import serial
import pynmea2
import paho.mqtt.client as mqtt

# Configuration
GPS_PORT = '/dev/ttyS0'  # change this if your GPS device is on a different port
MQTT_BROKER = '65.108.199.212'
MQTT_PORT = 1883
TOPIC = 'iiot/coordinates'

def on_connect(client, userdata, flags, rc):
    """Callback for when the client connects to the broker."""
    print(f"Connected with result code {rc}")
    client.subscribe(TOPIC)

def on_message(client, userdata, msg):
    """Callback for when a message is received from the broker."""
    print(f"Received message: {msg.payload.decode('utf-8')}")

# Create MQTT client
client = mqtt.Client()

# Connect to MQTT broker
client.on_connect = on_connect
client.on_message = on_message
try:
    client.connect(MQTT_BROKER, MQTT_PORT)
except Exception as e:
    print(f"Error connecting to MQTT broker: {e}")
    exit()

# Open GPS device serial port
try:
    gps_dev = serial.Serial(GPS_PORT, 9600, timeout=1)  # change baudrate and timeout if needed
except serial.SerialException as e:
    print(f"Error opening GPS device serial port: {e}")
    exit()

while True:
    try:
        line = gps_dev.readline().decode('utf-8')
        if line.startswith('$GPGGA'):
            msg = pynmea2.parse(line)
            latitude = msg.latitude
            longitude = msg.longitude
            print(f"Latitude: {latitude}, Longitude: {longitude}")
            client.publish(TOPIC, f"{latitude},{longitude}")
    except Exception as e:
        print(f"Error parsing GPS data or publishing to MQTT broker: {e}")