import tkinter as tk
from tkinter import messagebox

# Fixed exchange rates
exchange_rates = {'NZD': {'USD': 0.68, 'CAD': 0.86},
                  'USD': {'NZD': 1.47, 'CAD': 1.27},
                  'CAD': {'NZD': 1.17, 'USD': 0.79}}

# Default button colors
DEFAULT_BUTTON_COLOR = "#4CAF50"  # Green
DEFAULT_HELP_BUTTON_COLOR = "#FFD700"  # Gold


def convert_currency():
    from_currency = from_currency_var.get()
    to_currency = to_currency_var.get()
    amount = float(amount_entry.get())

    if from_currency == to_currency:
        messagebox.showerror("Error", "Please select different currencies.")
        return

    converted_amount = amount * exchange_rates[from_currency][to_currency]
    result_label.config(text=f"{amount} {from_currency} equals {converted_amount:.2f} {to_currency}")


def display_help():
    help_text = ("Welcome to the Currency Converter!\n\n"
                 "1. Select the 'From Currency' and 'To Currency' from the dropdown menus.\n"
                 "2. Enter the amount you want to convert in the 'Amount' field.\n"
                 "3. Click the 'Convert' button to see the conversion result.\n\n"
                 "Thank you for using our Currency Converter!")
    messagebox.showinfo("Help", help_text)


# GUI setup
root = tk.Tk()
root.title("Currency Converter")

from_currency_var = tk.StringVar(root)
from_currency_var.set("NZD")  # default value
to_currency_var = tk.StringVar(root)
to_currency_var.set("USD")  # default value

tk.Label(root, text="From Currency:").grid(row=0, column=0, padx=5, pady=5)
from_currency_menu = tk.OptionMenu(root, from_currency_var, *exchange_rates.keys())
from_currency_menu.grid(row=0, column=1, padx=5, pady=5)

tk.Label(root, text="To Currency:").grid(row=1, column=0, padx=5, pady=5)
to_currency_menu = tk.OptionMenu(root, to_currency_var, *exchange_rates.keys())
to_currency_menu.grid(row=1, column=1, padx=5, pady=5)

tk.Label(root, text="Amount:").grid(row=2, column=0, padx=5, pady=5)
amount_entry = tk.Entry(root)
amount_entry.grid(row=2, column=1, padx=5, pady=5)

convert_button = tk.Button(root, text="Convert", command=convert_currency)
convert_button.grid(row=3, column=0, columnspan=2, padx=5, pady=5)
convert_button_color = DEFAULT_BUTTON_COLOR  # Set default color
convert_button.config(bg=convert_button_color)

result_label = tk.Label(root, text="")
result_label.grid(row=4, column=0, columnspan=2, padx=5, pady=5)

help_button = tk.Button(root, text="Help", command=display_help)
help_button.grid(row=5, column=0, columnspan=2, padx=5, pady=5)
help_button_color = DEFAULT_HELP_BUTTON_COLOR  # Set default color
help_button.config(bg=help_button_color)

root.mainloop()