# non-specific helper functions
def chunks(n, l):
    for i in range(0, len(l), n):
        yield l[i:i+n]

# specific helper functions
DAYS_PER_MONTH = [ 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 ]
def date_to_days(date):
    splitted = date.split('/')
    return sum(DAYS_PER_MONTH[1:int(splitted[0])]) + int(splitted[1])

def read_guests(fpath):
    return (
        ( x[0], date_to_days(x[1]), date_to_days(x[2]) ) for x in
            chunks(3,
                open(fpath).read().split()
            )
    )

# main part
def number_of_unique_tourists(fpath):
    """Return number of unique tourists loaded from file
    :param fpath: string, path to a datafile
    :return:int - number of unique tourists
    """
    guests = read_guests(fpath)
    return len(set(x[0] for x in guests))

def longest_stay(fpath):
    """ Return info about the tourist with the longest stay

    :param fpath: string, path to a datafile
    :return: name(string) - the name of the tourist
        number_of_nights (int) the length of the stay
    """
    guests = read_guests(fpath)
    return max(
        ( ( x[0], 1 + x[2] - x[1] ) for x in guests ),
        key = lambda x: x[1]
    )

def max_occupancy(fpath):
    guests = read_guests(fpath)
    current_guests, max_current = [], 0
    for entry in sorted(guests, key = lambda x: x[1]):
        current_guests = list(filter(lambda x: x > entry[1], current_guests)) + [ entry[2] ]
        if len(current_guests) > max_current:
            max_current = len(current_guests)
    return max_current

def guests_for_night(fpath, from_date, to_date):
    guests = read_guests(fpath)
    from_value = date_to_days(from_date)
    to_value = date_to_days(to_date)
    return list(
        x[0] for x in
            filter(
                lambda x: x[1] <= from_value and x[2] >= to_value,
                guests
            )
    )

# testing
print(number_of_unique_tourists("tourists.txt"))
print(longest_stay("tourists.txt"))
print(max_occupancy("tourists.txt"))
print(guests_for_night("tourists.txt", "01/16", "01/17"))