arduino-timetable/arduino_timetable/__init__.py

''' Controlling an Arduino with a time table '''

import asyncio
import serial
import serial.tools.list_ports

from collections import namedtuple
from datetime import datetime, timedelta


# example time table for the TrapControl
example = ''' 
        00:00.0    close
        00:06.0    open
        00:08.0    close
        00:10.0    open
        00:12.0    close
        00:14.0    open
        00:16.0    close
        00:18.0    open
        00:20.0    close
        00:22.0    open
        '''


# datetime formats for timetable parsing
TIMETABLE_FORMATS = ['%M:%S', '%M:%S.%f', '%H:%M:%S', '%H:%M:%S.%f']


# named tuple for a single scheduled command
ScheduledCommand = namedtuple('ScheduledCommand', 'delta command cmd')


def parse_time_table(timetable, available_commands):
    ''' parses a (text) time table into a list of ScheduledCommands

    timetable:
        a textual representaion of time and commands like
        
        00:12.0    close
        00:14.0    open
        00:16.0    close
        00:18.0    open
        
    available_commands:
        a dictionary containing the available human readable commands as
        keys and the commands to send as values

        {'open': 0, 'close': 1}

    returns a list consisting of ScheduledCommands
    '''
    # split the time table text by line break
    raw_lines = timetable.split('\n')
    # remove surrounding white space
    content_lines = (line.strip() for line in raw_lines)
    # remove empty lines
    lines = (line for line in content_lines if line)
    
    timed_commands =[]
    for line in lines:
        # split the lines into time and command
        try:
            raw_time, raw_command = line.split(None, 1)
        except ValueError:
            msg = "error in line '{}'".format(line)
            raise ValueError(msg)
        # parse time and commands
        delta = parse_time(raw_time)
        cmd = parse_command(raw_command, available_commands)
        # add a ScheduledCommand to the resulting list
        tc = ScheduledCommand(delta, raw_command, cmd)
        timed_commands.append(tc)
    return timed_commands


def parse_time(time_str):
    ''' parses a string to extract the time information

    time_str:
        string representaion of a time like '00:03.0'

    returns a timedelta object, e.g. timedelta(seconds=3)
    '''
    # try the available time formats
    for format_str in TIMETABLE_FORMATS:
        try:
            time_obj = datetime.strptime(time_str, format_str)
            break
        except ValueError:
            pass
    else:
        msg = "time data '{}' does not match any format".format(time_str)
        raise ValueError(msg)
    return timedelta(
        hours=time_obj.hour,
        minutes=time_obj.minute,
        seconds=time_obj.second,
        microseconds=time_obj.microsecond
        )


def parse_command(command, available_commands):
    ''' parses a string and checks if it is a valid command

    raw_command:
        human readable representation of the command

    available_commands:
        a dictionary containing the available human readable commands as
        keys and the commands to send as values

        {'open': 0, 'close': 1}

    returns the command to send over serial
    ''' 
    try:
        cmd = available_commands[command.lower()]
    except KeyError:
        msg = "unknown command '{}'".format(command)
        raise ValueError(msg)
    if isinstance(cmd, str):
        cmd = cmd.encode('utf-8')
    return cmd


def find_arduino_port():
    ''' returns the port where an arduino is connected '''
    # some regular expressions matching arduino and genuino
    tmp = serial.tools.list_ports.grep('.+uino.+')
    port_list = list(tmp)
    # rais an error, if no or more than one arduinos are found
    if len(port_list) == 0:
        raise IOError('no arduino port found')
    elif len(port_list) > 1:
        raise IOError('{} arduino ports found'.format(len(port_list)))
    # return only the device name
    port_info = port_list[0]
    return port_info.device


def send_command(scheduled_command, serial_connection):
    ''' sends a command over a serial connection '''
    serial_connection.write(scheduled_command.cmd)
    print(str(scheduled_command.delta), scheduled_command.command)


def run(scheduled_commands, serial_connection):
    ''' run scheduled commands

    scheduled_commands:
        list of ScheduledCommands

    serial_connection:
        serial connection object to send commands
    '''
    # use a new event loop every time
    # if only one eventloop is used, the interactive use of run()
    # does not work since the loop is closed in the end
    loop = asyncio.new_event_loop()
    for scheduled_command in scheduled_commands:
        loop.call_later(
            scheduled_command.delta.total_seconds(),
            send_command,
            scheduled_command,
            serial_connection
            )
    # loop should stop one second after last command in list
    timed_loop_stop = scheduled_command.delta + timedelta(seconds=1)
    loop.call_later(timed_loop_stop.total_seconds(), loop.stop)
    try:
        loop.run_forever()
    except KeyboardInterrupt:
        loop.stop()
    loop.close()
    

class TimedCommands(object):
    ''' lightweight encapsulation of the functions in the module '''

    def __init__(self,
                 timetable,
                 available_commands,
                 port=None,
                 baudrate=9600,
                 **serial_kwargs):
        ''' parses a time table and establishes a serial connection

        timetable:
            a textual representaion of time and commands like
        
            00:12.0    close
            00:14.0    open
            00:16.0    close
            00:18.0    open
        
        available_commands:
            a dictionary containing the available human readable commands
            as keys and the commands to send as values.
            If an other iterable with strings is provided, the lowercase
            version of the strings will be used as human readable commands
            and the first letter of the strings as commands to send over the
            wire.

        port [None]
            port where the Arduino is connected
            if port is None, the ports are scanned for an Arduino

        baudrate [9600]
            speed of the serial connection

        serial_kwargs
            dictionary with further arguments for the serial connection
        '''
        # make sure the available commands are a dictionary
        cmd_dict = self._ensure_command_dict(available_commands)
        # parse the time table into something suitable
        self.commands = parse_time_table(timetable, cmd_dict)

        # establish the serial connection
        port = port or find_arduino_port()
        self.serial = serial.Serial(port, baudrate, **serial_kwargs)


    def _ensure_command_dict(self, iterable):
        ''' ensures, that the available commands are a dictionary

        iterable:
            if the itarable is a dictionary, the keys will be
            transformed to lowercase
            if it is not a dictionary, the lowercase version of the
            items is used as a human readable command and the first
            character of this command will be sent over the wire
        '''
        
        try:
            if isinstance(iterable, dict):
                pairs = list(iterable.items())
                keys = [key.lower() for key, value in pairs]
                values = [value for key, value in pairs]
            else:
                tmp = (str(item) for item in iterable)
                keys = [item.lower() for item in tmp]
                values = [item[0] for item in keys]
            pairs = zip(keys, values)
            return dict(pairs)
        except:
            msg = 'available commands should be a list or dict of strings'
            raise TypeError(msg)
                    

    def run(self):
        ''' run the scheduled commands '''
        run(self.commands, self.serial)


class TrapControl(TimedCommands):
    ''' A simple, stripped down version for the magnetic plug trap '''
    
    def __init__(self, timetable):
        super().__init__(timetable, ['open', 'close'])