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# Copyright 2011 GRNET S.A. All rights reserved.

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from django.core.urlresolvers import reverse

from django.utils.translation import ugettext as _

from django.utils.datastructures import SortedDict

from django.conf import settings

from astakos.im import settings as astakos_settings

from astakos.im import messages as astakos_messages

import logging

logger = logging.getLogger(__name__)

# providers registry

PROVIDERS = {}

REQUIRED_PROVIDERS = {}

class AuthProviderBase(type):

    def __new__(cls, name, bases, dct):

        include = False

        if [b for b in bases if isinstance(b, AuthProviderBase)]:

            type_id = dct.get('module')

            if type_id:

                include = True

            if type_id in astakos_settings.IM_MODULES:

                dct['module_enabled'] = True

        newcls = super(AuthProviderBase, cls).__new__(cls, name, bases, dct)

        if include:

            PROVIDERS[type_id] = newcls

            if newcls().is_required():

                REQUIRED_PROVIDERS[type_id] = newcls

        return newcls

class AuthProvider(object):

    __metaclass__ = AuthProviderBase

    module = None

    module_active = False

    module_enabled = False

    one_per_user = False

    login_prompt = _('Login using ')

    primary_login_prompt = _('Login using ')

    def get_message(self, msg, **kwargs):

        params = kwargs

        params.update({'provider': self.get_title_display})

        override_msg = getattr(self, 'get_%s_message_display' % msg.lower(), None)

        msg = 'AUTH_PROVIDER_%s' % msg

        return override_msg or getattr(astakos_messages, msg, msg) % params

    def __init__(self, user=None):

        self.user = user

    def __getattr__(self, key):

        if not key.startswith('get_'):

            return super(AuthProvider, self).__getattribute__(key)

        if key.endswith('_display') or key.endswith('template'):

            attr = key.replace('_display', '').replace('get_','')

            settings_attr = self.get_setting(attr.upper())

            if not settings_attr:

                return getattr(self, attr)

            return _(settings_attr)

        else:

            return super(AuthProvider, self).__getattr__(key)

    def get_setting(self, name, default=None):

        attr = 'ASTAKOS_AUTH_PROVIDER_%s_%s' % (self.module.upper(), name.upper())

        attr_sec = 'ASTAKOS_%s_%s' % (self.module.upper(), name.upper())

        if not hasattr(settings, attr):

            return getattr(settings, attr_sec, default)

        return getattr(settings, attr, default)

    def is_available_for_login(self):

        """ A user can login using authentication provider"""

        return self.is_active() and self.get_setting('CAN_LOGIN',

                                                     self.is_active())

    def is_available_for_create(self):

        """ A user can create an account using this provider"""

        return self.is_active() and self.get_setting('CAN_CREATE',

                                                   self.is_active())

    def is_available_for_add(self):

        """ A user can assign provider authentication method"""

        return self.is_active() and self.get_setting('CAN_ADD',

                                                   self.is_active())

    def is_required(self):

        """Provider required (user cannot remove the last one)"""

        return self.is_active() and self.get_setting('REQUIRED', False)

    def is_active(self):

        return self.module in astakos_settings.IM_MODULES

class LocalAuthProvider(AuthProvider):

    module = 'local'

    title = _('Local password')

    description = _('Create a local password for your account')

    add_prompt =  _('Create a local password for your account')

    login_prompt = _('if you already have a username and password')

    signup_prompt = _('New to ~okeanos ?')

    signup_link_prompt = _('create an account now')

    @property

    def add_url(self):

        return reverse('password_change')

    one_per_user = True

    login_template = 'im/auth/local_login_form.html'

    login_prompt_template = 'im/auth/local_login_prompt.html'

    signup_prompt_template = 'im/auth/local_signup_prompt.html'

    details_tpl = _('You can login to your account using your'

                    ' %(auth_backend)s password.')

    @property

    def extra_actions(self):

        return [(_('Change password'), reverse('password_change')), ]

class ShibbolethAuthProvider(AuthProvider):

    module = 'shibboleth'

    title = _('Academic credentials (Shibboleth)')

    add_prompt = _('Allows you to login to your account using your academic '

                    'account')

    details_tpl = _('Shibboleth account \'%(identifier)s\' is connected to your '

                    ' account.')

    user_title = _('Academic credentials (%(identifier)s)')

    primary_login_prompt = _('If you are a student/researcher/faculty you can'

                             ' login using your university-credentials in'

                             ' the following page')

    @property

    def add_url(self):

        return reverse('astakos.im.target.shibboleth.login')

    login_template = 'im/auth/shibboleth_login.html'

    login_prompt_template = 'im/auth/shibboleth_login_prompt.html'

class TwitterAuthProvider(AuthProvider):

    module = 'twitter'

    title = _('Twitter')

    add_prompt = _('Allows you to login to your account using Twitter')

    details_tpl = _('Twitter screen name: %(info_screen_name)s')

    user_title = _('Twitter (%(info_screen_name)s)')

    @property

    def add_url(self):

        return reverse('astakos.im.target.twitter.login')

    login_template = 'im/auth/third_party_provider_generic_login.html'

    login_prompt_template = 'im/auth/third_party_provider_generic_login_prompt.html'

class GoogleAuthProvider(AuthProvider):

    module = 'google'

    title = _('Google')

    add_prompt = _('Allows you to login to your account using Google')

    details_tpl = _('Google account: %(info_email)s')

    user_title = _('Google (%(info_email)s)')

    @property

    def add_url(self):

        return reverse('astakos.im.target.google.login')

    login_template = 'im/auth/third_party_provider_generic_login.html'

    login_prompt_template = 'im/auth/third_party_provider_generic_login_prompt.html'

class LinkedInAuthProvider(AuthProvider):

    module = 'linkedin'

    title = _('LinkedIn')

    add_prompt = _('Allows you to login to your account using LinkedIn')

    user_title = _('LinkedIn (%(info_emailAddress)s)')

    details_tpl = _('LinkedIn account: %(info_emailAddress)s')

    @property

    def add_url(self):

        return reverse('astakos.im.target.linkedin.login')

    login_template = 'im/auth/third_party_provider_generic_login.html'

    login_prompt_template = 'im/auth/third_party_provider_generic_login_prompt.html'

def get_provider(id, user_obj=None, default=None):

    """

    Return a provider instance from the auth providers registry.

    """

    return PROVIDERS.get(id, default)(user_obj)