From f5db2ab83500d2b1409f978ea2679f7fff71d9ac Mon Sep 17 00:00:00 2001
From: Jason Robinson <mail@jasonrobinson.me>
Date: Sat, 29 Jun 2019 01:21:33 +0300
Subject: [PATCH] Add support for outgoing unfollow in ActivityPub

Sent as Unfo{Follow}.

Also don't send an accept to an Undo{Follow}..
---
 federation/entities/activitypub/entities.py   | 31 ++++++++++++++-----
 .../entities/activitypub/test_entities.py     | 26 ++++++++++++++++
 federation/tests/fixtures/entities.py         | 10 ++++++
 3 files changed, 60 insertions(+), 7 deletions(-)

diff --git a/federation/entities/activitypub/entities.py b/federation/entities/activitypub/entities.py
index 2c1a6e3..d36a797 100644
--- a/federation/entities/activitypub/entities.py
+++ b/federation/entities/activitypub/entities.py
@@ -36,6 +36,9 @@ class ActivitypubFollow(ActivitypubObjectMixin, Follow):
         """
         Post receive hook - send back follow ack.
         """
+        if not self.following:
+            return
+
         from federation.utils.activitypub import retrieve_and_parse_profile  # Circulars
         try:
             from federation.utils.django import get_function_from_config
@@ -76,13 +79,27 @@ class ActivitypubFollow(ActivitypubObjectMixin, Follow):
             logger.exception("ActivitypubFollow.post_receive - Failed to send Accept back")
 
     def to_as2(self) -> Dict:
-        as2 = {
-            "@context": CONTEXTS_DEFAULT,
-            "id": self.activity_id,
-            "type": self._type,
-            "actor": self.actor_id,
-            "object": self.target_id,
-        }
+        if self.following:
+            as2 = {
+                "@context": CONTEXTS_DEFAULT,
+                "id": self.activity_id,
+                "type": self._type,
+                "actor": self.actor_id,
+                "object": self.target_id,
+            }
+        else:
+            as2 = {
+                "@context": CONTEXTS_DEFAULT,
+                "id": self.activity_id,
+                "type": ActivityType.UNDO.value,
+                "actor": self.actor_id,
+                "object": {
+                    "id": f"{self.actor_id}#follow-{uuid.uuid4()}",
+                    "type": self._type,
+                    "actor": self.actor_id,
+                    "object": self.target_id,
+                },
+            }
         return as2
 
 
diff --git a/federation/tests/entities/activitypub/test_entities.py b/federation/tests/entities/activitypub/test_entities.py
index 68f50d7..23bef3f 100644
--- a/federation/tests/entities/activitypub/test_entities.py
+++ b/federation/tests/entities/activitypub/test_entities.py
@@ -20,6 +20,32 @@ class TestEntitiesConvertToAS2:
             "object": "https://example.com/follow/1234",
         }
 
+    def test_follow_to_as2(self, activitypubfollow):
+        result = activitypubfollow.to_as2()
+        assert result == {
+            "@context": CONTEXTS_DEFAULT,
+            "id": "https://localhost/follow",
+            "type": "Follow",
+            "actor": "https://localhost/profile",
+            "object": "https://example.com/profile"
+        }
+
+    def test_follow_to_as2__undo(self, activitypubundofollow):
+        result = activitypubundofollow.to_as2()
+        result["object"]["id"] = "https://localhost/follow"  # Real object will have a random UUID postfix here
+        assert result == {
+            "@context": CONTEXTS_DEFAULT,
+            "id": "https://localhost/undo",
+            "type": "Undo",
+            "actor": "https://localhost/profile",
+            "object": {
+                "id": "https://localhost/follow",
+                "type": "Follow",
+                "actor": "https://localhost/profile",
+                "object": "https://example.com/profile",
+            }
+        }
+
     def test_post_to_as2(self, activitypubpost):
         result = activitypubpost.to_as2()
         assert result == {
diff --git a/federation/tests/fixtures/entities.py b/federation/tests/fixtures/entities.py
index 03df259..019a69b 100644
--- a/federation/tests/fixtures/entities.py
+++ b/federation/tests/fixtures/entities.py
@@ -59,6 +59,16 @@ def activitypubprofile():
     )
 
 
+@pytest.fixture
+def activitypubundofollow():
+    return ActivitypubFollow(
+        activity_id="https://localhost/undo",
+        actor_id="https://localhost/profile",
+        target_id="https://example.com/profile",
+        following=False,
+    )
+
+
 @pytest.fixture
 def profile():
     return Profile(