import json
import string

def sanitiseInput(dirtyQuestion):
  """Sanitise a user inputted question to make it lower case, remove punctuation

  Arguments:
  dirtyQuestion -- a question that contains punctuation and different-cased letter

  Returns:
  String with the user's input without punctuation and all in lower cawse
  """
  # Translate the dirty input into a sanitised one by removing all punctuation characters
  # maketrans creates a table of characters to change, change with, and remove. In this case, no changes except remove punctuation.
  # Derived from: https://datagy.io/python-remove-punctuation-from-string/
  newQuestion = dirtyQuestion.translate(str.maketrans('', '', string.punctuation))
  newQuestion = newQuestion.lower().strip()
  return newQuestion

def jaccardSimilarity(userQuestion, questionBank):
  """Check the similarity of a user defined question to the bank of questions available

  Arguments:
  userQuestion -- question that the user has entered
  questionBank -- python json object of questions and answers

  Returns:
  Float between 0 and 1 of similarity (1 being exactly the same)
  """
  s1 = set(sanitiseInput(userQuestion))
  s2 = set(sanitiseInput(questionBank))
  return float(len(s1.intersection(s2)) / len(s1.union(s2))) 

def mostLikely(userQuestion):
  """Checks how likely a user entered question is to the list of known questions

  Arguments:
  userQuestion -- question that the user has entered

  Returns:
  String of the most likely question from the known user bank
  """
  likelihoodScore = []
  fileObject = open("faq.json", "r")
  jsonContent = fileObject.read()
  questionBank = json.loads(jsonContent)
  # Using list of known questions, iterate through and determine similarity of all of them
  for faqPair in questionBank:
    likelihoodScore.append(jaccardSimilarity(userQuestion, faqPair['question']))

  # Get the question that has the highest likelihood
  mostLikelyIndex = likelihoodScore.index(max(likelihoodScore))
  mostLikely = questionBank[mostLikelyIndex]
    
  fileObject.close() # Close file to prevent IO errors

  return mostLikely

def continueQuestions(userQuestion):
  """Check whether question has any content in it.

  Arguments:
  userQuestion -- question that the user has entered

  Returns:
  Boolean value. Is False if input is empty or True if required to re-loop and allow user to ask more questions
  """
  if sanitiseInput(userQuestion):
    likelyQuestion = mostLikely(userQuestion)
    print ("I think that you asked " + "'" + (likelyQuestion['question']) + "'" + " and conclude that the answer is " + "'" + (likelyQuestion['answer']) + "'.\n")
    # Open the file in append & read mode ('a+')
    with open("asked_questions_log.txt", "a+") as file_object:
      file_object.write(userQuestion + "\n")
    return True
  else:
    # return False if there is no input to exit the program
    return False

def main():
  print("Hello, I am a question answering bot.\n")

  userQuestion = ''
  userQuestion = input('Please enter a question, and press the ENTER key: \n')

  # Loop again and again when user enters a question and provide user with results
  while continueQuestions(userQuestion):
    userQuestion = input('Please enter a question, and press the ENTER key: \n')

  # Exit program gracefully with a message
  print("Goodbye!")

if __name__ == "__main__":
  main()