Device.py

"""
#
# Author:       L. Saetta
# created:      10 december 2017
# last update:  04/02/2018
#
# published under MIT license (see LICENSE file)
#
# This module implement a class representing a Device
#
# Class providing methods to interact with MQTT broker
# L.S. 2017
#
"""
# pylint: disable=invalid-name

import configparser
import json
import os
import sys
import time

import paho.mqtt.client as mqtt

#
# Configuration for MQTT protocol
# is written in gateway.ini file !
# host is the broker, in my Ravello env
# read OBD2_HOME env variable
OBD2HOME = os.getenv('OBD2_HOME')
config = configparser.ConfigParser()
config.read(OBD2HOME + '/gateway.ini')

HOST = config['DEFAULT']['host']
PORT = int(config['DEFAULT']['port'])
TIMEOUT = int(config['DEFAULT']['timeout'])
MYQOS = int(config['DEFAULT']['myQos'])
mqttLogging = config['DEFAULT']['mqttLogging']
# config to enable TLS
# TLS = config['DEFAULT']['TLS']
CAFILEPATH = config['DEFAULT']['CAFILEPATH']


class Device(object):
    """ This class encapsulate Device communication with MQTT broker """

    # Constructor
    def __init__(self, clientID):
        self.connOK = False

        # Create MQTT client and set MQTT client ID
        self.mqttClient = mqtt.Client(clientID, protocol=mqtt.MQTTv311)
        # note that the client id must be unique on the broker

        # MQTT callbacks registration
        self.mqttClient.on_message = self.on_message
        self.mqttClient.on_connect = self.on_connect
        self.mqttClient.on_disconnect = self.on_disconnect

        self.mqttClient.on_publish = self.on_publish

        if mqttLogging == "YES":
            self.mqttClient.on_log = self.on_log

    # MQTT callbacks definition

    def on_connect(self, mqttc, obj, flags, connResult):

        if connResult == 0:
            self.connOK = True

        print("")
        if self.connOK == True:
            print("*** MQTT Connection  OK")
        else:
            print("*** MQTT Connection NON OK")

    def on_disconnect(self, client, userdata, rc):
        self.connOK = False
        print("*** MQTT disconnected...")

    def isConnected(self):
        return self.connOK

    # this function can be redefined... see set_on_message
    def on_message(self, mqttc, obj, msg):
        print('Received command: ')

        try:
            msgJson = json.loads(msg.payload)

            print('CARID: ', msgJson['CARID'])
            print('DTIME: ', msgJson['DTIME'])
            print('COMMAND: ', msgJson['COMM_TYPE'])
            print('PARAMS: ', msgJson['PARAMS'])
        except:
            print('Error in parsing command: ')
            print(msg.payload)

    def on_publish(self, mqttc, obj, mid):
        # print("mid: " + str(mid))
        pass

    def on_log(self, client, userdata, level, buf):
        print("log: ", buf)

    # end MQTT callbacks definition

    #
    # Public Methods
    #
    def connect(self, host, port, TLS):
        if TLS == "YES":
            # this is the path to CA crt file (needed)
            self.mqttClient.tls_set(ca_certs=CAFILEPATH)

        try:
            self.mqttClient.connect(host, port, TIMEOUT)

            # start a background thread to process networks events. It should also
            # handle automatical reconnection...
            self.mqttClient.loop_start()
        except:
            print("connect...")
            print('*** Error info: ', sys.exc_info()[0], sys.exc_info()[1])

    def wait_for_conn_ok(self):
        while self.connOK != True:
            print("Waiting for MQTT connection...")
            time.sleep(1)

    def publish(self, topic, msg):
        if mqttLogging == "YES":
            print("message published ", msg)

        (result, mid) = self.mqttClient.publish(topic, msg, qos=MYQOS)

    def subscribe(self, topic):
        self.mqttClient.subscribe(topic, qos=1)

    #
    # this function must be called to redefine the callback called when a msgs is received
    # to be called from the main (for example the Command Processor)
    #
    def set_on_message(self, func_to_call_back):
        # redefines the func to call when a message arrives
        self.mqttClient.on_message = func_to_call_back