#!/usr/bin/env python3

GUI_WIN = 0
GUI_LINUX = 1

import sys
if sys.platform == 'win32':
    GUI = GUI_WIN
else:
    GUI = GUI_LINUX

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

if GUI == GUI_WIN:
    from multiprocessing import Process, Manager, Queue, Value
    from queue import Empty
else:
    from multiprocessing import Queue, Process
    import queue

from decimal import Decimal, getcontext
from time import sleep

DELAY1 = 20
DELAY2 = 20

if GUI == GUI_WIN:
    # Queue must be global
    q = Queue()

class commonUI(Frame):
    def __init__(self, parent):
        Frame.__init__(self, parent)   
        self.parent = parent
        self.initUI()

    def initUI(self):
          
        self.val = Value('i', 0)
        self.dig = Value('i', 4000)
        self.acc = Value('i', 100)

        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, self.dig.value)
        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, self.acc.value)
        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='determinate')        
        self.pbar.grid(row=1, column=1, columnspan=3, sticky=W+E)     
        self.pbar.config(value=0, maximum=self.dig.value)

        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)
        
        digits = int(self.ent1.get())
        accuracy = int(self.ent2.get())
                
        self.p1 = Process(target=generatePi, args=(q, digits, accuracy))
        self.p1.start()
        self.after(DELAY1, self.onGetValue)
        
       
    def onGetValue(self):
        
        if (self.p1.is_alive()):
            self.val.value += 1000
            self.update_pbar()
            self.after(DELAY1, self.onGetValue)
            return
        else:    
        
           try:
   
                self.txt.insert('end', q.get(0))
                self.txt.insert('end', "\n")
                self.startBtn.config(state=NORMAL)

           except Empty:
                print("queue is empty")

    def update_pbar(self):
        self.pbar.config(value=self.val.value)

class win_Example(Frame):
      
    def __init__(self, parent):
        Frame.__init__(self, parent, name="frame")   
        commonUI(parent)
            
if GUI == GUI_WIN:
    # Generate function must be a top-level module funtion            
    def generatePi(q, digs, acc):

        getcontext().prec = digs
    
        pi = Decimal(0)
        k = 0
        n = acc
        
        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
        q.put(pi)
        time.sleep(1)

class linux_Example(Frame):
      
    def __init__(self, parent, q):
        Frame.__init__(self, parent)   
         
        self.queue = q 
        commonUI(parent)
                   
    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")    

def main():  
    if GUI == GUI_LINUX:
        q = Queue()

    root = Tk()
    root.geometry("400x350+300+300")
    app = win_Example(root) if GUI == GUI_WIN else linux_Example(root)
    root.mainloop()  


if __name__ == '__main__':
    main()