##Written by Farran Monique Ram
##fmr0040@arastudent.ac.nz
##Assessment 3 Part B Question 2
##create a Speed Analysis application
##observed speeds are stored in seperate file which application opens & closes

from tkinter import *
from tkinter.simpledialog import *
from tkinter.messagebox import *
from tkinter.filedialog import *
import os

def get_nearest_speed(recorded_speeds, speed_limit):
    """
    This function takes a list of integers and compares them to see
    which is closest to the given speed limit
    Returns: integer
    """
    list_number = 0
    single_number = 1
    negative_integer = -1
    miniumum_positive_num = 0
    speed_differences = []

    for each_speed in recorded_speeds:
        speed_difference = speed_limit - each_speed
        #if negative difference then make net positive for comparison
        if speed_difference < miniumum_positive_num:
            speed_difference = speed_difference*negative_integer
        #put speed differences in a list
        speed_differences.append(speed_difference)

    #get minimum difference and its index in recorded_speeds list
    smallest_difference = min(speed_differences)
    closest_speed_index = speed_differences.index(smallest_difference)

    return recorded_speeds[closest_speed_index]

def display_about():
    """
    Displays an about message box.
    Returns: showinfo dialogue box
    """
    showinfo(title = "Speed Analyser",
                     message = "v1 by Farran Monique Ram")
    return

def exit_menu():
    """
    Closes the root window when asked to exit
    returns: none
    """
    root_window.destroy()
    return

def get_data():
    """
    This function creates a list from a file then runs the get_nearest_speed function
    Provides a dialogue box message which tells user the closest number to the selected speed limit
    Returns: dialogue message
    """
    speed_differences = []
    selection = option_value.get()

    if selection == 0:
        showwarning(title = "Speed analysis.", message = "Please select a speed limit.")
    else:
        name_of_file =  askopenfilename(initialdir = ".", title = "Select file",
                                        filetypes = (("Text files","*.txt"), ("All files","*.*")))
        #open file, add to list then
        the_file = open(name_of_file)
        for each_line in the_file:
            each_line = int(each_line)
            speed_differences.append(each_line)
        the_file.close()

        #get closest value to speed limit
        closest_speed = get_nearest_speed(speed_differences, selection)
        showinfo(title = "Speed analysis status.",
                 message = "The nearest recorded speed to {} was {}".format(selection, closest_speed))

        #clear selection
        option_value.set(0)
    return


button_width = 25
root_window = Tk()
root_window.title("Speed analyser")

# Set window size and disable resizing in px
root_window.geometry("275x125")
root_window.resizable(width=False, height=False)


##add a menu
menubar = Menu(root_window)

##menu option to clear window
file_menu = Menu(menubar, tearoff=0)
file_menu.add_command(label = "Get data", command = get_data)
file_menu.add_separator()

##menu option to exit root menu
file_menu.add_command(label = "Exit", command = exit_menu)
menubar.add_cascade(label = "File", menu = file_menu)

##help follwed by an cascading about option to display help
help_menu = Menu(menubar, tearoff=0)
help_menu.add_command(label = "About", command = display_about)
menubar.add_cascade(label = "Help", menu = help_menu)
root_window.config(menu = menubar)


##radio button options
option_value = IntVar()
# Start with no button selected
option_value.set(0)

#30km/h button
button1 = Radiobutton(root_window , text="30 km/h", variable = option_value, value = 30)
button1.pack(anchor = W)
#50km/h button
button2 = Radiobutton(root_window , text="50 km/h", variable = option_value, value = 50)
button2.pack(anchor = W)
#70km/h button
button3 = Radiobutton(root_window , text="70 km/h", variable = option_value, value = 70)
button3.pack(anchor = W)


##Add a button to root window to confirm radio button selection and start get_data function
enter_button = Button(None, text = "Get data", command = get_data)
enter_button.pack()


#do not exit until asked to
root_window.mainloop()