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

MAXIMUM_COMMUNICATION_FAILURE=1000

TEMPERATUR_MIN_DIFFERENCE   = 2
TARGET_MIN_DIFFERENCE       = 1
RPM_MIN_DIFFERENCE          = 50

COMMAND_PREFIX = "ollpe"

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

# Logging
try:
    if (os.environ['PY_LOGGING']):
        customLevel = os.environ['PY_LOGGING'].upper()
except (KeyError):
    customLevel = 'WARNING'

logging.basicConfig(
    level=customLevel,
    filename="/var/log/app.log",
    filemode="w",
    format="%(asctime)s - %(levelname)s - %(message)s"
)

logging.debug("Start Serial connect")
# Start Serial communication
ser = serial.Serial(serial_device, 115200, timeout=1)  # open serial port

if (ser is None):
    logging.error("Cannot open device" + str(serial_device))
    sys.exit()

# The callback for when a PUBLISH message is received from the server.
def on_message(client, userdata, msg):
    payload = msg.payload.decode("utf-8")
    if ((mqtt_topic + "cmd/rpm") == msg.topic):
        if (ser.is_open):
            command = COMMAND_PREFIX+"f{:02x}".format(int(payload))
            ser.write(command.encode('utf-8'))
        else:
            client.publish(mqtt_topic + "cmd/exception", "Serial Connection closed") # clear exception
    elif ((mqtt_topic + "cmd/led") == msg.topic):
        command = COMMAND_PREFIX+"l" + payload
        ser.write(command.encode('utf-8'))
    else:
        logging.warning(msg.topic+" "+str(msg.payload))

# Handle MQTT Commands
def on_connect(client, obj, flags, reason_code, properties):
    client.subscribe(mqtt_topic + "cmd/led")
    client.subscribe(mqtt_topic + "cmd/rpm")
    client.publish(mqtt_topic + "online", payload="true", qos=1, retain=True)
    logging.debug("Connected: " + str(reason_code))

# Start mqtt
client_id = f'python-fan-ctrl'
client = mqtt_client.Client(mqtt_client.CallbackAPIVersion.VERSION2)
client.on_message = on_message
client.on_connect = on_connect

if (not (mqtt_server)):
    logging.error("MQTT_SERVER is not set")

if (not (mqtt_topic)):
    logging.error("MQTT_TOPIC is not set")

# Start MQTT Client
client.will_set(mqtt_topic + "online", payload="false", qos=1, retain=True)
client.connect(mqtt_server, 1883)
client.loop_start()

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

# Reset Serial Communication statistic
SerialCommunicationFailureCounter=0
client.publish(mqtt_topic + "serialcom/failure", str(SerialCommunicationFailureCounter))

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

# Endless Loop
try:
    while ((mqtt_topic is not None) and (mqtt_server is not None)):
        try:
            if (not (ser.is_open)):
                ser.open()
                continue
        except (serial.SerialException):
            logging.error("Could not open serial connection")
            client.publish(mqtt_topic + "exception", "serial reopen") # check which port was really used
            time.sleep(3.0)

        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
            # activate debug code, by default
            temperatur = None
            percent = None
            rpm = None

            # convert byte array to string
            l = line.decode("utf-8")
            if (COMMAND_PREFIX in l):
                logging.debug("Skip '" + str(l) + "', found " + str(COMMAND_PREFIX))
                continue

            try:
                # Parse the controller information
                # e.g. : 22.00;0%;0RPM
                temperatur, percent, rpm = l.split(";")
            except (ValueError):
                logging.debug("Unparsable '" + str(l) + "'")

            if ((temperatur) and (percent) and (rpm)):
                parseError=False
                try:
                    currentTemperatur = float(temperatur)
                except (ValueError):
                    logging.error("Temperatur Error: could not convert string to float:" + temperatur)
                    currentTemperatur = lastTemperatur
                if (abs(currentTemperatur - lastTemperatur) > TEMPERATUR_MIN_DIFFERENCE):
                    client.publish(mqtt_topic + "temperatur", str(currentTemperatur))
                    lastTemperatur = currentTemperatur

                if (percent.endswith('/100')):
                    try:
                        currentTarget = int(percent[:-4])
                    except (ValueError):
                        logging.error("Percent Error: could not convert string to int:" + (percent[:-4]))
                        currentTarget = lastTarget

                    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')):
                    try:
                        currentRPM = int(rpm[:-3])
                    except (ValueError):
                        logging.error("RPM Error: could not convert string to int:" + (rpm[:-3]))
                        currentRPM = lastRPM

                    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(0.5)

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

client.loop_stop()