# -*- coding: utf-8 -*-

'''

Created on Jun 11, 2013

@author: ymh

'''

from rdflib import plugin, ConjunctiveGraph, URIRef, Literal

from rdflib.store import Store

from django.db import connections

class TermGraph(ConjunctiveGraph):

    def __init__(self, do_open=False, create=False):

        identifier = "jocondelab"        

        store = plugin.get("SQLAlchemy", Store)(identifier=identifier)

        ConjunctiveGraph.__init__(self, store=store, identifier=identifier)

        if do_open:

            self.open(create)

    def open(self, create=False):

        db_settings = connections['default'].settings_dict

        sa_db_settings = {

            'engine': 'postgresql+psycopg2' if db_settings['ENGINE'] == "django.db.backends.postgresql_psycopg2" else db_settings['ENGINE'],

            'user': db_settings['USER'],

            'password': db_settings['PASSWORD'],

            'port': db_settings['PORT'] if db_settings['PORT'] else "5432",

            'host': db_settings['HOST'] if db_settings['HOST'] else "localhost",

            'name': db_settings['NAME']             

        } 

        connect_config = "%(engine)s://%(user)s:%(password)s@%(host)s:%(port)s/%(name)s"%sa_db_settings 

        return ConjunctiveGraph.open(self, connect_config, create=create)

    def get_uri_for_term(self, term, context):

        c = URIRef(context)

        tl = Literal(term)

        for s,p,_ in self.triples((None, None, tl), context=c):

            if p in [URIRef("http://www.w3.org/2004/02/skos/core#prefLabel"), URIRef("http://www.w3.org/2004/02/skos/core#alternateLabel")]:

                return unicode(s)

        return None

graph = TermGraph(do_open=True, create=False)