# Copyright (C) 2012  SPARTA, Inc. a Parsons Company
#
# Permission to use, copy, modify, and distribute this software for any
# purpose with or without fee is hereby granted, provided that the above
# copyright notice and this permission notice appear in all copies.
#
# THE SOFTWARE IS PROVIDED "AS IS" AND SPARTA DISCLAIMS ALL WARRANTIES WITH
# REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
# AND FITNESS.  IN NO EVENT SHALL SPARTA BE LIABLE FOR ANY SPECIAL, DIRECT,
# INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
# LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE
# OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
# PERFORMANCE OF THIS SOFTWARE.

"""
Common classes for reuse in apps.
"""

__version__ = '$Id$'

from django.db import models

import rpki.resource_set
import rpki.POW
from south.modelsinspector import add_introspection_rules


class IPv6AddressField(models.Field):
    "Field large enough to hold a 128-bit unsigned integer."

    __metaclass__ = models.SubfieldBase

    def db_type(self, connection):
        return 'binary(16)'

    def to_python(self, value):
        if isinstance(value, rpki.POW.IPAddress):
            return value
        return rpki.POW.IPAddress.fromBytes(value)

    def get_db_prep_value(self, value, connection, prepared):
        """
        Note that we add a custom conversion to encode long values as hex
        strings in SQL statements.  See settings.get_conv() for details.
        """

        return value.toBytes()


class IPv4AddressField(models.Field):
    "Wrapper around rpki.POW.IPAddress."

    __metaclass__ = models.SubfieldBase

    def db_type(self, connection):
        return 'int UNSIGNED'

    def to_python(self, value):
        if isinstance(value, rpki.POW.IPAddress):
            return value
        return rpki.POW.IPAddress(value, version=4)

    def get_db_prep_value(self, value, connection, prepared):
        return long(value)

add_introspection_rules(
    [
        ([IPv4AddressField, IPv6AddressField], [], {})
    ],
    [r'^rpki\.gui\.models\.IPv4AddressField',
     r'^rpki\.gui\.models\.IPv6AddressField']
)


class Prefix(models.Model):
    """Common implementation for models with an IP address range.

    Expects that `range_cls` is set to the appropriate subclass of
    rpki.resource_set.resource_range_ip."""

    def as_resource_range(self):
        """
        Returns the prefix as a rpki.resource_set.resource_range_ip object.
        """

        return self.range_cls(self.prefix_min, self.prefix_max)

    @property
    def prefixlen(self):
        "Returns the prefix length for the prefix in this object."
        return self.as_resource_range().prefixlen()

    def get_prefix_display(self):
        "Return a string representatation of this IP prefix."
        return str(self.as_resource_range())

    def __unicode__(self):
        """This method may be overridden by subclasses.  The default
        implementation calls get_prefix_display(). """

        return self.get_prefix_display()

    class Meta:
        abstract = True

        # default sort order reflects what "sh ip bgp" outputs
        ordering = ('prefix_min',)


class PrefixV4(Prefix):
    "IPv4 Prefix."

    range_cls = rpki.resource_set.resource_range_ipv4

    prefix_min = IPv4AddressField(db_index=True, null=False)
    prefix_max = IPv4AddressField(db_index=True, null=False)

    class Meta(Prefix.Meta):
        abstract = True


class PrefixV6(Prefix):
    "IPv6 Prefix."

    range_cls = rpki.resource_set.resource_range_ipv6

    prefix_min = IPv6AddressField(db_index=True, null=False)
    prefix_max = IPv6AddressField(db_index=True, null=False)

    class Meta(Prefix.Meta):
        abstract = True


class ASN(models.Model):
    """Represents a range of ASNs.

    This model is abstract, and is intended to be reused by applications."""

    min = models.PositiveIntegerField(null=False)
    max = models.PositiveIntegerField(null=False)

    class Meta:
        abstract = True
        ordering = ('min', 'max')

    def as_resource_range(self):
        return rpki.resource_set.resource_range_as(self.min, self.max)

    def __unicode__(self):
        return u'AS%s' % self.as_resource_range()

# vim:sw=4 ts=8 expandtab