from time import sleep, strftime
user = "Cytus"
calendar = {}
def welcome():
  print "Welcome to use this calendar. %s" % user
  print "Calendar is opening."
  sleep(1)
  print strftime("%A %B %d %Y")
  print strftime("%H:%M:%S")
  sleep(1)
  print "What would you like to do?"
def start_calendar():
  welcome()
  start = True
  while start:
    user_choice = raw_input("A to add, U to Update, V to View, D to Delete, X to Exit: ")
    user_choice = user_choice.upper()
    if user_choice == "V":
      if len(calendar.keys()) < 1:
        print "The calendar is empty."
      else:
        print calendar
    elif user_choice == "U":
      date = raw_input("What date? ")
      update = raw_input("Enter the update: ")
      calendar[date] = update
      print "Update successful."
      print calendar
    elif user_choice == "A":
      event = raw_input("Enter event: ")
      date = raw_input("Enter date (MM/DD/YYYY): ")
      if (len(date) > 10) or int(date[6:]) < int(strftime("%Y")):
        print "invaild date."
        try_again = raw_input("Try again? Y for yes, N for No: ")
        try_again = try_again.upper()
        if try_again == "Y":
          continue
        else:
          start = False
      else:
        calendar[date] = event
        print "Successfully added."
        print calendar
    elif user_choice == "D":
      if len(calendar.keys()) < 1:
        print "The calendar is empty."
      else:
        event = raw_input("What event? ")
        for date in calendar.keys():
          if calendar[date] == event:
            del calendar[date]
            print "Delete successfully."
            print calendar
          else:
            print "incorrect event was specified."
    elif user_choice == "X":
      start = False
    else:
      print "invalid input."
      start = False
start_calendar()