from django.contrib.auth import get_user_model

from .backends import AccountBackend

User = get_user_model()


class TemporaryAuthMiddleware:
    """Authenticate another user for this request if AccountBackend succeeds.

    By the way, if a user is authenticated, we refresh its from db to add
    values from CofProfile and Account of this user.

    """
    def __init__(self, get_response):
        self.get_response = get_response

    def __call__(self, request):
        if request.user.is_authenticated:
            # avoid multiple db accesses in views and templates
            request.user = (
                User.objects
                .select_related('profile__account_kfet')
                .get(pk=request.user.pk)
            )

        temp_request_user = AccountBackend().authenticate(
            request,
            kfet_password=self.get_kfet_password(request),
        )

        if temp_request_user:
            request.real_user = request.user
            request.user = temp_request_user

        return self.get_response(request)

    def get_kfet_password(self, request):
        return (
            request.META.get('HTTP_KFETPASSWORD') or
            request.POST.get('KFETPASSWORD')
        )