# copyright 2003-2013 LOGILAB S.A. (Paris, 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 ldap user source

this source is for now limited to a read-only CWUser source

"""

from __future__ import division, with_statement

from base64 import b64decode

import ldap

from ldap.filter import escape_filter_chars

from rql.nodes import Relation, VariableRef, Constant, Function

from cubicweb import UnknownEid, RepositoryError

from cubicweb.server import ldaputils

from cubicweb.server.utils import cartesian_product

from cubicweb.server.sources import (AbstractSource, TrFunc, GlobTrFunc,

                                     TimedCache)

# search scopes

BASE = ldap.SCOPE_BASE

ONELEVEL = ldap.SCOPE_ONELEVEL

SUBTREE = ldap.SCOPE_SUBTREE

# map ldap protocol to their standard port

PROTO_PORT = {'ldap': 389,

              'ldaps': 636,

              'ldapi': None,

              }

class LDAPUserSource(ldaputils.LDAPSourceMixIn, AbstractSource):

    """LDAP read-only CWUser source"""

    support_entities = {'CWUser': False}

    options = ldaputils.LDAPSourceMixIn.options + (

        ('synchronization-interval',

         {'type' : 'time',

          'default': '1d',

          'help': 'interval between synchronization with the ldap \

directory (default to once a day).',

          'group': 'ldap-source', 'level': 3,

          }),

        ('cache-life-time',

         {'type' : 'time',

          'default': '2h',

          'help': 'life time of query cache (default to two hours).',

          'group': 'ldap-source', 'level': 3,

          }),

    )

    def update_config(self, source_entity, typedconfig):

        """update configuration from source entity. `typedconfig` is config

        properly typed with defaults set

        """

        super(LDAPUserSource, self).update_config(source_entity, typedconfig)

        self._interval = typedconfig['synchronization-interval']

        self._cache_ttl = max(71, typedconfig['cache-life-time'])

        self.reset_caches()

        # XXX copy from datafeed source

        if source_entity is not None:

            self._entity_update(source_entity)

        self.config = typedconfig

        # /end XXX

    def reset_caches(self):

        """method called during test to reset potential source caches"""

        self._cache = {}

        self._query_cache = TimedCache(self._cache_ttl)

    def init(self, activated, source_entity):

        """method called by the repository once ready to handle request"""

        super(LDAPUserSource, self).init(activated, source_entity)

        if activated:

            self.info('ldap init')

            # set minimum period of 5min 1s (the additional second is to

            # minimize resonnance effet)

            if self.user_rev_attrs['email']:

                self.repo.looping_task(max(301, self._interval), self.synchronize)

            self.repo.looping_task(self._cache_ttl // 10,

                                   self._query_cache.clear_expired)

    def synchronize(self):

        with self.repo.internal_session() as session:

            self.pull_data(session)

    def pull_data(self, session, force=False, raise_on_error=False):

        """synchronize content known by this repository with content in the

        external repository

        """

        self.info('synchronizing ldap source %s', self.uri)

        ldap_emailattr = self.user_rev_attrs['email']

        assert ldap_emailattr

        execute = session.execute

        cursor = session.system_sql("SELECT eid, extid FROM entities WHERE "

                                    "source='%s'" % self.uri)

        for eid, b64extid in cursor.fetchall():

            extid = b64decode(b64extid)

            self.debug('ldap eid %s', eid)

            # if no result found, _search automatically delete entity information

            res = self._search(session, extid, BASE)

            self.debug('ldap search %s', res)

            if res:

                ldapemailaddr = res[0].get(ldap_emailattr)

                if ldapemailaddr:

                    if isinstance(ldapemailaddr, list):

                        ldapemailaddr = ldapemailaddr[0] # XXX consider only the first email in the list

                    rset = execute('Any X,A WHERE '

                                   'X address A, U use_email X, U eid %(u)s',

                                   {'u': eid})

                    ldapemailaddr = unicode(ldapemailaddr)

                    for emaileid, emailaddr, in rset:

                        if emailaddr == ldapemailaddr:

                            break

                    else:

                        self.debug('updating email address of user %s to %s',

                                  extid, ldapemailaddr)

                        emailrset = execute('EmailAddress A WHERE A address %(addr)s',

                                            {'addr': ldapemailaddr})

                        if emailrset:

                            execute('SET U use_email X WHERE '

                                    'X eid %(x)s, U eid %(u)s',

                                    {'x': emailrset[0][0], 'u': eid})

                        elif rset:

                            if not execute('SET X address %(addr)s WHERE '

                                           'U primary_email X, U eid %(u)s',

                                           {'addr': ldapemailaddr, 'u': eid}):

                                execute('SET X address %(addr)s WHERE '

                                        'X eid %(x)s',

                                        {'addr': ldapemailaddr, 'x': rset[0][0]})

                        else:

                            # no email found, create it

                            _insert_email(session, ldapemailaddr, eid)

        session.commit()

    def ldap_name(self, var):

        if var.stinfo['relations']:

            relname = iter(var.stinfo['relations']).next().r_type

            return self.user_rev_attrs.get(relname)

        return None

    def prepare_columns(self, mainvars, rqlst):

        """return two list describing how to build the final results

        from the result of an ldap search (ie a list of dictionary)

        """

        columns = []

        global_transforms = []

        for i, term in enumerate(rqlst.selection):

            if isinstance(term, Constant):

                columns.append(term)

                continue

            if isinstance(term, Function): # LOWER, UPPER, COUNT...

                var = term.get_nodes(VariableRef)[0]

                var = var.variable

                try:

                    mainvar = var.stinfo['attrvar'].name

                except AttributeError: # no attrvar set

                    mainvar = var.name

                assert mainvar in mainvars

                trname = term.name

                ldapname = self.ldap_name(var)

                if trname in ('COUNT', 'MIN', 'MAX', 'SUM'):

                    global_transforms.append(GlobTrFunc(trname, i, ldapname))

                    columns.append((mainvar, ldapname))

                    continue

                if trname in ('LOWER', 'UPPER'):

                    columns.append((mainvar, TrFunc(trname, i, ldapname)))

                    continue

                raise NotImplementedError('no support for %s function' % trname)

            if term.name in mainvars:

                columns.append((term.name, 'dn'))

                continue

            var = term.variable

            mainvar = var.stinfo['attrvar'].name

            columns.append((mainvar, self.ldap_name(var)))

            #else:

            #    # probably a bug in rql splitting if we arrive here

            #    raise NotImplementedError

        return columns, global_transforms

    def syntax_tree_search(self, session, union,

                           args=None, cachekey=None, varmap=None, debug=0):

        """return result from this source for a rql query (actually from a rql

        syntax tree and a solution dictionary mapping each used variable to a

        possible type). If cachekey is given, the query necessary to fetch the

        results (but not the results themselves) may be cached using this key.

        """

        self.debug('ldap syntax tree search')

        # XXX not handled : transform/aggregat function, join on multiple users...

        assert len(union.children) == 1, 'union not supported'

        rqlst = union.children[0]

        assert not rqlst.with_, 'subquery not supported'

        rqlkey = rqlst.as_string(kwargs=args)

        try:

            results = self._query_cache[rqlkey]

        except KeyError:

            try:

                results = self.rqlst_search(session, rqlst, args)

                self._query_cache[rqlkey] = results

            except ldap.SERVER_DOWN:

                # cant connect to server

                msg = session._("can't connect to source %s, some data may be missing")

                session.set_shared_data('sources_error', msg % self.uri, txdata=True)

                return []

        return results

    def rqlst_search(self, session, rqlst, args):

        mainvars = []

        for varname in rqlst.defined_vars:

            for sol in rqlst.solutions:

                if sol[varname] == 'CWUser':

                    mainvars.append(varname)

                    break

        assert mainvars, rqlst

        columns, globtransforms = self.prepare_columns(mainvars, rqlst)

        eidfilters = [lambda x: x > 0]

        allresults = []

        generator = RQL2LDAPFilter(self, session, args, mainvars)

        for mainvar in mainvars:

            # handle restriction

            try:

                eidfilters_, ldapfilter = generator.generate(rqlst, mainvar)

            except GotDN as ex:

                assert ex.dn, 'no dn!'

                try:

                    res = [self._cache[ex.dn]]

                except KeyError:

                    res = self._search(session, ex.dn, BASE)

            except UnknownEid as ex:

                # raised when we are looking for the dn of an eid which is not

                # coming from this source

                res = []

            else:

                eidfilters += eidfilters_

                res = self._search(session, self.user_base_dn,

                                   self.user_base_scope, ldapfilter)

            allresults.append(res)

        # 1. get eid for each dn and filter according to that eid if necessary

        for i, res in enumerate(allresults):

            filteredres = []

            for resdict in res:

                # get sure the entity exists in the system table

                eid = self.repo.extid2eid(self, resdict['dn'], 'CWUser', session)

                for eidfilter in eidfilters:

                    if not eidfilter(eid):

                        break

                else:

                    resdict['eid'] = eid

                    filteredres.append(resdict)

            allresults[i] = filteredres

        # 2. merge result for each "mainvar": cartesian product

        allresults = cartesian_product(allresults)

        # 3. build final result according to column definition

        result = []

        for rawline in allresults:

            rawline = dict(zip(mainvars, rawline))

            line = []

            for varname, ldapname in columns:

                if ldapname is None:

                    value = None # no mapping available

                elif ldapname == 'dn':

                    value = rawline[varname]['eid']

                elif isinstance(ldapname, Constant):

                    if ldapname.type == 'Substitute':

                        value = args[ldapname.value]

                    else:

                        value = ldapname.value

                elif isinstance(ldapname, TrFunc):

                    value = ldapname.apply(rawline[varname])

                else:

                    value = rawline[varname].get(ldapname)

                line.append(value)

            result.append(line)

        for trfunc in globtransforms:

            result = trfunc.apply(result)

        #print '--> ldap result', result

        return result

    def _process_ldap_item(self, dn, iterator):

        itemdict = super(LDAPUserSource, self)._process_ldap_item(dn, iterator)

        self._cache[dn] = itemdict

        return itemdict

    def _process_no_such_object(self, session, dn):

        eid = self.repo.extid2eid(self, dn, 'CWUser', session, insert=False)

        if eid:

            self.warning('deleting ldap user with eid %s and dn %s', eid, dn)

            entity = session.entity_from_eid(eid, 'CWUser')

            self.repo.delete_info(session, entity, self.uri)

            self.reset_caches()

    def before_entity_insertion(self, session, lid, etype, eid, sourceparams):

        """called by the repository when an eid has been attributed for an

        entity stored here but the entity has not been inserted in the system

        table yet.

        This method must return the an Entity instance representation of this

        entity.

        """

        self.debug('ldap before entity insertion')

        entity = super(LDAPUserSource, self).before_entity_insertion(

            session, lid, etype, eid, sourceparams)

        res = self._search(session, lid, BASE)[0]

        for attr in entity.e_schema.indexable_attributes():

            entity.cw_edited[attr] = res[self.user_rev_attrs[attr]]

        return entity

    def after_entity_insertion(self, session, lid, entity, sourceparams):

        """called by the repository after an entity stored here has been

        inserted in the system table.

        """

        self.debug('ldap after entity insertion')

        super(LDAPUserSource, self).after_entity_insertion(

            session, lid, entity, sourceparams)

        for group in self.user_default_groups:

            session.execute('SET X in_group G WHERE X eid %(x)s, G name %(group)s',

                            {'x': entity.eid, 'group': group})

        # search for existant email first

        try:

            # lid = dn

            emailaddr = self._cache[lid][self.user_rev_attrs['email']]

        except KeyError:

            return

        if isinstance(emailaddr, list):

            emailaddr = emailaddr[0] # XXX consider only the first email in the list

        rset = session.execute('EmailAddress X WHERE X address %(addr)s',

                               {'addr': emailaddr})

        if rset:

            session.execute('SET U primary_email X WHERE U eid %(u)s, X eid %(x)s',

                            {'x': rset[0][0], 'u': entity.eid})

        else:

            # not found, create it

            _insert_email(session, emailaddr, entity.eid)

    def update_entity(self, session, entity):

        """replace an entity in the source"""

        raise RepositoryError('this source is read only')

    def delete_entity(self, session, entity):

        """delete an entity from the source"""

        raise RepositoryError('this source is read only')

def _insert_email(session, emailaddr, ueid):

    session.execute('INSERT EmailAddress X: X address %(addr)s, U primary_email X '

                    'WHERE U eid %(x)s', {'addr': emailaddr, 'x': ueid})

class GotDN(Exception):

    """exception used when a dn localizing the searched user has been found"""

    def __init__(self, dn):

        self.dn = dn

class RQL2LDAPFilter(object):

    """generate an LDAP filter for a rql query"""

    def __init__(self, source, session, args=None, mainvars=()):

        self.source = source

        self.repo = source.repo

        self._ldap_attrs = source.user_rev_attrs

        self._base_filters = source.base_filters