"""Views for displaying or manipulating instances of :class:`Relationship`."""

import typing

from django.contrib.auth.mixins import LoginRequiredMixin
from django.urls import reverse
from django.utils import timezone
from django.views.generic import DetailView, RedirectView, UpdateView
from django.views.generic.detail import SingleObjectMixin

from people import forms, models, permissions


class RelationshipDetailView(permissions.UserIsLinkedPersonMixin, DetailView):
    """
    View displaying details of a :class:`Relationship`.
    """
    model = models.Relationship
    template_name = 'people/relationship/detail.html'
    related_person_field = 'source'


class RelationshipCreateView(LoginRequiredMixin, RedirectView):
    """View for creating a :class:`Relationship`.

    Redirects to a form containing the :class:`RelationshipQuestion`s.
    """
    def get_redirect_url(self, *args: typing.Any,
                         **kwargs: typing.Any) -> typing.Optional[str]:
        target = models.Person.objects.get(pk=self.kwargs.get('person_pk'))
        relationship, _ = models.Relationship.objects.get_or_create(
            source=self.request.user.person, target=target)

        return reverse('people:relationship.update',
                       kwargs={'pk': relationship.pk})


class RelationshipUpdateView(permissions.UserIsLinkedPersonMixin, UpdateView):
    """View for updating the details of a relationship.

    Creates a new :class:`RelationshipAnswerSet` for the :class:`Relationship`.
    Displays / processes a form containing the :class:`RelationshipQuestion`s.
    """
    model = models.Relationship
    context_object_name = 'relationship'
    template_name = 'people/relationship/update.html'
    form_class = forms.RelationshipAnswerSetForm

    def get_test_person(self) -> models.Person:
        """Get the person instance which should be used for access control checks."""
        return self.get_object().source

    def get_context_data(self, **kwargs):
        context = super().get_context_data(**kwargs)
        context['person'] = self.object.source
        return context

    def get_initial(self):
        try:
            previous_answers = self.object.current_answers.as_dict()

        except AttributeError:
            previous_answers = {}

        previous_answers.update({
            'relationship': self.object,
        })

        return previous_answers

    def get_form_kwargs(self) -> typing.Dict[str, typing.Any]:
        """Remove instance from form kwargs as it's a person, but expects a PersonAnswerSet."""
        kwargs = super().get_form_kwargs()
        kwargs.pop('instance')

        return kwargs

    def form_valid(self, form):
        """Mark any previous answer sets as replaced."""
        response = super().form_valid(form)
        now_date = timezone.now().date()

        # Shouldn't be more than one after initial updates after migration
        for answer_set in self.object.relationship.answer_sets.exclude(
                pk=self.object.pk):
            answer_set.replaced_timestamp = now_date
            answer_set.save()

        return response

    def get_success_url(self) -> str:
        return self.object.get_absolute_url()


class RelationshipEndView(permissions.UserIsLinkedPersonMixin,
                          SingleObjectMixin, RedirectView):
    """View for marking a relationship as ended.

    Sets `replaced_timestamp` on all answer sets where this is currently null.
    """
    model = models.Relationship

    def get_test_person(self) -> models.Person:
        """Get the person instance which should be used for access control checks."""
        return self.get_object().source

    def get_redirect_url(self, *args, **kwargs):
        """Mark any previous answer sets as replaced."""
        now_date = timezone.now().date()
        relationship = self.get_object()

        relationship.answer_sets.filter(
            replaced_timestamp__isnull=True).update(
                replaced_timestamp=now_date)

        return relationship.target.get_absolute_url()


class OrganisationRelationshipEndView(RelationshipEndView):
    """View for marking an organisation relationship as ended.

    Sets `replaced_timestamp` on all answer sets where this is currently null.
    """
    model = models.OrganisationRelationship


class OrganisationRelationshipDetailView(permissions.UserIsLinkedPersonMixin,
                                         DetailView):
    """View displaying details of an :class:`OrganisationRelationship`."""
    model = models.OrganisationRelationship
    template_name = 'people/organisation-relationship/detail.html'
    related_person_field = 'source'
    context_object_name = 'relationship'


class OrganisationRelationshipCreateView(LoginRequiredMixin, RedirectView):
    """View for creating a :class:`OrganisationRelationship`.

    Redirects to a form containing the :class:`OrganisationRelationshipQuestion`s.
    """
    def get_redirect_url(self, *args: typing.Any,
                         **kwargs: typing.Any) -> typing.Optional[str]:
        target = models.Organisation.objects.get(
            pk=self.kwargs.get('organisation_pk'))
        relationship, _ = models.OrganisationRelationship.objects.get_or_create(
            source=self.request.user.person, target=target)

        return reverse('people:organisation.relationship.update',
                       kwargs={'pk': relationship.pk})


class OrganisationRelationshipUpdateView(RelationshipUpdateView):
    """View for updating the details of a Organisationrelationship.

    Creates a new :class:`OrganisationRelationshipAnswerSet` for the :class:`OrganisationRelationship`.
    Displays / processes a form containing the :class:`OrganisationRelationshipQuestion`s.
    """
    model = models.OrganisationRelationship
    context_object_name = 'relationship'
    template_name = 'people/relationship/update.html'
    form_class = forms.OrganisationRelationshipAnswerSetForm