♻️(backend) refacto email invitation

Remove email invitation from Invitation model
to be able to use it in other context.
We add it in utils.py instead, and it will be called
from the viewset.
We add the document_id to link to the document from
the mail.

src/backend/core/models.py

@@ -3,7 +3,6 @@ Declare and configure the models for the impress core application
 """
 import hashlib
 import os
-import smtplib
 import tempfile
 import textwrap
 import uuid
@@ -14,7 +13,6 @@ from logging import getLogger
 from django.conf import settings
 from django.contrib.auth import models as auth_models
 from django.contrib.auth.base_user import AbstractBaseUser
-from django.contrib.sites.models import Site
 from django.core import exceptions, mail, validators
 from django.core.files.base import ContentFile
 from django.core.files.storage import default_storage
@@ -22,11 +20,9 @@ from django.db import models
 from django.http import FileResponse
 from django.template.base import Template as DjangoTemplate
 from django.template.context import Context
-from django.template.loader import render_to_string
 from django.utils import html, timezone
 from django.utils.functional import lazy
 from django.utils.translation import gettext_lazy as _
-from django.utils.translation import override
 
 import frontmatter
 import markdown
@@ -752,7 +748,6 @@ class Invitation(BaseModel):
             raise exceptions.PermissionDenied()
 
         super().save(*args, **kwargs)
-        self.email_invitation()
 
     def clean(self):
         """Validate fields."""
@@ -800,23 +795,3 @@ class Invitation(BaseModel):
             "partial_update": False,
             "retrieve": bool(roles),
         }
-
-    def email_invitation(self):
-        """Email invitation to the user."""
-        try:
-            with override(self.issuer.language):
-                title = _("Invitation to join Docs!")
-                template_vars = {"title": title, "site": Site.objects.get_current()}
-                msg_html = render_to_string("mail/html/invitation.html", template_vars)
-                msg_plain = render_to_string("mail/text/invitation.txt", template_vars)
-                mail.send_mail(
-                    title,
-                    msg_plain,
-                    settings.EMAIL_FROM,
-                    [self.email],
-                    html_message=msg_html,
-                    fail_silently=False,
-                )
-
-        except smtplib.SMTPException as exception:
-            logger.error("invitation to %s was not sent: %s", self.email, exception)