from django.contrib import messages
from django.contrib.messages.views import SuccessMessageMixin
from django.db.models import Q
from django.http import Http404, HttpResponseRedirect
from django.urls import reverse
from django.utils import timezone
from django.utils.decorators import method_decorator
from django.utils.text import slugify
from django.utils.translation import gettext_lazy as _
from django.views.decorators.http import require_POST
from django.views.generic import (
    CreateView,
    DetailView,
    FormView,
    ListView,
    RedirectView,
    UpdateView,
)

from .forms import (
    ElectionForm,
    OptionForm,
    OptionFormSet,
    QuestionForm,
    UploadVotersForm,
    VoterMailForm,
)
from .mixins import (
    AdminOnlyMixin,
    ClosedElectionMixin,
    CreatorOnlyEditMixin,
    CreatorOnlyMixin,
    OpenElectionOnlyMixin,
)
from .models import Election, Option, Question
from .staticdefs import MAIL_VOTERS, QUESTION_TYPES, VOTE_RULES
from .utils import create_users, send_mail

# TODO: access control *everywhere*

# #############################################################################
#  Utils Views
# #############################################################################


class BackgroundUpdateView(RedirectView):
    success_message = ""

    def get_success_message(self):
        return self.success_message

    def get(self, request, *args, **kwargs):
        success_message = self.get_success_message()
        if success_message:
            messages.success(self.request, success_message)
        return super().get(request, *args, **kwargs)


# #############################################################################
#  Administration Views
# #############################################################################


class ElectionCreateView(AdminOnlyMixin, SuccessMessageMixin, CreateView):
    model = Election
    form_class = ElectionForm
    success_message = _("Élection créée avec succès !")
    template_name = "elections/election_create.html"

    def get_success_url(self):
        return reverse("election.admin", args=[self.object.pk])

    def form_valid(self, form):
        # We need to add the short name and the creator od the election
        form.instance.short_name = slugify(
            form.instance.start_date.strftime("%Y-%m-%d") + "_" + form.instance.name
        )[:50]
        # TODO: Change this if we modify the user model
        form.instance.created_by = self.request.user
        return super().form_valid(form)


class ElectionAdminView(CreatorOnlyMixin, DetailView):
    model = Election
    template_name = "elections/election_admin.html"

    def get_next_url(self):
        return reverse("election.view", args=[self.object.pk])

    def get_context_data(self, **kwargs):
        kwargs.update(
            {"current_time": timezone.now(), "question_types": QUESTION_TYPES}
        )
        return super().get_context_data(**kwargs)

    def get_queryset(self):
        return super().get_queryset().prefetch_related("questions__options")


class ElectionUploadVotersView(CreatorOnlyEditMixin, SuccessMessageMixin, FormView):
    model = Election
    form_class = UploadVotersForm
    success_message = _("Liste de votant·e·s importée avec succès !")
    template_name = "elections/upload_voters.html"

    def get_queryset(self):
        # On ne peut ajouter une liste d'électeurs que sur une élection restreinte
        return super().get_queryset().filter(restricted=True)

    def get_success_url(self):
        return reverse("election.upload-voters", args=[self.object.pk])

    def get_context_data(self, **kwargs):
        context = super().get_context_data(**kwargs)
        context["voters"] = self.object.registered_voters.all()
        return context

    def get(self, request, *args, **kwargs):
        self.object = self.get_object()
        return super().get(request, *args, **kwargs)

    def post(self, request, *args, **kwargs):
        self.object = self.get_object()
        return super().post(request, *args, **kwargs)

    def form_valid(self, form):
        # On crée les comptes nécessaires à l'élection, en supprimant ceux
        # existant déjà pour ne pas avoir de doublons
        self.object.registered_voters.all().delete()
        create_users(self.object, form.cleaned_data["csv_file"])
        return super().form_valid(form)


class ElectionMailVotersView(CreatorOnlyEditMixin, SuccessMessageMixin, FormView):
    model = Election
    form_class = VoterMailForm
    success_message = _("Mail d'annonce envoyé avec succès !")
    template_name = "elections/mail_voters.html"

    def get_queryset(self):
        # On ne peut envoyer un mail que sur une élection restreinte qui n'a pas
        # déjà vu son mail envoyé
        return super().get_queryset().filter(restricted=True, sent_mail=False)

    def get_success_url(self):
        return reverse("election.upload-voters", args=[self.object.pk])

    def get_initial(self):
        return {"objet": f"Vote : {self.object.name}", "message": MAIL_VOTERS}

    def get(self, request, *args, **kwargs):
        self.object = self.get_object()
        return super().get(request, *args, **kwargs)

    def post(self, request, *args, **kwargs):
        self.object = self.get_object()
        return super().post(request, *args, **kwargs)

    def form_valid(self, form):
        self.object.sent_mail = True
        send_mail(self.object, form)
        self.object.save()
        return super().form_valid(form)


class ElectionUpdateView(CreatorOnlyEditMixin, SuccessMessageMixin, UpdateView):
    model = Election
    form_class = ElectionForm
    success_message = _("Élection modifiée avec succès !")
    template_name = "elections/election_update.html"

    def get_success_url(self):
        return reverse("election.admin", args=[self.object.pk])


class ElectionTallyView(ClosedElectionMixin, BackgroundUpdateView):
    model = Election
    pattern_name = "election.admin"
    success_message = _("Élection dépouillée avec succès !")

    def get_queryset(self):
        return (
            super()
            .get_queryset()
            .filter(tallied=False)
            .prefetch_related("questions__options")
        )

    def get(self, request, *args, **kwargs):
        election = self.get_object()
        for q in election.questions.all():
            q.tally()

        election.tallied = True
        election.save()
        return super().get(request, *args, **kwargs)


class ElectionChangePublicationView(ClosedElectionMixin, BackgroundUpdateView):
    model = Election
    pattern_name = "election.admin"

    def get_success_message(self):
        if self.election.results_public:
            return _("Élection publiée avec succès !")
        return _("Élection dépubliée avec succès !")

    def get(self, request, *args, **kwargs):
        self.election = self.get_object()
        self.election.results_public = not self.election.results_public
        self.election.save()
        return super().get(request, *args, **kwargs)


class ElectionArchiveView(ClosedElectionMixin, BackgroundUpdateView):
    model = Election
    pattern_name = "election.admin"
    success_message = _("Élection archivée avec succès !")

    def get(self, request, *args, **kwargs):
        election = self.get_object()
        election.archived = True
        election.save()
        return super().get(request, *args, **kwargs)


# #############################################################################
#  Question Views
# #############################################################################


@method_decorator(require_POST, name="dispatch")
class AddQuestionView(CreatorOnlyEditMixin, CreateView):
    model = Election
    form_class = QuestionForm

    def get_success_url(self):
        return reverse("election.admin", args=[self.election.pk]) + "#q_add"

    def form_valid(self, form):
        self.election = self.get_object()
        # On ajoute l'élection voulue à la question créée
        form.instance.election = self.election
        return super().form_valid(form)


class ModQuestionView(CreatorOnlyEditMixin, SuccessMessageMixin, UpdateView):
    model = Question
    form_class = QuestionForm
    success_message = _("Question modifiée avec succès !")
    template_name = "elections/question_update.html"

    def get_success_url(self):
        return (
            reverse("election.admin", args=[self.object.election.pk])
            + f"#q_{self.object.pk}"
        )


class DelQuestionView(CreatorOnlyEditMixin, BackgroundUpdateView):
    model = Question
    success_message = _("Question supprimée !")

    def get_redirect_url(self, *args, **kwargs):
        return reverse("election.admin", args=[self.election.pk]) + "#q_add"

    def get(self, request, *args, **kwargs):
        question = self.get_object()
        self.election = question.election
        question.delete()
        return super().get(request, *args, **kwargs)


# #############################################################################
#  Option Views
# #############################################################################


@method_decorator(require_POST, name="dispatch")
class AddOptionView(CreatorOnlyEditMixin, CreateView):
    model = Question
    form_class = OptionForm

    def get_queryset(self):
        return super().get_queryset()

    def get_success_url(self):
        return (
            reverse("election.admin", args=[self.question.election.pk])
            + f"#q_{self.question.pk}"
        )

    def form_valid(self, form):
        self.question = self.get_object()
        # On ajoute l'élection voulue à la question créée
        form.instance.question = self.question
        return super().form_valid(form)


class ModOptionView(CreatorOnlyEditMixin, SuccessMessageMixin, UpdateView):
    model = Option
    form_class = OptionForm
    success_message = _("Option modifiée avec succès !")
    template_name = "elections/option_update.html"

    def get_success_url(self):
        return (
            reverse("election.admin", args=[self.object.question.election.pk])
            + f"#o_{self.object.pk}"
        )


class DelOptionView(CreatorOnlyEditMixin, BackgroundUpdateView):
    model = Option
    success_message = _("Option supprimée !")

    def get_redirect_url(self, *args, **kwargs):
        return reverse("election.admin", args=[self.election.pk]) + "#q_add"

    def get(self, request, *args, **kwargs):
        option = self.get_object()
        self.election = option.question.election
        option.delete()
        return super().get(request, *args, **kwargs)


# #############################################################################
#  Public Views
# #############################################################################


class ElectionListView(ListView):
    model = Election
    template_name = "elections/election_list.html"

    def get_queryset(self):
        return (
            super()
            .get_queryset()
            .filter(Q(archived=False) | Q(created_by=self.request.user))
        )


class ElectionView(DetailView):
    model = Election
    template_name = "elections/election.html"

    def get_next_url(self):
        return self.request.path

    def get_context_data(self, **kwargs):
        user = self.request.user
        context = super().get_context_data(**kwargs)
        context["current_time"] = timezone.now()

        if user.is_authenticated:
            context["can_vote"] = user.can_vote(self.request, context["election"])
            context["cast_questions"] = user.cast_questions.all()
            context["has_voted"] = user.cast_elections.filter(
                pk=context["election"].pk
            ).exists()

        return context

    def get_queryset(self):
        return (
            super()
            .get_queryset()
            .filter(archived=False)
            .prefetch_related("questions__options")
        )


class ElectionVotersView(DetailView):
    model = Election
    template_name = "elections/election_voters.html"


class VoteView(OpenElectionOnlyMixin, DetailView):
    model = Question
    template_name = "elections/vote.html"

    def get_next_url(self):
        return reverse("election.view", args=[self.object.election.pk])

    def get_success_url(self):
        questions = list(self.object.election.questions.all())
        q_index = questions.index(self.object)
        if q_index + 1 == len(questions):
            # On était à la dernière question
            # On enregistre le vote pour l'élection
            self.object.election.voters.add(self.request.user)
            return reverse("election.view", args=[self.object.election.pk])

        # On récupère l'id de la prochaine question
        q_next = questions[q_index + 1].pk

        return reverse("election.vote", args=[q_next])

    def get_context_data(self, **kwargs):
        context = super().get_context_data(**kwargs)
        questions = list(self.object.election.questions.all())
        context["q_index"] = questions.index(self.object) + 1
        context["q_total"] = len(questions)
        context["vote_rule"] = VOTE_RULES[self.object.type]
        return context

    def get_object(self):
        question = super().get_object()
        # Seulement les utilisateur·ice·s ayant le droit de voter dans l'élection
        # peuvent voir la page
        if not self.request.user.can_vote(self.request, question.election):
            raise Http404
        return question

    def get(self, request, *args, **kwargs):
        self.object = self.get_object()
        vote_form = OptionFormSet(instance=self.object)

        return self.render_to_response(self.get_context_data(formset=vote_form))

    def post(self, request, *args, **kwargs):
        self.object = self.get_object()
        vote_form = OptionFormSet(self.request.POST, instance=self.object)

        if self.object.is_form_valid(vote_form):
            # On enregistre le vote
            self.object.cast_ballot(self.request.user, vote_form)
            self.object.voters.add(self.request.user)
            messages.success(self.request, _("Votre choix a bien été enregistré !"))

            return HttpResponseRedirect(self.get_success_url())
        else:
            return self.render_to_response(self.get_context_data(formset=vote_form))