# Portions Copyright (C) 2009 Nokia Corporation and/or its subsidiary(-ies).
# All rights reserved. Contact: Pasi Eronen <pasi.eronen@nokia.com>
#
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# modification, are permitted provided that the following conditions
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#  * Redistributions of source code must retain the above copyright
#    notice, this list of conditions and the following disclaimer.
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#    copyright notice, this list of conditions and the following
#    disclaimer in the documentation and/or other materials provided
#    with the distribution.
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#    subsidiary(-ies) nor the names of its contributors may be used
#    to endorse or promote products derived from this software
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# Copyright The IETF Trust 2007, All Rights Reserved

from django.contrib.auth.backends import RemoteUserBackend
from django.contrib.auth.models import Group
from ietf.idtracker.models import IESGLogin, Role
from ietf.ietfauth.models import IetfUserProfile

from ietf.utils import log

AUTOMATIC_GROUPS = ["Area_Director", "Secretariat", "IETF_Chair",
                    "IAB_Chair", "IRTF_Chair", ]

class IetfUserBackend(RemoteUserBackend):

    def find_groups(username):
        """
        Role/Group:
        Area_Director          currently sitting AD
        IETF_Chair             currently sitting IETF Chair
        IAB_Chair              currently sitting IAB Chair
        IRTF_Chair             currently sitting IRTF Chair
        Secretariat            secretariat staff

        Roles/Groups NOT YET IMPLEMENTED
        WG_Chair               currently sitting chair of some WG
        IESG_Liaison           non-ADs on iesg@ietf.org and telechats
        Session_Chair          chairing a non-WG session in IETF meeting
        Ex_Area_Director       past AD
        """
        # Any group name added by this method should be added to the 
        # AUTOMATIC_GROUPS list
        groups = []
        try:
            login = IESGLogin.objects.get(login_name=username)
            if login.user_level == 1:
                groups.append("Area_Director")
            elif login.user_level == 0:
                groups.append("Secretariat")
            if login.person:
                for role in login.person.role_set.all():
                    if role.id == Role.IETF_CHAIR:
                        groups.append("IETF_Chair")
                    elif role.id == Role.IAB_CHAIR:
                        groups.append("IAB_Chair")
                    elif role.id == Role.IRTF_CHAIR:
                        groups.append("IRTF_Chair")
        except IESGLogin.DoesNotExist:
            pass
        #
        # Additional sources of group memberships: 
        # - wg_password table 
        # - other Roles 
        # - the /etc/.../*.perms files
        return groups

    find_groups = staticmethod(find_groups)

    def authenticate(self, remote_user):
        user = RemoteUserBackend.authenticate(self, remote_user)
        if not user:
            return user

        # Create profile if it doesn't exist
        try:
            profile = user.get_profile()
        except IetfUserProfile.DoesNotExist:
            profile = IetfUserProfile(user=user)
            profile.save()

        # Remove any automatic groups, the proper ones will be retrieved by 
        # find_groups
        groups = [group for group in user.groups.exclude(name__in=AUTOMATIC_GROUPS)]

        # Update group memberships
        group_names = IetfUserBackend.find_groups(user.username)
        for group_name in group_names:
            # Create groups as needed
            group,created = Group.objects.get_or_create(name=group_name)
            if created:
                log("IetfUserBackend created Group '%s'" % (group_name,))
            groups.append(group)
        user.groups = groups
        return user