nixos-config/pkgs/wordclock-dimmer/wordclock-dimmer.py

#!/usr/bin/env python3
from astral.location import Location, LocationInfo
from math import cos, pi
from time import sleep
import datetime
import os
import paho.mqtt.client as mqtt
import sys


def time_as_float_hours(time: datetime.time) -> float:
    return time.hour + time.minute / 60 + time.second / 3600


def set_color(client: mqtt.Client, red: int, green: int, blue: int, retain=True):
    client.reconnect()
    # my wordclock’s red and green LEDs seem to be switched
    client.publish("wordclock/color/red", green, retain=True)
    client.publish("wordclock/color/green", red, retain=True)
    client.publish("wordclock/color/blue", blue, retain=True)


def get_color_for_time(time: datetime.time, base=(60, 60, 60)) -> (int, int, int):
    if time.hour >= 22 or time.hour < 7:
        # night mode: dim red
        return (3, 0, 0)
    else:
        # day mode: calculated depending on sun (https://www.desmos.com/calculator/nrseefnaom)
        now = time_as_float_hours(time)

        # returns at least (3, 3, 3)
        min_factors = (3 / base[0], 3 / base[1], 3 / base[2])

        rate = 5

        location_info = LocationInfo(
            timezone="Europe/Berlin", latitude=49.52, longitude=10.18
        )
        location = Location(location_info)
        sunrise = time_as_float_hours(location.sunrise().time())
        sunset = time_as_float_hours(location.sunset().time())

        factors = []
        for min_factor in min_factors:
            factor = min_factor
            if now > sunrise and now < sunset:
                factor = 1 - (
                    (1 - min_factor) * cos((pi / (sunrise - sunset)) * (now - sunset))
                ) ** (2 * rate)
            factors.append(factor)

        return (
            round(base[0] * factors[0]),
            round(base[1] * factors[1]),
            round(base[2] * factors[2]),
        )


def update(client: mqtt.Client):
    time = datetime.datetime.now().time()
    color = get_color_for_time(time)
    print(f"{time}: setting color to {color}")
    sys.stdout.flush()
    set_color(client, *color)
    pass


client = mqtt.Client("wordclock.py")

user = os.environ["WORDCLOCK_MQTT_USER"]
try:
    password = os.environ["WORDCLOCK_MQTT_PASSWORD"]
except KeyError:
    with open(os.environ["WORDCLOCK_MQTT_PASSWORD_FILE"]) as f:
        password = f.read().rstrip()
host = os.environ["WORDCLOCK_MQTT_HOST"]

client.username_pw_set(user, password)
client.connect(host, 1883, 60)

while True:
    update(client)
    sleep(300)