#!/usr/bin/python2.4 -tt
# Copyright 2010 Google Inc.
# Licensed under the Apache License, Version 2.0
# http://www.apache.org/licenses/LICENSE-2.0

# Google's Python Class
# http://code.google.com/edu/languages/google-python-class/

# Additional basic string exercises

# D. verbing
# Given a string, if its length is at least 3,
# add 'ing' to its end.
# Unless it already ends in 'ing', in which case
# add 'ly' instead.
# If the string length is less than 3, leave it unchanged.
# Return the resulting string.
def verbing(s):
  if len(s) >= 3:
      if 'ing' in s:
          x = s + 'ly'
      else:
          x = s + 'ing'
  else:
      x = s
  return x


# E. not_bad
# Given a string, find the first appearance of the
# substring 'not' and 'bad'. If the 'bad' follows
# the 'not', replace the whole 'not'...'bad' substring
# with 'good'.
# Return the resulting string.
# So 'This dinner is not that bad!' yields:
# This dinner is good!
def not_bad(s):
  a = s.find('not')
  b = s.find('bad')
  last = b + 2
  if a < b:
      x = s[:a] + 'good' + s[last + 1:]
  else:
      x = s
  return x


# F. front_back
# Consider dividing a string into two halves.
# If the length is even, the front and back halves are the same length.
# If the length is odd, we'll say that the extra char goes in the front half.
# e.g. 'abcde', the front half is 'abc', the back half 'de'.
# Given 2 strings, a and b, return a string of the form
#  a-front + b-front + a-back + b-back
def front_back(a, b):
    x = len(a)
    y = len(b)
    is_odd = []
    for val in [x,y]:
        if val % 2 > 0:
            is_odd.append(1)
        else:
            is_odd.append(0)

    if is_odd[0] == 0:
        half_a = len(a)//2
    else:
        half_a = len(a)//2 + 1
    if is_odd[1] == 0:
        half_b = len(b)//2
    else:
        half_b = len(b)//2 + 1
    x = a[:half_a] + b[:half_b] + a[half_a:] + b[half_b:]
    return x


# Simple provided test() function used in main() to print
# what each function returns vs. what it's supposed to return.
def test(got, expected):
  if got == expected:
    prefix = ' OK '
  else:
    prefix = '  X '
  print ('%s got: %s expected: %s' % (prefix, repr(got), repr(expected)))


# main() calls the above functions with interesting inputs,
# using the above test() to check if the result is correct or not.
def main():
  print( 'verbing')
  test(verbing('hail'), 'hailing')
  test(verbing('swiming'), 'swimingly')
  test(verbing('do'), 'do')

  print()
  print( 'not_bad')
  test(not_bad('This movie is not so bad'), 'This movie is good')
  test(not_bad('This dinner is not that bad!'), 'This dinner is good!')
  test(not_bad('This tea is not hot'), 'This tea is not hot')
  test(not_bad("It's bad yet not"), "It's bad yet not")

  print()
  print( 'front_back')
  test(front_back('abcd', 'xy'), 'abxcdy')
  test(front_back('abcde', 'xyz'), 'abcxydez')
  test(front_back('Kitten', 'Donut'), 'KitDontenut')

if __name__ == '__main__':
  main()
