from django.core.urlresolvers import RegexURLPattern, RegexURLResolver

from django.core.exceptions import ImproperlyConfigured

__all__ = ['handler404', 'handler500', 'include', 'patterns', 'url']

handler404 = 'django.views.defaults.page_not_found'

handler500 = 'django.views.defaults.server_error'

def include(arg, namespace=None, app_name=None):

    if isinstance(arg, tuple):

        # callable returning a namespace hint

        if namespace:

            raise ImproperlyConfigured('Cannot override the namespace for a dynamic module that provides a namespace')

        urlconf_module, app_name, namespace = arg

    else:

        # No namespace hint - use manually provided namespace

        urlconf_module = arg

    return (urlconf_module, app_name, namespace)

def patterns(prefix, *args):

    pattern_list = []

    for t in args:

        if isinstance(t, (list, tuple)):

            t = url(prefix=prefix, *t)

        elif isinstance(t, RegexURLPattern):

            t.add_prefix(prefix)

        pattern_list.append(t)

    return pattern_list

def url(regex, view, kwargs=None, name=None, prefix=''):

    if isinstance(view, (list,tuple)):

        # For include(...) processing.

        urlconf_module, app_name, namespace = view

        return RegexURLResolver(regex, urlconf_module, kwargs, app_name=app_name, namespace=namespace)

    else:

        if isinstance(view, basestring):

            if not view:

                raise ImproperlyConfigured('Empty URL pattern view name not permitted (for pattern %r)' % regex)

            if prefix:

                view = prefix + '.' + view

        return RegexURLPattern(regex, view, kwargs, name)