from tkinter import *

# Trial - Radio Buttons as an alternative to OptionMenu dropdowns
# Purpose: Compare radio buttons vs dropdowns for unit selection.
#          This was the other main option trialled before choosing dropdowns.
#
# Conclusion (at the bottom of this file):
# Radio buttons work but do NOT scale well when you have many options.
# With 4 units and needing TWO selections (from + to), you would need
# 8 radio buttons on screen at once, making the GUI cluttered.
# OptionMenu dropdowns were chosen instead.

UNITS = ["km", "m", "cm", "mm"]


class RadioButtonTrial:

    def __init__(self):

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

        self.heading = Label(self.frame,
                             text="Radio Button Trial",
                             font=("Arial", "16", "bold"))
        self.heading.grid(row=0, columnspan=2)

        # --- Convert FROM group ---
        from_label = Label(self.frame,
                           text="Convert FROM:",
                           font=("Arial", "12", "bold"))
        from_label.grid(row=1, column=0, sticky="w", pady=(10, 2))

        # IntVar or StringVar works - StringVar is cleaner for text values
        self.from_var = StringVar(value="km")

        for i, unit in enumerate(UNITS):
            rb = Radiobutton(self.frame,
                             text=unit,
                             variable=self.from_var,
                             value=unit,
                             font=("Arial", "12"))
            rb.grid(row=2 + i, column=0, sticky="w", padx=20)

        # --- Convert TO group ---
        to_label = Label(self.frame,
                         text="Convert TO:",
                         font=("Arial", "12", "bold"))
        to_label.grid(row=1, column=1, sticky="w", pady=(10, 2), padx=20)

        self.to_var = StringVar(value="m")

        for i, unit in enumerate(UNITS):
            rb = Radiobutton(self.frame,
                             text=unit,
                             variable=self.to_var,
                             value=unit,
                             font=("Arial", "12"))
            rb.grid(row=2 + i, column=1, sticky="w", padx=40)

        # --- Button and result ---
        self.convert_button = Button(self.frame,
                                     text="Convert",
                                     font=("Arial", "12", "bold"),
                                     bg="#009900", fg="#FFFFFF",
                                     width=12,
                                     command=self.show_selected)
        self.convert_button.grid(row=7, column=0, columnspan=2, pady=10)

        self.result_label = Label(self.frame,
                                  text="",
                                  font=("Arial", "12"))
        self.result_label.grid(row=8, column=0, columnspan=2)

        # Comparison note
        note = ("NOTE: Radio buttons work, but with 4 units and 2 groups\n"
                "this is already 8 radio buttons. Adding more units would\n"
                "make this very crowded. Dropdowns scale much better.")
        Label(self.frame,
              text=note,
              font=("Arial", "10"),
              fg="#CC6600",
              justify="left").grid(row=9, column=0, columnspan=2,
                                   pady=10, padx=5)

    def show_selected(self):
        from_unit = self.from_var.get()
        to_unit = self.to_var.get()

        if from_unit == to_unit:
            self.result_label.config(
                text="Error: please choose two different units",
                fg="#9C0000"
            )
        else:
            self.result_label.config(
                text=f"Converting from {from_unit} to {to_unit}",
                fg="#004C99"
            )


# main routine
if __name__ == "__main__":
    root = Tk()
    root.title("Radio Button Trial")
    RadioButtonTrial()
    root.mainloop()