from django.contrib.auth import REDIRECT_FIELD_NAME
from django.http import HttpResponseRedirect
from django.utils.http import urlquote

def user_passes_test(test_func, login_url=None, redirect_field_name=REDIRECT_FIELD_NAME):
    """
    Decorator for views that checks that the user passes the given test,
    redirecting to the log-in page if necessary. The test should be a callable
    that takes the user object and returns True if the user passes.
    """
    if not login_url:
        from django.conf import settings
        login_url = settings.LOGIN_URL
    def _dec(view_func):
        def _checklogin(request, *args, **kwargs):
            if test_func(request.user):
                return view_func(request, *args, **kwargs)
            return HttpResponseRedirect('%s?%s=%s' % (login_url, redirect_field_name, urlquote(request.get_full_path())))
        _checklogin.__doc__ = view_func.__doc__
        _checklogin.__dict__ = view_func.__dict__

        return _checklogin
    return _dec

def login_required(function=None, redirect_field_name=REDIRECT_FIELD_NAME):
    """
    Decorator for views that checks that the user is logged in, redirecting
    to the log-in page if necessary.
    """
    actual_decorator = user_passes_test(
        lambda u: u.is_authenticated(),
        redirect_field_name=redirect_field_name
    )
    if function:
        return actual_decorator(function)
    return actual_decorator

def permission_required(perm, login_url=None):
    """
    Decorator for views that checks whether a user has a particular permission
    enabled, redirecting to the log-in page if necessary.
    """
    return user_passes_test(lambda u: u.has_perm(perm), login_url=login_url)