import csv

from django.contrib import messages
from django.contrib.auth import get_user_model
from django.contrib.messages.views import SuccessMessageMixin
from django.core.mail import EmailMessage
from django.db import transaction
from django.http import Http404, HttpResponse, HttpResponseRedirect
from django.urls import reverse
from django.utils import timezone
from django.utils.text import slugify
from django.utils.translation import gettext_lazy as _
from django.views.generic import (
    CreateView,
    DetailView,
    FormView,
    ListView,
    UpdateView,
    View,
)

from shared.json import JsonCreateView, JsonDeleteView, JsonUpdateView
from shared.views import BackgroundUpdateView, TimeMixin

from .forms import (
    DeleteVoteForm,
    ElectionForm,
    OptionForm,
    QuestionForm,
    UploadVotersForm,
    VoterMailForm,
)
from .mixins import (
    AdminOnlyMixin,
    ClosedElectionMixin,
    CreatorOnlyEditMixin,
    CreatorOnlyMixin,
    NotArchivedMixin,
    OpenElectionOnlyMixin,
)
from .models import Election, Option, Question, Vote
from .staticdefs import MAIL_VOTE_DELETED, MAIL_VOTERS, QUESTION_TYPES, VOTE_RULES
from .tasks import send_election_mail
from .utils import create_users

User = get_user_model()

# TODO: access control *everywhere*

# #############################################################################
#  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 ElectionDeleteView(CreatorOnlyMixin, BackgroundUpdateView):
    model = Election
    pattern_name = "election.list"

    def get_object(self, queryset=None):
        obj = self.get_object()
        # On ne peut supprimer que les élections n'ayant pas eu de vote et dont
        # le mail d'annonce n'a pas été fait
        if obj.voters.exists() or obj.send_election_mail:
            raise Http404
        return obj

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


class ElectionAdminView(CreatorOnlyMixin, TimeMixin, 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(
            {
                "question_types": QUESTION_TYPES,
                "o_form": OptionForm,
                "q_form": QuestionForm,
            }
        )
        return super().get_context_data(**kwargs)

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


class ElectionSetVisibleView(CreatorOnlyMixin, BackgroundUpdateView):
    model = Election
    pattern_name = "election.admin"
    success_message = _("Élection visible !")

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


class ExportVotersView(CreatorOnlyMixin, View):
    model = Election

    def get(self, request, *args, **kwargs):
        response = HttpResponse(content_type="text/csv")

        writer = csv.writer(response)
        response["Content-Disposition"] = "attachment; filename=voters.csv"
        writer.writerow(["Nom", "login"])

        for v in self.get_object().voters.all():
            writer.writerow([v.full_name, v.base_username])

        return response


class ElectionUploadVotersView(CreatorOnlyEditMixin, SuccessMessageMixin, FormView):
    model = Election
    form_class = UploadVotersForm
    success_message = _("Liste de votant·e·s importée avec succès !")
    template_name = "elections/election_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 en cours d'envoi !")
    template_name = "elections/election_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 = None
        self.object.save()
        send_election_mail(
            election_pk=self.object.pk,
            subject=form.cleaned_data["objet"],
            body=form.cleaned_data["message"],
            reply_to=self.request.user.email,
        )
        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_form(self, form_class=None):
        form = super().get_form(form_class)
        if self.object.sent_mail:
            form.fields["restricted"].disabled = True
        return form

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

    def form_valid(self, form):
        # Si on ouvre l'élection à tout le monde, on supprime les votant·e·s
        # pré-enregistré·e·s
        if not form.cleaned_data["restricted"]:
            self.object.registered_voters.all().delete()
        return super().form_valid(form)


class DeleteVoteView(ClosedElectionMixin, JsonDeleteView):
    model = Election

    def get_message(self):
        return {
            "content": _("Vote de {} supprimé !").format(self.voter.full_name),
            "class": "success",
        }

    @transaction.atomic
    def get(self, request, *args, **kwargs):
        election = self.get_object()
        self.voter = User.objects.get(pk=self.kwargs["user_pk"])

        # On envoie un mail à la personne lui indiquant que le vote est supprimé
        EmailMessage(
            subject="Vote removed",
            body=MAIL_VOTE_DELETED.format(
                full_name=self.voter.full_name,
                election_name=election.name,
            ),
            to=[self.voter.email],
        ).send()

        # On supprime les votes
        Vote.objects.filter(
            user=self.voter,
            option__question__election=election,
        ).delete()

        # On marque les questions comme non votées
        self.voter.cast_elections.remove(election)
        self.voter.cast_questions.remove(*list(election.questions.all()))
        return self.render_to_json(action="delete")


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.time_tallied = timezone.now()
        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.time_published = (
            timezone.now() if self.election.results_public else None
        )

        self.election.save()
        return super().get(request, *args, **kwargs)


class DownloadResultsView(CreatorOnlyMixin, View):
    model = Election

    def get_queryset(self):
        return super().get_queryset().filter(tallied=True)

    def get(self, request, *args, **kwargs):
        content = "\n".join([q.results for q in self.get_object().questions.all()])

        response = HttpResponse(content, content_type="text/plain")
        response["Content-Disposition"] = "attachment; filename=results.txt"

        return response


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
# #############################################################################


class CreateQuestionView(CreatorOnlyEditMixin, TimeMixin, JsonCreateView):
    model = Election
    form_class = QuestionForm
    context_object_name = "q"
    template_name = "elections/admin/question.html"

    def form_valid(self, form):
        form.instance.election = self.get_object()
        return super().form_valid(form)


class UpdateQuestionView(CreatorOnlyEditMixin, TimeMixin, JsonUpdateView):
    model = Question
    form_class = QuestionForm
    context_object_name = "q"
    template_name = "elections/admin/question.html"


class DeleteQuestionView(CreatorOnlyEditMixin, JsonDeleteView):
    model = Question
    message = _("Question supprimée !")


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


class CreateOptionView(CreatorOnlyEditMixin, TimeMixin, JsonCreateView):
    model = Question
    form_class = OptionForm
    context_object_name = "o"
    template_name = "elections/admin/option.html"

    def form_valid(self, form):
        form.instance.question = self.get_object()
        return super().form_valid(form)


class UpdateOptionView(CreatorOnlyEditMixin, TimeMixin, JsonUpdateView):
    model = Option
    form_class = OptionForm
    context_object_name = "o"
    template_name = "elections/admin/option.html"


class DeleteOptionView(CreatorOnlyEditMixin, JsonDeleteView):
    model = Option
    message = _("Option supprimée !")


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


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


class ElectionView(NotArchivedMixin, 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()
            .select_related("created_by")
            .prefetch_related("questions__options", "questions__duels")
        )


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

    def get_context_data(self, **kwargs):
        user = self.request.user
        context = super().get_context_data(**kwargs)
        election = context["election"]
        voters = list(election.voters.all())

        if user.is_authenticated:
            can_delete = (
                election.created_by == user
                and election.end_date < timezone.now()
                and not election.tallied
            )
            if can_delete:
                context["d_form"] = DeleteVoteForm()

            context["can_delete"] = can_delete
            context["from_admin"] = self.request.GET.get("prev") == "admin"
        context["voters"] = voters

        return context


class ElectionBallotsView(NotArchivedMixin, DetailView):
    model = Election
    template_name = "elections/election_ballots.html"

    def get_queryset(self):
        return (
            super()
            .get_queryset()
            .filter(results_public=True, tallied=True)
            .prefetch_related("questions__options")
        )


class VoteView(OpenElectionOnlyMixin, DetailView):
    model = Question

    def dispatch(self, request, *args, **kwargs):
        # Si l'utilisateur n'est pas connecté on renvoie sur la vue de l'élection
        if not request.user.is_authenticated:
            return HttpResponseRedirect(
                reverse("election.view", args=[super().get_object().election.pk])
            )
        return super().dispatch(request, *args, **kwargs)

    def get_template_names(self):
        return [f"elections/vote/{self.object.vote_type}.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["nb_options"] = self.object.options.count()
        context["range_options"] = range(1, context["nb_options"] + 1)
        context["vote_rule"] = VOTE_RULES[self.object.type].format(**context)
        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 = self.object.get_formset()(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 = self.object.get_formset()(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))