import re
from serial import Serial

parameters = {
        'acvoltsin': (1, '01 V In +([0-9]+[.]?[0-9]*)'),
        'acvoltsout': (2, '02 V Out +([0-9]+[.]?[0-9]*)'),
        'vaout': (5, '05 VA Out +([0-9]+[.]?[0-9]*)'),
        'vbattery': (7, '07 V Batt +([0-9]+[.]?[0-9]*)'),
        'frequency': (8, '08 Freq ([0-9]+[.]?[0-9]*) Hz'),
        'fullload': (16, '16 FullLoad% ([0-9]+[.]?[0-9]*)'),
        'watts': (17, '17 Watts +([0-9]+[.]?[0-9]*)'),
        'powerfactor': (18, '18 PF +([0-9]+[.]?[0-9]*) ----'),
        'crestfactor': (19, '19 CrestF +([0-9]+[.]?[0-9]*)'),
        'powerout': (20, '20 #PwrOut +([0-9]+[.]?[0-9]*)'),
        'inverterminutes': (23, '23 InvMin +([0-9]+[.]?[0-9]*)')
        }


class UsvSerialHandler(object):
    def __init__(self, device_path):
        """ Handles the serial connection to the usv """

        self._serial_port = Serial(device_path,
                baudrate=600,
                timeout=0.8)

        # force clean prompt
        self._serial_port.write('\r')
        self._serial_port.read(100)

    def request(self, index):
        """ Write and read until prompt """

        self._serial_port.write('d {}\r'.format(index))

        return self._serial_port.read(21)


class Usv(UsvSerialHandler):
    def __init__(self, device_path):
        super().__init__(device_path)

    def read(self):
        fields = {}

        for name, (index, regex) in parameters.items():
            result = self.request(index)
            
            match = re.search(regex, result, re.MULTILINE)

            if match:
                value = float(match.group(1))

                fields[name] = value

        return fields