"""

A set of request processors that return dictionaries to be merged into a

template context. Each function takes the request object as its only parameter

and returns a dictionary to add to the context.

These are referenced from the setting TEMPLATE_CONTEXT_PROCESSORS and used by

RequestContext.

"""

from django.conf import settings

def auth(request):

    """

    Returns context variables required by apps that use Django's authentication

    system.

    If there is no 'user' attribute in the request, uses AnonymousUser (from

    django.contrib.auth).

    """

    if hasattr(request, 'user'):

        user = request.user

    else:

        from django.contrib.auth.models import AnonymousUser

        user = AnonymousUser()

    return {

        'user': user,

        'messages': user.get_and_delete_messages(),

        'perms': PermWrapper(user),

    }

def debug(request):

    "Returns context variables helpful for debugging."

    context_extras = {}

    if settings.DEBUG and request.META.get('REMOTE_ADDR') in settings.INTERNAL_IPS:

        context_extras['debug'] = True

        from django.db import connection

        context_extras['sql_queries'] = connection.queries

    return context_extras

def i18n(request):

    from django.utils import translation

    context_extras = {}

    context_extras['LANGUAGES'] = settings.LANGUAGES

    context_extras['LANGUAGE_CODE'] = translation.get_language()

    context_extras['LANGUAGE_BIDI'] = translation.get_language_bidi()

    return context_extras

def media(request):

    """

    Adds media-related context variables to the context.

    """

    return {'MEDIA_URL': settings.MEDIA_URL}

def request(request):

    return {'request': request}

# PermWrapper and PermLookupDict proxy the permissions system into objects that

# the template system can understand.

class PermLookupDict(object):

    def __init__(self, user, module_name):

        self.user, self.module_name = user, module_name

    def __repr__(self):

        return str(self.user.get_all_permissions())

    def __getitem__(self, perm_name):

        return self.user.has_perm("%s.%s" % (self.module_name, perm_name))

    def __nonzero__(self):

        return self.user.has_module_perms(self.module_name)

class PermWrapper(object):

    def __init__(self, user):

        self.user = user

    def __getitem__(self, module_name):

        return PermLookupDict(self.user, module_name)

    def __iter__(self):

        # I am large, I contain multitudes.

        raise TypeError("PermWrapper is not iterable.")