# 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/>.

"""Defines the central class for the CubicWeb RQL server: the repository.

The repository is an abstraction allowing execution of rql queries against

data sources. Most of the work is actually done in helper classes. The

repository mainly:

* brings these classes all together to provide a single access

  point to a cubicweb instance.

* handles session management

* provides method for pyro registration, to call if pyro is enabled

"""

from __future__ import with_statement

__docformat__ = "restructuredtext en"

import sys

import threading

import Queue

from itertools import chain

from os.path import join

from datetime import datetime

from time import time, localtime, strftime

from logilab.common.decorators import cached, clear_cache

from logilab.common.compat import any

from logilab.common import flatten

from yams import BadSchemaDefinition

from yams.schema import role_name

from rql import RQLSyntaxError

from rql.utils import rqlvar_maker

from cubicweb import (CW_SOFTWARE_ROOT, CW_MIGRATION_MAP, QueryError,

                      UnknownEid, AuthenticationError, ExecutionError,

                      ETypeNotSupportedBySources, MultiSourcesError,

                      BadConnectionId, Unauthorized, ValidationError,

                      RepositoryError, UniqueTogetherError, typed_eid, onevent)

from cubicweb import cwvreg, schema, server

from cubicweb.server import utils, hook, pool, querier, sources

from cubicweb.server.session import Session, InternalSession, InternalManager, \

     security_enabled

from cubicweb.server.ssplanner import EditedEntity

def prefill_entity_caches(entity, relations):

    session = entity._cw

    # prefill entity relation caches

    for rschema in entity.e_schema.subject_relations():

        rtype = str(rschema)

        if rtype in schema.VIRTUAL_RTYPES:

            continue

        if rschema.final:

            entity.cw_attr_cache.setdefault(rtype, None)

        else:

            entity.cw_set_relation_cache(rtype, 'subject',

                                         session.empty_rset())

    for rschema in entity.e_schema.object_relations():

        rtype = str(rschema)

        if rtype in schema.VIRTUAL_RTYPES:

            continue

        entity.cw_set_relation_cache(rtype, 'object', session.empty_rset())

    # set inlined relation cache before call to after_add_entity

    for attr, value in relations:

        session.update_rel_cache_add(entity.eid, attr, value)

        del_existing_rel_if_needed(session, entity.eid, attr, value)

def del_existing_rel_if_needed(session, eidfrom, rtype, eidto):

    """delete existing relation when adding a new one if card is 1 or ?

    have to be done once the new relation has been inserted to avoid having

    an entity without a relation for some time

    this kind of behaviour has to be done in the repository so we don't have

    hooks order hazardness

    """

    # skip that for internal session or if integrity explicitly disabled

    #

    # XXX we should imo rely on the orm to first fetch existing entity if any

    # then delete it.

    if session.is_internal_session \

           or not session.is_hook_category_activated('activeintegrity'):

        return

    card = session.schema_rproperty(rtype, eidfrom, eidto, 'cardinality')

    # one may be tented to check for neweids but this may cause more than one

    # relation even with '1?'  cardinality if thoses relations are added in the

    # same transaction where the entity is being created. This never occurs from

    # the web interface but may occurs during test or dbapi connection (though

    # not expected for this).  So: don't do it, we pretend to ensure repository

    # consistency.

    #

    # notes:

    # * inlined relations will be implicitly deleted for the subject entity

    # * we don't want read permissions to be applied but we want delete

    #   permission to be checked

    if card[0] in '1?' and not session.repo.schema.rschema(rtype).inlined:

        with security_enabled(session, read=False):

            session.execute('DELETE X %s Y WHERE X eid %%(x)s, '

                            'NOT Y eid %%(y)s' % rtype,

                                {'x': eidfrom, 'y': eidto})

    if card[1] in '1?':

        with security_enabled(session, read=False):

            session.execute('DELETE X %s Y WHERE Y eid %%(y)s, '

                            'NOT X eid %%(x)s' % rtype,

                            {'x': eidfrom, 'y': eidto})

class Repository(object):

    """a repository provides access to a set of persistent storages for

    entities and relations

    XXX protect pyro access

    """

    def __init__(self, config, vreg=None):

        self.config = config

        if vreg is None:

            vreg = cwvreg.CubicWebVRegistry(config)

        self.vreg = vreg

        self.pyro_registered = False

        self.info('starting repository from %s', self.config.apphome)

        # dictionary of opened sessions

        self._sessions = {}

        # list of functions to be called at regular interval

        self._looping_tasks = []

        # list of running threads

        self._running_threads = []

        # initial schema, should be build or replaced latter

        self.schema = schema.CubicWebSchema(config.appid)

        self.vreg.schema = self.schema # until actual schema is loaded...

        # shutdown flag

        self.shutting_down = False

        # sources (additional sources info in the system database)

        self.system_source = self.get_source('native', 'system',

                                             config.sources()['system'])

        self.sources = [self.system_source]

        self.sources_by_uri = {'system': self.system_source}

        # querier helper, need to be created after sources initialization

        self.querier = querier.QuerierHelper(self, self.schema)

        # cache eid -> type / source

        self._type_source_cache = {}

        # cache (extid, source uri) -> eid

        self._extid_cache = {}

        # open some connections pools

        if config.open_connections_pools:

            self.open_connections_pools()

        @onevent('after-registry-reload', self)

        def fix_user_classes(self):

            usercls = self.vreg['etypes'].etype_class('CWUser')

            for session in self._sessions.values():

                if not isinstance(session.user, InternalManager):

                    session.user.__class__ = usercls

    def open_connections_pools(self):

        config = self.config

        self._available_pools = Queue.Queue()

        self._available_pools.put_nowait(pool.ConnectionsPool(self.sources))

        if config.quick_start:

            # quick start, usually only to get a minimal repository to get cubes

            # information (eg dump/restore/...)

            config._cubes = ()

            # only load hooks and entity classes in the registry

            config.cube_appobject_path = set(('hooks', 'entities'))

            config.cubicweb_appobject_path = set(('hooks', 'entities'))

            self.set_schema(config.load_schema())

            config['connections-pool-size'] = 1

            # will be reinitialized later from cubes found in the database

            config._cubes = None

        elif config.creating:

            # repository creation

            config.bootstrap_cubes()

            self.set_schema(config.load_schema(), resetvreg=False)

            # need to load the Any and CWUser entity types

            etdirectory = join(CW_SOFTWARE_ROOT, 'entities')

            self.vreg.init_registration([etdirectory])

            for modname in ('__init__', 'authobjs', 'wfobjs'):

                self.vreg.load_file(join(etdirectory, '%s.py' % modname),

                                    'cubicweb.entities.%s' % modname)

            hooksdirectory = join(CW_SOFTWARE_ROOT, 'hooks')

            self.vreg.load_file(join(hooksdirectory, 'metadata.py'),

                                'cubicweb.hooks.metadata')

        elif config.read_instance_schema:

            # normal start: load the instance schema from the database

            self.fill_schema()

        else:

            # test start: use the file system schema (quicker)

            self.warning("set fs instance'schema")

            config.bootstrap_cubes()

            self.set_schema(config.load_schema())

        if not config.creating:

            self.init_sources_from_database()

            if 'CWProperty' in self.schema:

                self.vreg.init_properties(self.properties())

            # call source's init method to complete their initialisation if

            # needed (for instance looking for persistent configuration using an

            # internal session, which is not possible until pools have been

            # initialized)

            for source in self.sources:

                source.init()

        else:

            # call init_creating so that for instance native source can

            # configurate tsearch according to postgres version

            for source in self.sources:

                source.init_creating()

        # close initialization pool and reopen fresh ones for proper

        # initialization now that we know cubes

        self._get_pool().close(True)

        # list of available pools (we can't iterate on Queue instance)

        self.pools = []

        for i in xrange(config['connections-pool-size']):

            self.pools.append(pool.ConnectionsPool(self.sources))

            self._available_pools.put_nowait(self.pools[-1])

        if config.quick_start:

            config.init_cubes(self.get_cubes())

        self.hm = hook.HooksManager(self.vreg)

    # internals ###############################################################

    def init_sources_from_database(self):

        self.sources_by_eid = {}

        if self.config.quick_start \

               or not 'CWSource' in self.schema: # # 3.10 migration

            return

        session = self.internal_session()

        try:

            # FIXME: sources should be ordered (add_entity priority)

            for sourceent in session.execute(

                'Any S, SN, SA, SC WHERE S is CWSource, '

                'S name SN, S type SA, S config SC').entities():

                if sourceent.name == 'system':

                    self.system_source.eid = sourceent.eid

                    self.sources_by_eid[sourceent.eid] = self.system_source

                    continue

                self.add_source(sourceent, add_to_pools=False)

        finally:

            session.close()

    def _clear_planning_caches(self):

        for cache in ('source_defs', 'is_multi_sources_relation',

                      'can_cross_relation', 'rel_type_sources'):

            clear_cache(self, cache)

    def add_source(self, sourceent, add_to_pools=True):

        source = self.get_source(sourceent.type, sourceent.name,

                                 sourceent.host_config)

        source.eid = sourceent.eid

        self.sources_by_eid[sourceent.eid] = source

        self.sources_by_uri[sourceent.name] = source

        if self.config.source_enabled(source):

            self.sources.append(source)

            self.querier.set_planner()

            if add_to_pools:

                for pool in self.pools:

                    pool.add_source(source)

        self._clear_planning_caches()

    def remove_source(self, uri):

        source = self.sources_by_uri.pop(uri)

        del self.sources_by_eid[source.eid]

        if self.config.source_enabled(source):

            self.sources.remove(source)

            self.querier.set_planner()

            for pool in self.pools:

                pool.remove_source(source)

        self._clear_planning_caches()

    def get_source(self, type, uri, source_config):

        # set uri and type in source config so it's available through

        # source_defs()

        source_config['uri'] = uri

        source_config['type'] = type

        return sources.get_source(type, source_config, self)

    def set_schema(self, schema, resetvreg=True, rebuildinfered=True):

        if rebuildinfered:

            schema.rebuild_infered_relations()

        self.info('set schema %s %#x', schema.name, id(schema))

        if resetvreg:

            if self.config._cubes is None:

                self.config.init_cubes(self.get_cubes())

            # trigger full reload of all appobjects

            self.vreg.set_schema(schema)

        else:

            self.vreg._set_schema(schema)

        self.querier.set_schema(schema)

        # don't use self.sources, we may want to give schema even to disabled

        # sources

        for source in self.sources_by_uri.values():

            source.set_schema(schema)

        self.schema = schema

    def fill_schema(self):

        """lod schema from the repository"""

        from cubicweb.server.schemaserial import deserialize_schema

        self.info('loading schema from the repository')

        appschema = schema.CubicWebSchema(self.config.appid)

        self.set_schema(self.config.load_bootstrap_schema(), resetvreg=False)

        self.debug('deserializing db schema into %s %#x', appschema.name, id(appschema))

        session = self.internal_session()

        try:

            try:

                deserialize_schema(appschema, session)

            except BadSchemaDefinition:

                raise

            except Exception, ex:

                import traceback

                traceback.print_exc()

                raise Exception('Is the database initialised ? (cause: %s)' %

                                (ex.args and ex.args[0].strip() or 'unknown')), \

                                None, sys.exc_info()[-1]

        finally:

            session.close()

        self.set_schema(appschema)

    def start_looping_tasks(self):

        if not (self.config.creating or self.config.repairing

                or self.config.quick_start):

            # call instance level initialisation hooks

            self.hm.call_hooks('server_startup', repo=self)

            # register a task to cleanup expired session

            self.cleanup_session_time = self.config['cleanup-session-time'] or 60 * 60 * 24

            assert self.cleanup_session_time > 0

            cleanup_session_interval = min(60*60, self.cleanup_session_time / 3)

            self.looping_task(cleanup_session_interval, self.clean_sessions)

        assert isinstance(self._looping_tasks, list), 'already started'

        for i, (interval, func, args) in enumerate(self._looping_tasks):

            self._looping_tasks[i] = task = utils.LoopTask(interval, func, args)

            self.info('starting task %s with interval %.2fs', task.name,

                      interval)

            task.start()

        # ensure no tasks will be further added

        self._looping_tasks = tuple(self._looping_tasks)

    def looping_task(self, interval, func, *args):

        """register a function to be called every `interval` seconds.

        looping tasks can only be registered during repository initialization,

        once done this method will fail.

        """

        try:

            self._looping_tasks.append( (interval, func, args) )

        except AttributeError:

            raise RuntimeError("can't add looping task once the repository is started")

    def threaded_task(self, func):

        """start function in a separated thread"""

        t = utils.RepoThread(func, self._running_threads)

        t.start()

    #@locked

    def _get_pool(self):

        try:

            return self._available_pools.get(True, timeout=5)

        except Queue.Empty:

            raise Exception('no pool available after 5 secs, probably either a '

                            'bug in code (too many uncommited/rollbacked '

                            'connections) or too much load on the server (in '

                            'which case you can try to set a bigger '

                            'connections pools size)')

    def _free_pool(self, pool):

        self._available_pools.put_nowait(pool)