from django.db import transaction
from django.shortcuts import get_object_or_404
from django.utils import timezone
from rest_framework import serializers
from rest_framework.exceptions import PermissionDenied, ValidationError
from rest_framework.permissions import IsAuthenticated
from rest_framework.response import Response
from rest_framework.views import APIView

from .models import Note, Poll, PollVote
from .permissions import can_edit_note
from .polls import can_vote, is_closed
from .serializers import NoteSerializer
from .views import visible_notes


class PollVoteView(APIView):
    permission_classes = [IsAuthenticated]

    @transaction.atomic
    def put(self, request, pk):
        note = get_object_or_404(visible_notes(request.user), pk=pk, kind='poll')
        get_object_or_404(Note.objects.select_for_update(), pk=note.pk)
        # Relire après le verrou : règles, droits et clôture peuvent avoir changé.
        note = get_object_or_404(visible_notes(request.user), pk=pk, kind='poll')
        poll = get_object_or_404(Poll, note=note)
        if is_closed(poll):
            raise ValidationError('Ce sondage est clôturé.')
        if not can_vote(request.user, note):
            raise PermissionDenied('Ce sondage est réservé aux destinataires indiqués.')
        choices = serializers.ListField(child=serializers.IntegerField(min_value=1), min_length=1, max_length=30).run_validation(request.data.get('option_ids'))
        if len(set(choices)) != len(choices) or poll.options.filter(pk__in=choices).count() != len(choices):
            raise ValidationError('Choisissez des réponses distinctes appartenant à ce sondage.')
        expected = 1 if poll.vote_mode == 'single' else poll.exact_choices if poll.vote_mode == 'exact' else None
        if expected is not None and len(choices) != expected:
            raise ValidationError(f'Sélectionnez exactement {expected} réponse(s).')
        vote, _ = PollVote.objects.get_or_create(poll=poll, user=request.user)
        vote.options.set(choices)
        vote.save()
        if not poll.locked_at:
            poll.locked_at = timezone.now()
            poll.save(update_fields=['locked_at'])
        fresh = visible_notes(request.user).get(pk=pk)
        return Response(NoteSerializer(fresh, context={'request': request}).data)


class PollCloseView(APIView):
    permission_classes = [IsAuthenticated]

    @transaction.atomic
    def post(self, request, pk):
        note = get_object_or_404(visible_notes(request.user), pk=pk, kind='poll')
        get_object_or_404(Note.objects.select_for_update(), pk=note.pk)
        note = get_object_or_404(visible_notes(request.user), pk=pk, kind='poll')
        if not can_edit_note(request.user, note):
            raise PermissionDenied('Seuls l’auteur et les administrateurs autorisés peuvent clôturer ce sondage.')
        poll = get_object_or_404(Poll, note=note)
        if not poll.closed_at:
            poll.closed_at = timezone.now()
            poll.save(update_fields=['closed_at'])
        return Response(NoteSerializer(visible_notes(request.user).get(pk=pk), context={'request': request}).data)