#!/usr/bin/env python3
# -*- coding: utf-8 -*-

"""
ZetCode Tkinter e-book

This script produces a long-running task of calculating 
a large Pi number, while keeping the GUI responsive.

Author: Jan Bodnar
Last modified: January 2016
Website: www.zetcode.com
"""

from tkinter import (Tk, BOTH, Text, E, W, S, N, END, 
    NORMAL, DISABLED, StringVar)
from tkinter.ttk import Frame, Label, Button, Progressbar, Entry
from tkinter import scrolledtext

from multiprocessing import Queue, Process
import queue 
from decimal import Decimal, getcontext

import time

DELAY1 = 20
DELAY2 = 20

class Example(Frame):
  
    def __init__(self, parent, q):
        Frame.__init__(self, parent)   
         
        self.queue = q 
        self.parent = parent
        self.initUI()
        
        
    def initUI(self):
      
        self.parent.title("Pi computation")
        self.pack(fill=BOTH, expand=True)
        
        self.grid_columnconfigure(4, weight=1)
        self.grid_rowconfigure(3, weight=1)
        
        lbl1 = Label(self, text="Digits:")
        lbl1.grid(row=0, column=0, sticky=E, padx=10, pady=10)
        
        self.ent1 = Entry(self, width=10)
        self.ent1.insert(END, "4000")
        self.ent1.grid(row=0, column=1, sticky=W)
        
        lbl2 = Label(self, text="Accuracy:")
        lbl2.grid(row=0, column=2, sticky=E, padx=10, pady=10)

        self.ent2 = Entry(self, width=10)
        self.ent2.insert(END, "100")
        self.ent2.grid(row=0, column=3, sticky=W)        
        
        self.startBtn = Button(self, text="Start", 
            command=self.onStart)
        self.startBtn.grid(row=1, column=0, padx=10, pady=5, sticky=W)
        
        self.pbar = Progressbar(self, mode='indeterminate')        
        self.pbar.grid(row=1, column=1, columnspan=3, sticky=W+E)     
        
        self.txt = scrolledtext.ScrolledText(self)  
        self.txt.grid(row=2, column=0, rowspan=4, padx=10, pady=5,
            columnspan=5, sticky=E+W+S+N)
       
        
    def onStart(self):
        
        self.startBtn.config(state=DISABLED)
        self.txt.delete("1.0", END)
        
        self.digits = int(self.ent1.get())
        self.accuracy = int(self.ent2.get())
        
        self.p1 = Process(target=self.generatePi, args=(self.queue,))
        self.p1.start()
        self.pbar.start(DELAY2)
        self.after(DELAY1, self.onGetValue)
        
       
    def onGetValue(self):
        
        if (self.p1.is_alive()):
            
            self.after(DELAY1, self.onGetValue)
            return
        else:    
        
            try:
                self.txt.insert('end', self.queue.get(0))
                self.txt.insert('end', "\n")
                self.pbar.stop()
                self.startBtn.config(state=NORMAL)
            
            except queue.Empty:
                print("queue is empty")
            
            
    def generatePi(self, queue):
        
        getcontext().prec = self.digits
        
        pi = Decimal(0)
        k = 0
        n = self.accuracy
        
        while k < n:
            pi += (Decimal(1)/(16**k))*((Decimal(4)/(8*k+1)) - \
                (Decimal(2)/(8*k+4)) - (Decimal(1)/(8*k+5))- \
                (Decimal(1)/(8*k+6)))
            k += 1
            print (self.p1.is_alive())
            
        queue.put(pi)    
        print("end")  
        time.sleep(1)  


def main():
    
    q = Queue()
  
    root = Tk()
    root.geometry("400x350+300+300")
    app = Example(root, q)
    root.mainloop()  


if __name__ == '__main__':
    main()