Prevent registration when we are not between registration dates

Signed-off-by: Emmy D'Anello <emmy.danello@animath.fr>

registration/forms.py

@@ -1,5 +1,6 @@
 # Copyright (C) 2020 by Animath
 # SPDX-License-Identifier: GPL-3.0-or-later
+from datetime import datetime
 
 from django import forms
 from django.conf import settings
@@ -7,6 +8,7 @@ from django.contrib.auth.forms import UserCreationForm
 from django.contrib.auth.models import User
 from django.core.exceptions import ValidationError
 from django.forms import FileInput
+from django.utils.text import format_lazy
 from django.utils.translation import gettext_lazy as _
 
 from .models import CoachRegistration, ParticipantRegistration, Payment, \
@@ -36,6 +38,19 @@ class SignupForm(UserCreationForm):
             self.add_error("email", _("This email address is already used."))
         return email
 
+    def clean(self):
+        # Check that registrations are opened
+        now = datetime.now()
+        if now < settings.REGISTRATION_DATES['open']:
+            self.add_error(None, format_lazy(_("Registrations are not opened yet. "
+                                                     "They will open on the {opening_date:%Y-%m-%d %H:%M}."),
+                                                  opening_date=settings.REGISTRATION_DATES['open']))
+        elif now > settings.REGISTRATION_DATES['close']:
+            self.add_error(None, format_lazy(_("Registrations for this year are closed since "
+                                                    "{opening_date:%Y-%m-%d %H:%M}."),
+                                                  opening_date=settings.REGISTRATION_DATES['close']))
+        return super().clean()
+
     def __init__(self, *args, **kwargs):
         super().__init__(*args, **kwargs)
         self.fields["first_name"].required = True