from tkinter import *
from functools import partial  # To prevent unwanted windows
import all_constants as c
from datetime import date


class Converter:
    """
    Currency conversion tool (placeholder)
    """

    def __init__(self):
        """
        Currency converter GUI
        """

        # self.all_calculations_list = ['10.0°F is -12°C', '20.0°F is -7°C',
        #                              '30.0°F is -1°C', '40.0°F is 4°C',
        #                              '50.0°F is 10°C', '60.0°F is 16°C']

        self.all_calculations_list = [
            "This is a test",
            "50CAD is 61.17NZD",
            "40USD is 69.98NZD",
            "30USD is 42.91CAD",
            "20NZD is 8.17CAD"
        ]

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

        self.to_history_button = Button(self.temp_frame,
                                        text="History / Export",
                                        bg="#CC6600",
                                        fg="#FFFFFF",
                                        font=("Arial", "14", "bold"), width=12,
                                        command=self.to_history)
        self.to_history_button.grid(row=1, padx=5, pady=5)

    def to_history(self):
        """
        Opens history dialogue box and disables history button
        (so that users can't create multiple history boxes).
        """
        HistoryExport(self, self.all_calculations_list)


class HistoryExport:
    """
    Displays history dialogue box
    """

    def __init__(self, partner, calculations):

        self.history_box = Toplevel()

        # disable history button
        partner.to_history_button.config(state=DISABLED)

        # If users press cross at top, closes history and
        # 'release' history button
        self.history_box.protocol('WM_DELETE_WINDOW',
                                  partial(self.close_history, partner))

        self.history_frame = Frame(self.history_box)
        self.history_frame.grid()

        # background colour and text for calculation area
        if len(calculations) <= c.MAX_CALCS:
            calc_back = "#D5E8D4"
            calc_amount = "all your"
        else:
            calc_back = "#ffe6cc"
            calc_amount = (f"your recent calculations - "
                           f"showing {c.MAX_CALCS} / {len(calculations)}")

        # strings for 'long' labels...
        recent_intro_txt = (f"Below are {calc_amount} calculations "
                            "(to the nearest degree).")

        # Create string from calculations list (newest calculations first)
        newest_first_string = ""
        newest_first_list = list(reversed(calculations))

        if len(newest_first_list) <= c.MAX_CALCS:

            for item in newest_first_list[:-1]:
                newest_first_string += item + "\n"

            newest_first_string += newest_first_list[-1]

        # If we have more than five items...
        else:
            for item in newest_first_list[:c.MAX_CALCS - 1]:
                newest_first_string += item + "\n"

            newest_first_string += newest_first_list[c.MAX_CALCS - 1]

        export_instruction_txt = ("Please push <Export> to save your calculations in"
                                  "file. If the filename already exists, it will be replaced.")

        # Label list (label text | format |bg)
        history_labels_list = [
            ["History / Export", ("Arial", "16", "bold"), None],
            [recent_intro_txt, ("Arial", "11",), None],
            [newest_first_string, ("Arial", "14"), calc_back],
            [export_instruction_txt, ("Arial", "11"), None],
        ]

        history_label_ref = []
        for count, item in enumerate(history_labels_list):
            make_label = Label(self.history_box, text=item[0], font=item[1],
                               bg=item[2],
                               wraplength=300, justify="left", pady=10, padx=20)
            make_label.grid(row=count)

            history_label_ref.append(make_label)

        # Retrieve export instruction label so that we can
        # configure it to show the filename if the user exports the file
        self.export_filename_label = history_label_ref[3]

        # make frame to hold buttons (two columns)
        self.history_button_frame = Frame(self.history_box)
        self.history_button_frame.grid(row=4)

        # button list (button text | bg colour | command | row | column)
        button_details_list = [
            ["Export", "#004C99", lambda: self.export_data(calculations), 0, 0],
            ["Close", "#666666", partial(self.close_history, partner), 0, 1],
        ]

        for btn in button_details_list:
            self.make_button = Button(self.history_button_frame,
                                      font=("Arial", "12", "bold"),
                                      text=btn[0], bg=btn[1],
                                      fg="#FFFFFF", width=12,
                                      command=btn[2])
            self.make_button.grid(row=btn[3], column=btn[4], padx=10, pady=10)

    def export_data(self, calculations):
        # **** Get current date for heading and file name ****
        today = date.today()

        # Get day, month and year as individual strings
        day = today.strftime("%d")
        month = today.strftime("%m")
        year = today.strftime("%Y")

        file_name = f"Currencies_{year}_{month}_{day}"

        # edit label so users know that their export has been done
        success_string = ("Export Successful! The file is called"
                          f"{file_name}.txt")
        self.export_filename_label.config(bg="#009900", text=success_string,
                                          font=("Arial", "12", "bold"))

        # write data to text file.
        write_to = f"{file_name}.txt"

        with open(write_to, "w") as text_file:
            text_file.write("***** Currency Calculations ******\n")
            text_file.write(f"Generated: {day}/{month}/{year}\n\n")
            text_file.write("Here is your calculation history (oldest to newest)...\n")

            # write the item to file
            for item in calculations:
                text_file.write(item)
                text_file.write("\n")

    def close_history(self, partner):
        """
        Closes history dialogue box (and enables history button)
        """
        # Put history button back to normal...
        partner.to_history_button.config(state=NORMAL)
        self.history_box.destroy()


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