"""SPARQL integration

:organization: Logilab

:copyright: 2009 LOGILAB S.A. (Paris, FRANCE), license is LGPL v2.

:contact: http://www.logilab.fr/ -- mailto:contact@logilab.fr

:license: GNU Lesser General Public License, v2.1 - http://www.gnu.org/licenses

"""

v__docformat__ = "restructuredtext en"

import rql

from yams import xy

from lxml import etree

from lxml.builder import E

from cubicweb.view import StartupView, AnyRsetView

from cubicweb.web import Redirect, form, formfields, formwidgets as fwdgs

from cubicweb.web.views import forms, urlrewrite

from cubicweb.spa2rql import Sparql2rqlTranslator

class SparqlForm(forms.FieldsForm):

    id = 'sparql'

    sparql = formfields.StringField(help=_('type here a sparql query'))

    resultvid = formfields.StringField(choices=((_('table'), 'table'),

                                                (_('sparql xml'), 'sparqlxml')),

                                       widget=fwdgs.Radio,

                                       initial='table')

    form_buttons = [fwdgs.SubmitButton()]

    @property

    def action(self):

        return self.req.url()

class SparqlFormView(form.FormViewMixIn, StartupView):

    id = 'sparql'

    def call(self):

        form = self.vreg.select('forms', 'sparql', self.req)

        self.w(form.form_render())

        sparql = self.req.form.get('sparql')

        vid = self.req.form.get('resultvid', 'table')

        if sparql:

            try:

                qinfo = Sparql2rqlTranslator(self.schema).translate(sparql)

            except rql.TypeResolverException, ex:

                self.w(self.req._('can not resolve entity types:') + u' ' + unicode('ex'))

            except UnsupportedQuery:

                self.w(self.req._('we are not yet ready to handle this query'))

            except xy.UnsupportedVocabulary, ex:

                self.w(self.req._('unknown vocabulary:') + u' ' + unicode('ex'))

            if vid == 'sparqlxml':

                url = self.build_url('view', rql=qinfo.finalize(), vid=vid)

                raise Redirect(url)

            rset = self.req.execute(qinfo.finalize())

            self.wview(vid, rset, 'null')

## sparql resultset views #####################################################

YAMS_XMLSCHEMA_MAPPING = {

    'String': 'string',

    'Int': 'integer',

    'Float': 'float',

    'Boolean': 'boolean',

    'Datetime': 'dateTime',

    'Date': 'date',

    'Time': 'time',

    # XXX the following types don't have direct mapping

    'Decimal': 'string',

    'Interval': 'duration',

    'Password': 'string',

    'Bytes': 'base64Binary',

    }

def xmlschema(yamstype):

    return 'http://www.w3.org/2001/XMLSchema#%s' % YAMS_XMLSCHEMA_MAPPING[yamstype]

class SparqlResultXmlView(AnyRsetView):

    """The spec can be found here: http://www.w3.org/TR/rdf-sparql-XMLres/

    """

    id = 'sparqlxml'

    content_type = 'application/sparql-results+xml'

    templatable = False

    def call(self):

        # XXX handle UNION

        rqlst = self.rset.syntax_tree().children[0]

        varnames = [var.name for var in rqlst.selection]

        results = E.results()

        for rowidx in xrange(len(self.rset)):

            result = E.result()

            for colidx, varname in enumerate(varnames):

                result.append(self.cell_binding(rowidx, colidx, varname))

            results.append(result)

        sparql = E.sparql(E.head(*(E.variable(name=name) for name in varnames)),

                          results)

        self.w(u'<?xml version="1.0"?>\n')

        self.w(etree.tostring(sparql, encoding=unicode, pretty_print=True))

    def cell_binding(self, row, col, varname):

        celltype = self.rset.description[row][col]

        if self.schema.eschema(celltype).is_final():

            cellcontent = self.view('cell', self.rset, row=row, col=col)

            return E.binding(E.literal(cellcontent,

                                       datatype=xmlschema(celltype)),

                             name=varname)

        else:

            entity = self.entity(row, col)

            return E.binding(E.uri(entity.absolute_url()), name=varname)

    def set_request_content_type(self):

        """overriden to set the correct filetype and filename"""

        self.req.set_content_type(self.content_type,

                                  filename='sparql.xml',

                                  encoding=self.req.encoding)