mediator.py

from threading import Lock
from paho.mqtt.client import Client

CLIENTID = "Mediator"
HOST = "localhost"
BASETOPIC = "actuator"
SUBTOPIC = "sensor/#"

table = dict()
mutex = Lock()

def to_color(data):
    if data < 10:
        return 0
    elif data >= 10 and data < 15:
        return 1
    elif data >= 15 and data < 20:
        return 2
    elif data >= 20 and data < 25:
        return 3
    elif data >= 25 and data < 30:
        return 4
    return 5

def on_message(client, userdata, msg):
    room = msg.topic.split("/")[1]
    value = str(msg.payload.decode())
    print("Received {} from room {}".format(value, room))
    with mutex:
        if not(room in table) or (room in table and not (value == table[room])):
            table[room] = value
            client.publish("{}/{}".format(BASETOPIC, room), to_color(int(value)))

def main():
    client = Client(CLIENTID)
    client.connect(HOST)
    client.on_message = on_message
    client.subscribe(SUBTOPIC)

    client.loop_forever()
        
if __name__ == "__main__":
    main()