text: # Problem Set 4C
  # Name: <your name here>
  # Collaborators:
  # Time Spent: x:xx
  
  import string
  from ps4a import get_permutations
  
  ### HELPER CODE ###
  def load_words(file_name):
      '''
      file_name (string): the name of the file containing 
      the list of words to load    
      
      Returns: a list of valid words. Words are strings of lowercase letters.
      
      Depending on the size of the word list, this function may
      take a while to finish.
      '''
      
      print("Loading word list from file...")
      # inFile: file
      inFile = open(file_name, 'r')
      # wordlist: list of strings
      wordlist = []
      for line in inFile:
          wordlist.extend([word.lower() for word in line.split(' ')])
      print("  ", len(wordlist), "words loaded.")
      return wordlist
  
  def is_word(word_list, word):
      '''
      Determines if word is a valid word, ignoring
      capitalization and punctuation
  
      word_list (list): list of words in the dictionary.
      word (string): a possible word.
      
      Returns: True if word is in word_list, False otherwise
  
      Example:
      >>> is_word(word_list, 'bat') returns
      True
      >>> is_word(word_list, 'asdf') returns
      False
      '''
      word = word.lower()
      word = word.strip(" !@#$%^&*()-_+={}[]|\:;'<>?,./\"")
      return word in word_list
  
  
  ### END HELPER CODE ###
  
  WORDLIST_FILENAME = 'words.txt'
  
  # you may find these constants helpful
  VOWELS_LOWER = 'aeiou'
  VOWELS_UPPER = 'AEIOU'
  CONSONANTS_LOWER = 'bcdfghjklmnpqrstvwxyz'
  CONSONANTS_UPPER = 'BCDFGHJKLMNPQRSTVWXYZ'
  
  class SubMessage(object):
      def __init__(self, text):
          '''
          Initializes a SubMessage object
                  
          text (string): the message's text
  
          A SubMessage object has two attributes:
              self.message_text (string, determined by input text)
              self.valid_words (list, determined using helper function load_words)
          '''
          self.message_text = text
          self.valid_words = load_words(WORDLIST_FILENAME)
      
      def get_message_text(self):
          '''
          Used to safely access self.message_text outside of the class
          
          Returns: self.message_text
          '''
          return self.message_text
  
      def get_valid_words(self):
          '''
          Used to safely access a copy of self.valid_words outside of the class.
          This helps you avoid accidentally mutating class attributes.
          
          Returns: a COPY of self.valid_words
          '''
          return self.valid_words
                  
      def build_transpose_dict(self, vowels_permutation):
          '''
          vowels_permutation (string): a string containing a permutation of vowels (a, e, i, o, u)
          
          Creates a dictionary that can be used to apply a cipher to a letter.
          The dictionary maps every uppercase and lowercase letter to an
          uppercase and lowercase letter, respectively. Vowels are shuffled 
          according to vowels_permutation. The first letter in vowels_permutation 
          corresponds to a, the second to e, and so on in the order a, e, i, o, u.
          The consonants remain the same. The dictionary should have 52 
          keys of all the uppercase letters and all the lowercase letters.
  
          Example: When input "eaiuo":
          Mapping is a->e, e->a, i->i, o->u, u->o
          and "Hello World!" maps to "Hallu Wurld!"
  
          Returns: a dictionary mapping a letter (string) to 
                   another letter (string). 
          '''
          
          t_dict = {}
          
          for n in range(len(VOWELS_LOWER)):
              t_dict[VOWELS_LOWER[n]] = vowels_permutation[n]
              t_dict[VOWELS_LOWER[n].upper()] = vowels_permutation[n].upper()
              
          for c in CONSONANTS_LOWER:
              t_dict[c] = c
              
          for c in CONSONANTS_UPPER:
              t_dict[c] = c
              
          return t_dict
      
      
      def apply_transpose(self, transpose_dict):
          '''
          transpose_dict (dict): a transpose dictionary
          
          Returns: an encrypted version of the message text, based 
          on the dictionary
          '''
          
          e_message = ''
          
          for c in self.message_text:
              if c in transpose_dict:
                  e_message += transpose_dict[c]
              else:
                  e_message += c
                  
          return e_message
      
          
  class EncryptedSubMessage(SubMessage):
      def __init__(self, text):
          '''
          Initializes an EncryptedSubMessage object
  
          text (string): the encrypted message text
  
          An EncryptedSubMessage object inherits from SubMessage and has two attributes:
              self.message_text (string, determined by input text)
              self.valid_words (list, determined using helper function load_words)
          '''
          SubMessage.__init__(self, text)
  
      def decrypt_message(self):
          '''
          Attempt to decrypt the encrypted message 
          
          Idea is to go through each permutation of the vowels and test it
          on the encrypted message. For each permutation, check how many
          words in the decrypted text are valid English words, and return
          the decrypted message with the most English words.
          
          If no good permutations are found (i.e. no permutations result in 
          at least 1 valid word), return the original string. If there are
          multiple permutations that yield the maximum number of words, return any
          one of them.
  
          Returns: the best decrypted message    
          
          Hint: use your function from Part 4A
          '''
          
          
          n_words = []
          
          vowels_permutations = get_permutations(VOWELS_LOWER)
          
          n_p = len(vowels_permutations)
          
          d_messages = []
          
          for v_p in vowels_permutations:
              
              transpose_dict = self.build_transpose_dict(v_p)
              
              d_mess = self.apply_transpose(transpose_dict)
              
              d_messages += [d_mess]
              
              d_words = d_mess.split()
              
              n = 0
              
              for word in d_words:
                  
                  if is_word(self.valid_words,word):
                      n += 1
                      
              n_words += [n]
              
              
          n_words_max = max(n_words)
          
          if n_words_max == 0:
              return (self.message_text)
          
          else:
              
              results = []
              
              for n in range(len(n_words)):
                  if n_words[n] == n_words_max:
                      
                      results += [d_messages[n]]
                      
              return results
      
  
  if __name__ == '__main__':
  
      # Example test case
      message = SubMessage("Hello World!")
      permutation = "eaiuo"
      enc_dict = message.build_transpose_dict(permutation)
      print("Original message:", message.get_message_text(), "Permutation:", permutation)
      print("Expected encryption:", "Hallu Wurld!")
      print("Actual encryption:", message.apply_transpose(enc_dict))
      enc_message = EncryptedSubMessage(message.apply_transpose(enc_dict))
      print("Decrypted message:", enc_message.decrypt_message())
       
      #TODO: WRITE YOUR TEST CASES HERE
      
      message = SubMessage('I am feeling happy. Done homework')
      permutation = 'ioeau'
      e_dict = message.build_transpose_dict(permutation)
      e_mess = EncryptedSubMessage(message.apply_transpose(e_dict))
      print("Decrypted message:", e_mess.decrypt_message())
  