''' Purpose: define some functions related to UVA
'''

def credits_to_go( n ) :
    ''' Returns number of credits needed for graduation, given n
        credits earned so far
    '''
    # When we use functions, we will pass in our "input" as arguments
    # to fill in the parameter n. Take a look at rotunda.py and
    # see how we call credits_to_go()!

    CLAS_GRADUATION_REQUIREMENT = 120
    # credits_remaining =  CLAS_GRADUATION_REQUIREMENT - n

    # Evaluate credits_remaining based on whether n is positive, 0 <= n <= 120, or >120
    # You could also directly return your return values instead of doing credits_remaining = return value
    # if/elif/else -> test three DISTINCT possibilities of n!
    if ( n < 0 ):
        credits_remaining = None
    elif ( n <= CLAS_GRADUATION_REQUIREMENT ):
        credits_remaining = CLAS_GRADUATION_REQUIREMENT - n
    else:
        credits_remaining = 0

    return credits_remaining        # The function hands back this value!

    # The testers usually have the input() to get the arguments we wanna
    # pass in to replace our parameters.

def how_old_is_UVA() : # This function has no parameters. Functions can but don't have to have parameters!
    ''' Returns the number of years since UVA was founded.
    '''
    YEAR_OF_FOUNDING = 1819
    import datetime     # standard Python module that provides information about
                        # current day and time
                        # we can import it and use functions/values from it!

    current_time = datetime.datetime.now() # gives the current time

    current_year = current_time.year    # This is how we get the current year!
                                        # We don't need the user to supply it.
                                        # or pass it in as an argument to a parameter
                                        # if we had one.

    age = current_year - YEAR_OF_FOUNDING # ex. 2020 - 1819

    return  age

# Same function but with a parameter where we now have a parameter.
def how_old_is_UVA_for_year( year ): # This is an example where a user can provide
                                    # an argument (like 2020) to provide the year to parameter year!
    YEAR_OF_FOUNDING = 1819
    age = year - YEAR_OF_FOUNDING
    return age

def grade_as_percent( score, total ):
    '''
    Returns the percentage of right with respect to total (right/total)
    '''
    grade = score/total
    percentage = grade * 100
    result = str(percentage) + "%" # You can't concatenate an int and a string
    return result # We return a string of the percent and %