import json
import os
import threading

import paho.mqtt.subscribe as mqtt

database_file = "clients.json"
database_lock = threading.Lock()

# noinspection PyUnusedLocal
def update_client_record(client, userdata, message):

    database_lock.acquire()

    if not os.path.exists(database_file):
        with open(database_file, 'w') as database_blank:
            json.dump({}, database_blank)

    with open(database_file, 'r') as infile:
        database = json.load(infile)

    payload = message.payload.decode('utf-8')
    response = json.loads(payload)

    database[response['clientId']] = response

    with open(database_file, 'w') as outfile:
        json.dump(database, outfile)

    database_lock.release()


def subscribe(broker_hostname, broker_port, topic="torch", tls=None, auth=None):
    mqtt.callback(update_client_record,
                  topic,
                  hostname=broker_hostname,
                  port=broker_port,
                  tls=tls,
                  auth=auth)