# copyright 2003-2011 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 xml and rss views"""

__docformat__ = "restructuredtext en"

_ = unicode

from yams import xy

from cubicweb.schema import VIRTUAL_RTYPES

from cubicweb.view import EntityView

from cubicweb.web.views.xmlrss import SERIALIZERS

try:

    import rdflib

except ImportError:

    rdflib = None

if rdflib is not None:

    RDF = rdflib.Namespace('http://www.w3.org/1999/02/22-rdf-syntax-ns#')

    CW = rdflib.Namespace('http://ns.cubicweb.org/cubicweb/0.0/')

    from rdflib import Literal, URIRef, Namespace

    def urijoin(item):

        base, ext = item

        return URIRef(Namespace(base)[ext])

    SKIP_RTYPES = VIRTUAL_RTYPES | set(['cwuri', 'is', 'is_instance_of'])

    class RDFView(EntityView):

        """rdf view for entities"""

        __regid__ = 'rdf'

        title = _('rdf export')

        templatable = False

        content_type = 'text/xml' # +rdf

        def call(self):

            graph = rdflib.Graph()

            graph.bind('cw', CW)

            for prefix, xmlns in xy.XY.prefixes.items():

                graph.bind(prefix, rdflib.Namespace(xmlns))

            for i in xrange(self.cw_rset.rowcount):

                entity = self.cw_rset.complete_entity(i, 0)

                self.entity2graph(graph, entity)

            self.w(graph.serialize().decode('utf-8'))

        def entity_call(self, entity):

            self.call()

        def entity2graph(self, graph, entity):

            cwuri = URIRef(entity.cwuri)

            add = graph.add

            add( (cwuri, RDF.type, CW[entity.e_schema.type]) )

            try:

                for item in xy.xeq(entity.e_schema.type):

                    add( (cwuri, RDF.type, urijoin(item)) )

            except xy.UnsupportedVocabulary:

                pass

            for rschema, eschemas, role in entity.e_schema.relation_definitions('relation'):

                rtype = rschema.type

                if rtype in SKIP_RTYPES or rtype.endswith('_permission'):

                    continue

                for eschema in eschemas:

                    if eschema.final:

                        try:

                            value = entity.cw_attr_cache[rtype]

                        except KeyError:

                            continue # assuming rtype is Bytes

                        if value is not None:

                            add( (cwuri, CW[rtype], Literal(value)) )

                            try:

                                for item in xy.xeq('%s %s' % (entity.e_schema.type, rtype)):

                                    add( (cwuri, urijoin(item[1]), Literal(value)) )

                            except xy.UnsupportedVocabulary:

                                pass

                    else:

                        for related in entity.related(rtype, role, entities=True, safe=True):

                            if role == 'subject':

                                add( (cwuri, CW[rtype], URIRef(related.cwuri)) )

                                try:

                                    for item in xy.xeq('%s %s' % (entity.e_schema.type, rtype)):

                                        add( (cwuri, urijoin(item), URIRef(related.cwuri)) )

                                except xy.UnsupportedVocabulary:

                                    pass

                            else:

                                add( (URIRef(related.cwuri), CW[rtype], cwuri) )