""" Replacement authentication decorators that work around redirection loops,
as well as the trackGrade decorator. """

try:
	from functools import wraps
except ImportError:
	from django.utils.functional import wraps

from django.contrib.auth import REDIRECT_FIELD_NAME
from django.contrib.auth.decorators import login_required
from django.http import HttpResponseForbidden, HttpResponseRedirect
from django.utils.http import urlquote

__all__ = ['login_required', 'permission_required', 'user_passes_test', 'trackGrade']

###
### Authentication decorators
###

def user_passes_test(test_func, login_url=None,
					 redirect_field_name=REDIRECT_FIELD_NAME):
	"""Replacement for django.contrib.auth.decorators.user_passes_test that
	returns 403 Forbidden if the user is already logged in.
	"""

	if not login_url:
		from django.conf import settings
		login_url = settings.LOGIN_URL

	def decorator(view_func):
		@wraps(view_func)
		def wrapper(request, *args, **kwargs):
			if test_func(request.user):
				return view_func(request, *args, **kwargs)
			elif request.user.is_authenticated():
				return HttpResponseForbidden('<h1>Permission denied</h1>')
			else:
				path = '%s?%s=%s' % (login_url, redirect_field_name,
									 urlquote(request.get_full_path()))
				return HttpResponseRedirect(path)
		return wrapper
	return decorator


def permission_required(perm, login_url=None):
	"""Replacement for django.contrib.auth.decorators.permission_required that
	returns 403 Forbidden if the user is already logged in.
	"""

	return user_passes_test(lambda u: u.has_perm(perm), login_url=login_url)


###
### Grade tracking
###


class trackGrade(object):
	""" This decorator expects that an HttpResponse has a context attribute,
	which it uses to retrieve the context. This is passed on to trackGrade.

	In order to use this import the following things 

		from courses.views import render
		from courses.decorators import trackGrade

	And then decorate a view function, passing a log entry heading to the
	decorator.

		@trackGrade("Leksa")
		def leksa_game(request, place=False):
			...

	Currently the more detailed behavior of log subheadings is defined in
	courses.views.trackGrade.

	"""

	def __init__(self, log_name):
		self.log_name = log_name
	
	def __call__(self, view_function):
		""" This must return the HttpResponse from the original function
		"""

		def decorated_function(*args, **kwargs):
			from courses.views import trackGrade

			# grab the request, and execute the view function as normal
			request = args[0]
			response = view_function(*args, **kwargs)

			# It may be that the view somehow doesn't have a context argument,
			# in this case we don't want to track or return anything
			try:
				context = response.context
			except:
				context = False

			if context:
				if self.log_name:
					trackGrade(self.log_name, request, context)

			return response

		return decorated_function