# copyright 2003-2016 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.NullStore

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

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

.. autoclass:: cubicweb.dataimport.stores.MetadataGenerator

"""

import inspect

import warnings

from datetime import datetime

from copy import copy

from itertools import count

from six import add_metaclass

import pytz

from logilab.common.decorators import cached

from cubicweb.schema import META_RTYPES, VIRTUAL_RTYPES

from cubicweb.server.edition import EditedEntity

class NullStore(object):

    """Store that mainly describe the store API.

    It may be handy to test input data files or to measure time taken by steps above the store

    (e.g. data parsing, importer, etc.): simply give a :class:`NullStore` instance instead of the

    actual store.

    """

    def __init__(self):

        self._eid_gen = count()

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

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

        eid.

        """

        return next(self._eid_gen)

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

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

        and inlined relations.

        """

    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``.

        """

    def flush(self):

        """Flush internal data structures."""

    def commit(self):

        """Commit the database transaction."""

    def finish(self):

        """Import is terminated, do necessary cleanup."""

class RQLObjectStore(NullStore):

    """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):

        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):

        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):

        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 commit(self):

        return self._commit()

class NoHookRQLObjectStore(RQLObjectStore):

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

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

    Arguments:

    - `cnx`, a connection to the repository

    - `metagen`, optional :class:`MetadataGenerator` instance

    """

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

        super(NoHookRQLObjectStore, self).__init__(cnx)

        if metagen is None:

            metagen = MetadataGenerator(cnx)

        if isinstance(metagen, MetadataGenerator):

            metagen = _MetaGeneratorBWCompatWrapper(metagen)

        self.metagen = metagen

        self._system_source = cnx.repo.system_source

        self._rschema = cnx.repo.schema.rschema

        self._create_eid = self._system_source.create_eid

        self._add_relation = self._system_source.add_relation

        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)

        cnx = self._cnx

        entity.eid = self._create_eid(cnx)

        entity_source = self.metagen.init_entity(entity)

        self._system_source.add_info(cnx, entity, entity_source)

        self._system_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_')

        rschema = self._rschema(rtype)

        self._add_relation(self._cnx, eid_from, rtype, eid_to, rschema.inlined)

        if rschema.symmetric:

            self._add_relation(self._cnx, eid_to, rtype, eid_from, rschema.inlined)

        self._nb_inserted_relations += 1

class MetadataGenerator(object):

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

    derive it to add application specific's metadata. This class (or a subclass) may either be

    given to a nohook or massive store.

    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 = frozenset(META_RTYPES

                               - VIRTUAL_RTYPES

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

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

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

        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._now = datetime.now(pytz.utc)

        # 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']

        rschema = cnx.vreg.schema.rschema

        self.meta_relations = self.META_RELATIONS - set(meta_skipped)

        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)

    # etype is provided in the 3 methods below as proven useful to custom implementation but not

    # used by the default implementation

    def etype_attrs(self, etype):

        """Return the list of attributes to be set for all entities of the given type."""

        return self._etype_attrs[:]

    def etype_rels(self, etype):

        """Return the list of relations to be set for all entities of the given type."""

        return self._etype_rels[:]

    def entity_attrs(self, etype):

        """Return the list of attributes whose value is set per instance, not per type, for the

        given type.

        """

        return self._entity_attrs[:]

    @cached

    def base_etype_attrs(self, etype):

        """Return a dictionary of attributes to be set for all entities of the given type."""

        attrs = {}

        for attr in self.etype_attrs(etype):

            genfunc = self._generator(attr)

            if genfunc:

                attrs[attr] = genfunc(etype)

        return attrs

    @cached

    def base_etype_rels(self, etype):

        """Return a dictionary of relations to be set for all entities of the given type."""

        rels = {}

        for rel in self.etype_rels(etype):

            genfunc = self._generator(rel)

            if genfunc:

                rels[rel] = genfunc(etype)

        return rels

    def init_entity_attrs(self, etype, eid, attrs):

        """Insert into an entity attrs dictionary attributes whose value is set per instance, not per

        type.

        """

        for attr in self.entity_attrs(etype):

            if attr in attrs:

                # already set, skip this attribute

                continue

            genfunc = self._generator(attr)

            if genfunc:

                attrs[attr] = genfunc(etype, eid, attrs)

    def _generator(self, rtype):

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

    def gen_cwuri(self, etype, eid, attrs):

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

        return u'%s%s' % (self._baseurl, eid)

    def gen_creation_date(self, etype):

        return self._now

    def gen_modification_date(self, etype):

        return self._now

    def gen_created_by(self, etype):

        return self._cnx.user.eid

    def gen_owned_by(self, etype):

        return self._cnx.user.eid

class _MetaGeneratorBWCompatWrapper(object):

    """Class wrapping a MetadataGenerator to adapt it to the MetaGenerator interface.

    """

    META_RELATIONS = (META_RTYPES

                      - VIRTUAL_RTYPES

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

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

    def __init__(self, mdgenerator):

        self._mdgen = mdgenerator

    @cached

    def base_etype_dicts(self, etype):

        cnx = self._mdgen._cnx

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

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

        del entity.cw_extra_kwargs

        entity.cw_edited = EditedEntity(entity)

        attrs = self._mdgen.base_etype_attrs(etype)

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

        rels = self._mdgen.base_etype_rels(etype)

        return entity, rels

    def init_entity(self, entity):

        attrs = dict(entity.cw_edited)

        self._mdgen.init_entity_attrs(entity.cw_etype, entity.eid, attrs)

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

        return self._mdgen.source

@add_metaclass(class_deprecated)

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

    """

    __deprecation_warning__ = '[3.23] this class is deprecated, use MetadataGenerator instead'

    META_RELATIONS = MetadataGenerator.META_RELATIONS

    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._now = datetime.now(pytz.utc)

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

        self.etype_attrs = []

        self.etype_rels = []