# 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 server sources support"""

__docformat__ = "restructuredtext en"

import itertools

from os.path import join, splitext

from time import time

from datetime import datetime, timedelta

from logging import getLogger

from logilab.common import configuration

from logilab.common.deprecation import deprecated

from yams.schema import role_name

from cubicweb import ValidationError, set_log_methods, server

from cubicweb.schema import VIRTUAL_RTYPES

from cubicweb.server.sqlutils import SQL_PREFIX

from cubicweb.server.edition import EditedEntity

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

    if server.DEBUG & server.DBG_RQL:

        global t

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

        t = time()

        if varmap:

            print '    using varmap', varmap

        if server.DEBUG & server.DBG_MORE:

            print '    args', repr(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,

        print 'time: ', time() - t

    # 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.utcnow(), value))

    def __getitem__(self, key):

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

    def clear_expired(self):

        now_ = datetime.utcnow()

        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"""

    # does the source copy data into the system source, or is it a *true* source

    # (i.e. entities are not stored physically here)

    copy_based_source = False

    # 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

    # boolean telling if cwuri of entities from this source is the url that

    # should be used as entity's absolute url

    use_cwuri_as_url = False

    # source configuration options

    options = ()

    # these are overridden by set_log_methods below

    # only defining here to prevent pylint from complaining

    info = warning = error = critical = exception = debug = lambda msg,*a,**kw: None

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

        self.repo = repo

        self.set_schema(repo.schema)

        self.support_relations['identity'] = False

        self.eid = eid

        self.public_config = source_config.copy()

        self.public_config.setdefault('use-cwuri-as-url', self.use_cwuri_as_url)

        self.remove_sensitive_information(self.public_config)

        self.uri = source_config.pop('uri')

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

        source_config.pop('type')

        self.update_config(None, self.check_conf_dict(eid, source_config,

                                                      fail_if_unknown=False))

    def __repr__(self):

        return '<%s %s source %s @%#x>' % (self.uri, self.__class__.__name__,

                                           self.eid, id(self))

    def __lt__(self, other):

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

        system source at last

        """

        if self.uri == other.uri:

            return False

        if self.uri == 'system':

            return False

        if other.uri == 'system':

            return True

        return self.uri < other.uri

    def __eq__(self, other):

        return self.uri == other.uri

    def backup(self, backupfile, confirm, format='native'):

        """method called to create a backup of source's data"""

        pass

    def restore(self, backupfile, confirm, drop, format='native'):

        """method called to restore a backup of source's data"""

        pass

    @classmethod

    def check_conf_dict(cls, eid, confdict, _=unicode, fail_if_unknown=True):

        """check configuration of source entity. Return config dict properly

        typed with defaults set.

        """

        processed = {}

        for optname, optdict in cls.options:

            value = confdict.pop(optname, optdict.get('default'))

            if value is configuration.REQUIRED:

                if not fail_if_unknown:

                    continue

                msg = _('specifying %s is mandatory' % optname)

                raise ValidationError(eid, {role_name('config', 'subject'): msg})

            elif value is not None:

                # type check

                try:

                    value = configuration._validate(value, optdict, optname)

                except Exception as ex:

                    msg = unicode(ex) # XXX internationalization

                    raise ValidationError(eid, {role_name('config', 'subject'): msg})

            processed[optname] = value

        # cw < 3.10 bw compat

        try:

            processed['adapter'] = confdict['adapter']

        except KeyError:

            pass

        # check for unknown options

        if confdict and tuple(confdict) != ('adapter',):

            if fail_if_unknown:

                msg = _('unknown options %s') % ', '.join(confdict)

                raise ValidationError(eid, {role_name('config', 'subject'): msg})

            else:

                logger = getLogger('cubicweb.sources')

                logger.warning('unknown options %s', ', '.join(confdict))

                # add options to processed, they may be necessary during migration

                processed.update(confdict)

        return processed

    @classmethod

    def check_config(cls, source_entity):

        """check configuration of source entity"""

        return cls.check_conf_dict(source_entity.eid, source_entity.host_config,

                                    _=source_entity._cw._)

    def update_config(self, source_entity, typedconfig):

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

        properly typed with defaults set

        """

        if source_entity is not None:

            self._entity_update(source_entity)

        self.config = typedconfig

    def _entity_update(self, source_entity):

        source_entity.complete()

        if source_entity.url:

            self.urls = [url.strip() for url in source_entity.url.splitlines()

                         if url.strip()]

        else:

            self.urls = []

    # source initialization / finalization #####################################

    def set_schema(self, schema):

        """set the instance'schema"""

        self.schema = schema

    def init_creating(self):

        """method called by the repository once ready to create a new instance"""

        pass

    def init(self, activated, source_entity):

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

        `activated` is a boolean flag telling if the source is activated or not.

        """

        if activated:

            self._entity_update(source_entity)

    PUBLIC_KEYS = ('type', 'uri', 'use-cwuri-as-url')

    def remove_sensitive_information(self, sourcedef):

        """remove sensitive information such as login / password from source

        definition

        """

        for key in list(sourcedef):

            if not key in self.PUBLIC_KEYS:

                sourcedef.pop(key)

    # connections handling #####################################################

    def get_connection(self):

        """open and return a connection to the source"""

        raise NotImplementedError(self)

    def check_connection(self, cnx):

        """Check connection validity, return None if the connection is still

        valid else a new connection (called when the connections set using the

        given connection is being attached to a session). Do nothing by default.

        """

        pass

    def close_source_connections(self):

        for cnxset in self.repo.cnxsets:

            cnxset._cursors.pop(self.uri, None)

            cnxset.source_cnxs[self.uri][1].close()

    def open_source_connections(self):

        for cnxset in self.repo.cnxsets:

            cnxset.source_cnxs[self.uri] = (self, self.get_connection())

    def cnxset_freed(self, cnx):

        """the connections set holding the given connection is being reseted

        from its current attached session.

        do nothing by default

        """

        pass

    # cache handling ###########################################################

    def reset_caches(self):

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

        pass

    def clear_eid_cache(self, eid, etype):

        """clear potential caches for the given eid"""

        pass

    # external source api ######################################################

    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?

        if self.support_relation(rtype):

            return rtype in self.cross_relations

        return rtype not in self.dont_cross_relations

    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.

        """

        entity = self.repo.vreg['etypes'].etype_class(etype)(session)

        entity.eid = eid

        entity.cw_edited = EditedEntity(entity)

        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.

        """

        pass

    def _load_mapping(self, session=None, **kwargs):

        if not 'CWSourceSchemaConfig' in self.schema:

            self.warning('instance is not mapping ready')

            return

        if session is None:

            _session = self.repo.internal_session()

        else:

            _session = session

        try:

            for schemacfg in _session.execute(

                'Any CFG,CFGO,S WHERE '

                'CFG options CFGO, CFG cw_schema S, '

                'CFG cw_for_source X, X eid %(x)s', {'x': self.eid}).entities():

                self.add_schema_config(schemacfg, **kwargs)

        finally:

            if session is None:

                _session.close()

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

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

        msg = schemacfg._cw._("this source doesn't use a mapping")

        raise ValidationError(schemacfg.eid, {None: msg})