import sys

if sys.version_info[0] < 3:
    raise "Must be using Python 3"

class Causal:
    def __init__(self, causalcode=""):
        self.causalcode = causalcode
        self._description = ""
        self._title = ""
        self._prechac = ""
        self._sequence = ""
        self._fourhanded = ""

    # https://docs.python.org/3/library/functions.html#property

    @property
    def description(self):
        return self._description

    @description.setter
    def description(self, value):
        self._description = value

    @property
    def title(self):
        return self._title

    @title.setter
    def title(self, value):
        self._title = value

    @property
    def prechac(self):
        return self._prechac

    @prechac.setter
    def prechac(self, value):
        self._prechac = value

    @property
    def sequence(self):
        return self._sequence

    @sequence.setter
    def sequence(self, value):
        self._sequence = value

    @property
    def fourhanded(self):
        return self._fourhanded

    @fourhanded.setter
    def fourhanded(self, value):
        if self.isvalid_fourhanded(value):
            self._fourhanded = str(value)
        else:
            raise Exception("Can't parse as fourhanded siteswap")
        # convert to prechac and fill prechac value

    def isvalid_fourhanded(self, value):
        if type(value) == int:
            value = str(value)
        elif type(value) == str:
            if value.isdigit():
                next
            else:
                return False
        else:
            return False

        # inspired by https://icculus.org/jugglemaster/docs/validate.txt
        lst = [1] * len(value)
        for i, c in enumerate(value):
            j = ( i + int(c) ) % len(value)
            lst[j] = lst[j] - 1
        for i in lst:
            if i != 0:
                return False
        return True

    def fourhanded_to_local(self, value):
        # local notation from https://jonglieren-jena.de/ppa/anthology.pdf
        # This is the local siteswap of the pattern accompanying a global siteswap. Subscripts
        # indicate the starting positions of the different jugglers. So than in
        # A7B65 the juggler A starts with a 7 while B starts with a 6

        if not self.isvalid_fourhanded(value):
            raise Exception("Can't parse as fourhanded siteswap")
        return