#! /usr/bin/python3
import time
import sys
from paho.mqtt import client as mqtt_client
import os
import serial

MAXIMUM_COMMUNICATION_FAILURE=100

TEMPERATUR_MIN_DIFFERENCE   = 2
TARGET_MIN_DIFFERENCE       = 1
RPM_MIN_DIFFERENCE          = 50

# MQTT Settings
mqtt_server=os.environ['MQTT_SERVER']
mqtt_topic=os.environ['MQTT_TOPIC']
# SERIAL Port
serial_device=os.environ['SERIAL_DEVICE']

# Start mqtt
client_id = f'python-fan-ctrl'
client = mqtt_client.Client(mqtt_client.CallbackAPIVersion.VERSION2)
# Start Serial communication
ser = serial.Serial(serial_device, 115200, timeout=1)  # open serial port

# The callback for when a PUBLISH message is received from the server.
def on_message(client, userdata, msg):
    print(msg.topic+" "+str(msg.payload))

# Handle MQTT Commands
def on_connect(mqttc, obj, flags, reason_code, properties):
    client.subscribe(mqtt_topic + "cmd/led")
    client.subscribe(mqtt_topic + "cmd/rpm")
    print("Connected: " + str(reason_code))

client.on_message = on_message
client.on_connect = on_connect

if (not (mqtt_server)):
    print("MQTT_SERVER is not set")

if (not (mqtt_topic)):
    print("MQTT_TOPIC is not set")

# Start MQTT Client
client.connect(mqtt_server, 1883)
client.loop_start()

client.publish(mqtt_topic + "device", ser.name) # check which port was really used

SerialCommunicationFailureCounter=0

# store last published value
lastTemperatur  = -1
lastRPM         = -1
lastTarget      = -1

# Endless Loop
try:
    while True:
        try:
            if (not (ser.is_open)):
                ser.open()
                continue
        except (serial.SerialException):
            client.publish(mqtt_topic + "exception", "serial reopen") # check which port was really used
            time.sleep(1.0)

        try:
            line = ser.readline()   # read a '\n' terminated line
        except (serial.SerialException):
            SerialCommunicationFailureCounter = SerialCommunicationFailureCounter + 1
            client.publish(mqtt_topic + "serialcom/failure", str(SerialCommunicationFailureCounter))
            line=None
            if (SerialCommunicationFailureCounter > MAXIMUM_COMMUNICATION_FAILURE):
                raise serial.SerialException("device reports readiness / device disconnected " + str(MAXIMUM_COMMUNICATION_FAILURE) + " times")

        if (line):
            client.publish(mqtt_topic + "exception", "") # clear exception
            # convert byte array to string
            l = line.decode("utf-8")
            try:
                # Parse the controller information
                # e.g. : 22.00;0%;0RPM
                temperatur, percent, rpm = l.split(";")
            except (ValueError):
                # activate debug code
                temperatur = None
                percent = None
                rpm = None

            if ((temperatur) and (percent) and (rpm)):
                parseError=False
                currentTemperatur = float(temperatur.strip())
                if (abs(currentTemperatur - lastTemperatur) > TEMPERATUR_MIN_DIFFERENCE):
                    client.publish(mqtt_topic + "temperatur", str(currentTemperatur))
                    lastTemperatur = currentTemperatur

                if (percent.endswith('/100')):
                    currentTarget = int(percent[:-4])
                    if (abs(lastTarget - currentTarget) > TARGET_MIN_DIFFERENCE):
                        client.publish(mqtt_topic + "target", str(currentTarget))
                        lastTarget = currentTarget
                else:
                    client.publish(mqtt_topic + "debug", "target%% invalid:" + str(percent))
                    parseError=True
                
                # remove new line for last element
                rpm = rpm.replace('\r','').replace('\n','')
                if (rpm.endswith('RPM')):
                    currentRPM = int(rpm[:-3])
                    if (abs(currentRPM-lastRPM) > RPM_MIN_DIFFERENCE):
                        client.publish(mqtt_topic + "rpm", str(currentRPM))
                        lastRPM = currentRPM
                else:
                    client.publish(mqtt_topic + "debug", "RPM invalid:" + str(rpm))
                    parseError=True

                # cleanup debugging
                if (parseError == False):
                    client.publish(mqtt_topic + "debug", None)
            else:
                client.publish(mqtt_topic + "debug", line) # line was invalid and could not be parsed
        else:
            time.sleep(0.2)

except (KeyboardInterrupt, SystemExit):
    print("User aborted service ...")
    client.publish(mqtt_topic + "debug", "User aborted service")
    time.sleep(0.5)
    print("service Dead")

client.loop_stop()