"""
Views for displaying networks of :class:`People` and :class:`Relationship`s.
"""

import logging

from django.contrib.auth.mixins import LoginRequiredMixin
from django.db.models import Q, QuerySet
from django.forms import ValidationError
from django.utils import timezone
from django.views.generic import TemplateView

from people import forms, models, serializers

logger = logging.getLogger(__name__)  # pylint: disable=invalid-name


def filter_by_form_answers(queryset: QuerySet, answerset_queryset: QuerySet, relationship_key: str):
    """Build a filter to select based on form responses."""
    def inner(form, at_date=None):
        # Filter on timestamp__date doesn't seem to work on MySQL
        # To compare datetimes we need at_date to be midnight at
        # the *end* of the day in question - so add one day

        if not at_date:
            at_date = timezone.now().date()
        at_date += timezone.timedelta(days=1)

        # Filter to answersets valid at required time
        answerset_set = answerset_queryset.prefetch_related('question_answers').filter(
            Q(replaced_timestamp__gte=at_date)
            | Q(replaced_timestamp__isnull=True),
            timestamp__lte=at_date
        )

        # Filter to answersets containing required answers
        for field, values in form.cleaned_data.items():
            if field.startswith(f'{form.question_prefix}question_') and values:
                answerset_set = answerset_set.filter(question_answers__in=values)

        return queryset.filter(pk__in=answerset_set.values_list(relationship_key, flat=True))

    return inner


filter_relationships = filter_by_form_answers(
    models.Relationship.objects.prefetch_related('source', 'target'),
    models.RelationshipAnswerSet.objects, 'relationship'
)

filter_organisations = filter_by_form_answers(
    models.Organisation.objects, models.OrganisationAnswerSet.objects, 'organisation'
)

filter_people = filter_by_form_answers(
    models.Person.objects, models.PersonAnswerSet.objects, 'person'
)


class NetworkView(LoginRequiredMixin, TemplateView):
    """View to display relationship network."""
    template_name = 'people/network.html'

    def post(self, request, *args, **kwargs):
        all_forms = self.get_forms()
        if all(map(lambda f: f.is_valid(), all_forms.values())):
            return self.forms_valid(all_forms)

        return self.forms_invalid(all_forms)

    def get_forms(self):
        form_kwargs = self.get_form_kwargs()

        return {
            'relationship': forms.NetworkRelationshipFilterForm(**form_kwargs),
            'person': forms.NetworkPersonFilterForm(**form_kwargs),
            'organisation': forms.NetworkOrganisationFilterForm(**form_kwargs),
            'date': forms.DateForm(**form_kwargs),
        }

    def get_form_kwargs(self):
        """Add GET params to form data."""
        kwargs = {}

        if self.request.method == 'GET':
            kwargs['data'] = self.request.GET

        if self.request.method in ('POST', 'PUT'):
            kwargs['data'] = self.request.POST

        return kwargs

    def get_context_data(self, **kwargs):
        """Add filtered QuerySets of :class:`Person` and :class:`Relationship` to the context."""
        context = super().get_context_data(**kwargs)
        context['full_width_page'] = True

        all_forms = self.get_forms()
        context['relationship_form'] = all_forms['relationship']
        context['person_form'] = all_forms['person']
        context['organisation_form'] = all_forms['organisation']
        context['date_form'] = all_forms['date']

        if not all(map(lambda f: f.is_valid(), all_forms.values())):
            return context

        date = all_forms['date'].cleaned_data['date']

        context['person_set'] = serializers.PersonSerializer(
            filter_people(all_forms['person'], at_date=date), many=True
        ).data

        context['organisation_set'] = serializers.OrganisationSerializer(
            filter_organisations(all_forms['organisation'], at_date=date), many=True
        ).data

        context['relationship_set'] = serializers.RelationshipSerializer(
            filter_relationships(all_forms['relationship'], at_date=date), many=True
        ).data

        context['organisation_relationship_set'] = serializers.OrganisationRelationshipSerializer(
            models.OrganisationRelationship.objects.prefetch_related('source', 'target').all(),
            many=True
        ).data

        for person in models.Person.objects.all():
            try:
                context['organisation_relationship_set'].append(
                    {
                        'pk': f'membership-{person.pk}',
                        'source': serializers.PersonSerializer(person).data,
                        'target': serializers.OrganisationSerializer(
                            person.current_answers.organisation
                        ).data,
                        'kind': 'organisation-membership'
                    }
                )

            except AttributeError:
                pass

        logger.info(
            'Found %d distinct relationships matching filters', len(context['relationship_set'])
        )

        return context

    def forms_valid(self, all_forms):
        try:
            return self.render_to_response(self.get_context_data())

        except ValidationError:
            return self.forms_invalid(all_forms)

    def forms_invalid(self, all_forms):
        return self.render_to_response(self.get_context_data())