from tkinter import *


class Converter:
    """
    Temperature conversion tool (C* to F* or F* to C*)
    """

    def __init__(self):
        """
        Temperature conversion GUI
        """

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

        self.to_help_button = Button(self.metric_frame,
                                     text="Help/ Info",
                                     bg="#00FF00",
                                     fg="#FFFFFF",
                                     font=("Arial", "14", "bold"), width=12,
                                     command=self.to_help)
        self.to_help_button.grid(row=1, padx=5, pady=5)

    def to_help(self):
        DisplayHelp()


class DisplayHelp:

    def __init__(self):
        # setup dialogue box and background colour
        background = "#FFFFFF"
        self.help_box = Toplevel()

        self.help_frame = Frame(self.help_box, width=300,
                                height=200,
                                bg=background)
        self.help_frame.grid()

        self.help_heading_label = Label(self.help_frame,
                                        text="Help / Info",
                                        font=("Arial", "14", "bold"))
        self.help_heading_label.grid(row=0)

        help_text = "To use the program, simply enter the value " \
                    "you wish to convert and then choose the metric units " \
                    "you want to convert from and to (e.g., meters to kilometers, " \
                    "grams to kilograms, etc.). \n\n" \
                    "Note that negative values may not be valid for all conversions, " \
                    "such as length or mass. If you enter an invalid value, " \
                    "you will get an error message. \n\n" \
                    "To see your calculation history and export it to a text " \
                    "file, please click the 'History / Export' button."

        self.help_text_label = Label(self.help_frame,
                                        text=help_text, wraplength=350,
                                        justify="left")
        self.help_text_label.grid(row=1, padx=10)

        self.dismiss_button = Button(self.help_frame,
                                    font=("Arial", "12", "bold"),
                                    text="Dismiss", bg="#FF0000",
                                    fg="#FFFFFF", command=self.close_help)
        self.dismiss_button.grid(row=2, padx=10, pady=10)

        # list and loop to set background colour on
        # everything except the buttons.
        recolour_list = [self.help_frame, self.help_heading_label,
                         self.help_heading_label]

        for item in recolour_list:
            item.config(bg=background)

    def close_help(self):
        self.help_box.destroy()

# main routine


if __name__ == "__main__":
    root = Tk()
    root.title("Temperature Convertor")
    Converter()
    root.mainloop()