from tkinter import *


def convert(event):
    x = entry.get()
    try:
        x = float(x)
        if length.get() == option_list[0]:
            millimeter_label["text"] = x
            centimeter_label["text"] = x / 10
            meter_label["text"] = x / 1000
            kilometer_label["text"] = x / 1000000
        if length.get() == option_list[1]:
            millimeter_label["text"] = x * 10
            centimeter_label["text"] = x
            meter_label["text"] = x / 100
            kilometer_label["text"] = x / 100000
        if length.get() == option_list[2]:
            millimeter_label["text"] = x * 1000
            centimeter_label["text"] = x * 100
            meter_label["text"] = x
            kilometer_label["text"] = x / 1000
        if length.get() == option_list[3]:
            millimeter_label["text"] = x * 1000000
            centimeter_label["text"] = x * 100000
            meter_label["text"] = x * 1000
            kilometer_label["text"] = x

    except ValueError:
        millimeter_label["text"] = "Please Enter Number"
        centimeter_label["text"] = "Please Enter Number"
        meter_label["text"] = "Please Enter Number"
        kilometer_label["text"] = "Please Enter Number"


window = Tk()

window.title("Unit Converter")

option_list = [
    "Millimeter",
    "Centimeter",
    "Meter",
    "Kilometer"
]

length = StringVar(window)
length.set(option_list[0])
option = OptionMenu(window, length, *option_list)

entry = Entry(window, width=13, font=18)
converter_button = Button(window, font=16, text="Convert")

header_label = Label(window, text="Unit Converter", background="yellow", font=16, width=18)
millimeter_label = Label(window, width=20, font=16)
centimeter_label = Label(window, width=20, font=16)
meter_label = Label(window, width=20, font=16)
kilometer_label = Label(window, width=20, font=16)

mm_label = Label(window, text="Millimeters: ", width=15, font=16)
cm_label = Label(window, text="Centimeters: ", width=15, font=16)
m_label = Label(window, text="Meters: ", width=15, font=16)
km_label = Label(window, text="Kilometers: ", width=15, font=16)

header_label.grid(row=0, column=3)
converter_button.grid(row=3, column=3)
entry.grid(row=2, column=4)
option.grid(row=2, column=2)
mm_label.grid(row=4, column=2)
cm_label.grid(row=7, column=2)
millimeter_label.grid(row=5, column=2)
centimeter_label.grid(row=8, column=2)

m_label.grid(row=4, column=4)
km_label.grid(row=7, column=4)
meter_label.grid(row=5, column=4)
kilometer_label.grid(row=8, column=4)

converter_button.bind("<Button-1>", convert)

window.mainloop()