arduino-timetable/arduino_timetable/gui.py

''' A Tkinter Gui Application for running scheduled commands '''

# library imports
import asyncio
import os
import serial
import tkinter as tk
import tkinter.ttk as ttk

from enum import Enum
from datetime import timedelta
from multiprocessing import Process, Lock
from tkinter import filedialog
from tkinter import messagebox

# local imports
from .timetable import parse_excel_file, find_arduino_port

# delay for checking if commands are running on the Arduino
CHECK_DELAY = 100
# delay after connecting to the arduino before a programm can be run
CONNECT_DELAY = 2500


class ArduinoState(Enum):
    ''' State of the current Arduino setup '''
    not_initialized = 'not_initialized'
    connected = 'connected'
    running = 'running'
    finished = 'finished'


def arduino_subprocess(lock, com_port, scheduled_commands, **kwargs):
    ''' connecting to the Arduiono and running the scheduled commands

    lock:
        Separaion controll between establishing connection and running
        commands. Must be of class multiprocessing.Lock
    com_port:
        port where the Arduino is connected
    scheduled_commands:
        list of .timetable.TimedCommands to run
    **kwargs:
        arguments used to open serial connection
        the most importent one is 'baudrate', defaults to 9600

    To run the scheduled commands a separate process is used. Otherwise the
    execution of the gui would stop until the commands finish. This would
    lead to an unresponsive gui programm.

    The serial connection is not pickable and therfore the connection to the
    arduino and running the commands must be made in the same process. To
    have a separation between establishing the connection and running the
    commands, a simple lock is used. Before starting the subprocess, the lock
    will be acquired by the main programm and releasing the lock will start
    the commands.
    '''
    # get a custom baudrate or use the default 9600
    baudrate = kwargs.pop('baudrate', 9600)
    with serial.Serial(com_port, baudrate=baudrate, **kwargs) as connection:
        # use a fresh asyncio event loop every time
        loop = asyncio.new_event_loop()
        # wait until the lock is released to start the commands
        lock.acquire()
        try:
            # schedule the commands for execution
            for scheduled_command in scheduled_commands:
                loop.call_later(
                    scheduled_command.delta.total_seconds(),
                    connection.write,
                    scheduled_command.cmd
                    )
            # 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)
            # run the loop
            try:
                loop.run_forever()
            except KeyboardInterrupt:
                loop.stop()
            loop.close()
        finally:
            lock.release()


def timedelta_as_str(timedelta):
    ''' a nice string output for a timedelta

    shamlessly copied from the original timedelta implementation, but the
    original implementation displays the microseconds always with six
    characters.
    '''
    mm, ss = divmod(timedelta.seconds, 60)
    hh, mm = divmod(mm, 60)
    s = "%d:%02d:%02d" % (hh, mm, ss)
    if timedelta.days:
        def plural(n):
            return n, abs(n) != 1 and "s" or ""
        s = ("%d day%s, " % plural(timedelta.days)) + s

    # microseconds are stored as int between 0 and 999999 inclusive
    s = s + ".%d" % (timedelta.microseconds / 10**5)

    return s


class FilePanel(tk.Frame):
    ''' Tkinter Panel for selecting files '''

    def __init__(self, parent):
        tk.Frame.__init__(self, parent.master)
        self._parent = parent
        self.btn_files = tk.Button(
            self,
            text="Select Excel File",
            command=self._parent.select_files
            )
        self.btn_files.pack(pady=5, padx=5)
        sep = ttk.Separator(self, orient=tk.HORIZONTAL)
        sep.pack(side=tk.BOTTOM, fill=tk.X)
        self.pack(side=tk.TOP, fill=tk.X)


class ParsedCommandsPanel(tk.Frame):
    ''' Tkinter Panel displaying the scheduled commands to be run '''

    def __init__(self, parent):
        tk.Frame.__init__(self, parent.master)
        self._parent = parent
        self.label = tk.Label(self)
        self.label.pack(fill=tk.X, pady=5, padx=5)
        self.messages = tk.Message(self, text='', font=("Courier", 8))
        self.messages.pack(fill=tk.X, pady=5, padx=5)
        self.pack(side=tk.TOP, fill=tk.X)

    def set_schedule_text(self, text):
        ''' display the scheuled commands to run '''
        self.messages.config(text=text)
        self.messages.update_idletasks()

    def set_label_text(self, text):
        ''' display the filename of the scheduled commands '''
        self.label.config(text=text)
        self.label.update_idletasks()

    def clear_text(self):
        ''' clear all text in this panel '''
        self.set_schedule_text('')
        self.set_label_text('')

    def show_schedule(self, command_list):
        ''' transformes the command list to a textual representation '''
        times = [timedelta_as_str(cmd.delta) for cmd in command_list]
        commands = [cmd.command for cmd in command_list]
        # search for the longest time text
        max_len_limes = max(len(time_str) for time_str in times)
        # template for each command line
        template = '{delta:<{size}}   {cmd}'
        # assemble all lines
        lines = [
            template.format(delta=delta, size=max_len_limes, cmd=cmd)
            for delta,cmd
            in zip(times, commands)
            ]
        # return the text for the command list
        self.set_schedule_text('\n'.join(lines))


class ActionPanel(tk.Frame):
    ''' Tkinter Panel for the action buttons '''

    def __init__(self, parent):
        tk.Frame.__init__(self, parent.master)
        self._parent = parent
        # different configurations for the 'run' button
        self.btn_config_disabled = {
            'text': 'Run Commands',
            'background': 'SystemButtonFace',
            'activebackground': 'SystemButtonFace',
            'state': 'disabled'
            }
        self.btn_config_wait = {
            'text': 'Connecting',
            'background': 'SystemButtonFace',
            'activebackground': 'SystemButtonFace',
            'state': 'disabled'
            }
        self.btn_config_ready = {
            'text': 'Run Comands',
            'background': 'green',
            'activebackground': 'green',
            'state': 'normal'
            }
        self.btn_config_running = {
            'text': 'Stop Comands',
            'background': 'red',
            'activebackground': 'red',
            'state': 'active'
            }
        ttk.Separator(self, orient=tk.HORIZONTAL).pack(side=tk.TOP, fill=tk.X)
        self.btn_go = tk.Button(
            self,
            command=self._parent.go_button_clicked,
            **self.btn_config_disabled
            )
        self.btn_go.pack(side=tk.LEFT, pady=5, padx=5)
        self.btn_quit = tk.Button(self, text="Quit", command=self._parent.quit)
        self.btn_quit.pack(side=tk.RIGHT, pady=5, padx=5)
        self.pack(side=tk.BOTTOM, fill=tk.X)

    def update_button_state(self):
        ''' update the button state reflecting the state of the Arduino '''
        if self._parent.arduino_state == ArduinoState.running:
            self.btn_go.config(**self.btn_config_running)
        elif self._parent.arduino_state == ArduinoState.not_initialized:
            self.btn_go.config(**self.btn_config_disabled)
        else:
            # establishing the connection takes some time, show a 'connecting'
            # state and after some time show the 'ready' state
            self.btn_go.config(**self.btn_config_wait)
            self.after(CONNECT_DELAY, self._enable_button)
        self.btn_go.update_idletasks()

    def _enable_button(self):
        ''' shows the 'ready' state of the button '''
        self.btn_go.config(**self.btn_config_ready)
        self.btn_go.update_idletasks()


class Application(tk.Frame):
    ''' The Tkinter application containing the buisiness logic '''

    def __init__(self, master, available_commands):
        ''' initialization

        master:
            tkinter root object

        available_commands:
            list of available commands for the Arduino
        '''
        master.minsize(height=330, width=300)
        tk.Frame.__init__(self, master)
        self._master = master
        self.pack(fill=tk.BOTH)

        # the layout sections
        self.file_panel = FilePanel(self)
        self.program_panel = ParsedCommandsPanel(self)
        self.action_panel = ActionPanel(self)

        # properties for the buisiness logic
        self.available_commands = available_commands
        self.scheduled_commands = []
        self.arduino_process = None
        self.arduino_lock = None
        self._arduino_state = ArduinoState.not_initialized
        self.reset()

    @property
    def arduino_state(self):
        ''' property for the current state of the arduino '''
        return self._arduino_state

    @arduino_state.setter
    def arduino_state(self, new_state):
        ''' setter for the arduino state property

        as soon as the property changes, the 'go'-button will be updated
        '''
        self._arduino_state = new_state
        self.action_panel.update_button_state()

    def select_files(self):
        ''' selecting a new excel file with scheduled_commands '''
        # open the file selection dialog
        opts = {
            'initialdir': '~/',
            'filetypes': [('Excel Files', '.xlsx')],
            'multiple': False}
        excel_file = tk.filedialog.askopenfilename(**opts)
        # if no excel file is selected, do nothing
        if not excel_file:
            return
        # reset the application
        self.reset()
        # try to parse the excel file
        self.scheduled_commands = parse_excel_file(
            excel_file,
            self.available_commands
            )
        if self.scheduled_commands:
            # if parsing resultet in a schedule, prepare everything to run
            self.arduino_prepare_process()
            self.program_panel.set_label_text(os.path.basename(excel_file))
            self.program_panel.show_schedule(self.scheduled_commands)

    def reset(self):
        ''' reset the application state '''
        # stop any connection to the Arduino
        if self.arduino_state in (ArduinoState.running, ArduinoState.connected):
            self.arduino_stop_process()
        self.action_panel.update_button_state()
        self.program_panel.clear_text()

    def go_button_clicked(self):
        ''' start scheduled commands or stop the execution '''
        if self.arduino_state == ArduinoState.running:
            # 'Stop Commands' clicked.
            self.arduino_stop_process()
            self.arduino_prepare_process()
        else:
            # 'Run Commands' clicked.
            # the connection is already established, we just need to release
            # the lock
            self.arduino_lock.release()
            self.arduino_state = ArduinoState.running
        # regular check if the scheduled commands finished
        self.after(CHECK_DELAY, self._check_process)

    def _check_process(self):
        ''' checks if the scheduled commands have already finished '''
        if self.arduino_process:
            if self.arduino_process.is_alive():
                # still running, recheck after a short delay
                self.after(CHECK_DELAY, self._check_process)
            else:
                # commands finished
                self.arduino_stop_process()
                self.arduino_prepare_process()

    def arduino_stop_process(self):
        ''' stops a connected Arduino '''
        if self.arduino_state != ArduinoState.not_initialized:
            # only do this if a connection was established
            loop = asyncio.get_event_loop()
            loop.stop()
            loop.close()
            self.arduino_process.terminate()
            self.arduino_process = None
            self.arduino_lock = None
            self.arduino_state = ArduinoState.not_initialized

    def arduino_prepare_process(self):
        ''' open a subprocess setting up the arduino '''
        # find the com port of the Arduino
        try:
            com_port = find_arduino_port()
        except IOError as e:
            messagebox.showerror('COM Port', 'No Arduino found')
            return
        except serial.SerialException:
            messagebox.showerror('COM Port', 'Could not talk to Arduino')
            return
        # Create a lock and acquire it. This will put the subprocess on hold
        # after establishing the connection. As soon as the lock is released,
        # the scheduled commands will be run
        self.arduino_lock = Lock()
        self.arduino_lock.acquire()
        # start the subprocess for the Arduino connection
        self.arduino_process = Process(
            target=arduino_subprocess,
            args = (
                self.arduino_lock,
                com_port,
                self.scheduled_commands
                )
            )
        self.arduino_process.start()
        self.arduino_state = ArduinoState.connected

    def quit(self):
        ''' stop the programm '''
        self.arduino_stop_process()
        self._master.destroy()


def run_application(available_commands, title='Arduino Scheduled Commands'):
    ''' run the gui application

    available_commands:
        list of available commands for the Arduino

    title:
        window title bar text
    '''

    # create the Tkinter root and instantiate the application
    root = tk.Tk()
    root.wm_title(title)
    app = Application(master=root, available_commands=available_commands)

    # use app.quit() as callback if the window is closed (with the 'X' button)
    # if an Arduino connection is established, the standard callback does not
    # stop the subprocess and therfore the application would not quit
    root.protocol("WM_DELETE_WINDOW", app.quit)

    # start the application
    app.mainloop()
    try:
        root.destroy()
    except tk.TclError:
        pass