# copyright 2003-2015 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/>.

"""

Stores are responsible to insert properly formatted entities and relations into the database. They

have the following API::

    >>> user_eid = store.prepare_insert_entity('CWUser', login=u'johndoe')

    >>> group_eid = store.prepare_insert_entity('CWUser', name=u'unknown')

    >>> store.prepare_insert_relation(user_eid, 'in_group', group_eid)

    >>> store.flush()

    >>> store.commit()

    >>> store.finish()

Some store **requires a flush** to copy data in the database, so if you want to have store

independant code you should explicitly call it. (There may be multiple flushes during the

process, or only one at the end if there is no memory issue). This is different from the

commit which validates the database transaction. At last, the `finish()` method should be called in

case the store requires additional work once everything is done.

* ``prepare_insert_entity(<entity type>, **kwargs) -> eid``: given an entity

  type, attributes and inlined relations, return the eid of the entity to be

  inserted, *with no guarantee that anything has been inserted in database*,

* ``prepare_update_entity(<entity type>, eid, **kwargs) -> None``: given an

  entity type and eid, promise for update given attributes and inlined

  relations *with no guarantee that anything has been inserted in database*,

* ``prepare_insert_relation(eid_from, rtype, eid_to) -> None``: indicate that a

  relation ``rtype`` should be added between entities with eids ``eid_from``

  and ``eid_to``. Similar to ``prepare_insert_entity()``, *there is no

  guarantee that the relation will be inserted in database*,

* ``flush() -> None``: flush any temporary data to database. May be called

  several times during an import,

* ``commit() -> None``: commit the database transaction,

* ``finish() -> None``: additional stuff to do after import is terminated.

.. autoclass:: cubicweb.dataimport.stores.RQLObjectStore

.. autoclass:: cubicweb.dataimport.stores.NoHookRQLObjectStore

.. autoclass:: cubicweb.dataimport.stores.MetaGenerator

"""

import inspect

import warnings

from datetime import datetime

from copy import copy

from six import text_type

from logilab.common.deprecation import deprecated

from logilab.common.decorators import cached

from cubicweb.schema import META_RTYPES, VIRTUAL_RTYPES

from cubicweb.server.edition import EditedEntity

class RQLObjectStore(object):

    """Store that works by making RQL queries, hence with all the cubicweb's machinery activated.

    """

    def __init__(self, cnx, commit=None):

        if commit is not None:

            warnings.warn('[3.19] commit argument should not be specified '

                          'as the cnx object already provides it.',

                          DeprecationWarning, stacklevel=2)

        self._cnx = cnx

        self._commit = commit or cnx.commit

        # XXX 3.21 deprecated attributes

        self.eids = {}

        self.types = {}

    def rql(self, *args):

        """Execute a RQL query. This is NOT part of the store API."""

        return self._cnx.execute(*args)

    def prepare_insert_entity(self, *args, **kwargs):

        """Given an entity type, attributes and inlined relations, returns the inserted entity's

        eid.

        """

        entity = self._cnx.create_entity(*args, **kwargs)

        self.eids[entity.eid] = entity

        self.types.setdefault(args[0], []).append(entity.eid)

        return entity.eid

    def prepare_update_entity(self, etype, eid, **kwargs):

        """Given an entity type and eid, updates the corresponding entity with specified attributes

        and inlined relations.

        """

        entity = self._cnx.entity_from_eid(eid)

        assert entity.cw_etype == etype, 'Trying to update with wrong type %s' % etype

        # XXX some inlined relations may already exists

        entity.cw_set(**kwargs)

    def prepare_insert_relation(self, eid_from, rtype, eid_to, **kwargs):

        """Insert into the database a  relation ``rtype`` between entities with eids ``eid_from``

        and ``eid_to``.

        """

        self.rql('SET X %s Y WHERE X eid %%(x)s, Y eid %%(y)s' % rtype,

                 {'x': int(eid_from), 'y': int(eid_to)})

    def flush(self):

        """Nothing to flush for this store."""

        pass

    def commit(self):

        """Commit the database transaction."""

        return self._commit()

    def finish(self):

        """Nothing to do once import is terminated for this store."""

        pass

    @property

    def session(self):

        warnings.warn('[3.19] deprecated property.', DeprecationWarning, stacklevel=2)

        return self._cnx.repo._get_session(self._cnx.sessionid)

    @deprecated("[3.19] use cnx.find(*args, **kwargs).entities() instead")

    def find_entities(self, *args, **kwargs):

        return self._cnx.find(*args, **kwargs).entities()

    @deprecated("[3.19] use cnx.find(*args, **kwargs).one() instead")

    def find_one_entity(self, *args, **kwargs):

        return self._cnx.find(*args, **kwargs).one()

    @deprecated('[3.21] use prepare_insert_entity instead')

    def create_entity(self, *args, **kwargs):

        eid = self.prepare_insert_entity(*args, **kwargs)

        return self._cnx.entity_from_eid(eid)

    @deprecated('[3.21] use prepare_insert_relation instead')

    def relate(self, eid_from, rtype, eid_to, **kwargs):

        self.prepare_insert_relation(eid_from, rtype, eid_to, **kwargs)

class NoHookRQLObjectStore(RQLObjectStore):

    """Store that works by accessing low-level CubicWeb's source API, with all hooks deactivated. It

    must be given a metadata generator object to handle metadata which are usually handled by hooks

    (see :class:`MetaGenerator`).

    """

    def __init__(self, cnx, metagen=None):

        super(NoHookRQLObjectStore, self).__init__(cnx)

        self.source = cnx.repo.system_source

        self.rschema = cnx.repo.schema.rschema

        self.add_relation = self.source.add_relation

        if metagen is None:

            metagen = MetaGenerator(cnx)

        self.metagen = metagen

        self._nb_inserted_entities = 0

        self._nb_inserted_types = 0

        self._nb_inserted_relations = 0

        # deactivate security

        cnx.read_security = False

        cnx.write_security = False

    def prepare_insert_entity(self, etype, **kwargs):

        """Given an entity type, attributes and inlined relations, returns the inserted entity's

        eid.

        """

        for k, v in kwargs.items():

            kwargs[k] = getattr(v, 'eid', v)

        entity, rels = self.metagen.base_etype_dicts(etype)

        # make a copy to keep cached entity pristine

        entity = copy(entity)

        entity.cw_edited = copy(entity.cw_edited)

        entity.cw_clear_relation_cache()

        entity.cw_edited.update(kwargs, skipsec=False)

        entity_source, extid = self.metagen.init_entity(entity)

        cnx = self._cnx

        self.source.add_info(cnx, entity, entity_source, extid)

        self.source.add_entity(cnx, entity)

        kwargs = dict()

        if inspect.getargspec(self.add_relation).keywords:

            kwargs['subjtype'] = entity.cw_etype

        for rtype, targeteids in rels.items():

            # targeteids may be a single eid or a list of eids

            inlined = self.rschema(rtype).inlined

            try:

                for targeteid in targeteids:

                    self.add_relation(cnx, entity.eid, rtype, targeteid,

                                      inlined, **kwargs)

            except TypeError:

                self.add_relation(cnx, entity.eid, rtype, targeteids,

                                  inlined, **kwargs)

        self._nb_inserted_entities += 1

        return entity.eid

    # XXX: prepare_update_entity is inherited from RQLObjectStore, it should be reimplemented to

    # actually skip hooks as prepare_insert_entity

    def prepare_insert_relation(self, eid_from, rtype, eid_to, **kwargs):

        """Insert into the database a  relation ``rtype`` between entities with eids ``eid_from``

        and ``eid_to``.

        """

        assert not rtype.startswith('reverse_')

        self.add_relation(self._cnx, eid_from, rtype, eid_to,

                          self.rschema(rtype).inlined)

        if self.rschema(rtype).symmetric:

            self.add_relation(self._cnx, eid_to, rtype, eid_from,

                              self.rschema(rtype).inlined)

        self._nb_inserted_relations += 1

    @property

    @deprecated('[3.21] deprecated')

    def nb_inserted_entities(self):

        return self._nb_inserted_entities

    @property

    @deprecated('[3.21] deprecated')

    def nb_inserted_types(self):

        return self._nb_inserted_types

    @property

    @deprecated('[3.21] deprecated')

    def nb_inserted_relations(self):

        return self._nb_inserted_relations

class MetaGenerator(object):

    """Class responsible for generating standard metadata for imported entities. You may want to

    derive it to add application specific's metadata.

    Parameters:

    * `cnx`: connection to the repository

    * `baseurl`: optional base URL to be used for `cwuri` generation - default to config['base-url']

    * `source`: optional source to be used as `cw_source` for imported entities

    """

    META_RELATIONS = (META_RTYPES

                      - VIRTUAL_RTYPES

                      - set(('eid', 'cwuri',

                             'is', 'is_instance_of', 'cw_source')))

    def __init__(self, cnx, baseurl=None, source=None):

        self._cnx = cnx

        if baseurl is None:

            config = cnx.vreg.config

            baseurl = config['base-url'] or config.default_base_url()

        if not baseurl[-1] == '/':

            baseurl += '/'

        self.baseurl = baseurl

        if source is None:

            source = cnx.repo.system_source

        self.source = source

        self.create_eid = cnx.repo.system_source.create_eid

        self.time = datetime.utcnow()

        # attributes/relations shared by all entities of the same type

        self.etype_attrs = []

        self.etype_rels = []

        # attributes/relations specific to each entity

        self.entity_attrs = ['cwuri']

        #self.entity_rels = [] XXX not handled (YAGNI?)

        schema = cnx.vreg.schema

        rschema = schema.rschema

        for rtype in self.META_RELATIONS:

            # skip owned_by / created_by if user is the internal manager

            if cnx.user.eid == -1 and rtype in ('owned_by', 'created_by'):

                continue

            if rschema(rtype).final:

                self.etype_attrs.append(rtype)

            else:

                self.etype_rels.append(rtype)

    @cached

    def base_etype_dicts(self, etype):

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

        # entity are "surface" copied, avoid shared dict between copies

        del entity.cw_extra_kwargs

        entity.cw_edited = EditedEntity(entity)

        for attr in self.etype_attrs:

            genfunc = self.generate(attr)

            if genfunc:

                entity.cw_edited.edited_attribute(attr, genfunc(entity))

        rels = {}

        for rel in self.etype_rels:

            genfunc = self.generate(rel)

            if genfunc:

                rels[rel] = genfunc(entity)

        return entity, rels

    def init_entity(self, entity):

        entity.eid = self.create_eid(self._cnx)

        extid = entity.cw_edited.get('cwuri')

        for attr in self.entity_attrs:

            if attr in entity.cw_edited:

                # already set, skip this attribute

                continue

            genfunc = self.generate(attr)

            if genfunc:

                entity.cw_edited.edited_attribute(attr, genfunc(entity))

        if isinstance(extid, text_type):

            extid = extid.encode('utf-8')

        return self.source, extid

    def generate(self, rtype):

        return getattr(self, 'gen_%s' % rtype, None)

    def gen_cwuri(self, entity):

        assert self.baseurl, 'baseurl is None while generating cwuri'

        return u'%s%s' % (self.baseurl, entity.eid)

    def gen_creation_date(self, entity):

        return self.time

    def gen_modification_date(self, entity):

        return self.time

    def gen_created_by(self, entity):

        return self._cnx.user.eid

    def gen_owned_by(self, entity):

        return self._cnx.user.eid