A python script to automatically control yeelight bulb when a target device (mobile phone for example) is connected on a specific network. For example, Brighten/Dim light when user enters/leaves the proximity.

bulb_client_monitor.py

#!/usr/bin/env python3.7

import os
from datetime import datetime,timedelta
from yeelight import Bulb,Flow,BulbException
from yeelight.flows import night_mode

# MAC Address target devices 
TARGET_DEVICES = [
    '00:00:00:00:00:00',
    '00:00:00:00:00:00'
]

# Yeelight IP Address
LIGHT_IP = "X.X.X.X"

bulb = Bulb(LIGHT_IP, model='color', effect='smooth')

def is_client_online():
    retry = 0
    while retry < 3:
        
        # Get connected devices on wlan.=
        # This should be more reliable than ping
        # But take note of the delay before the arp cache gets updated
        scan_network = "arp -a -n | grep wlan"
        network_list = os.popen(scan_network).read()
        for HOST in TARGET_DEVICES:
            if HOST in network_list:
                return True

        retry += 1
    return False

last_scan = None
is_previously_online = False

while True:
    # on sunset, scan if target user is online
    current_datetime = datetime.now()
    current_hour = current_datetime.hour
    # Between 6:00 PM and 11:00 PM 
    if (current_hour >= 18 and current_hour < 23):
        # Scan every 10 seconds
        if not last_scan or ((current_datetime - last_scan).total_seconds()) >= 10:
            last_scan = current_datetime
        
            is_currently_online = is_client_online()
            if (is_currently_online != is_previously_online):
                is_previously_online = is_currently_online
                if (is_currently_online):
                    # if user is online, brighten light
                    print('Lights: In Use', current_datetime, flush=True)
                  
                    try:
                        bulb.set_brightness(50)
                       
                    except BulbException as error:
                        print(error)
                
                    try:
                        bulb.set_color_temp(3500)
                    except BulbException as error:
                        print(error)

                else: 
                    # if user is offline, dim light
                    print('Lights: Night Mode', current_datetime, flush=True)
                    try:
                        bulb.start_flow(night_mode())
                    except BulbException as error:
                        print(error)
    else:
        # reset state when outside time range
        if is_previously_online:
            is_previously_online = False