gcs_client.py

import json
import time
from paho.mqtt import client as mqtt_client
import paho.mqtt
import constants


# Callback function to be called whenever the MEA receives a message from GCS
def on_message(client: mqtt_client.Client, userdata, msg: mqtt_client.MQTTMessage):
    dataString: str = msg.payload.decode()
    print(dataString)
    jsonMsg = json.loads(dataString)

    x = jsonMsg.get("search_area")
    y = jsonMsg.get("home_coordinates")
    z = jsonMsg.get("drop_coordinates")
    a = jsonMsg.get("geofence")
    # search_area array with 3 objects holding lng and lat
    if x != None:
        search_lat_0 = x[0]["lat"]
        search_long_0 = x[0]["lng"]
        search_lat_1 = x[1]["lat"]
        search_long_1 = x[1]["lng"]
        search_lat_2 = x[2]["lat"]
        search_long_2 = x[2]["lng"]
        print("lat_0", search_lat_0, "long_0", search_long_0)
        print("lat_1", search_lat_1, "long_1", search_long_1)
        print("lat_2", search_lat_2, "long_2", search_long_2)
    # home_coordinates
    # assuming "4" is vehicle: MEDEVAC
    elif y != None:
        home_lat = y["2"]["lat"]
        home_long = y["2"]["lng"]
        print("home_lat", home_lat, "home_long", home_long)

    # drop_coordinates
    elif z != None:
        drop_lat = z["lat"]
        drop_long = z["lng"]
        print("drop_lat", drop_lat, "drop_long", drop_long)

    elif a != None:
        # keep_in: true
        geo_lat_0_t = a[0]["coordinates"][0]["lat"]
        geo_lng_0_t = a[0]["coordinates"][0]["lng"]
        geo_lat_1_t = a[0]["coordinates"][1]["lat"]
        geo_lng_1_t = a[0]["coordinates"][1]["lng"]
        geo_lat_2_t = a[0]["coordinates"][2]["lat"]
        geo_lng_2_t = a[0]["coordinates"][2]["lng"]

        print("coordinates")
        print("lat_0", geo_lat_0_t, "long_0", geo_lng_0_t)
        print("lat_1", geo_lat_1_t, "long_1", geo_lng_1_t)
        print("lat_2", geo_lat_2_t, "long_2", geo_lng_2_t)

        # keep_in: false
        geo_lat_0_f = a[1]["coordinates"][0]["lat"]
        geo_lng_0_f = a[1]["coordinates"][0]["lng"]
        geo_lat_1_f = a[1]["coordinates"][1]["lat"]
        geo_lng_1_f = a[1]["coordinates"][1]["lng"]
        geo_lat_2_f = a[1]["coordinates"][2]["lat"]
        geo_lng_2_f = a[1]["coordinates"][2]["lng"]

        print("coordinates")
        print("lat_0", geo_lat_0_f, "long_0", geo_lng_0_f)
        print("lat_1", geo_lat_1_f, "long_1", geo_lng_1_f)
        print("lat_2", geo_lat_2_f, "long_2", geo_lng_2_f)


def on_connect(client: mqtt_client.Client, userdata, flags: dict[str, int], rc: int):
    if (rc == 0):
        print("Connected to GCS successfully")
    elif (rc == 1):
        print("Connection refused - incorrect protocol version")
    elif (rc == 2):
        print("Connection refused - invalid client identifier")
    elif (rc == 3):
        print("Connection refused - server unavailable")
    elif (rc == 4):
        print("Connection refused - bad username or password")
    elif (rc == 5):
        print("Connection refused - not authorised")
    else:
        print("rc value incorrect, something went wrong")


class GCSClient:
    # Initializes a GCS Client object, set the topic to be MEA so GCS can target messages for us
    def __init__(self, broker: str = constants.broker,
                 port: int = constants.port,
                 topic: str = constants.topic,
                 onMessageFunc=on_message,
                 clientId: str = None) -> None:
        print("Initializing Client")
        self.topic = topic
        self.client = mqtt_client.Client("user")
        self.client.on_connect = on_connect
        self.client.on_message = onMessageFunc
        self.client.connect(broker, port)

    def subscribe(self):
        self.client.subscribe(self.topic)
        self.client.loop_start()

    # Publishes a message to the MQTT service
    def send(self, message: str, timeout: int = None):
        msgInfo: mqtt_client.MQTTMessageInfo = self.client.publish(
            self.topic, message, qos=2)
        msgInfo.wait_for_publish(timeout)


if __name__ == '__main__':
    backend = GCSClient()
    backend.subscribe()
    while (True):
        pass