##############################################################################
#
# Copyright (c) 2001 Zope Corporation and Contributors. All Rights
# Reserved.
#
# This software is subject to the provisions of the Zope Public License,
# Version 2.1 (ZPL).  A copy of the ZPL should accompany this
# distribution.
# THIS SOFTWARE IS PROVIDED "AS IS" AND ANY AND ALL EXPRESS OR IMPLIED
# WARRANTIES ARE DISCLAIMED, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
# WARRANTIES OF TITLE, MERCHANTABILITY, AGAINST INFRINGEMENT, AND FITNESS
# FOR A PARTICULAR PURPOSE.
#
##############################################################################
""" Classes: PluggableAuthService

$Id: PluggableAuthService.py 79562 2007-09-11 10:12:20Z wichert $
"""

import logging
import sys
import re
import types

from ZPublisher import BeforeTraverse

from Acquisition import Implicit, aq_parent, aq_base, aq_inner

from AccessControl import ClassSecurityInfo, ModuleSecurityInfo
from AccessControl.SecurityManagement import newSecurityManager
from AccessControl.SecurityManagement import getSecurityManager
from AccessControl.SecurityManagement import noSecurityManager
from AccessControl.Permissions import manage_users as ManageUsers
from AccessControl.User import nobody
from AccessControl.SpecialUsers import emergency_user

from App.ImageFile import ImageFile

from zExceptions import Unauthorized
from Persistence import PersistentMapping
from OFS.Folder import Folder
from OFS.Cache import Cacheable
from Products.StandardCacheManagers.RAMCacheManager import RAMCacheManager
from Products.PageTemplates.PageTemplateFile import PageTemplateFile
from ZTUtils import Batch
from App.class_init import default__class_init__ as InitializeClass

from OFS.interfaces import IObjectManager
from OFS.interfaces import ISimpleItem
from OFS.interfaces import IPropertyManager

from Products.PluginRegistry.PluginRegistry import PluginRegistry
import Products

from zope import event

from interfaces.authservice import IPluggableAuthService
from interfaces.authservice import _noroles
from interfaces.plugins import IExtractionPlugin
from interfaces.plugins import ILoginPasswordHostExtractionPlugin
from interfaces.plugins import IAuthenticationPlugin
from interfaces.plugins import IChallengePlugin
from interfaces.plugins import ICredentialsUpdatePlugin
from interfaces.plugins import ICredentialsResetPlugin
from interfaces.plugins import IUserFactoryPlugin
from interfaces.plugins import IAnonymousUserFactoryPlugin
from interfaces.plugins import IPropertiesPlugin
from interfaces.plugins import IGroupsPlugin
from interfaces.plugins import IRolesPlugin
from interfaces.plugins import IUpdatePlugin
from interfaces.plugins import IValidationPlugin
from interfaces.plugins import IUserEnumerationPlugin
from interfaces.plugins import IUserAdderPlugin
from interfaces.plugins import IGroupEnumerationPlugin
from interfaces.plugins import IRoleEnumerationPlugin
from interfaces.plugins import IRoleAssignerPlugin
from interfaces.plugins import IChallengeProtocolChooser
from interfaces.plugins import IRequestTypeSniffer

from events import PrincipalCreated

from permissions import SearchPrincipals

from PropertiedUser import PropertiedUser
from utils import _wwwdir
from utils import createViewName
from utils import createKeywords
from utils import classImplements

security = ModuleSecurityInfo(
    'Products.PluggableAuthService.PluggableAuthService' )

logger = logging.getLogger('PluggableAuthService')

#   Errors which plugins may raise, and which we suppress:
_SWALLOWABLE_PLUGIN_EXCEPTIONS = ( NameError
                                 , AttributeError
                                 , KeyError
                                 , TypeError
                                 , ValueError
                                 )

MultiPlugins = []
def registerMultiPlugin(meta_type):
    """ Register a 'multi-plugin' in order to expose it to the Add List
    """
    if meta_type in MultiPlugins:
        raise RuntimeError('Meta-type (%s) already available to Add List'
                           % meta_type)
    MultiPlugins.append(meta_type)

class DumbHTTPExtractor( Implicit ):

    security = ClassSecurityInfo()

    security.declarePrivate( 'extractCredentials' )
    def extractCredentials( self, request ):

        """ Pull HTTP credentials out of the request.
        """
        creds = {}
        login_pw = request._authUserPW()

        if login_pw is not None:
            name, password = login_pw

            creds[ 'login' ] = name
            creds[ 'password' ] = password
            creds[ 'remote_host' ] = request.get( 'REMOTE_HOST', '' )

            try:
                creds[ 'remote_address' ] = request.getClientAddr()
            except AttributeError:
                creds[ 'remote_address' ] = request.get( 'REMOTE_ADDR', '' )

        return creds

classImplements( DumbHTTPExtractor
               , ILoginPasswordHostExtractionPlugin
               )

InitializeClass( DumbHTTPExtractor )


class EmergencyUserAuthenticator( Implicit ):

    security = ClassSecurityInfo()

    security.declarePrivate( 'authenticateCredentials' )
    def authenticateCredentials( self, credentials ):

        """ Check credentials against the emergency user.
        """
        if isinstance( credentials, dict ):

            eu = emergency_user
            eu_name = eu.getUserName()
            login = credentials.get( 'login' )

            if login == eu_name:
                password = credentials.get( 'password' )

                if eu.authenticate( password, {} ):
                    return (eu_name, None)

        return (None, None)

classImplements( EmergencyUserAuthenticator
               , IAuthenticationPlugin
               )

InitializeClass( EmergencyUserAuthenticator )


class PluggableAuthService( Folder, Cacheable ):

    """ All-singing, all-dancing user folder.
    """
    security = ClassSecurityInfo()

    meta_type = 'Pluggable Auth Service'

    _id = id = 'acl_users'

    _emergency_user = emergency_user
    _nobody = nobody

    maxlistusers = -1   # Don't allow local role form to try to list us!

    def getId( self ):

        return self._id

    #
    #   IUserFolder implementation
    #
    security.declareProtected( ManageUsers, 'getUser' )
    def getUser( self, name ):

        """ See IUserFolder.
        """
        plugins = self._getOb( 'plugins' )

        user_info = self._verifyUser( plugins, login=name )

        if not user_info:
            return None

        return self._findUser( plugins, user_info['id'], user_info['login'])

    security.declareProtected( ManageUsers, 'getUserById' )
    def getUserById( self, id, default=None ):

        """ See IUserFolder.
        """
        plugins = self._getOb( 'plugins' )

        user_info = self._verifyUser( plugins, user_id=id )

        if not user_info:
            return default

        return self._findUser( plugins, user_info['id'], user_info['login'])

    security.declarePublic( 'validate' )     # XXX: public?
    def validate( self, request, auth='', roles=_noroles ):

        """ See IUserFolder.
        """
        plugins = self._getOb( 'plugins' )
        is_top = self._isTop()

        user_ids = self._extractUserIds(request, plugins)
        ( accessed
        , container
        , name
        , value
        ) = self._getObjectContext( request[ 'PUBLISHED' ], request )

        for user_id, login in user_ids:

            user = self._findUser(plugins, user_id, login, request=request)

            if aq_base( user ) is emergency_user:

                if is_top:
                    return user
                else:
                    return None

            if self._authorizeUser( user
                                  , accessed
                                  , container
                                  , name
                                  , value
                                  , roles
                                  ):
                return user

        if not is_top:
            return None

        #
        #   No other user folder above us can satisfy, and we have no user;
        #   return a constructed anonymous only if anonymous is authorized.
        #
        anonymous = self._createAnonymousUser( plugins )
        if self._authorizeUser( anonymous
                              , accessed
                              , container
                              , name
                              , value
                              , roles
                              ):
            return anonymous

        return None

    security.declareProtected( SearchPrincipals, 'searchUsers')
    def searchUsers(self, **kw):
        """ Search for users
        """
        search_id = kw.get( 'id', None )
        search_name = kw.get( 'name', None )

        result = []
        max_results = kw.get('max_results', '')
        sort_by = kw.get('sort_by', '')

        # We apply sorting and slicing here across all sets, so don't
        # make the plugin do it
        if sort_by:
            del kw['sort_by']
        if max_results:
            del kw['max_results']
        if search_name:
            if kw.get('id') is not None:
                del kw['id'] # don't even bother searching by id
            kw['login'] = kw['name']

        plugins = self._getOb( 'plugins' )
        enumerators = plugins.listPlugins( IUserEnumerationPlugin )

        for enumerator_id, enum in enumerators:
            try:
                user_list = enum.enumerateUsers(**kw)
                for user_info in user_list:
                    info = {}
                    info.update( user_info )
                    info[ 'userid' ] = info[ 'id' ]
                    info[ 'principal_type' ] = 'user'
                    if not info.has_key('title'):
                        info[ 'title' ] = info[ 'login' ]
                    result.append(info)

            except _SWALLOWABLE_PLUGIN_EXCEPTIONS:
                logger.debug( 'UserEnumerationPlugin %s error' % enumerator_id
                            , exc_info=True
                            )

        if sort_by:
            result.sort( lambda a, b: cmp( a.get(sort_by, '').lower()
                                         , b.get(sort_by, '').lower()
                                         ) )

        if max_results:
            try:
                max_results = int(max_results)
                result = result[:max_results]
            except ValueError:
                pass

        return tuple(result)

    security.declareProtected( SearchPrincipals, 'searchGroups')
    def searchGroups(self, **kw):
        """ Search for groups
        """
        search_id = kw.get( 'id', None )
        search_name = kw.get( 'name', None )

        result = []
        max_results = kw.get('max_results', '')
        sort_by = kw.get('sort_by', '')

        # We apply sorting and slicing here across all sets, so don't
        # make the plugin do it
        if sort_by:
            del kw['sort_by']
        if max_results:
            del kw['max_results']
        if search_name:
            if kw.get('id') is not None:
                del kw['id']
            if not kw.has_key('title'):
                kw['title'] = kw['name']

        plugins = self._getOb( 'plugins' )
        enumerators = plugins.listPlugins( IGroupEnumerationPlugin )

        for enumerator_id, enum in enumerators:
            try:
                 group_list = enum.enumerateGroups(**kw)
                 for group_info in group_list:
                    info = {}
                    info.update( group_info )
                    info[ 'groupid' ] = info[ 'id' ]
                    info[ 'principal_type' ] = 'group'
                    if not info.has_key('title'):
                        info[ 'title' ] = "(Group) %s" % info[ 'groupid' ]
                    result.append(info)
            except _SWALLOWABLE_PLUGIN_EXCEPTIONS:
                logger.debug( 'GroupEnumerationPlugin %s error' % enumerator_id
                            , exc_info=True
                            )

        if sort_by:
            result.sort( lambda a, b: cmp( a.get(sort_by, '').lower()
                                         , b.get(sort_by, '').lower()
                                         ) )

        if max_results:
            try:
                max_results = int(max_results)
                result = result[:max_results + 1]
            except ValueError:
                pass

        return tuple(result)

    security.declareProtected( SearchPrincipals, 'searchPrincipals')
    def searchPrincipals(self, groups_first=False, **kw):
        """ Search for principals (users, groups, or both)
        """
        max_results = kw.get( 'max_results', '' )

        search_id = kw.get( 'id', None )
        search_name = kw.get( 'name', None )
        if search_name:
            if not kw.has_key('title'):
                kw['title'] = search_name
            kw['login'] = search_name

        users = [ d.copy() for d in self.searchUsers( **kw ) ]
        groups = [ d.copy() for d in self.searchGroups( **kw ) ]

        if groups_first:
            result = groups + users
        else:
            result = users + groups

        if max_results:
            try:
                max_results = int( max_results )
                result = result[ :max_results + 1 ]
            except ValueError:
                pass

        return tuple( result )

    security.declarePrivate( '__creatable_by_emergency_user__' )
    def __creatable_by_emergency_user__( self ):
        return 1

    security.declarePrivate( '_setObject' )
    def _setObject( self, id, object, roles=None, user=None, set_owner=0 ):
        #
        #   Override ObjectManager's version to change the default for
        #   'set_owner' (we don't want to enforce ownership on contained
        #   objects).
        Folder._setObject( self, id, object, roles, user, set_owner )

    security.declarePrivate( '_delOb' )
    def _delOb( self, id ):
        #
        #   Override ObjectManager's version to clean up any plugin
        #   registrations for the deleted object
        #
        plugins = self._getOb( 'plugins', None )

        if plugins is not None:
            plugins.removePluginById( id )

        Folder._delOb( self, id )

    #
    # ZMI stuff
    #
    
    arrow_right_gif = ImageFile( 'www/arrow-right.gif', globals() )
    arrow_left_gif = ImageFile( 'www/arrow-left.gif', globals() )
    arrow_up_gif = ImageFile( 'www/arrow-up.gif', globals() )
    arrow_down_gif = ImageFile( 'www/arrow-down.gif', globals() )

    security.declareProtected(ManageUsers, 'manage_search')
    manage_search = PageTemplateFile('www/pasSearch', globals())

    manage_options = ( Folder.manage_options[:1]
                      + ( { 'label' : 'Search'
                          , 'action': 'manage_search' }
                        ,
                        )
                      + Folder.manage_options[2:]
                      + Cacheable.manage_options
                      )

    security.declareProtected(ManageUsers, 'resultsBatch')
    def resultsBatch(self, results, REQUEST, size=20, orphan=2, overlap=0):
        """ ZMI helper for getting batching for displaying search results
        """
        try:
            start_val = REQUEST.get('batch_start', '0')
            start = int(start_val)
            size = int(REQUEST.get('batch_size', size))
        except ValueError:
            start = 0

        batch = Batch(results, size, start, 0, orphan, overlap)

        if batch.end < len(results):
            qs = self._getBatchLink( REQUEST.get('QUERY_STRING', '')
                                   , start
                                   , batch.end
                                   )
            REQUEST.set( 'next_batch_url'
                       , '%s?%s' % (REQUEST.get('URL'), qs)
                       )

        if start > 0:
            new_start = start - size - 1

            if new_start < 0:
                new_start = 0

            qs = self._getBatchLink( REQUEST.get('QUERY_STRING', '')
                                   , start
                                   , new_start
                                   )
            REQUEST.set( 'previous_batch_url'
                       , '%s?%s' % (REQUEST.get('URL'), qs)
                       )

        return batch


    security.declarePrivate('_getBatchLink')
    def _getBatchLink(self, qs, old_start, new_start):
        """ Internal helper to generate correct query strings
        """
        if new_start is not None:
            if not qs:
                qs = 'batch_start=%d' % new_start
            elif qs.startswith('batch_start='):
                qs = qs.replace( 'batch_start=%d' % old_start
                               , 'batch_start=%d' % new_start
                               )
            elif qs.find('&batch_start=') != -1:
                qs = qs.replace( '&batch_start=%d' % old_start
                               , '&batch_start=%d' % new_start
                               )
            else:
                qs = '%s&batch_start=%d' % (qs, new_start)

        return qs


    #
    #   Helper methods
    #
    security.declarePrivate( '_extractUserIds' )
    def _extractUserIds( self, request, plugins ):

        """ request -> [ validated_user_id ]

        o For each set of extracted credentials, try to authenticate
          a user;  accumulate a list of the IDs of such users over all
          our authentication and extraction plugins.
        """
        try:
            extractors = plugins.listPlugins( IExtractionPlugin )
        except _SWALLOWABLE_PLUGIN_EXCEPTIONS:
            logger.debug('Extractor plugin listing error', exc_info=True)
            extractors = ()

        if not extractors:
            extractors = ( ( 'default', DumbHTTPExtractor() ), )

        try:
            authenticators = plugins.listPlugins( IAuthenticationPlugin )
        except _SWALLOWABLE_PLUGIN_EXCEPTIONS:
            logger.debug('Authenticator plugin listing error', exc_info=True)
            authenticators = ()

        result = []

        for extractor_id, extractor in extractors:

            try:
                credentials = extractor.extractCredentials( request )
            except _SWALLOWABLE_PLUGIN_EXCEPTIONS:
                logger.debug( 'ExtractionPlugin %s error' % extractor_id
                            , exc_info=True
                            )
                continue

            if credentials:

                try:
                    credentials[ 'extractor' ] = extractor_id # XXX: in key?
                    # Test if ObjectCacheEntries.aggregateIndex would work
                    items = credentials.items()
                    items.sort()
                except _SWALLOWABLE_PLUGIN_EXCEPTIONS:
                    logger.debug( 'Credentials error: %s' % credentials
                                , exc_info=True
                                )
                    continue

                # First try to authenticate against the emergency
                # user and return immediately if authenticated
                user_id, name = self._tryEmergencyUserAuthentication(
                                                            credentials )

                if user_id is not None:
                    return [ ( user_id, name ) ]

                # Now see if the user ids can be retrieved from the cache
                view_name = createViewName('_extractUserIds', credentials.get('login'))
                keywords = createKeywords(**credentials)
                user_ids = self.ZCacheable_get( view_name=view_name
                                              , keywords=keywords
                                              , default=None
                                              )
                if user_ids is None:
                    user_ids = []

                    for authenticator_id, auth in authenticators:

                        try:
                            uid_and_info = auth.authenticateCredentials(
                                credentials )

                            if uid_and_info is None:
                                continue

                            user_id, info = uid_and_info

                        except _SWALLOWABLE_PLUGIN_EXCEPTIONS:
                            msg = 'AuthenticationPlugin %s error' % ( 
                                    authenticator_id, )
                            logger.debug(msg, exc_info=True) 
                            continue

                        if user_id is not None:
                            user_ids.append( (user_id, info) )

                    if user_ids:
                        self.ZCacheable_set( user_ids
                                           , view_name=view_name
                                           , keywords=keywords
                                           )

                result.extend( user_ids )

        # Emergency user via HTTP basic auth always wins
        user_id, name = self._tryEmergencyUserAuthentication(
                DumbHTTPExtractor().extractCredentials( request ) )

        if user_id is not None:
            return [ ( user_id, name ) ]

        return result

    security.declarePrivate( '_tryEmergencyUserAuthentication' )
    def _tryEmergencyUserAuthentication( self, credentials ):

        """ credentials -> emergency_user or None
        """
        try:
            eua = EmergencyUserAuthenticator()
            user_id, name = eua.authenticateCredentials( credentials )
        except _SWALLOWABLE_PLUGIN_EXCEPTIONS:
            logger.debug('Credentials error: %s' % credentials, exc_info=True)
            user_id, name = ( None, None )

        return ( user_id, name )

    security.declarePrivate( '_getGroupsForPrincipal' )
    def _getGroupsForPrincipal( self
                              , principal
                              , request=None
                              , plugins=None
                              , ignore_plugins=None
                              ):
        all_groups = {}

        if ignore_plugins is None:
            ignore_plugins = ()

        if plugins is None:
            plugins = self._getOb( 'plugins' )
        groupmakers = plugins.listPlugins( IGroupsPlugin )

        for groupmaker_id, groupmaker in groupmakers:

            if groupmaker_id in ignore_plugins:
                continue
            groups = groupmaker.getGroupsForPrincipal( principal, request )
            for group in groups:
                principal._addGroups( [ group ] )
                all_groups[ group ] = 1

        return all_groups.keys()

    security.declarePrivate( '_createAnonymousUser' )
    def _createAnonymousUser( self, plugins ):

        """ Allow IAnonymousUserFactoryPlugins to create or fall back.
        """
        factories = plugins.listPlugins( IAnonymousUserFactoryPlugin )

        for factory_id, factory in factories:

            anon = factory.createAnonymousUser()

            if anon is not None:
                return anon.__of__( self )

        return nobody.__of__( self )

    security.declarePrivate( '_createUser' )
    def _createUser( self, plugins, user_id, name ):

        """ Allow IUserFactoryPlugins to create, or fall back to default.
        """
        factories = plugins.listPlugins( IUserFactoryPlugin )

        for factory_id, factory in factories:

            user = factory.createUser( user_id, name )

            if user is not None:
                return user.__of__( self )

        return PropertiedUser( user_id, name ).__of__( self )

    security.declarePrivate( '_findUser' )
    def _findUser( self, plugins, user_id, name=None, request=None ):

        """ user_id -> decorated_user
        """
        if user_id == self._emergency_user.getUserName():
            return self._emergency_user

        # See if the user can be retrieved from the cache
        view_name = createViewName('_findUser', user_id)
        keywords = createKeywords(user_id=user_id, name=name)
        user = self.ZCacheable_get( view_name=view_name
                                  , keywords=keywords
                                  , default=None
                                  )

        if user is None:

            user = self._createUser( plugins, user_id, name )
            propfinders = plugins.listPlugins( IPropertiesPlugin )

            for propfinder_id, propfinder in propfinders:

                data = propfinder.getPropertiesForUser( user, request )
                if data:
                    user.addPropertysheet( propfinder_id, data )

            groups = self._getGroupsForPrincipal( user, request
                                                , plugins=plugins )
            user._addGroups( groups )

            rolemakers = plugins.listPlugins( IRolesPlugin )

            for rolemaker_id, rolemaker in rolemakers:

                roles = rolemaker.getRolesForPrincipal( user, request )

                if roles:
                    user._addRoles( roles )

            user._addRoles( ['Authenticated'] )

            # Cache the user if caching is enabled
            base_user = aq_base(user)
            if getattr(base_user, '_p_jar', None) is None:
                self.ZCacheable_set( base_user
                                   , view_name=view_name
                                   , keywords=keywords
                                   )

        return user.__of__( self )

    security.declarePrivate( '_verifyUser' )
    def _verifyUser( self, plugins, user_id=None, login=None ):

        """ user_id -> info_dict or None
        """
        criteria = {'exact_match': True}

        if user_id is not None:
            criteria[ 'id' ] = user_id

        if login is not None:
            criteria[ 'login' ] = login

        if criteria:
            view_name = createViewName('_verifyUser', user_id or login)
            keywords = createKeywords(**criteria)
            cached_info = self.ZCacheable_get( view_name=view_name
                                             , keywords=keywords
                                             , default=None
                                             )

            if cached_info is not None:
                return cached_info


            enumerators = plugins.listPlugins( IUserEnumerationPlugin )

            for enumerator_id, enumerator in enumerators:
                try:
                    info = enumerator.enumerateUsers( **criteria )

                    if info:
                        # Put the computed value into the cache
                        self.ZCacheable_set( info[0]
                                           , view_name=view_name
                                           , keywords=keywords
                                           )
                        return info[0]

                except _SWALLOWABLE_PLUGIN_EXCEPTIONS:
                    msg = 'UserEnumerationPlugin %s error' % enumerator_id
                    logger.debug(msg, exc_info=True)

        return None

    security.declarePrivate( '_authorizeUser' )
    def _authorizeUser( self
                      , user
                      , accessed
                      , container
                      , name
                      , value
                      , roles=_noroles
                      ):

        """ -> boolean (whether user has roles).

        o Add the user to the SM's stack, if successful.

        o Return
        """
        user = aq_base( user ).__of__( self )
        newSecurityManager( None, user )
        security = getSecurityManager()
        try:
            try:
                if roles is _noroles:
                    if security.validate( accessed
                                        , container
                                        , name
                                        , value
                                        ):
                        return 1
                else:
                    if security.validate( accessed
                                        , container
                                        , name
                                        , value
                                        , roles
                                        ):
                        return 1
            except:
                noSecurityManager()
                raise

        except Unauthorized:
            pass

        return 0


    security.declarePrivate( '_isTop' )
    def _isTop( self ):

        """ Are we the user folder in the root object?
        """
        try:
            parent = aq_base( aq_parent( self ) )
            if parent is None:
                return 0
            return parent.isTopLevelPrincipiaApplicationObject
        except AttributeError:
            return 0


    security.declarePrivate( '_getObjectContext' )
    def _getObjectContext( self, v, request ):

        """ request -> ( a, c, n, v )

        o 'a 'is the object the object was accessed through

        o 'c 'is the physical container of the object

        o 'n 'is the name used to access the object

        o 'v' is the object (value) we're validating access to

        o XXX:  Lifted from AccessControl.User.BasicUserFolder._getobcontext
        """
        if len( request.steps ) == 0: # someone deleted root index_html

            request[ 'RESPONSE' ].notFoundError(
                'no default view (root default view was probably deleted)' )

        root = request[ 'PARENTS' ][ -1 ]
        request_container = aq_parent( root )

        n = request.steps[ -1 ]

        # default to accessed and container as v.aq_parent
        a = c = request[ 'PARENTS' ][ 0 ]

        # try to find actual container
        inner = aq_inner( v )
        innerparent = aq_parent( inner )

        if innerparent is not None:

            # this is not a method, we needn't treat it specially
            c = innerparent

        elif hasattr(v, 'im_self'):

            # this is a method, we need to treat it specially
            c = v.im_self
            c = aq_inner( v )

        # if pub's aq_parent or container is the request container, it
        # means pub was accessed from the root
        if a is request_container:
            a = root

        if c is request_container:
            c = root

        return a, c, n, v

    security.declarePrivate( '_getEmergencyUser' )
    def _getEmergencyUser( self ):

        return emergency_user.__of__( self )


    security.declarePrivate( '_doAddUser' )
    def _doAddUser( self, login, password, roles, domains, **kw ):
        """ Create a user with login, password and roles if, and only if,
            we have a registered user manager and role manager that will
            accept specific plugin interfaces.
        """
        plugins = self._getOb( 'plugins' )
        useradders = plugins.listPlugins( IUserAdderPlugin )
        roleassigners = plugins.listPlugins( IRoleAssignerPlugin )

        user = None

        if not (useradders and roleassigners):
            raise NotImplementedError( "There are no plugins"
                                       " that can create"
                                       " users and assign roles to them." )

        for useradder_id, useradder in useradders:
            if useradder.doAddUser( login, password ):
                # XXX: Adds user to cache, but without roles...
                user = self.getUser( login )
                break

        # XXX What should we do if no useradder was succesfull?

        for roleassigner_id, roleassigner in roleassigners:
            for role in roles:
                try:
                    roleassigner.doAssignRoleToPrincipal( user.getId(), role )
                except _SWALLOWABLE_PLUGIN_EXCEPTIONS:
                    logger.debug( 'RoleAssigner %s error' % roleassigner_id
                                , exc_info=True
                                )
                    pass

        if user is not None:
            event.notify(PrincipalCreated(user))


    security.declarePublic('all_meta_types')
    def all_meta_types(self):
        """ What objects can be put in here?
        """
        allowed_types = tuple(MultiPlugins) + (RAMCacheManager.meta_type,)

        return [x for x in Products.meta_types if x['name'] in allowed_types]

    security.declarePrivate( 'manage_beforeDelete' )
    def manage_beforeDelete(self, item, container):
        if item is self:
            try:
                del container.__allow_groups__
            except:
                pass

            handle = self.meta_type + '/' + self.getId()
            BeforeTraverse.unregisterBeforeTraverse(container, handle)

    security.declarePrivate( 'manage_afterAdd' )
    def manage_afterAdd(self, item, container):
        if item is self:
            container.__allow_groups__ = aq_base(self)

            handle = self.meta_type + '/' + self.getId()
            container = container.this()
            nc = BeforeTraverse.NameCaller(self.getId())
            BeforeTraverse.registerBeforeTraverse(container, nc, handle)

    def __call__(self, container, req):
        """ The __before_publishing_traverse__ hook.
        """
        resp = req['RESPONSE']
        req._hold(ResponseCleanup(resp))
        stack = getattr(resp, '_unauthorized_stack', [])
        stack.append(resp._unauthorized)
        resp._unauthorized_stack = stack
        resp._unauthorized = self._unauthorized
        resp._has_challenged = False

    #
    # Response override
    #
    def _unauthorized(self):
        req = self.REQUEST
        resp = req['RESPONSE']
        if resp._has_challenged: # Been here already
            return
        if not self.challenge(req, resp):
            # Need to fall back here
            resp = self._cleanupResponse()
            resp._unauthorized()
        else:
            resp._has_challenged = True

    def challenge(self, request, response):
        plugins = self._getOb('plugins')

        # Find valid protocols for this request type
        valid_protocols = []
        choosers = []
        try:
            choosers = plugins.listPlugins( IChallengeProtocolChooser )
        except KeyError:
            # Work around the fact that old instances might not have
            # IChallengeProtocolChooser registered with the
            # PluginRegistry.
            pass

        for chooser_id, chooser in choosers:
            choosen = chooser.chooseProtocols(request)
            if choosen is None:
                continue
            valid_protocols.extend(choosen)

        # Go through all challenge plugins
        challengers = plugins.listPlugins( IChallengePlugin )

        protocol = None

        for challenger_id, challenger in challengers:
            challenger_protocol = getattr(challenger, 'protocol',
                                          challenger_id)
            if valid_protocols and challenger_protocol not in valid_protocols:
                # Skip invalid protocol for this request type.
                continue
            if protocol is None or protocol == challenger_protocol:
                if challenger.challenge(request, response):
                    protocol = challenger_protocol

        if protocol is not None:
            # something fired, so it was a successful PAS challenge
            return True

        # nothing fired, so trigger the fallback
        return False

    def _cleanupResponse(self):
        resp = self.REQUEST['RESPONSE']
        # No errors of any sort may propagate, and we don't care *what*
        # they are, even to log them.
        stack = getattr(resp, '_unauthorized_stack', [])

        if stack:
            resp._unauthorized = stack.pop()
        else:
            try:
                del resp._unauthorized
            except:
                pass

        return resp

    security.declarePublic( 'hasUsers' )
    def hasUsers(self):
        """Zope quick start sacrifice.

        The quick start page expects a hasUsers() method.
        """
        return True

    security.declarePublic('updateCredentials')
    def updateCredentials(self, request, response, login, new_password):
        """Central updateCredentials method

        This method is needed for cases where the credentials storage and
        the credentials extraction is handled by different plugins. Example
        case would be if the CookieAuthHelper is used as a Challenge and
        Extraction plugin only to take advantage of the login page feature
        but the credentials are not stored in the CookieAuthHelper cookie
        but somewhere else, like in a Session.
        """
        plugins = self._getOb('plugins')
        cred_updaters = plugins.listPlugins(ICredentialsUpdatePlugin)

        for updater_id, updater in cred_updaters:
            updater.updateCredentials(request, response, login, new_password)


    security.declarePublic('logout')
    def logout(self, REQUEST):
        """Publicly accessible method to log out a user
        """
        self.resetCredentials(REQUEST, REQUEST['RESPONSE'])

        # Little bit of a hack: Issuing a redirect to the same place
        # where the user was so that in the second request the now-destroyed
        # credentials can be acted upon to e.g. go back to the login page
        referrer = REQUEST.get('HTTP_REFERER') # HTTP_REFERER is optional header
        if referrer:
            REQUEST['RESPONSE'].redirect(referrer)

    security.declarePublic('resetCredentials')
    def resetCredentials(self, request, response):
        """Reset credentials by informing all active resetCredentials plugins
        """
        user = getSecurityManager().getUser()
        if aq_base(user) is not nobody:
            plugins = self._getOb('plugins')
            cred_resetters = plugins.listPlugins(ICredentialsResetPlugin)

            for resetter_id, resetter in cred_resetters:
                resetter.resetCredentials(request, response)

classImplements( PluggableAuthService
               , (IPluggableAuthService, IObjectManager, IPropertyManager)
               )

InitializeClass( PluggableAuthService )

class ResponseCleanup:
    def __init__(self, resp):
        self.resp = resp

    def __del__(self):
        # Free the references.
        #
        # No errors of any sort may propagate, and we don't care *what*
        # they are, even to log them.
        stack = getattr(self.resp, '_unauthorized_stack', [])
        old = None

        while stack:
            old = stack.pop()

        if old is not None:
            self.resp._unauthorized = old
        else:
            try:
                del self.resp._unauthorized
            except:
                pass

        try:
            del self.resp
        except:
            pass

_PLUGIN_TYPE_INFO = (
    ( IExtractionPlugin
    , 'IExtractionPlugin'
    , 'extraction'
    , "Extraction plugins are responsible for extracting credentials "
      "from the request."
    )
  , ( IAuthenticationPlugin
    , 'IAuthenticationPlugin'
    , 'authentication'
    , "Authentication plugins are responsible for validating credentials "
      "generated by the Extraction Plugin."
    )
  , ( IChallengePlugin
    , 'IChallengePlugin'
    , 'challenge'
    , "Challenge plugins initiate a challenge to the user to provide "
      "credentials."
    )
  , ( ICredentialsUpdatePlugin
    , 'ICredentialsUpdatePlugin'
    , 'update credentials'
    , "Credential update plugins respond to the user changing "
      "credentials."
    )
  , ( ICredentialsResetPlugin
    , 'ICredentialsResetPlugin'
    , 'reset credentials'
    , "Credential clear plugins respond to a user logging out."
    )
  , ( IUserFactoryPlugin
    , 'IUserFactoryPlugin'
    , 'userfactory'
    , "Create users."
    )
  , ( IAnonymousUserFactoryPlugin
    , 'IAnonymousUserFactoryPlugin'
    , 'anonymoususerfactory'
    , "Create anonymous users."
    )
  , ( IPropertiesPlugin
    , 'IPropertiesPlugin'
    , 'properties'
    , "Properties plugins generate property sheets for users."
    )
  , ( IGroupsPlugin
    , 'IGroupsPlugin'
    , 'groups'
    , "Groups plugins determine the groups to which a user belongs."
    )
  , ( IRolesPlugin
    , 'IRolesPlugin'
    , 'roles'
    , "Roles plugins determine the global roles which a user has."
    )
  , ( IUpdatePlugin
    , 'IUpdatePlugin'
    , 'update'
    , "Update plugins allow the user or the application to update "
      "the user's properties."
    )
  , ( IValidationPlugin
    , 'IValidationPlugin'
    , 'validation'
    , "Validation plugins specify allowable values for user properties "
      "(e.g., minimum password length, allowed characters, etc.)"
    )
  , ( IUserEnumerationPlugin
    , 'IUserEnumerationPlugin'
    , 'user_enumeration'
    , "Enumeration plugins allow querying users by ID, and searching for "
      "users who match particular criteria."
    )
  , ( IUserAdderPlugin
    , 'IUserAdderPlugin'
    , 'user_adder'
    , "User Adder plugins allow the Pluggable Auth Service to create users."
    )
  , ( IGroupEnumerationPlugin
    , 'IGroupEnumerationPlugin'
    , 'group_enumeration'
    , "Enumeration plugins allow querying groups by ID."
    )
  , ( IRoleEnumerationPlugin
    , 'IRoleEnumerationPlugin'
    , 'role_enumeration'
    , "Enumeration plugins allow querying roles by ID."
    )
  , ( IRoleAssignerPlugin
    , 'IRoleAssignerPlugin'
    , 'role_assigner'
    , "Role Assigner plugins allow the Pluggable Auth Service to assign"
      " roles to principals."
    )
  , ( IChallengeProtocolChooser
    , 'IChallengeProtocolChooser'
    , 'challenge_protocol_chooser'
    , "Challenge Protocol Chooser plugins decide what authorization"
      "protocol to use for a given request type."
    )
  , ( IRequestTypeSniffer
    , 'IRequestTypeSniffer'
    , 'request_type_sniffer'
    , "Request Type Sniffer plugins detect the type of an incoming request."
    )
  )

def addPluggableAuthService( dispatcher
                           , base_profile=None
                           , extension_profiles=()
                           , create_snapshot=True
                           , setup_tool_id='setup_tool'
                           , REQUEST=None
                           ):
    """ Add a PluggableAuthService to 'dispatcher'.

    o BBB for non-GenericSetup use.
    """
    pas = PluggableAuthService()
    preg = PluginRegistry( _PLUGIN_TYPE_INFO )
    preg._setId( 'plugins' )
    pas._setObject( 'plugins', preg )
    dispatcher._setObject( pas.getId(), pas )

    if REQUEST is not None:
        REQUEST['RESPONSE'].redirect(
                                '%s/manage_workspace'
                                '?manage_tabs_message='
                                'PluggableAuthService+added.'
                              % dispatcher.absolute_url() )

def addConfiguredPASForm(dispatcher):
    """ Wrap the PTF in 'dispatcher', including 'profile_registry' in options.
    """
    from Products.GenericSetup import EXTENSION
    from Products.GenericSetup import profile_registry

    wrapped = PageTemplateFile( 'pasAddForm', _wwwdir ).__of__( dispatcher )

    base_profiles = []
    extension_profiles = []

    for info in profile_registry.listProfileInfo(for_=IPluggableAuthService):
        if info.get('type') == EXTENSION:
            extension_profiles.append(info)
        else:
            base_profiles.append(info)

    return wrapped( base_profiles=tuple(base_profiles),
                    extension_profiles =tuple(extension_profiles) )

def addConfiguredPAS( dispatcher
                    , base_profile
                    , extension_profiles=()
                    , create_snapshot=True
                    , setup_tool_id='setup_tool'
                    , REQUEST=None
                    ):
    """ Add a PluggableAuthService to 'self.
    """
    from Products.GenericSetup.tool import SetupTool

    pas = PluggableAuthService()
    preg = PluginRegistry( _PLUGIN_TYPE_INFO )
    preg._setId( 'plugins' )
    pas._setObject( 'plugins', preg )
    dispatcher._setObject( pas.getId(), pas )

    pas = dispatcher._getOb( pas.getId() )    # wrapped
    tool = SetupTool( setup_tool_id )
    pas._setObject( tool.getId(), tool )

    tool = pas._getOb( tool.getId() )       # wrapped
    tool.setImportContext( 'profile-%s' % base_profile )
    tool.runAllImportSteps()

    for extension_profile in extension_profiles:
        tool.setImportContext( 'profile-%s' % extension_profile )
        tool.runAllImportSteps()

    tool.setImportContext( 'profile-%s' % base_profile )

    if create_snapshot:
        tool.createSnapshot( 'initial_configuration' )

    if REQUEST is not None:
        REQUEST['RESPONSE'].redirect(
                                '%s/manage_workspace'
                                '?manage_tabs_message='
                                'PluggableAuthService+added.'
                              % dispatcher.absolute_url() )

