"""change.py

Created by Thomas Mangin on 2009-11-05.
Copyright (c) 2009-2017 Exa Networks. All rights reserved.
License: 3-clause BSD. (See the COPYRIGHT file)
"""


class Change:
    @staticmethod
    def family_prefix(family):
        return b'%02x%02x' % family

    def __init__(self, nlri, attributes):
        self.nlri = nlri
        self.attributes = attributes
        # prevent multiple allocation of the index when calling .index()
        # storing the value at __init__ time causes api-attributes.sequence to fail
        # XXX: the NLRI content is half missing !!
        self.__index = ''

    def index(self):
        if not self.__index:
            self.__index = b'%02x%02x' % self.nlri.family().afi_safi() + self.nlri.index()
        return self.__index

    def __eq__(self, other):
        return self.nlri == other.nlri and self.attributes == other.attributes

    def __ne__(self, other):
        return self.nlri != other.nlri or self.attributes != other.attributes

    def __lt__(self, other):
        raise RuntimeError('comparing Change for ordering does not make sense')

    def __le__(self, other):
        raise RuntimeError('comparing Change for ordering does not make sense')

    def __gt__(self, other):
        raise RuntimeError('comparing Change for ordering does not make sense')

    def __ge__(self, other):
        raise RuntimeError('comparing Change for ordering does not make sense')

    def extensive(self):
        # If you change this you must change as well extensive in Update
        return f'{self.nlri!s}{self.attributes!s}'

    def __repr__(self):
        return self.extensive()

    def feedback(self):
        if self.nlri is not None:
            return self.nlri.feedback(self.nlri.action)
        return 'no check implemented for the family {} {}'.format(*self.nlri.family().afi_safi())
