from pyramid.interfaces import IRendererFactory, PHASE1_CONFIG

from pyramid import renderers
from pyramid.config.actions import action_method

DEFAULT_RENDERERS = (
    ('json', renderers.json_renderer_factory),
    ('string', renderers.string_renderer_factory),
)


class RenderingConfiguratorMixin(object):
    def add_default_renderers(self):
        for name, renderer in DEFAULT_RENDERERS:
            self.add_renderer(name, renderer)

    @action_method
    def add_renderer(self, name, factory):
        """
        Add a :app:`Pyramid` :term:`renderer` factory to the
        current configuration state.

        The ``name`` argument is the renderer name.  Use ``None`` to
        represent the default renderer (a renderer which will be used for all
        views unless they name another renderer specifically).

        The ``factory`` argument is Python reference to an
        implementation of a :term:`renderer` factory or a
        :term:`dotted Python name` to same.
        """
        factory = self.maybe_dotted(factory)
        # if name is None or the empty string, we're trying to register
        # a default renderer, but registerUtility is too dumb to accept None
        # as a name
        if not name:
            name = ''

        def register():
            self.registry.registerUtility(factory, IRendererFactory, name=name)

        intr = self.introspectable(
            'renderer factories',
            name,
            self.object_description(factory),
            'renderer factory',
        )
        intr['factory'] = factory
        intr['name'] = name
        # we need to register renderers early (in phase 1) because they are
        # used during view configuration (which happens in phase 3)
        self.action(
            (IRendererFactory, name),
            register,
            order=PHASE1_CONFIG,
            introspectables=(intr,),
        )