import dht
import machine
import time
import paho.mqtt.client as mqtt

# Initialize the DHT22 sensor on GPIO pin 13
dht_pin = machine.Pin(13)
sensor = dht.DHT22(dht_pin)

# MQTT setup
mqtt_broker = "broker.emqx.io"
mqtt_port = 1883
mqtt_topic = "sensor/temperature_humidity"
mqtt_client_id = "dht22_sensor_client"

# Create an MQTT client
mqtt_client = mqtt.Client(mqtt_client_id)

# Connect to the broker
mqtt_client.connect(mqtt_broker, mqtt_port)

# Variables to store last measured values
last_temp = None
last_hum = None

def read_sensor_data():
    """Read data from the DHT22 sensor and return temperature and humidity."""
    try:
        sensor.measure()  # Take a measurement
        temperature = sensor.temperature()  # Get temperature in Celsius
        humidity = sensor.humidity()  # Get humidity in percentage
        return temperature, humidity
    except Exception as e:
        print('Error occurred: ', e)
        return None, None

def print_if_changed(current_value, last_value, label):
    """Print the value if it has changed from the last one."""
    if current_value != last_value:
        print(f'{label}: {current_value}')
        return current_value
    return last_value

def send_mqtt_message(temperature, humidity):
    """Send the temperature and humidity to the MQTT broker."""
    message = f"Temperature: {temperature} °C, Humidity: {humidity} %"
    mqtt_client.publish(mqtt_topic, message)
    print(f"Sent to MQTT: {message}")

while True:
    temperature, humidity = read_sensor_data()
    
    if temperature is not None and humidity is not None:
        # Print and send data if it has changed
        last_temp = print_if_changed(temperature, last_temp, 'Temperature (°C)')
        last_hum = print_if_changed(humidity, last_hum, 'Humidity (%)')

        # Send the data to the MQTT broker
        send_mqtt_message(temperature, humidity)

    # Wait for a short period before taking another reading
    time.sleep(2)  # Adjusted sleep time for better performance