# authentic2 - versatile identity manager
# Copyright (C) 2010-2019 Entr'ouvert
#
# This program is free software: you can redistribute it and/or modify it
# under the terms of the GNU Affero General Public License as published
# by the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU Affero General Public License for more details.
#
# You should have received a copy of the GNU Affero General Public License
# along with this program.  If not, see <http://www.gnu.org/licenses/>.

import datetime
import logging
import unicodedata

from django.contrib.contenttypes.models import ContentType
from django.contrib.postgres.search import TrigramDistance
from django.db import models, transaction, connection
from django.db.models import F, Value, FloatField, Subquery, OuterRef
from django.db.models.functions import Lower, Coalesce
from django.utils import six
from django.utils import timezone
from django.contrib.auth.models import BaseUserManager

from authentic2 import app_settings
from authentic2.models import Attribute, AttributeValue
from authentic2.utils.lookups import Unaccent, ImmutableConcat


class UserQuerySet(models.QuerySet):

    def free_text_search(self, search):
        terms = search.split()

        if not terms:
            return self

        searchable_attributes = Attribute.objects.filter(searchable=True)
        queries = []
        for term in terms:
            q = None

            specific_queries = []
            for a in searchable_attributes:
                kind = a.get_kind()
                free_text_search_function = kind.get('free_text_search')
                if free_text_search_function:
                    q = free_text_search_function(term)
                    if q is not None:
                        specific_queries.append(q & models.query.Q(attribute_values__attribute=a))

            # if the term is recognized by some specific attribute type, like a
            # date, does not use the later generic matcher
            if specific_queries:
                queries.append(six.moves.reduce(models.query.Q.__or__, specific_queries))
                continue

            q = (
                models.query.Q(username__icontains=term)
                | models.query.Q(first_name__icontains=term)
                | models.query.Q(last_name__icontains=term)
                | models.query.Q(email__icontains=term)
            )
            for a in searchable_attributes:
                if a.name in ('first_name', 'last_name'):
                    continue
                q = q | models.query.Q(
                    attribute_values__content__icontains=term, attribute_values__attribute=a)
            queries.append(q)
        self = self.filter(six.moves.reduce(models.query.Q.__and__, queries))
        # search by attributes can match multiple times
        if searchable_attributes:
            self = self.distinct()
        return self

    def find_duplicates(self, first_name, last_name, birthdate=None):
        with connection.cursor() as cursor:
            cursor.execute(
                "SET pg_trgm.similarity_threshold = %f" % app_settings.A2_DUPLICATES_THRESHOLD
            )

        name = '%s %s' % (first_name, last_name)
        name = unicodedata.normalize('NFKD', name).encode('ascii', 'ignore').decode('ascii').lower()

        qs = self.filter(deleted__isnull=True)
        qs = qs.annotate(name=Lower(Unaccent(ImmutableConcat('first_name', Value(' '), 'last_name'))))
        qs = qs.filter(name__trigram_similar=name)
        qs = qs.annotate(dist=TrigramDistance('name', name))
        qs = qs.order_by('dist')
        qs = qs[:5]

        # alter distance according to additionnal parameters
        if birthdate:
            bonus = app_settings.A2_DUPLICATES_BIRTHDATE_BONUS
            content_type = ContentType.objects.get_for_model(self.model)
            same_birthdate = AttributeValue.objects.filter(
                object_id=OuterRef('pk'),
                content_type=content_type,
                attribute__kind='birthdate',
                content=birthdate
            ).annotate(bonus=Value(1 - bonus, output_field=FloatField()))
            qs = qs.annotate(dist=Coalesce(
                Subquery(same_birthdate.values('bonus'), output_field=FloatField()) * F('dist'),
                F('dist')
            ))

        return qs

    @transaction.atomic
    def cleanup(self, threshold=600, timestamp=None):
        '''Delete all deleted users for more than 10 minutes.'''
        from .models import DeletedUser

        not_after = (timestamp or timezone.now()) - datetime.timedelta(seconds=threshold)
        qs = self.filter(deleted__lt=not_after)

        loaded = list(qs)

        def log():
            logger = logging.getLogger('authentic2')
            for user in loaded:
                logger.info(u'deleted account %s', user)
        transaction.on_commit(log)
        deleted_users = []
        for user in qs:
            deleted_user = DeletedUser(deleted=user.deleted, old_user_id=user.id)
            if 'email' in app_settings.A2_USER_DELETED_KEEP_DATA:
                deleted_user.old_email = user.email.rsplit('#', 1)[0]
            if 'uuid' in app_settings.A2_USER_DELETED_KEEP_DATA:
                deleted_user.old_uuid = user.uuid
            deleted_users.append(deleted_user)
        DeletedUser.objects.bulk_create(deleted_users)
        qs.delete()


class UserManager(BaseUserManager):

    def _create_user(self, username, email, password,
                     is_staff, is_superuser, **extra_fields):
        """
        Creates and saves a User with the given username, email and password.
        """
        now = timezone.now()
        if not username:
            raise ValueError('The given username must be set')
        email = self.normalize_email(email)
        user = self.model(username=username, email=email,
                          is_staff=is_staff, is_active=True,
                          is_superuser=is_superuser, last_login=now,
                          date_joined=now, **extra_fields)
        user.set_password(password)
        user.save(using=self._db)
        return user

    def create_user(self, username, email=None, password=None, **extra_fields):
        return self._create_user(username, email, password, False, False,
                                 **extra_fields)

    def create_superuser(self, username, email, password, **extra_fields):
        return self._create_user(username, email, password, True, True,
                                 **extra_fields)

    def get_by_natural_key(self, uuid):
        return self.get(uuid=uuid)