from tkinter import *

# Trial 1 - Basic OptionMenu dropdown
# Purpose: Learn how to create a simple dropdown and read the selected value

class DropdownTrial:

    def __init__(self):

        self.frame = Frame(padx=10, pady=10)
        self.frame.grid()

        self.heading = Label(self.frame,
                             text="Dropdown Trial - v1",
                             font=("Arial", "16", "bold"))
        self.heading.grid(row=0)

        # StringVar holds the currently selected value
        self.unit_var = StringVar()

        # Set a default value
        self.unit_var.set("km")

        # OptionMenu takes: parent, StringVar, *options
        self.unit_menu = OptionMenu(self.frame, self.unit_var,
                                    "km", "m", "cm", "mm")
        self.unit_menu.config(font=("Arial", "12"), width=8)
        self.unit_menu.grid(row=1, pady=10)

        self.check_button = Button(self.frame,
                                   text="Show Selected",
                                   font=("Arial", "12", "bold"),
                                   bg="#009900", fg="#FFFFFF",
                                   width=14,
                                   command=self.show_selected)
        self.check_button.grid(row=2, pady=5)

        self.result_label = Label(self.frame,
                                  text="No unit selected yet",
                                  font=("Arial", "12"))
        self.result_label.grid(row=3, pady=10)

    def show_selected(self):
        # .get() reads the current value from the StringVar
        selected = self.unit_var.get()
        self.result_label.config(text=f"You selected: {selected}")


# main routine
if __name__ == "__main__":
    root = Tk()
    root.title("Dropdown Trial v1")
    DropdownTrial()
    root.mainloop()