import tkinter as tk
def validate_login():
    userid = username_entry.get()
    password = password_entry.get()

    if userid == "123" and password == "library":
        # Creates the libraary window one the correct userid and password are answered

        def validate_choice():
            openName = opentions_entry.get()

        if optionName.lower() == "withdraw":
            def validate_withdraw():
                wbook = withdraw_entry.get()

            withdraw = tk.Tk()
            withdraw.title("Withdraw System")
            wbookname_label = tk.Label(withdraw, text="Book Name:")
            wbookname_label.pack()

            wbookname_entry = tk.Entry(withdraw)
            wbookname_entry.pack(padx=70, pady=20)
        elif optionName.lower() == "return":
            def validate_return():
                rbook = return_entry.get()

            return_book = tk.Tk()
            return_book.title("Return System")
            rbookname_label = tk.Label(return_book, text="Book Name:")
            rbookname_label.pack()

            rbookname_entry = tk.Entry(return_book)
            rbookname_entry.pack(padx=70, pady=20)
            return_book.mainloop()
        else:
            messagebox.showerror("Invalid option", "Please try again")
        choice = tk.Tk()
        # optional extra 3: choice of withdrawing or returning a book
        choice.title("Withdraw or Return System")

        options_label = tk.Label(choice, text="Would you like to withdraw or return a book?")
        options_label.pack()

        options_entry = tk.Entry(choice)
        options_entry.pack(padx=70, pady=20)
        option_button = tk.Button(choice, text="Enter", command=validate_choice)
        option_button.pack(pady=20)
        choice.mainloop()

    else:
        messagebox.showerror("Login Failed", "Invalid username or password")

# Creates the main window
parent = tk.Tk()
parent.title("Login Form")

# Creates and places the username label and entry
username_label = tk.Label(parent, text="Userid:")
username_label.pack()