smok-serwis/firanka

import math

from .base import Series
from ..intervals import REAL_SET


class ModuloSeries(Series):
    def __init__(self, series, *args, **kwargs):
        """
        Construct a modulo series
        :param series: base series to use
        :raise ValueError: invalid domain length
        """
        super(ModuloSeries, self).__init__(REAL_SET, *args, **kwargs)

        self.series = series
        self.period = self.series.domain.length()

        if self.period == 0:
            raise ValueError('Modulo series cannot have a period of 0')
        elif math.isinf(self.period):
            raise ValueError('Modulo series cannot have an infinite period')

        # We internally translate the start of the series' domain to be at 0, because it simpler for us :D
        self.intertrans = -self.series.domain.start

    def _get_for(self, item):
        item += self.intertrans

        if item < 0:
            item = -(item // self.period) * self.period + item
        elif item > self.period:
            item = item - (item // self.period) * self.period
        elif item == self.period:
            item = 0

        return self.series._get_for(self.series.domain.start + item)