change_date.py

'''
    Author: Cássio Antoniazzi
    email: [email protected]
'''

months = {}
months[1] = 31
months[2] = 28
months[3] = 31
months[4] = 30
months[5] = 31
months[6] = 30
months[7] = 30
months[8] = 31
months[9] = 30
months[10] = 31
months[11] = 30
months[12] = 31


'''
    descrip: recursive function to add dates
    params: dictionary with day, month, year
    return: dictionary with day, month, year
'''
def add_date(tmp_date):
    date_return = {}
    while True:
        tmp_day = int(int(months[int(tmp_date['month'])]) - int(int(tmp_date['day'])))

        if tmp_day > 0:
            tmp_date['day'] = tmp_day
        else:
            tmp_date['day'] = tmp_day * - 1

        tmp_date['month'] += 1

        if int(tmp_date['month']) > 12:
            tmp_date['month'] = 1
            tmp_date['year'] += 1

        if tmp_date['day'] > months[tmp_date['month']]:
            if tmp_date['month'] > 12:
                return add_date(tmp_date)
        else:
            date_return['day'] = tmp_date['day']
            date_return['month'] = tmp_date['month']
            date_return['year'] = tmp_date['year']
            return date_return


'''
    descrip: recursive function to sub dates
    params: dictionary with day, month, year
    return: dictionary with day, month, year
'''
def sub_date(tmp_date):
    date_return = {}

    if tmp_date['day'] <= 0:
        tmp_date['month'] -= 1

    if int(tmp_date['month']) <= 0:
        tmp_date['month'] = 12 - tmp_date['month']
        tmp_date['year'] -= 1

    tmp_date['day'] = months[tmp_date['month']] - (tmp_date['day'] * - 1)

    if tmp_date['day'] < 0:
        return sub_date(tmp_date)
    else:
        date_return['day'] = tmp_date['day']
        date_return['month'] = tmp_date['month']
        date_return['year'] = tmp_date['year']
        return date_return


def change_date(date, op, value):
    if op not in ('+', '-'): # check operator is valid
       raise ValueError('This "{}" is not operator valid.'.format(op))

    tmp_date = date.split(' ')
    day, month, year = tmp_date[0].split('/')
    hour, minute = tmp_date[1].split(':')

    return_date = {
        'day': int(day),
        'month': int(month),
        'year': int(year),
        'hour': int(hour),
        'minute': int(minute)
    }

    if op == '+':
        return_date['hour'] += int(value / 60)
        return_date['minute'] += value % 60

        if return_date['minute'] >= 60:
            return_date['hour'] += int(return_date['minute'] / 60)
            return_date['minute'] = return_date['minute'] % 60

        if return_date['hour'] >= 24:
            return_date['day'] += int(return_date['hour'] / 24)
            return_date['hour'] = return_date['hour'] % 24

        if return_date['day'] > months[return_date['month']]:
            tmp_date = add_date({
                'day': return_date['day'],
                'month': return_date['month'],
                'year': return_date['year']
            })
            return_date['day'] = tmp_date['day']
            return_date['month'] = tmp_date['month']
            return_date['year'] = tmp_date['year']
    else:
        return_date['hour'] -= int(value / 60)
        return_date['minute'] -= (value % 60)

        if return_date['minute'] < 0:
            return_date['hour'] -= int(return_date['minute'] / 60)
            return_date['minute'] = int(return_date['minute'] % 60)

        if return_date['hour'] < 0:
            return_date['day'] -= (int(return_date['hour'] / 24) * - 1)
            return_date['hour'] = int(return_date['hour'] % 24)

        if int(return_date['day']) <= 0:
            tmp_date = sub_date({
                'day': return_date['day'],
                'month': return_date['month'],
                'year': return_date['year']
            })
            return_date['day'] = tmp_date['day']
            return_date['month'] = tmp_date['month']
            return_date['year'] = tmp_date['year']

    return_date = str(return_date['day']) + '/' + str(return_date['month']) + '/' + str(return_date['year']) + \
        ' ' + str(return_date['hour']) + ':' + str(return_date['minute'])

    return return_date