"""
This module provides auth token authorization for djapi.
It is closely based on rest_framework.authtoken module coming under following license.

Copyright (c) 2011-2017, Tom Christie
All rights reserved.

Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions are met:

Redistributions of source code must retain the above copyright notice, this
list of conditions and the following disclaimer.
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 HOLDER 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 re
from funcy import re_find

from django.apps import apps, AppConfig
from django.conf import settings
from django.core.exceptions import PermissionDenied
from django.utils.translation import ugettext_lazy as _


class AuthTokenConfig(AppConfig):
    name = 'djapi.authtoken'
    verbose_name = _("Auth Token")

default_app_config = 'djapi.authtoken.AuthTokenConfig'


def use_token(request):
    """
    Implement token based authentication.
    """
    header = request.META.get('HTTP_AUTHORIZATION', '')
    key = re_find(r'^\s*token\s+([a-z0-9]+)\s*$', header, re.I)
    if not key:
        raise PermissionDenied('Invalid token header')

    model = apps.get_model(getattr(settings, 'DJAPI_TOKEN_MODEL', 'authtoken.token'))
    try:
        return model.objects.select_related('user').get(key=key).user
    except model.DoesNotExist:
        raise PermissionDenied('Invalid token')
