# copyright 2017 LOGILAB S.A. (Paris, FRANCE), all rights reserved.
# copyright 2014-2016 UNLISH S.A.S. (Montpellier, FRANCE), all rights reserved.
#
# contact http://www.logilab.fr/ -- mailto:contact@logilab.fr
#
# This file is part of CubicWeb.
#
# CubicWeb is free software: you can redistribute it and/or modify it under the
# terms of the GNU Lesser General Public License as published by the Free
# Software Foundation, either version 2.1 of the License, or (at your option)
# any later version.
#
# CubicWeb 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 Lesser General Public License for more
# details.
#
# You should have received a copy of the GNU Lesser General Public License along
# with CubicWeb.  If not, see <http://www.gnu.org/licenses/>.
"""
CubicWeb AuthTkt authentication policy
--------------------------------------

When using the `cubicweb.pyramid.auth` module, which is the default in most
cases, you may have to configure the behaviour of these authentication
policies using standard's Pyramid configuration. You may want to configure in
your pyramid configuration file:

:Session Authentication:

    This is a `AuthTktAuthenticationPolicy`_ so you may overwrite default
    configuration values by adding configuration entries using the prefix
    ``cubicweb.auth.authtkt.session``. Default values are:

    ::

        cubicweb.auth.authtkt.session.hashalg = sha512
        cubicweb.auth.authtkt.session.cookie_name = auth_tkt
        cubicweb.auth.authtkt.session.timeout = 1200
        cubicweb.auth.authtkt.session.reissue_time = 120
        cubicweb.auth.authtkt.session.http_only = True
        cubicweb.auth.authtkt.session.secure = True


:Persistent Authentication:

    This is also a `AuthTktAuthenticationPolicy`_. It is used when persistent
    sessions are activated (typically when using the cubicweb-rememberme_
    cube). You may overwrite default configuration values by adding
    configuration entries using the prefix
    ``cubicweb.auth.authtkt.persistent``. Default values are:

    ::

        cubicweb.auth.authtkt.persistent.hashalg = sha512
        cubicweb.auth.authtkt.persistent.cookie_name = pauth_tkt
        cubicweb.auth.authtkt.persistent.max_age = 3600*24*30
        cubicweb.auth.authtkt.persistent.reissue_time = 3600*24
        cubicweb.auth.authtkt.persistent.http_only = True
        cubicweb.auth.authtkt.persistent.secure = True


.. Warning:: Legacy timeout values from the instance's
             ``all-in-one.conf`` are **not** used at all (``
             http-session-time`` and ``cleanup-session-time``)

.. _CubicWeb: https://www.cubicweb.org/
.. _`cubicweb-rememberme`: \
    https://www.cubicweb.org/project/cubicweb-rememberme
.. _AuthTktAuthenticationPolicy: \
    http://docs.pylonsproject.org/projects/pyramid/en/latest/api/authentication.html#pyramid.authentication.AuthTktAuthenticationPolicy


Secrets
~~~~~~~
There are a number of secrets to configure in ``pyramid.ini``. They
should be different one from each other, as explained in `Pyramid's
documentation`_.

For the record, regarding authentication:

:cubicweb.auth.authtkt.session.secret: This secret is used to encrypt
   the authentication cookie.

:cubicweb.auth.authtkt.persistent.secret: This secret is used to
   encrypt the persistent authentication cookie.
"""

import datetime
import logging
import warnings

from zope.interface import implementer

from pyramid.settings import asbool
from pyramid.authorization import ACLAuthorizationPolicy
from cubicweb.pyramid.core import get_principals
from pyramid_multiauth import MultiAuthenticationPolicy

from pyramid.authentication import AuthTktAuthenticationPolicy

from pyramid.interfaces import IAuthenticationPolicy

log = logging.getLogger(__name__)


@implementer(IAuthenticationPolicy)
class UpdateLoginTimeAuthenticationPolicy(object):
    """An authentication policy that update the user last_login_time.

    The update is done in the 'remember' method, which is called by the login
    views login,

    Usually used via :func:`includeme`.
    """

    def authenticated_userid(self, request):
        pass

    def effective_principals(self, request):
        return ()

    def remember(self, request, principal, **kw):
        repo = request.registry['cubicweb.repository']
        with repo.internal_cnx() as cnx:
            try:
                cnx.execute(
                    "SET U last_login_time %(now)s WHERE U eid %(user)s", {
                        'now': datetime.datetime.now(),
                        'user': principal})
                cnx.commit()
            except Exception:
                log.exception("Failed to update last_login_time")
        return ()

    def forget(self, request):
        return ()


class CWAuthTktAuthenticationPolicy(AuthTktAuthenticationPolicy):
    """
    An authentication policy that inhibate the call the 'remember' if a
    'persistent' argument is passed to it, and is equal to the value that
    was passed to the constructor.

    This allow to combine two policies with different settings and select them
    by just setting this argument.
    """
    def __init__(self, secret, persistent, defaults={}, prefix='', **settings):
        self.persistent = persistent
        unset = object()
        kw = {}
        # load string settings
        for name in ('cookie_name', 'path', 'domain', 'hashalg'):
            value = settings.get(prefix + name, defaults.get(name, unset))
            if value is not unset:
                kw[name] = value
        # load boolean settings
        for name in ('secure', 'include_ip', 'http_only', 'wild_domain',
                     'parent_domain', 'debug'):
            value = settings.get(prefix + name, defaults.get(name, unset))
            if value is not unset:
                kw[name] = asbool(value)
        # load int settings
        for name in ('timeout', 'reissue_time', 'max_age'):
            value = settings.get(prefix + name, defaults.get(name, unset))
            if value is not unset:
                kw[name] = int(value)
        super(CWAuthTktAuthenticationPolicy, self).__init__(secret, **kw)

    def remember(self, request, principals, **kw):
        if 'persistent' not in kw or kw.pop('persistent') == self.persistent:
            return super(CWAuthTktAuthenticationPolicy, self).remember(
                request, principals, **kw)
        else:
            return ()


def includeme(config):
    """ Activate the CubicWeb AuthTkt authentication policy.

    Usually called via ``config.include('cubicweb.pyramid.auth')``.

    See also :ref:`defaults_module`
    """
    settings = config.registry.settings

    policies = []

    if asbool(settings.get('cubicweb.auth.update_login_time', True)):
        policies.append(UpdateLoginTimeAuthenticationPolicy())

    if asbool(settings.get('cubicweb.auth.authtkt', True)):
        session_prefix = 'cubicweb.auth.authtkt.session.'
        persistent_prefix = 'cubicweb.auth.authtkt.persistent.'

        session_secret = settings.get(
            session_prefix + 'secret', 'notsosecret')
        persistent_secret = settings.get(
            persistent_prefix + 'secret', 'notsosecret')
        if ('notsosecret' in (session_secret, persistent_secret)
                and config.registry['cubicweb.config'].mode != 'test'):
            warnings.warn('''

                !! SECURITY WARNING !!

                The authentication cookies are signed with a static secret key.

                Configure the following options in your pyramid.ini file:

                - cubicweb.auth.authtkt.session.secret
                - cubicweb.auth.authtkt.persistent.secret

                YOU SHOULD STOP THIS INSTANCE unless your really know what you
                are doing !!

                Please refer to to cubicweb-pyramid documentation on how to
                write this pyramid.ini file:
                https://cubicweb.readthedocs.io/en/latest/book/pyramid/settings/#pyramid-settings-file
                Without it authentication WON'T work.

            ''')

        policies.append(
            CWAuthTktAuthenticationPolicy(
                session_secret, False,
                defaults={
                    'hashalg': 'sha512',
                    'cookie_name': 'auth_tkt',
                    'timeout': 1200,
                    'reissue_time': 120,
                    'http_only': True,
                    'secure': True
                },
                prefix=session_prefix,
                **settings
            )
        )

        policies.append(
            CWAuthTktAuthenticationPolicy(
                persistent_secret, True,
                defaults={
                    'hashalg': 'sha512',
                    'cookie_name': 'pauth_tkt',
                    'max_age': 3600 * 24 * 30,
                    'reissue_time': 3600 * 24,
                    'http_only': True,
                    'secure': True
                },
                prefix=persistent_prefix,
                **settings
            )
        )

    kw = {}
    if asbool(settings.get('cubicweb.auth.groups_principals', True)):
        kw['callback'] = get_principals

    authpolicy = MultiAuthenticationPolicy(policies, **kw)
    config.registry['cubicweb.authpolicy'] = authpolicy

    config.set_authentication_policy(authpolicy)
    config.set_authorization_policy(ACLAuthorizationPolicy())