from django.conf import settings
from django.contrib.auth.mixins import LoginRequiredMixin
from django.contrib.auth.models import User
from django.core.exceptions import ValidationError
from django.db import transaction
from django.shortcuts import resolve_url, redirect
from django.urls import reverse_lazy
from django.utils.http import urlsafe_base64_decode
from django.utils.translation import gettext_lazy as _
from django.views.generic import CreateView, TemplateView, DetailView

from corres2math.tokens import email_validation_token
from .forms import SignupForm, StudentRegistrationForm, CoachRegistrationForm


class SignupView(CreateView):
    model = User
    form_class = SignupForm
    template_name = "registration/signup.html"

    def get_context_data(self, **kwargs):
        context = super().get_context_data()

        context["student_registration_form"] = StudentRegistrationForm(self.request.POST or None)
        context["coach_registration_form"] = CoachRegistrationForm(self.request.POST or None)

        return context

    @transaction.atomic
    def form_valid(self, form):
        role = form.cleaned_data["role"]
        if role == "participant":
            registration_form = StudentRegistrationForm(self.request.POST)
        else:
            registration_form = CoachRegistrationForm(self.request.POST)

        if not registration_form.is_valid():
            return self.form_invalid(form)

        ret = super().form_valid(form)
        registration = registration_form.instance
        registration.user = form.instance
        registration.save()

        return ret

    def get_success_url(self):
        return reverse_lazy("index")


class UserValidateView(TemplateView):
    """
    A view to validate the email address.
    """
    title = _("Email validation")
    template_name = 'registration/email_validation_complete.html'
    extra_context = {"title": _("Validate email")}

    def get(self, *args, **kwargs):
        """
        With a given token and user id (in params), validate the email address.
        """
        assert 'uidb64' in kwargs and 'token' in kwargs

        self.validlink = False
        user = self.get_user(kwargs['uidb64'])
        token = kwargs['token']

        # Validate the token
        if user is not None and email_validation_token.check_token(user, token):
            self.validlink = True
            user.registration.email_confirmed = True
            user.save()
        return self.render_to_response(self.get_context_data(), status=200 if self.validlink else 400)

    def get_user(self, uidb64):
        """
        Get user from the base64-encoded string.
        """
        try:
            # urlsafe_base64_decode() decodes to bytestring
            uid = urlsafe_base64_decode(uidb64).decode()
            user = User.objects.get(pk=uid)
        except (TypeError, ValueError, OverflowError, User.DoesNotExist, ValidationError):
            user = None
        return user

    def get_context_data(self, **kwargs):
        context = super().get_context_data(**kwargs)
        context['user_object'] = self.get_user(self.kwargs["uidb64"])
        context['login_url'] = resolve_url(settings.LOGIN_URL)
        if self.validlink:
            context['validlink'] = True
        else:
            context.update({
                'title': _('Email validation unsuccessful'),
                'validlink': False,
            })
        return context


class UserValidationEmailSentView(TemplateView):
    """
    Display the information that the validation link has been sent.
    """
    template_name = 'registration/email_validation_email_sent.html'
    extra_context = {"title": _('Email validation email sent')}


class UserResendValidationEmailView(LoginRequiredMixin, DetailView):
    """
    Rensend the email validation link.
    """
    model = User
    extra_context = {"title": _("Resend email validation link")}

    def get(self, request, *args, **kwargs):
        user = self.get_object()

        user.profile.send_email_validation_link()

        # TODO Change URL
        return redirect('index')