# This module collects helper functions and classes that "span" multiple levels
# of MVC. In other words, these functions/classes introduce controlled coupling
# for convenience's sake.

from django.core.exceptions import Http404, ObjectDoesNotExist
from django.core.template import Context, loader
from django.conf.settings import DEBUG, INTERNAL_IPS
from django.utils.httpwrappers import HttpResponse

def render_to_response(*args, **kwargs):
    return HttpResponse(loader.render_to_string(*args, **kwargs))
load_and_render = render_to_response # For backwards compatibility.

def get_object_or_404(mod, **kwargs):
    try:
        return mod.get_object(**kwargs)
    except ObjectDoesNotExist:
        raise Http404

def get_list_or_404(mod, **kwargs):
    obj_list = mod.get_list(**kwargs)
    if not obj_list:
        raise Http404
    return obj_list

class DjangoContext(Context):
    """
    This subclass of template.Context automatically populates 'user' and
    'messages' in the context.
    """
    def __init__(self, request, dict=None):
        Context.__init__(self, dict)
        self['user'] = request.user
        self['messages'] = request.user.get_and_delete_messages()
        self['perms'] = PermWrapper(request.user)
        from django.conf import settings
        self['LANGUAGES'] = settings.LANGUAGES
        if hasattr(request, 'LANGUAGE_CODE'):
            self['LANGUAGE_CODE'] = request.LANGUAGE_CODE
        else:
            self['LANGUAGE_CODE'] = settings.LANGUAGE_CODE
        if DEBUG and request.META.get('REMOTE_ADDR') in INTERNAL_IPS:
            self['debug'] = True
            from django.core import db
            self['sql_queries'] = db.db.queries

# PermWrapper and PermLookupDict proxy the permissions system into objects that
# the template system can understand.

class PermLookupDict:
    def __init__(self, user, module_name):
        self.user, self.module_name = user, module_name
    def __repr__(self):
        return str(self.user.get_permission_list())
    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:
    def __init__(self, user):
        self.user = user
    def __getitem__(self, module_name):
        return PermLookupDict(self.user, module_name)