from django.views.generic import DeleteView
from django.http import HttpResponseRedirect
from django.contrib import messages
from django.db.models import Q


class DeleteCheckView(DeleteView):
	""" Check if object actually can be deleted. Provide reasons to template
		if not.
	"""
	def delete(self, request, *args, **kwargs):
		self.object = self.get_object()
		success_url = self.get_success_url()

		reasons = self.object.getNoDeleteReasons()
		if reasons:
			# do not delete, do what get does...
			return self.get(request, *args, **kwargs)
		else:
			self.object.delete()
			messages.info(request, "Object %s has been deleted" % str(self.object))
			return HttpResponseRedirect(success_url)

	def get_context_data(self, **kwargs):
		if 'reasons' not in kwargs:
			kwargs['reasons'] = self.object.getNoDeleteReasons()
		return super(DeleteCheckView, self).get_context_data(**kwargs)


class MntGenericMixin(object):
	def get_queryset(self):
		mnts = self.request.user.maintainer_set.all()

		q = Q(mnt_by__in=mnts)
		if hasattr(self.model, "mnt_lower"):
			q |= Q(mnt_lower__in=mnts)

		return self.model.objects.filter(q).distinct()

	def get_form_kwargs(self, *args, **kwargs):
		kwargs = super(MntGenericMixin, self).get_form_kwargs(*args, **kwargs)

		if hasattr(self.model, "mnt_lower"):
			mnts = self.request.user.maintainer_set.all()
			if not any(mnt in self.object.mnt_by.all() for mnt in mnts):
				# we are in mnt_lower
				kwargs["lower"] = True

		return kwargs