# 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 utilities for ldap sources

Part of the code is coming form Zope's LDAPUserFolder

Copyright (c) 2004 Jens Vagelpohl.
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.
"""

from __future__ import division # XXX why?

from datetime import datetime

import ldap
from ldap.ldapobject import ReconnectLDAPObject
from ldap.filter import filter_format
from ldapurl import LDAPUrl

from cubicweb import ValidationError, AuthenticationError, Binary
from cubicweb.server import utils
from cubicweb.server.sources import ConnectionWrapper

_ = unicode

# 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 LDAPSourceMixIn(object):
    """a mix-in for LDAP based source"""
    options = (
        ('auth-mode',
         {'type' : 'choice',
          'default': 'simple',
          'choices': ('simple', 'cram_md5', 'digest_md5', 'gssapi'),
          'help': 'authentication mode used to authenticate user to the ldap.',
          'group': 'ldap-source', 'level': 3,
          }),
        ('auth-realm',
         {'type' : 'string',
          'default': None,
          'help': 'realm to use when using gssapi/kerberos authentication.',
          'group': 'ldap-source', 'level': 3,
          }),

        ('data-cnx-dn',
         {'type' : 'string',
          'default': '',
          'help': 'user dn to use to open data connection to the ldap (eg used \
to respond to rql queries). Leave empty for anonymous bind',
          'group': 'ldap-source', 'level': 1,
          }),
        ('data-cnx-password',
         {'type' : 'string',
          'default': '',
          'help': 'password to use to open data connection to the ldap (eg used to respond to rql queries). Leave empty for anonymous bind.',
          'group': 'ldap-source', 'level': 1,
          }),

        ('user-base-dn',
         {'type' : 'string',
          'default': '',
          'help': 'base DN to lookup for users; disable user importation mechanism if unset',
          'group': 'ldap-source', 'level': 1,
          }),
        ('user-scope',
         {'type' : 'choice',
          'default': 'ONELEVEL',
          'choices': ('BASE', 'ONELEVEL', 'SUBTREE'),
          'help': 'user search scope (valid values: "BASE", "ONELEVEL", "SUBTREE")',
          'group': 'ldap-source', 'level': 1,
          }),
        ('user-classes',
         {'type' : 'csv',
          'default': ('top', 'posixAccount'),
          'help': 'classes of user (with Active Directory, you want to say "user" here)',
          'group': 'ldap-source', 'level': 1,
          }),
        ('user-filter',
         {'type': 'string',
          'default': '',
          'help': 'additional filters to be set in the ldap query to find valid users',
          'group': 'ldap-source', 'level': 2,
          }),
        ('user-login-attr',
         {'type' : 'string',
          'default': 'uid',
          'help': 'attribute used as login on authentication (with Active Directory, you want to use "sAMAccountName" here)',
          'group': 'ldap-source', 'level': 1,
          }),
        ('user-default-group',
         {'type' : 'csv',
          'default': ('users',),
          'help': 'name of a group in which ldap users will be by default. \
You can set multiple groups by separating them by a comma.',
          'group': 'ldap-source', 'level': 1,
          }),
        ('user-attrs-map',
         {'type' : 'named',
          'default': {'uid': 'login', 'gecos': 'email', 'userPassword': 'upassword'},
          'help': 'map from ldap user attributes to cubicweb attributes (with Active Directory, you want to use sAMAccountName:login,mail:email,givenName:firstname,sn:surname)',
          'group': 'ldap-source', 'level': 1,
          }),

    )

    _conn = None

    def _entity_update(self, source_entity):
        super(LDAPSourceMixIn, self)._entity_update(source_entity)
        if self.urls:
            if len(self.urls) > 1:
                raise ValidationError(source_entity.eid, {'url': _('can only have one url')})
            try:
                protocol, hostport = self.urls[0].split('://')
            except ValueError:
                raise ValidationError(source_entity.eid, {'url': _('badly formatted url')})
            if protocol not in PROTO_PORT:
                raise ValidationError(source_entity.eid, {'url': _('unsupported protocol')})

    def update_config(self, source_entity, typedconfig):
        """update configuration from source entity. `typedconfig` is config
        properly typed with defaults set
        """
        super(LDAPSourceMixIn, self).update_config(source_entity, typedconfig)
        self.authmode = typedconfig['auth-mode']
        self._authenticate = getattr(self, '_auth_%s' % self.authmode)
        self.cnx_dn = typedconfig['data-cnx-dn']
        self.cnx_pwd = typedconfig['data-cnx-password']
        self.user_base_dn = str(typedconfig['user-base-dn'])
        self.user_base_scope = globals()[typedconfig['user-scope']]
        self.user_login_attr = typedconfig['user-login-attr']
        self.user_default_groups = typedconfig['user-default-group']
        self.user_attrs = {'dn': 'eid', 'modifyTimestamp': 'modification_date'}
        self.user_attrs.update(typedconfig['user-attrs-map'])
        self.user_rev_attrs = dict((v, k) for k, v in self.user_attrs.iteritems())
        self.base_filters = [filter_format('(%s=%s)', ('objectClass', o))
                             for o in typedconfig['user-classes']]
        if typedconfig['user-filter']:
            self.base_filters.append(typedconfig['user-filter'])
        self._conn = None

    def connection_info(self):
        assert len(self.urls) == 1, self.urls
        protocol, hostport = self.urls[0].split('://')
        if protocol != 'ldapi' and not ':' in hostport:
            hostport = '%s:%s' % (hostport, PROTO_PORT[protocol])
        return protocol, hostport

    def get_connection(self):
        """open and return a connection to the source"""
        if self._conn is None:
            try:
                self._connect()
            except Exception:
                self.exception('unable to connect to ldap')
        return ConnectionWrapper(self._conn)

    def authenticate(self, session, login, password=None, **kwargs):
        """return CWUser eid for the given login/password if this account is
        defined in this source, else raise `AuthenticationError`

        two queries are needed since passwords are stored crypted, so we have
        to fetch the salt first
        """
        self.info('ldap authenticate %s', login)
        if not password:
            # On Windows + ADAM this would have succeeded (!!!)
            # You get Authenticated as: 'NT AUTHORITY\ANONYMOUS LOGON'.
            # we really really don't want that
            raise AuthenticationError()
        searchfilter = [filter_format('(%s=%s)', (self.user_login_attr, login))]
        searchfilter.extend(self.base_filters)
        searchstr = '(&%s)' % ''.join(searchfilter)
        # first search the user
        try:
            user = self._search(session, self.user_base_dn,
                                self.user_base_scope, searchstr)[0]
        except (IndexError, ldap.SERVER_DOWN):
            # no such user
            raise AuthenticationError()
        # check password by establishing a (unused) connection
        try:
            self._connect(user, password)
        except ldap.LDAPError as ex:
            # Something went wrong, most likely bad credentials
            self.info('while trying to authenticate %s: %s', user, ex)
            raise AuthenticationError()
        except Exception:
            self.error('while trying to authenticate %s', user, exc_info=True)
            raise AuthenticationError()
        eid = self.repo.extid2eid(self, user['dn'], 'CWUser', session, {})
        if eid < 0:
            # user has been moved away from this source
            raise AuthenticationError()
        return eid

    def _connect(self, user=None, userpwd=None):
        protocol, hostport = self.connection_info()
        self.info('connecting %s://%s as %s', protocol, hostport,
                  user and user['dn'] or 'anonymous')
        # don't require server certificate when using ldaps (will
        # enable self signed certs)
        ldap.set_option(ldap.OPT_X_TLS_REQUIRE_CERT, ldap.OPT_X_TLS_NEVER)
        url = LDAPUrl(urlscheme=protocol, hostport=hostport)
        conn = ReconnectLDAPObject(url.initializeUrl())
        # Set the protocol version - version 3 is preferred
        try:
            conn.set_option(ldap.OPT_PROTOCOL_VERSION, ldap.VERSION3)
        except ldap.LDAPError: # Invalid protocol version, fall back safely
            conn.set_option(ldap.OPT_PROTOCOL_VERSION, ldap.VERSION2)
        # Deny auto-chasing of referrals to be safe, we handle them instead
        # Required for AD
        try:
           conn.set_option(ldap.OPT_REFERRALS, 0)
        except ldap.LDAPError: # Cannot set referrals, so do nothing
           pass
        #conn.set_option(ldap.OPT_NETWORK_TIMEOUT, conn_timeout)
        #conn.timeout = op_timeout
        # Now bind with the credentials given. Let exceptions propagate out.
        if user is None:
            # no user specified, we want to initialize the 'data' connection,
            assert self._conn is None
            self._conn = conn
            # XXX always use simple bind for data connection
            if not self.cnx_dn:
                conn.simple_bind_s(self.cnx_dn, self.cnx_pwd)
            else:
                self._authenticate(conn, {'dn': self.cnx_dn}, self.cnx_pwd)
        else:
            # user specified, we want to check user/password, no need to return
            # the connection which will be thrown out
            self._authenticate(conn, user, userpwd)
        return conn

    def _auth_simple(self, conn, user, userpwd):
        conn.simple_bind_s(user['dn'], userpwd)

    def _auth_cram_md5(self, conn, user, userpwd):
        from ldap import sasl
        auth_token = sasl.cram_md5(user['dn'], userpwd)
        conn.sasl_interactive_bind_s('', auth_token)

    def _auth_digest_md5(self, conn, user, userpwd):
        from ldap import sasl
        auth_token = sasl.digest_md5(user['dn'], userpwd)
        conn.sasl_interactive_bind_s('', auth_token)

    def _auth_gssapi(self, conn, user, userpwd):
        # print XXX not proper sasl/gssapi
        import kerberos
        if not kerberos.checkPassword(user[self.user_login_attr], userpwd):
            raise Exception('BAD login / mdp')
        #from ldap import sasl
        #conn.sasl_interactive_bind_s('', sasl.gssapi())

    def _search(self, session, base, scope,
                searchstr='(objectClass=*)', attrs=()):
        """make an ldap query"""
        self.debug('ldap search %s %s %s %s %s', self.uri, base, scope,
                   searchstr, list(attrs))
        # XXX for now, we do not have connections set support for LDAP, so
        # this is always self._conn
        cnx = self.get_connection().cnx #session.cnxset.connection(self.uri).cnx
        if cnx is None:
            # 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 []
        try:
            res = cnx.search_s(base, scope, searchstr, attrs)
        except ldap.PARTIAL_RESULTS:
            res = cnx.result(all=0)[1]
        except ldap.NO_SUCH_OBJECT:
            self.info('ldap NO SUCH OBJECT %s %s %s', base, scope, searchstr)
            self._process_no_such_object(session, base)
            return []
        # except ldap.REFERRAL as e:
        #     cnx = self.handle_referral(e)
        #     try:
        #         res = cnx.search_s(base, scope, searchstr, attrs)
        #     except ldap.PARTIAL_RESULTS:
        #         res_type, res = cnx.result(all=0)
        result = []
        for rec_dn, rec_dict in res:
            # When used against Active Directory, "rec_dict" may not be
            # be a dictionary in some cases (instead, it can be a list)
            #
            # An example of a useless "res" entry that can be ignored
            # from AD is
            # (None, ['ldap://ForestDnsZones.PORTAL.LOCAL/DC=ForestDnsZones,DC=PORTAL,DC=LOCAL'])
            # This appears to be some sort of internal referral, but
            # we can't handle it, so we need to skip over it.
            try:
                items = rec_dict.iteritems()
            except AttributeError:
                continue
            else:
                itemdict = self._process_ldap_item(rec_dn, items)
                result.append(itemdict)
        self.debug('ldap built results %s', len(result))
        return result

    def _process_ldap_item(self, dn, iterator):
        """Turn an ldap received item into a proper dict."""
        itemdict = {'dn': dn}
        for key, value in iterator:
            if self.user_attrs.get(key) == 'upassword': # XXx better password detection
                value = value[0].encode('utf-8')
                # we only support ldap_salted_sha1 for ldap sources, see: server/utils.py
                if not value.startswith('{SSHA}'):
                    value = utils.crypt_password(value)
                itemdict[key] = Binary(value)
            elif self.user_attrs.get(key) == 'modification_date':
                itemdict[key] = datetime.strptime(value[0], '%Y%m%d%H%M%SZ')
            else:
                value = [unicode(val, 'utf-8', 'replace') for val in value]
                if len(value) == 1:
                    itemdict[key] = value = value[0]
                else:
                    itemdict[key] = value
        return itemdict

    def _process_no_such_object(self, session, dn):
        """Some search return NO_SUCH_OBJECT error, handle this (usually because
        an object whose dn is no more existent in ldap as been encountered).

        Do nothing by default, let sub-classes handle that.
        """