'''
Script to get CO2 values from MH-Z19 sensor
need parameter: CO2_port
/usr/bin/python3 /var/www/nebuleair_pro_4g/MH-Z19/get_data.py ttyAMA4
'''

import serial
import json
import sys
import time

parameter = sys.argv[1:]
port = '/dev/' + parameter[0]

ser = serial.Serial(
    port=port,
    baudrate=9600,
    parity=serial.PARITY_NONE,
    stopbits=serial.STOPBITS_ONE,
    bytesize=serial.EIGHTBITS,
    timeout=1
)

READ_CO2_COMMAND = b'\xFF\x01\x86\x00\x00\x00\x00\x00\x79'


def read_co2():
    ser.write(READ_CO2_COMMAND)
    time.sleep(2)
    response = ser.read(9)
    if len(response) < 9:
        print("Error: No data or incomplete data received.")
        return None
    if response[0] == 0xFF:
        co2_concentration = response[2] * 256 + response[3]
        return co2_concentration
    else:
        print("Error reading data from sensor.")
        return None


def main():
    try:
        co2 = read_co2()
        if co2 is not None:
            data = {"CO2": co2}
            json_data = json.dumps(data)
            print(json_data)
        else:
            print("Failed to get CO2 data.")
    except KeyboardInterrupt:
        print("Program terminated.")
    finally:
        ser.close()


if __name__ == '__main__':
    main()