#!/usr/bin/env python
import PySimpleGUI as sg

'''
A chatbot with history
Scroll up and down through prior commands using the arrow keys
Special keyboard keys:
    Up arrow - scroll up in commands
    Down arrow - scroll down in commands
    Escape - clear current command
    Control C - exit form
'''


def ChatBotWithHistory():
    # -------  Make a new Window  ------- #
    # give our form a spiffy set of colors
    sg.change_look_and_feel('GreenTan')

    layout = [[sg.Text('Your output will go here', size=(40, 1))],
              [sg.Output(size=(127, 30), font=('Helvetica 10'))],
              [sg.Text('Command History'),
               sg.Text('', size=(20, 3), key='history')],
              [sg.ML(size=(85, 5), enter_submits=True, key='query', do_not_clear=False),
               sg.Button('SEND', button_color=(sg.YELLOWS[0], sg.BLUES[0]), bind_return_key=True),
               sg.Button('EXIT', button_color=(sg.YELLOWS[0], sg.GREENS[0]))]]

    window = sg.Window('Chat window with history', layout,
                       default_element_size=(30, 2),
                       font=('Helvetica', ' 13'),
                       default_button_element_size=(8, 2),
                       return_keyboard_events=True)

    # ---===--- Loop taking in user input and using it  --- #
    command_history = []
    history_offset = 0

    while True:
        event, value = window.read()

        if event == 'SEND':
            query = value['query'].rstrip()
            # EXECUTE YOUR COMMAND HERE
            print('The command you entered was {}'.format(query))
            command_history.append(query)
            history_offset = len(command_history)-1
            # manually clear input because keyboard events blocks clear
            window['query'].update('')
            window['history'].update('\n'.join(command_history[-3:]))
        
        elif event in (None, 'EXIT'):            # quit if exit event or X
            break
        
        elif 'Up' in event and len(command_history):
            command = command_history[history_offset]
            # decrement is not zero
            history_offset -= 1 * (history_offset > 0)
            window['query'].update(command)
        
        elif 'Down' in event and len(command_history):
            # increment up to end of list
            history_offset += 1 * (history_offset < len(command_history)-1)
            command = command_history[history_offset]
            window['query'].update(command)
        
        elif 'Escape' in event:
            window['query'].update('')


ChatBotWithHistory()