# Copyright (C) Dnspython Contributors, see LICENSE for text of ISC license

# Copyright (C) 2001-2017 Nominum, Inc.
#
# Permission to use, copy, modify, and distribute this software and its
# documentation for any purpose with or without fee is hereby granted,
# provided that the above copyright notice and this permission notice
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# WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
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"""DNS Rdata Classes."""

import dns.enum
import dns.exception

class RdataClass(dns.enum.IntEnum):
    """DNS Rdata Class"""
    RESERVED0 = 0
    IN = 1
    INTERNET = IN
    CH = 3
    CHAOS = CH
    HS = 4
    HESIOD = HS
    NONE = 254
    ANY = 255

    @classmethod
    def _maximum(cls):
        return 65535

    @classmethod
    def _short_name(cls):
        return "class"

    @classmethod
    def _prefix(cls):
        return "CLASS"

    @classmethod
    def _unknown_exception_class(cls):
        return UnknownRdataclass

globals().update(RdataClass.__members__)

_metaclasses = {RdataClass.NONE, RdataClass.ANY}


class UnknownRdataclass(dns.exception.DNSException):
    """A DNS class is unknown."""


def from_text(text):
    """Convert text into a DNS rdata class value.

    The input text can be a defined DNS RR class mnemonic or
    instance of the DNS generic class syntax.

    For example, "IN" and "CLASS1" will both result in a value of 1.

    Raises ``dns.rdatatype.UnknownRdataclass`` if the class is unknown.

    Raises ``ValueError`` if the rdata class value is not >= 0 and <= 65535.

    Returns an ``int``.
    """

    return RdataClass.from_text(text)


def to_text(value):
    """Convert a DNS rdata class value to text.

    If the value has a known mnemonic, it will be used, otherwise the
    DNS generic class syntax will be used.

    Raises ``ValueError`` if the rdata class value is not >= 0 and <= 65535.

    Returns a ``str``.
    """

    return RdataClass.to_text(value)


def is_metaclass(rdclass):
    """True if the specified class is a metaclass.

    The currently defined metaclasses are ANY and NONE.

    *rdclass* is an ``int``.
    """

    if rdclass in _metaclasses:
        return True
    return False
