paperwork: Add certification_definition/mailing_lists API endpoint

paperwork/api.py

@@ -1,5 +1,9 @@
+from django.db.models import Prefetch
 from rest_framework import routers, serializers, viewsets
+from rest_framework.decorators import action
+from rest_framework.response import Response
 
+from membershipworks.models import Member
 from .models import Certification, CertificationDefinition, CertificationVersion
 
 
@@ -13,6 +17,32 @@ class CertificationDefinitionViewSet(viewsets.ModelViewSet):
     queryset = CertificationDefinition.objects.all()
     serializer_class = CertificationDefinitionSerializer
 
+    @action(detail=False, methods=["get"])
+    def mailing_lists(self, request, format=None):
+        """
+        Generate a mailing list for each certification definition,
+        containing all certified users for that tool
+        """
+        lists = {}
+        for definition in self.queryset.exclude(mailing_list="").prefetch_related(
+            Prefetch(
+                "certificationversion_set__certification_set__member",
+                queryset=Member.with_is_active(),
+            ),
+        ):
+            if definition.mailing_list not in lists:
+                lists[definition.mailing_list] = set()
+            # TODO: this could be done in sql instead; was planning to
+            # maybe also filter to only active certs
+            for version in definition.certificationversion_set.all():
+                for cert in version.certification_set.all():
+                    if cert.member and cert.member.is_active:
+                        lists[definition.mailing_list].add(
+                            f"{cert.member.account_name} <{cert.member.email}>"
+                        )
+
+        return Response(lists)
+
 
 class CertificationVersionSerializer(serializers.HyperlinkedModelSerializer):
     class Meta: