Allow message download as .eml files in the admin

froide/foirequest/admin.py

@@ -4,6 +4,7 @@
 from django.contrib import admin
 from django.db import models
 from django.shortcuts import redirect
+from django.http import HttpResponse
 from django.utils.translation import gettext_lazy as _
 from django.core.exceptions import PermissionDenied
 from django.urls import reverse, reverse_lazy
@@ -346,6 +347,9 @@ def get_urls(self):
             path('<int:pk>/resend-message/',
                 self.admin_site.admin_view(self.resend_message),
                 name='foirequest-foimessage-resend_message'),
+            path('<int:pk>/download-eml/',
+                self.admin_site.admin_view(self.download_eml),
+                name='foirequest-foimessage-download_eml'),
         ]
         return my_urls + urls
 
@@ -406,6 +410,23 @@ def resend_message(self, request, pk):
         self.message_user(request, _('Message was send again.'))
         return redirect('admin:foirequest_foimessage_change', message.id)
 
+    def download_eml(self, request, pk):
+        if not self.has_change_permission(request):
+            raise PermissionDenied
+
+        message = FoiMessage.objects.get(pk=pk, kind='email')
+
+        response = HttpResponse(
+            message.as_mime_message().as_bytes(),
+            content_type='application/octet-stream'
+        )
+        response['Content-Disposition'] = (
+            'attachment; filename="message-{}.eml"'.format(
+                message.id
+            )
+        )
+        return response
+
     def resend_messages(self, request, queryset):
         if not request.method == 'POST':
             raise PermissionDenied

froide/foirequest/models/message.py

@@ -1,10 +1,14 @@
+import calendar
+from email.utils import formatdate
+
 from django.db import models
 from django.conf import settings
 from django.utils.translation import gettext_lazy as _
 from django.template.loader import render_to_string
 from django.utils import timezone
 from django.utils.html import format_html
 from django.utils.functional import cached_property
+from django.core.mail import EmailMessage, EmailMultiAlternatives
 
 from taggit.managers import TaggableManager
 from taggit.models import TagBase, TaggedItemBase
@@ -380,8 +384,10 @@ def attachments(self):
             self._attachments = list(self.foiattachment_set.all().order_by('id'))
         return self._attachments
 
-    def get_mime_attachments(self):
-        return [(a.name, a.get_bytes(), a.filetype) for a in self.attachments]
+    def get_mime_attachments(self, attachments=None):
+        if attachments is None:
+            attachments = self.attachments
+        return [(a.name, a.get_bytes(), a.filetype) for a in attachments]
 
     def get_original_attachments(self):
         return [a for a in self.attachments if not a.is_redacted and not a.is_converted]
@@ -431,6 +437,41 @@ def get_public_body_recipient_form(self):
         from ..forms import get_message_recipient_form
         return get_message_recipient_form(foimessage=self)
 
+    def as_mime_message(self):
+        klass = EmailMessage
+        if self.html:
+            klass = EmailMultiAlternatives
+
+        headers = {
+            'Date': formatdate(
+                int(calendar.timegm(self.timestamp.timetuple()))
+            ),
+            'Message-ID': self.email_message_id,
+            'X-Froide-Hint': 'replica',
+            'X-Froide-Message-Id': self.get_absolute_domain_short_url(),
+        }
+
+        if not self.is_response:
+            headers.update({
+                'Reply-To': self.sender_email
+            })
+
+        email = klass(
+            self.subject,
+            self.plaintext,
+            self.sender_email,
+            to=[self.recipient_email],
+            headers=headers,
+        )
+        if self.html:
+            email.attach_alternative(self.html, "text/html")
+
+        atts = self.get_original_attachments()
+        mime_atts = self.get_mime_attachments(attachments=atts)
+        for mime_data in mime_atts:
+            email.attach(*mime_data)
+        return email.message()
+
     def has_delivery_status(self):
         if not self.sent or self.is_response:
             return False

froide/foirequest/templates/admin/foirequest/foimessage/change_form.html

@@ -7,6 +7,13 @@
       <button type="submit" class="btn btn-secondary">{% blocktrans %}Resend message{% endblocktrans %}</button>
     </form></li>
   {% endif %}
+  {% if original and original.is_email %}
+    <li>
+      <a href="{% url 'admin:foirequest-foimessage-download_eml' pk=original.pk %}">
+        {% translate "Download as .eml" %}
+      </a>
+    </li>
+  {% endif %}
   {{ block.super }}
 {% endblock %}