"""Contains resources classes.

"""

from rql import TypeResolverException

from pyramid.decorator import reify

from pyramid.httpexceptions import HTTPNotFound

class EntityResource(object):

    """A resource class for an entity. It provide method to retrieve an entity

    by eid.

    """

    @classmethod

    def from_eid(cls):

        def factory(request):

            return cls(request, None, None, request.matchdict['eid'])

        return factory

    def __init__(self, request, cls, attrname, value):

        self.request = request

        self.cls = cls

        self.attrname = attrname

        self.value = value

    @reify

    def rset(self):

        req = self.request.cw_request

        if self.cls is None:

            return req.execute('Any X WHERE X eid %(x)s',

                               {'x': int(self.value)})

        st = self.cls.fetch_rqlst(self.request.cw_cnx.user, ordermethod=None)

        st.add_constant_restriction(st.get_variable('X'), self.attrname,

                                    'x', 'Substitute')

        if self.attrname == 'eid':

            try:

                rset = req.execute(st.as_string(), {'x': int(self.value)})

            except (ValueError, TypeResolverException):

                # conflicting eid/type

                raise HTTPNotFound()

        else:

            rset = req.execute(st.as_string(), {'x': unicode(self.value)})

        return rset

class ETypeResource(object):

    """A resource for etype.

    """

    @classmethod

    def from_match(cls, matchname):

        def factory(request):

            return cls(request, request.matchdict[matchname])

        return factory

    def __init__(self, request, etype):

        vreg = request.registry['cubicweb.registry']

        self.request = request

        self.etype = vreg.case_insensitive_etypes[etype.lower()]

        self.cls = vreg['etypes'].etype_class(self.etype)

    def __getitem__(self, value):

        attrname = self.cls.cw_rest_attr_info()[0]

        return EntityResource(self.request, self.cls, attrname, value)

    @reify

    def rset(self):

        rql = self.cls.fetch_rql(self.request.cw_cnx.user)

        rset = self.request.cw_request.execute(rql)

        return rset