home, 'redshift.conf'),
    '/etc/redshift.conf',
])

try:
    lat = config.getfloat('manual', 'lat')
    lon = config.getfloat('manual', 'lon')
except ConfigParser.NoOptionError:
    log.error('Latitude and longitude must be set.')
    raise
log.debug(
    'Location: %.2f %s, %.2f %s',
    abs(lat), 'SN'[lat >= 0.], abs(lon), 'WE'[lon >= 0.])

temperature_day = config.getint('redshift', 'temp-day')
temperature_night = config.getint('redshift', 'temp-night')
log.debug(
    'Temperatures: %dK at day, %dK at night',
    temperature_day, temperature_night)

transition_low = -6.0
transition_high = 3.0
log.debug(
    'Solar elevations: day above %.1f, night below %.1f',
    transition_high, transition_low)

brightness = config.getfloat('redshift', 'brightness')
try:
    brightness_day = config.getfloat('redshift', 'brightness-day')
except ConfigParser.NoOptionError:
    brightness_day = brightness
try:
    brightness_night = config.getfloat('redshift', 'brightness-night')
except ConfigParser.NoOptionError:
    brightness_night = brightness

bridge_address = config.get('hue', 'address')
dimmable_lights = map(int, config.get('hue', 'dimmable-lights').split(','))
color_lights = map(int, config.get('hue', 'color-lights').split(','))

bridge = Bridge(bridge_address)
bridge.connect()


def get_alpha(elevation):
    alpha = (transition_low - elevation) / (transition_low - transition_high)
    return min(max(0.0, alpha), 1.0)


def get_period(elevation):
    if elevation < transition_low:
        return 'Night'
    elif elevation < transition_high:
        return 'Transition'
    else:
        return 'Daytime'


def log_period(period, transition):
    if period == 'Transition':
        log.info('Period: %s (%.2f%% day)', period, transition * 100)
    else:
        log.info('Period: %s', period)


def get_transition_progress(elevation):
    period = get_period(elevation)
    return {
        'Night': 0.0,
        'Transition': get_alpha(elevation),
        'Daytime': 1.0,
    }[period]


def interpolate(elevation):
    alpha = get_alpha(elevation)
    temperature = (1.0 - alpha) * temperature_night + alpha * temperature_day
    brightness = (1.0 - alpha) * brightness_night + alpha * brightness_day
    return temperature, brightness


while True:
    now = datetime.datetime.utcnow()
    elevation = GetAltitude(lat, lon, now)
    log.debug('Solar elevation: %f', elevation)

    temperature, brightness = interpolate(elevation)
    transition = get_transition_progress(elevation)
    log_period(get_period(elevation), transition)
    log.info('Color temperature: %dK', temperature)
    log.info('Brightness: %.2f', brightness)

    mired = int(1000000. / temperature)
    bridge.set_light(color_lights, 'ct', mired)

    bridge.set_light(dimmable_lights, 'bri', int(brightness * 255))

    time.sleep(5.0)