# copyright 2003-2010 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 server sources support"""

__docformat__ = "restructuredtext en"

from os.path import join, splitext

from datetime import datetime, timedelta

from logging import getLogger

from cubicweb import set_log_methods, server

from cubicweb.schema import VIRTUAL_RTYPES

from cubicweb.server.sqlutils import SQL_PREFIX

from cubicweb.server.ssplanner import EditedEntity

def dbg_st_search(uri, union, varmap, args, cachekey=None, prefix='rql for'):

    if server.DEBUG & server.DBG_RQL:

        print '  %s %s source: %s' % (prefix, uri, union.as_string())

        if varmap:

            print '    using varmap', varmap

        if server.DEBUG & server.DBG_MORE:

            print '    args', args

            print '    cache key', cachekey

            print '    solutions', ','.join(str(s.solutions)

                                            for s in union.children)

    # return true so it can be used as assertion (and so be killed by python -O)

    return True

def dbg_results(results):

    if server.DEBUG & server.DBG_RQL:

        if len(results) > 10:

            print '  -->', results[:10], '...', len(results)

        else:

            print '  -->', results

    # return true so it can be used as assertion (and so be killed by python -O)

    return True

class TimedCache(dict):

    def __init__(self, ttl):

        # time to live in seconds

        if ttl <= 0:

            raise ValueError('TimedCache initialized with a ttl of %ss' % ttl.seconds)

        self.ttl = timedelta(seconds=ttl)

    def __setitem__(self, key, value):

        dict.__setitem__(self, key, (datetime.now(), value))

    def __getitem__(self, key):

        return dict.__getitem__(self, key)[1]

    def clear_expired(self):

        now_ = datetime.now()

        ttl = self.ttl

        for key, (timestamp, value) in self.items():

            if now_ - timestamp > ttl:

                del self[key]

class AbstractSource(object):

    """an abstract class for sources"""

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

    # modified in this source

    should_call_hooks = True

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

    # migration

    connect_for_migration = True

    # mappings telling which entities and relations are available in the source

    # keys are supported entity/relation types and values are boolean indicating

    # wether the support is read-only (False) or read-write (True)

    support_entities = {}

    support_relations = {}

    # a global identifier for this source, which has to be set by the source

    # instance

    uri = None

    # a reference to the system information helper

    repo = None

    # a reference to the instance'schema (may differs from the source'schema)

    schema = None

    # multi-sources planning control

    dont_cross_relations = ()

    cross_relations = ()

    # force deactivation (configuration error for instance)

    disabled = False

    def __init__(self, repo, source_config, *args, **kwargs):

        self.repo = repo

        self.uri = source_config['uri']

        set_log_methods(self, getLogger('cubicweb.sources.'+self.uri))

        self.set_schema(repo.schema)

        self.support_relations['identity'] = False

        self.eid = None

        self.public_config = source_config.copy()

        self.remove_sensitive_information(self.public_config)

    def __repr__(self):

        return '<%s source %s @%#x>' % (self.uri, self.eid, id(self))

    def __cmp__(self, other):

        """simple comparison function to get predictable source order, with the

        system source at last

        """

        if self.uri == other.uri:

            return 0

        if self.uri == 'system':

            return 1

        if other.uri == 'system':

            return -1

        return cmp(self.uri, other.uri)

    def set_schema(self, schema):

        """set the instance'schema"""

        self.schema = schema

    def support_entity(self, etype, write=False):

        """return true if the given entity's type is handled by this adapter

        if write is true, return true only if it's a RW support

        """

        try:

            wsupport = self.support_entities[etype]

        except KeyError:

            return False

        if write:

            return wsupport

        return True

    def support_relation(self, rtype, write=False):

        """return true if the given relation's type is handled by this adapter

        if write is true, return true only if it's a RW support

        current implementation return true if the relation is defined into

        `support_relations` or if it is a final relation of a supported entity

        type

        """

        try:

            wsupport = self.support_relations[rtype]

        except KeyError:

            rschema = self.schema.rschema(rtype)

            if not rschema.final or rschema.type == 'has_text':

                return False

            for etype in rschema.subjects():

                try:

                    wsupport = self.support_entities[etype]

                    break

                except KeyError:

                    continue

            else:

                return False

        if write:

            return wsupport

        return True

    def may_cross_relation(self, rtype):

        """return True if the relation may be crossed among sources. Rules are:

        * if this source support the relation, can't be crossed unless explicitly

          specified in .cross_relations

        * if this source doesn't support the relation, can be crossed unless

          explicitly specified in .dont_cross_relations

        """

        # XXX find a way to have relation such as state_of in dont cross

        #     relation (eg composite relation without both end type available?

        #     card 1 relation ? ...)

        if self.support_relation(rtype):

            return rtype in self.cross_relations

        return rtype not in self.dont_cross_relations

        """

        """

        pass

    def authenticate(self, session, login, **kwargs):

        """if the source support CWUser entity type, it should implement

        this method which should return CWUser eid for the given login/password

        if this account is defined in this source and valid login / password is

        given. Else raise `AuthenticationError`

        """

        raise NotImplementedError()

    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.

        """

        raise NotImplementedError()

    def flying_insert(self, table, session, union, args=None, varmap=None):

        """similar as .syntax_tree_search, but inserts data in the temporary

        table (on-the-fly if possible, eg for the system source whose the given

        cursor come from). If not possible, inserts all data by calling

        .executemany().

        """

        res = self.syntax_tree_search(session, union, args, varmap=varmap)

        session.pool.source('system').manual_insert(res, table, session)

    # read-only sources don't have to implement methods below

    def get_extid(self, entity):

        """return the external id for the given newly inserted entity"""

        raise NotImplementedError()

    def add_entity(self, session, entity):

        """add a new entity to the source"""

        raise NotImplementedError()

    def update_entity(self, session, entity):

        """update an entity in the source"""

        raise NotImplementedError()

    def delete_entities(self, session, entities):

        """delete several entities from the source"""

        for entity in entities:

            self.delete_entity(session, entity)

    def delete_entity(self, session, entity):

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

        raise NotImplementedError()

    def add_relation(self, session, subject, rtype, object):

        """add a relation to the source"""

        raise NotImplementedError()

    def delete_relation(self, session, subject, rtype, object):

        """delete a relation from the source"""

        raise NotImplementedError()

    # system source interface #################################################

    def eid_type_source(self, session, eid):

        """return a tuple (type, source, extid) for the entity with id <eid>"""

        raise NotImplementedError()

    def create_eid(self, session):

        raise NotImplementedError()

    def add_info(self, session, entity, source, extid):

        """add type and source info for an eid into the system table"""

        raise NotImplementedError()

    def update_info(self, session, entity, need_fti_update):

        """mark entity as being modified, fulltext reindex if needed"""

        raise NotImplementedError()

    def delete_info(self, session, entity, uri, extid):

        """delete system information on deletion of an entity by transfering

        record from the entities table to the deleted_entities table

        """

        raise NotImplementedError()

    def delete_info_multi(self, session, entities, uri, extids):

        """ame as delete_info but accepts a list of entities with

        the same etype and belinging to the same source.

        """

        for entity, extid in itertools.izip(entities, extids):

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

    def modified_entities(self, session, etypes, mtime):

        """return a 2-uple:

        * list of (etype, eid) of entities of the given types which have been

          modified since the given timestamp (actually entities whose full text

          index content has changed)

        * list of (etype, eid) of entities of the given types which have been

          deleted since the given timestamp

        """

        raise NotImplementedError()

    def index_entity(self, session, entity):

        """create an operation to [re]index textual content of the given entity

        on commit

        """

        raise NotImplementedError()

    def fti_unindex_entities(self, session, entities):

        """remove text content for entities from the full text index

        """

        raise NotImplementedError()

    def fti_index_entities(self, session, entities):

        """add text content of created/modified entities to the full text index

        """

        raise NotImplementedError()

    # sql system source interface #############################################

    def sqlexec(self, session, sql, args=None):