# SCRIPT B: DHT22 NODE
import network, time, machine, dht
from umqtt.simple import MQTTClient

# --- CONFIG ---
SSID, PASS = "Wokwi-GUEST", ""
BROKER = "broker.hivemq.com"
CLIENT_ID = "UiTM_Node_B_DHT"
TOPIC_PUB = b"uitm/class/dht"
TOPIC_SUB = b"uitm/class/control"

# --- HARDWARE ---
sensor = dht.DHT22(machine.Pin(15))
led_green = machine.Pin(18, machine.Pin.OUT)
led_red = machine.Pin(19, machine.Pin.OUT)
led_green.on() 

# --- MQTT CALLBACK ---
def sub_cb(topic, msg):
    print(f"Command received: {msg}")
    if msg == b"HALT":
        led_green.off()
        led_red.on()
    elif msg == b"GO":
        led_green.on()
        led_red.off()

# --- SETUP ---
print("Connecting Wi-Fi...")
wlan = network.WLAN(network.STA_IF)
wlan.active(True)
wlan.connect(SSID, PASS)
while not wlan.isconnected(): time.sleep(0.5)

client = MQTTClient(CLIENT_ID, BROKER)
client.set_callback(sub_cb)
client.connect()
client.subscribe(TOPIC_SUB)
print("Node B Ready.")

# --- MAIN LOOP ---
while True:
    client.check_msg() 
    
    try:
        sensor.measure()
        temp = sensor.temperature()
        msg = str(temp)
        client.publish(TOPIC_PUB, msg)
        print(f"Sent Temp: {msg}")
    except:
        print("Sensor Error")

    time.sleep(2)