from tkinter import *

class Converter:
    """
    Temperature conversion tool (C to F or F to C)
    """
    def __init__(self):
        """
        Temperature converter GUI
        """

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

        self.temp_heading = Label(self.temp_frame,
                                  text="Temperature Converter",
                                  font=("Arial", "16", "bold")
                                  )
        self.temp_heading.grid(row=0)

        instructions = ("Please enter a temperature below and then press " 
                        "one of the buttons to convert it from centigrade " 
                        "to Fahrenheit.")
        self.temp_instructions = Label(self.temp_frame,
                                       text=instructions,
                                       wraplength=250, width=40,
                                       justify="left")
        self.temp_instructions.grid(row=1)

        self.temp_entry = Entry(self.temp_frame,
                                font=("Arial", "14")
                                )

        self.temp_entry.grid(row=2, padx=10, pady=10)

        error = "Please enter a number"
        self.temp_error = Label(self.temp_frame, text=error,
                                fg="#9C0000")
        self.temp_error.grid(row=3)

        # Conversion, help and history / export buttons
        self.button_frame = Frame(self.temp_frame)
        self.button_frame.grid(row=4)

        self.to_celsius_button = Button(self.button_frame,
                                        text="To Celsius",
                                        bg="#990099",
                                        fg="#ffffff",
                                        font=("Arial", "12", "bold"), width=12)
        self.to_celsius_button.grid(row=0, column=0, padx=5, pady=5)

        self.to_fahrenheit_button = Button(self.button_frame,
                                           text="To Fahrenheit",
                                           bg="#009900",
                                           fg="#ffffff",
                                           font=("Arial", "12", "bold"), width=12)
        self.to_fahrenheit_button.grid(row=0, column=1, padx=5, pady=5)

        self.to_help_button = Button(self.button_frame,
                                     text="Help / Info",
                                     bg="#CC6600",
                                     fg="#ffffff",
                                     font=("Arial", "12", "bold"), width=12)
        self.to_help_button.grid(row=1, column=0, padx=5, pady=5)

        self.to_history = Button(self.button_frame,
                                 text="History / Export",
                                 bg="#004C99",
                                 fg="#ffffff",
                                 font=("Arial", "12", "bold"), width=12)
        self.to_history.grid(row=1, column=1, padx=5, pady=5)

# main routine
if __name__ == "__main__":
    root = Tk()
    root.title("Temperature Converter")
    Converter()
    root.mainloop()