#!/usr/bin/env python
from Tkinter import *

def lettermath(key, ptxt, fun):
  lha, rha = key.lower(), ptxt.lower()
  if not (lha in 'abcdefghijklmnopqrstuvwxyz'):
    return ptxt
  if not (rha in 'abcdefghijklmnopqrstuvwxyz'):
    return ptxt
  va = ord('a')
  lhv, rhv = ord(lha)-va, ord(rha)-va
  return chr(fun(lhv, rhv) + va)

def stringmath(key, ptxt, fun):
  maxlen = max(len(key), len(ptxt))
  left, right = '', ''
  while len(left) < len(ptxt):
    left = left + key
  while len(right) < len(key):
    right = right + ptxt
  left, right = left[:maxlen], right[:maxlen]
  return ''.join([lettermath(left[x], right[x], fun) for x in range(maxlen)])[:-1]

def demo():
  kk, vv = raw_input("Key? "), raw_input("String? ")
  add = lambda x, y: (x + y) % 26
  print stringmath(kk, vv, add)

def doupdate(keybox, textbox, ff):
  lhs = keybox.get()
  if lhs == '':
    return
  rhs = textbox.get('1.0', END)
  if rhs == '':
    return
  newphrase = stringmath(lhs, rhs, ff)
  textbox.delete('1.0', END)
  textbox.insert('1.0', newphrase)

def main():
  #global keybox, textbox
  f = Frame()
  f.master.title("Vigenere")
  keylabel = Label(f, text="Key:")
  txtlabel = Label(f, text="Text:")
  keybox = Entry(f, width=40, text='')
  txtbox = Text(f, width=60, height=10)
  addtext = lambda x, y: (x + y) % 26
  subtext = lambda x, y: (y - x) % 26 # Remember, it's key, then plaintext.
  addcall = lambda: doupdate(keybox, txtbox, addtext)
  subcall = lambda: doupdate(keybox, txtbox, subtext)
  addbutton = Button(f, text=">>", command=addcall)
  subbutton = Button(f, text="<<", command=subcall)

  keylabel.grid_configure(row=0, column=0)
  keybox.grid_configure(row=0, column=1)
  subbutton.grid_configure(row=0, column=2)
  addbutton.grid_configure(row=0, column=3)
  txtlabel.grid_configure(row=1, column=0)
  txtbox.grid_configure(row=1, column=1, columnspan=3)

  f.grid()
  f.mainloop()

if __name__ == '__main__':
  main()