import time
import paho.mqtt.client as mqtt

# Configuration
BROKER = "localhost"  # Public test broker
PORT = 1883
TOPIC = "python/mqtt/test"

def on_connect(client, userdata, flags, reason_code, properties):
    print(f"Connected with result code {reason_code}")
    # Subscribe to the topic immediately upon connection
    client.subscribe(TOPIC)

def on_message(client, userdata, msg):
    print(f"Received message on {msg.topic}: {msg.payload.decode()}")

# Create client instance
client = mqtt.Client(mqtt.CallbackAPIVersion.VERSION2)
client.on_connect = on_connect
client.on_message = on_message

# Connect to broker
try:
    client.connect(BROKER, PORT, 60)
    client.loop_start()  # Start network loop in a background thread
    
    # Publish a message
    time.sleep(2)  # Wait for subscription to settle
    client.publish(TOPIC, "Hello from Paho MQTT!", qos=1)
    print("Message published.")
    
    # Keep running to receive messages
    time.sleep(5)
    
except Exception as e:
    print(f"Error: {e}")
finally:
    # how to disconnect
    # client.loop_stop()
    # client.disconnect()
    print("Disconnected.")