# -*- coding: utf-8 -*-
#
# django-ldapdb
# Copyright (c) 2009-2011, Bolloré telecom
# Copyright (c) 2013, Jeremy Lainé
# All rights reserved.
#
# See AUTHORS file for a full list of contributors.
#
# Redistribution and use in source and binary forms, with or without
# modification, are permitted provided that the following conditions are met:
#
#     1. Redistributions of source code must retain the above copyright notice,
#        this list of conditions and the following disclaimer.
#
#     2. Redistributions in binary form must reproduce the above copyright
#        notice, this list of conditions and the following disclaimer in the
#        documentation and/or other materials provided with the distribution.
#
# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
# AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
# IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
# ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
# LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
# CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
# SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
# INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
# CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
# ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
# POSSIBILITY OF SUCH DAMAGE.
#

import ldap
import logging

import django.db.models
from django.db import connections, router
from django.db.models import signals

import ldapdb  # noqa


logger = logging.getLogger('ldapdb')


class Model(django.db.models.base.Model):
    """
    Base class for all LDAP models.
    """
    dn = django.db.models.fields.CharField(max_length=200)

    # meta-data
    base_dn = None
    search_scope = ldap.SCOPE_SUBTREE
    object_classes = ['top']

    def __init__(self, *args, **kwargs):
        super(Model, self).__init__(*args, **kwargs)
        self.saved_pk = self.pk

    def build_rdn(self):
        """
        Build the Relative Distinguished Name for this entry.
        """
        bits = []
        for field in self._meta.fields:
            if field.db_column and field.primary_key:
                bits.append("%s=%s" % (field.db_column,
                                       getattr(self, field.name)))
        if not len(bits):
            raise Exception("Could not build Distinguished Name")
        return '+'.join(bits)

    def build_dn(self):
        """
        Build the Distinguished Name for this entry.
        """
        return "%s,%s" % (self.build_rdn(), self.base_dn)
        raise Exception("Could not build Distinguished Name")

    def delete(self, using=None):
        """
        Delete this entry.
        """
        using = using or router.db_for_write(self.__class__, instance=self)
        connection = connections[using]
        logger.debug("Deleting LDAP entry %s" % self.dn)
        connection.delete_s(self.dn)
        signals.post_delete.send(sender=self.__class__, instance=self)

    def save(self, using=None):
        """
        Saves the current instance.
        """
        signals.pre_save.send(sender=self.__class__, instance=self)
        
        using = using or router.db_for_write(self.__class__, instance=self)
        connection = connections[using]
        if not self.dn:
            # create a new entry
            record_exists = False
            entry = [('objectClass', self.object_classes)]
            new_dn = self.build_dn()

            for field in self._meta.fields:
                if not field.db_column:
                    continue
                value = getattr(self, field.name)
                if value:
                    entry.append((field.db_column,
                                  field.get_db_prep_save(
                                      value, connection=connection)))

            logger.debug("Creating new LDAP entry %s" % new_dn)
            connection.add_s(new_dn, entry)

            # update object
            self.dn = new_dn

        else:
            # update an existing entry
            record_exists = True
            modlist = []
            orig = self.__class__.objects.get(pk=self.saved_pk)
            for field in self._meta.fields:
                if not field.db_column:
                    continue
                old_value = getattr(orig, field.name, None)
                new_value = getattr(self, field.name, None)
                if old_value != new_value:
                    if new_value:
                        modlist.append(
                            (ldap.MOD_REPLACE, field.db_column,
                             field.get_db_prep_save(new_value,
                                                    connection=connection)))
                    elif old_value:
                        modlist.append((ldap.MOD_DELETE, field.db_column,
                                        None))

            if len(modlist):
                # handle renaming
                new_dn = self.build_dn()
                if new_dn != self.dn:
                    logger.debug("Renaming LDAP entry %s to %s" % (self.dn,
                                                                   new_dn))
                    connection.rename_s(self.dn, self.build_rdn())
                    self.dn = new_dn

                logger.debug("Modifying existing LDAP entry %s" % self.dn)
                connection.modify_s(self.dn, modlist)
            else:
                logger.debug("No changes to be saved to LDAP entry %s" %
                             self.dn)

        # done
        self.saved_pk = self.pk
        signals.post_save.send(sender=self.__class__, instance=self,
                               created=(not record_exists))

    @classmethod
    def scoped(base_class, base_dn):
        """
        Returns a copy of the current class with a different base_dn.
        """
        class Meta:
            proxy = True
        import re
        suffix = re.sub('[=,]', '_', base_dn)
        name = "%s_%s" % (base_class.__name__, str(suffix))
        new_class = type(name, (base_class,), {
            'base_dn': base_dn, '__module__': base_class.__module__,
            'Meta': Meta})
        return new_class

    class Meta:
        abstract = True
