#!/usr/bin/python3
import sys
import json
import time

import paho.mqtt.client as mqtt

def on_connect(client, userdata, flags, rc):
    print("connected")

def on_disconnect(client, userdata, rc):
    print("disconnected")

def main():
    if len(sys.argv) < 3:
        print(len(sys.argv))
        print(f'usage: {sys.argv[0]} json-file mqtt-host')
        return 1

    filename = sys.argv[1]
    mqtthost = sys.argv[2]

    client = mqtt.Client()
    client.on_connect = on_connect
    client.on_disconnect = on_disconnect

    pvalues = {}
    while True:
        if not client.is_connected():
            client.connect(mqtthost, 1883)

        with open(filename, 'r', encoding = 'utf-8') as f:
            values = json.loads(f.read())

        for key in ('co2', 'temperature', 'humidity'):
            curr = values.get(key)
            prev = pvalues.get(key)
            if prev and prev == curr:
                continue

            topic = f'sensors/{key}/scd4x/{values.get("serial")}'
            #print(f'{topic} = {curr}')
            client.publish(topic, curr)

        pvalues = values
        time.sleep(10)

if __name__ == '__main__':
    sys.exit(main())