# Copyright (c) 2011,  2012 Free Software Foundation

#     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/>.


# This project incorporates work covered by the following copyright and permission notice:  

#    Copyright (c) 2009, Julien Fache
#    All rights reserved.

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#    modification, are permitted provided that the following conditions
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#      notice, this list of conditions and the following disclaimer in
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#    LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
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# Copyright (c) 2011,  2012 Free Software Foundation

#     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/>.


"""Url shortener for Objectapp"""
import warnings

from django.utils.importlib import import_module
from django.core.exceptions import ImproperlyConfigured

from objectapp.settings import URL_SHORTENER_BACKEND
from objectapp.url_shortener.backends.default import backend as default_backend


def get_url_shortener():
    """Return the selected url shortener backend"""
    try:
        backend_module = import_module(URL_SHORTENER_BACKEND)
        backend = getattr(backend_module, 'backend')
    except (ImportError, AttributeError):
        warnings.warn('%s backend cannot be imported' % URL_SHORTENER_BACKEND,
                      RuntimeWarning)
        backend = default_backend
    except ImproperlyConfigured, e:
        warnings.warn(str(e), RuntimeWarning)
        backend = default_backend

    return backend