#!/usr/bin/env python3
# Copyright (c) 2008-11 Qtrac Ltd. All rights reserved.
# This program or module is free software: you can redistribute it and/or
# modify it under the terms of the GNU General Public License as published
# by the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version. It is provided for educational
# purposes and is distributed in the hope that it will be useful, but
# WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
# General Public License for more details.

import os
import sys
import tkinter


class MainWindow(tkinter.Frame):

    def __init__(self, parent):
        super().__init__(parent)
        self.parent = parent
        self.grid(row=0, column=0)

        self.principal = tkinter.DoubleVar()
        self.principal.set(1000.0)
        self.rate = tkinter.DoubleVar()
        self.rate.set(5.0)
        self.years = tkinter.IntVar()
        self.amount = tkinter.StringVar()

        principalLabel = tkinter.Label(self, text="Principal $:",
                                       anchor=tkinter.W, underline=0)
        principalScale = tkinter.Scale(self, variable=self.principal,
                command=self.updateUi, from_=100, to=10000000,
                resolution=100, orient=tkinter.HORIZONTAL)
        rateLabel = tkinter.Label(self, text="Rate %:", underline=0,
                                  anchor=tkinter.W)
        rateScale = tkinter.Scale(self, variable=self.rate,
                command=self.updateUi, from_=1, to=100,
                resolution=0.25, digits=5, orient=tkinter.HORIZONTAL)
        yearsLabel = tkinter.Label(self, text="Years:", underline=0,
                                   anchor=tkinter.W)
        yearsScale = tkinter.Scale(self, variable=self.years,
                command=self.updateUi, from_=1, to=50,
                orient=tkinter.HORIZONTAL)
        amountLabel = tkinter.Label(self, text="Amount $",
                                    anchor=tkinter.W)
        actualAmountLabel = tkinter.Label(self,
                textvariable=self.amount, relief=tkinter.SUNKEN,
                anchor=tkinter.E)

        principalLabel.grid(row=0, column=0, padx=2, pady=2,
                            sticky=tkinter.W)
        principalScale.grid(row=0, column=1, padx=2, pady=2,
                            sticky=tkinter.EW)
        rateLabel.grid(row=1, column=0, padx=2, pady=2,
                       sticky=tkinter.W)
        rateScale.grid(row=1, column=1, padx=2, pady=2,
                       sticky=tkinter.EW)
        yearsLabel.grid(row=2, column=0, padx=2, pady=2,
                        sticky=tkinter.W)
        yearsScale.grid(row=2, column=1, padx=2, pady=2,
                        sticky=tkinter.EW)
        amountLabel.grid(row=3, column=0, padx=2, pady=2,
                         sticky=tkinter.W)
        actualAmountLabel.grid(row=3, column=1, padx=2, pady=2,
                               sticky=tkinter.EW)

        principalScale.focus_set()
        self.updateUi()
        parent.bind("<Alt-p>", lambda *ignore: principalScale.focus_set())
        parent.bind("<Alt-r>", lambda *ignore: rateScale.focus_set())
        parent.bind("<Alt-y>", lambda *ignore: yearsScale.focus_set())
        parent.bind("<Control-q>", self.quit)
        parent.bind("<Escape>", self.quit)


    def updateUi(self, *ignore):
        amount = self.principal.get() * (
                 (1 + (self.rate.get() / 100.0)) ** self.years.get())
        self.amount.set("{0:.2f}".format(amount))


    def quit(self, event=None):
        self.parent.destroy()


application = tkinter.Tk()
path = os.path.join(os.path.dirname(__file__), "images/")
if sys.platform.startswith("win"):
    icon = path + "interest.ico"
else:
    icon = "@" + path + "interest.xbm"
application.iconbitmap(icon)
application.title("Interest")
window = MainWindow(application)
application.protocol("WM_DELETE_WINDOW", window.quit)
application.mainloop()