Add the @@survey-group-image view

This view is necessary to retrieve the image for the survey group in the
best possible way, given the constraints.

Survey groups are assigned via a script across all survey versions (see
syslabcom/scrum#2552 for details).

The view redirects to the first meaningful image it can find. While this
approach helps achieve the desired functionality, it is more of a
workaround and isn't highly efficient. One downside is that browser
caching may retain the image longer than intended, potentially affecting
freshness.

This solution is a trade-off between performance and practicality.

src/osha/oira/content/browser/configure.zcml

@@ -3,6 +3,12 @@
     xmlns:browser="http://namespaces.zope.org/browser"
     >
 
+  <browser:resourceDirectory
+      name="osha.oira.content"
+      directory="resources"
+      layer="osha.oira.interfaces.IOSHAContentSkinLayer"
+      />
+
   <browser:page
       name="manage-ldap-users"
       for="euphorie.content.country.ICountry"
@@ -65,6 +71,14 @@
         />
   </configure>
 
+  <browser:page
+      name="survey-group-image"
+      for="euphorie.content.surveygroup.ISurveyGroup"
+      class=".surveygroup.SurveyGroupImage"
+      permission="zope2.View"
+      layer="osha.oira.interfaces.IOSHAContentSkinLayer"
+      />
+
   <!-- Sector -->
   <adapter
       name="euphorie.sector"

src/osha/oira/content/browser/surveygroup.py

@@ -1,7 +1,9 @@
+from Acquisition import aq_base
 from Acquisition import aq_parent
 from euphorie.content import MessageFactory as _
 from plone import api
 from plonetheme.nuplone.skin import actions
+from Products.Five import BrowserView
 
 
 class Delete(actions.Delete):
@@ -37,3 +39,49 @@ def verify(self, container, context):
             self.request.response.redirect(context.absolute_url())
             return False
         return True
+
+
+class SurveyGroupImage(BrowserView):
+    """Return the image of the surveygroup."""
+
+    @property
+    def surveys(self):
+        """Iterator over the surveys contained in the surveygroup.
+
+        The published survey (if it exists) comes first.
+        """
+        published = self.context.published
+        if published:
+            published_obj = self.context.get(published)
+            if published_obj:
+                yield published_obj
+
+        for obj in self.context.listFolderContents({"portal_type": "Survey"}):
+            if obj.getId() != published:
+                yield obj
+
+    def get_obj_image_url(self, obj):
+        """Return the URL of the image of the given object.
+
+        The image is set by a cron script,
+        see e.g. https://github.com/syslabcom/scrum/issues/2552.
+
+        This might change in the future.
+        """
+        if obj and aq_base(obj.image):
+            return f"{obj.absolute_url()}/@@images/image"
+
+    def __call__(self):
+        """Check all the surveys, if they have an image, redirect to that image.
+
+        Return a fallback if it does not exist.
+        """
+        for survey in self.surveys:
+            image_url = self.get_obj_image_url(survey)
+            if image_url:
+                return self.request.response.redirect(image_url)
+
+        self.request.response.redirect(
+            f"{api.portal.get().absolute_url()}"
+            f"/++resource++osha.oira.content/clipboard.svg"
+        )