# fargo - document box
# Copyright (C) 2016-2019  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

from django.db import models
from django.utils.timezone import now

from . import utils


class DocumentManager(models.Manager):
    def cleanup(self, n=None):
        '''Delete all orphaned documents'''
        n = n or now()
        # use a window of 60 seconds to be sure this document will never be used
        qs = self.filter(creation_date__lt=n - datetime.timedelta(seconds=60))
        qs = qs.filter(user_documents__isnull=True,
                       oauth2_tempfiles__isnull=True)
        for document in qs:
            document.content.delete(False)
        qs.delete()

    def get_by_file(self, f):
        '''Get document with the same SHA-256 hash as the passde Django file
           like object.
        '''
        file_hash = utils.sha256_of_file(f)
        try:
            o = self.get(content_hash=file_hash)
        except self.model.DoesNotExist:
            o = self.model()
            o.content.save(file_hash, f)
        return o

    def used_space(self, user):
        return sum([doc.content.size for doc in self.filter(user_documents__user=user).distinct()])