# 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/>.

"""base application's entities class implementation: `AnyEntity`"""

__docformat__ = "restructuredtext en"

from six import text_type, string_types

from logilab.common.decorators import classproperty

from cubicweb import Unauthorized

from cubicweb.entity import Entity

def chunks(seq, step):

    """See http://stackoverflow.com/questions/312443/how-do-you-split-a-list-into-evenly-sized-chunks-in-python)"""

    return (seq[i:i+step]

            for i in xrange(0, len(seq), step))

class AnyEntity(Entity):

    """an entity instance has e_schema automagically set on the class and

    instances have access to their issuing cursor

    """

    __regid__ = 'Any'

    @classproperty

    def cw_etype(cls):

        """entity type as a unicode string"""

        return text_type(cls.__regid__)

    @classmethod

    def cw_create_url(cls, req, **kwargs):

        """ return the url of the entity creation form for this entity type"""

        return req.build_url('add/%s' % cls.__regid__, **kwargs)

    @classmethod

    def cw_fti_index_rql_queries(cls, req):

        """return an iterator on rql queries to fetch entities to FT-index

        The default is to fetch entities 1000 per 1000 and to prefetch

        indexable attributes, but one could imagine iterating over

        "smaller" resultsets if the table is very big or returning

        a subset of entities that match some business-logic condition.

        """

        restrictions = []

        selected = ['X']

        for attrschema in sorted(cls.e_schema.indexable_attributes()):

            varname = attrschema.type.upper()

            restrictions.append('X %s %s' % (attrschema, varname))

            selected.append(varname)

        rset = req.execute('Any EID WHERE X eid EID, X is %s' % cls.__regid__)

        for rows in chunks(rset.rows, 1000):

            q_restrictions = restrictions + [

                'X eid IN (%s)' % ', '.join(str(r[0]) for r in rows)]

            yield 'Any %s WHERE %s' % (', '.join(selected),

                                       ', '.join(q_restrictions))

    # meta data api ###########################################################

    def dc_title(self):

        """return a suitable *unicode* title for this entity"""

        for rschema, attrschema in self.e_schema.attribute_definitions():

            if rschema.meta:

                continue

            value = self.cw_attr_value(rschema.type)

            if value is not None:

                # make the value printable (dates, floats, bytes, etc.)

                return self.printable_value(rschema.type, value, attrschema.type,

                                            format='text/plain')

        return u'%s #%s' % (self.dc_type(), self.eid)

    def dc_long_title(self):

        """return a more detailled title for this entity"""

        return self.dc_title()

    def dc_description(self, format='text/plain'):

        """return a suitable description for this entity"""

        if 'description' in self.e_schema.subjrels:

            return self.printable_value('description', format=format)

        return u''

    def dc_authors(self):

        """return a suitable description for the author(s) of the entity"""

        try:

            return ', '.join(u.name() for u in self.owned_by)

        except Unauthorized:

            return u''

    def dc_creator(self):

        """return a suitable description for the creator of the entity"""

        if self.creator:

            return self.creator.name()

        return u''

    def dc_date(self, date_format=None):# XXX default to ISO 8601 ?

        """return latest modification date of this entity"""

        return self._cw.format_date(self.modification_date, date_format=date_format)

    def dc_type(self, form=''):

        """return the display name for the type of this entity (translated)"""

        return self.e_schema.display_name(self._cw, form)

    def dc_language(self):

        """return language used by this entity (translated)"""

        # check if entities has internationalizable attributes

        # XXX one is enough or check if all String attributes are internationalizable?

        for rschema, attrschema in self.e_schema.attribute_definitions():

            if rschema.rdef(self.e_schema, attrschema).internationalizable:

                return self._cw._(self._cw.user.property_value('ui.language'))

        return self._cw._(self._cw.vreg.property_value('ui.language'))

    @property

    def creator(self):

        """return the CWUser entity which has created this entity, or None if

        unknown or if the curent user doesn't has access to this euser

        """

        try:

            return self.created_by[0]

        except (Unauthorized, IndexError):

            return None

    # abstractions making the whole things (well, some at least) working ######

    def sortvalue(self, rtype=None):

        """return a value which can be used to sort this entity or given

        entity's attribute

        """

        if rtype is None:

            return self.dc_title().lower()

        value = self.cw_attr_value(rtype)

        # do not restrict to `unicode` because Bytes will return a `str` value

        if isinstance(value, string_types):

            return self.printable_value(rtype, format='text/plain').lower()

        return value

def fetch_config(fetchattrs, mainattr=None, pclass=AnyEntity, order='ASC'):

    """function to ease basic configuration of an entity class ORM. Basic usage

    is:

    .. sourcecode:: python

      class MyEntity(AnyEntity):

          fetch_attrs, cw_fetch_order = fetch_config(['attr1', 'attr2'])

          # uncomment line below if you want the same sorting for 'unrelated' entities

          # cw_fetch_unrelated_order = cw_fetch_order

    Using this, when using ORM methods retrieving this type of entity, 'attr1'

    and 'attr2' will be automatically prefetched and results will be sorted on

    'attr1' ascending (ie the first attribute in the list).

    This function will automatically add to fetched attributes those defined in

    parent class given using the `pclass` argument.

    Also, You can use `mainattr` and `order` argument to have a different

    sorting.

    """

    if pclass is not None:

        fetchattrs += pclass.fetch_attrs

    if mainattr is None:

        mainattr = fetchattrs[0]

    @classmethod

    def fetch_order(cls, select, attr, var):

        if attr == mainattr:

            select.add_sort_var(var, order=='ASC')

    return fetchattrs, fetch_order