# copyright 2003-2012 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/>.

"""Source to query another RQL remote repository"""

__docformat__ = "restructuredtext en"

_ = unicode

from os.path import join

from base64 import b64decode

from logilab.common.configuration import REQUIRED

from yams.schema import role_name

from rql.nodes import Constant

from rql.utils import rqlvar_maker

from cubicweb import dbapi, server

from cubicweb import ValidationError, BadConnectionId, UnknownEid

from cubicweb.schema import VIRTUAL_RTYPES

from cubicweb.server.sources import (AbstractSource, ConnectionWrapper,

                                     TimedCache, dbg_st_search, dbg_results)

from cubicweb.server.msplanner import neged_relation

def uidtype(union, col, etype, args):

    select, col = union.locate_subquery(col, etype, args)

    return getattr(select.selection[col], 'uidtype', None)

class ReplaceByInOperator(Exception):

    def __init__(self, eids):

        self.eids = eids

class RemoteSource(AbstractSource):

    """Generic external repository source"""

    # boolean telling if modification hooks should be called when something is

    # modified in this source

    should_call_hooks = False

    # boolean telling if the repository should connect to this source during

    # migration

    connect_for_migration = False

    options = (

        ('cubicweb-user',

         {'type' : 'string',

          'default': REQUIRED,

          'help': 'user to use for connection on the distant repository',

          'group': 'remote-source', 'level': 0,

          }),

        ('cubicweb-password',

         {'type' : 'password',

          'default': '',

          'help': 'user to use for connection on the distant repository',

          'group': 'remote-source', 'level': 0,

          }),

        ('base-url',

         {'type' : 'string',

          'default': '',

          'help': 'url of the web site for the distant repository, if you want '

          'to generate external link to entities from this repository',

          'group': 'remote-source', 'level': 1,

          }),

        ('skip-external-entities',

         {'type' : 'yn',

          'default': False,

          'help': 'should entities not local to the source be considered or not',

          'group': 'remote-source', 'level': 0,

          }),

        ('synchronization-interval',

         {'type' : 'time',

          'default': '5min',

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

repository (default to 5 minutes).',

          'group': 'remote-source', 'level': 2,

          }))

    PUBLIC_KEYS = AbstractSource.PUBLIC_KEYS + ('base-url',)

    _conn = None

    def __init__(self, repo, source_config, eid=None):

        super(RemoteSource, self).__init__(repo, source_config, eid)

        self._query_cache = TimedCache(1800)

    def update_config(self, source_entity, processed_config):

        """update configuration from source entity"""

        super(RemoteSource, self).update_config(source_entity, processed_config)

        baseurl = processed_config.get('base-url')

        if baseurl and not baseurl.endswith('/'):

            processed_config['base-url'] += '/'

        self.config = processed_config

        self._skip_externals = processed_config['skip-external-entities']

        if source_entity is not None:

            self.latest_retrieval = source_entity.latest_retrieval

    def get_connection(self):

        try:

            return self._get_connection()

        except ConnectionError, ex:

            self.critical("can't get connection to source %s: %s", self.uri, ex)

            return ConnectionWrapper()

    def reset_caches(self):

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

        self._query_cache = TimedCache(1800)

    def init(self, activated, source_entity):

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

        self.load_mapping(source_entity._cw)

        if activated:

            interval = self.config['synchronization-interval']

            self.repo.looping_task(interval, self.synchronize)

            self.repo.looping_task(self._query_cache.ttl.seconds/10,

                                   self._query_cache.clear_expired)

            self.latest_retrieval = source_entity.latest_retrieval

    def load_mapping(self, session=None):

        self.support_entities = {}

        self.support_relations = {}

        self.dont_cross_relations = set(('owned_by', 'created_by'))

        self.cross_relations = set()

        assert self.eid is not None

        self._schemacfg_idx = {}

        self._load_mapping(session)

    etype_options = set(('write',))

    rtype_options = set(('maycross', 'dontcross', 'write',))

    def _check_options(self, schemacfg, allowedoptions):

        if schemacfg.options:

            options = set(w.strip() for w in schemacfg.options.split(':'))

        else:

            options = set()

        if options - allowedoptions:

            options = ', '.join(sorted(options - allowedoptions))

            msg = _('unknown option(s): %s' % options)

            raise ValidationError(schemacfg.eid, {role_name('options', 'subject'): msg})

        return options

    def add_schema_config(self, schemacfg, checkonly=False):

        """added CWSourceSchemaConfig, modify mapping accordingly"""

        try:

            ertype = schemacfg.schema.name

        except AttributeError:

            msg = schemacfg._cw._("attribute/relation can't be mapped, only "

                                  "entity and relation types")

            raise ValidationError(schemacfg.eid, {role_name('cw_for_schema', 'subject'): msg})

        if schemacfg.schema.__regid__ == 'CWEType':

            options = self._check_options(schemacfg, self.etype_options)

            if not checkonly:

                self.support_entities[ertype] = 'write' in options

        else: # CWRType

            if ertype in ('is', 'is_instance_of', 'cw_source') or ertype in VIRTUAL_RTYPES:

                msg = schemacfg._cw._('%s relation should not be in mapped') % ertype

                raise ValidationError(schemacfg.eid, {role_name('cw_for_schema', 'subject'): msg})

            options = self._check_options(schemacfg, self.rtype_options)

            if 'dontcross' in options:

                if 'maycross' in options:

                    msg = schemacfg._("can't mix dontcross and maycross options")

                    raise ValidationError(schemacfg.eid, {role_name('options', 'subject'): msg})

                if 'write' in options:

                    msg = schemacfg._("can't mix dontcross and write options")

                    raise ValidationError(schemacfg.eid, {role_name('options', 'subject'): msg})

                if not checkonly:

                    self.dont_cross_relations.add(ertype)

            elif not checkonly:

                self.support_relations[ertype] = 'write' in options

                if 'maycross' in options:

                    self.cross_relations.add(ertype)

        if not checkonly:

            # add to an index to ease deletion handling

            self._schemacfg_idx[schemacfg.eid] = ertype

    def del_schema_config(self, schemacfg, checkonly=False):

        """deleted CWSourceSchemaConfig, modify mapping accordingly"""

        if checkonly:

            return

        try:

            ertype = self._schemacfg_idx[schemacfg.eid]

            if ertype[0].isupper():

                del self.support_entities[ertype]

            else:

                if ertype in self.support_relations:

                    del self.support_relations[ertype]

                    if ertype in self.cross_relations:

                        self.cross_relations.remove(ertype)

                else:

                    self.dont_cross_relations.remove(ertype)

        except Exception:

            self.error('while updating mapping consequently to removal of %s',

                       schemacfg)

    def local_eid(self, cnx, extid, session):

        etype, dexturi, dextid = cnx.describe(extid)

        if dexturi == 'system' or not (

            dexturi in self.repo.sources_by_uri or self._skip_externals):

            assert etype in self.support_entities, etype

            eid = self.repo.extid2eid(self, str(extid), etype, session)

            if eid > 0:

                return eid, True

        elif dexturi in self.repo.sources_by_uri:

            source = self.repo.sources_by_uri[dexturi]

            cnx = session.cnxset.connection(source.uri)

            eid = source.local_eid(cnx, dextid, session)[0]

            return eid, False

        return None, None

    def synchronize(self, mtime=None):

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

        external repository

        """

        cnx = self.get_connection()

        try:

            extrepo = cnx._repo

        except AttributeError:

            # fake connection wrapper returned when we can't connect to the

            # external source (hence we've no chance to synchronize...)

            return

        etypes = self.support_entities.keys()

        if mtime is None:

            mtime = self.latest_retrieval

        updatetime, modified, deleted = extrepo.entities_modified_since(

            etypes, mtime)

        self._query_cache.clear()

        repo = self.repo

        session = repo.internal_session()

        source = repo.system_source

        try:

            for etype, extid in modified:

                try:

                    eid = self.local_eid(cnx, extid, session)[0]

                    if eid is not None:

                        rset = session.eid_rset(eid, etype)

                        entity = rset.get_entity(0, 0)

                        entity.complete(entity.e_schema.indexable_attributes())

                        source.index_entity(session, entity)

                except Exception:

                    self.exception('while updating %s with external id %s of source %s',

                                   etype, extid, self.uri)

                    continue

            for etype, extid in deleted:

                try:

                    eid = self.repo.extid2eid(self, str(extid), etype, session,

                                              insert=False)

                    # entity has been deleted from external repository but is not known here

                    if eid is not None:

                        entity = session.entity_from_eid(eid, etype)

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

                                         scleanup=self.eid)

                except Exception:

                    if self.repo.config.mode == 'test':

                        raise

                    self.exception('while updating %s with external id %s of source %s',

                                   etype, extid, self.uri)

                    continue

            self.latest_retrieval = updatetime

            session.execute('SET X latest_retrieval %(date)s WHERE X eid %(x)s',

                            {'x': self.eid, 'date': self.latest_retrieval})

            session.commit()

        finally:

            session.close()

    def get_connection(self):

        raise NotImplementedError()

    def check_connection(self, cnx):

        """check connection validity, return None if the connection is still valid

        else a new connection

        """

        if not isinstance(cnx, ConnectionWrapper):

            try:

                cnx.check()

                return # ok

            except BadConnectionId:

                pass

        # try to reconnect

        return self.get_connection()

    def syntax_tree_search(self, session, union, args=None, cachekey=None,

                           varmap=None):

        assert dbg_st_search(self.uri, union, varmap, args, cachekey)

        rqlkey = union.as_string(kwargs=args)

        try:

            results = self._query_cache[rqlkey]

        except KeyError:

            results = self._syntax_tree_search(session, union, args)

            self._query_cache[rqlkey] = results

        assert dbg_results(results)

        return results

    def _syntax_tree_search(self, session, union, args):

        """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.

        """

        if not args is None:

            args = args.copy()

        # get cached cursor anyway

        cu = session.cnxset[self.uri]

        if cu is None:

            # this is a ConnectionWrapper instance

            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 []

        translator = RQL2RQL(self)

        try:

            rql = translator.generate(session, union, args)

        except UnknownEid, ex:

            if server.DEBUG:

                print '  unknown eid', ex, 'no results'

            return []

        if server.DEBUG & server.DBG_RQL:

            print '  translated rql', rql

        try:

            rset = cu.execute(rql, args)

        except Exception, ex:

            self.exception(str(ex))

            msg = session._("error while querying source %s, some data may be missing")

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

            return []

        descr = rset.description

        if rset:

            needtranslation = []

            rows = rset.rows

            for i, etype in enumerate(descr[0]):

                if (etype is None or not self.schema.eschema(etype).final

                    or uidtype(union, i, etype, args)):

                    needtranslation.append(i)

            if needtranslation:

                cnx = session.cnxset.connection(self.uri)

                for rowindex in xrange(rset.rowcount - 1, -1, -1):

                    row = rows[rowindex]

                    localrow = False

                    for colindex in needtranslation:

                        if row[colindex] is not None: # optional variable

                            eid, local = self.local_eid(cnx, row[colindex], session)

                            if local:

                                localrow = True

                            if eid is not None:

                                row[colindex] = eid

                            else:

                                # skip this row

                                del rows[rowindex]

                                del descr[rowindex]

                                break

                    else:

                        # skip row if it only contains eids of entities which

                        # are actually from a source we also know locally,

                        # except if some args specified (XXX should actually

                        # check if there are some args local to the source)

                        if not (translator.has_local_eid or localrow):

                            del rows[rowindex]

                            del descr[rowindex]

            results = rows