Change the reply detection system

- The In-Reply-To header has the priority
- The last message-id in the Reference header is used, not the first
  one

2 files changed, 31 insertions, 7 deletions

diff --git a/kittystore/test/test_utils.py b/kittystore/test/test_utils.py
index 7662e81..8e78d5b 100644
--- a/kittystore/test/test_utils.py
+++ b/kittystore/test/test_utils.py
@@ -33,6 +33,30 @@ class TestUtils(unittest.TestCase):
                 msg, "example-list", store)[0]
         self.assertEqual(ref_id, None)
 
+    def test_in_reply_to(self):
+        msg = Message()
+        msg["From"] = "dummy@example.com"
+        msg["Message-ID"] = "<dummy>"
+        msg["In-Reply-To"] = " <ref-1> "
+        msg.set_payload("Dummy message")
+        store = Mock()
+        ref_id = kittystore.utils.get_ref_and_thread_id(
+                msg, "example-list", store)[0]
+        self.assertEqual(ref_id, "ref-1")
+
+    def test_in_reply_to_and_reference(self):
+        """The In-Reply-To header should win over References"""
+        msg = Message()
+        msg["From"] = "dummy@example.com"
+        msg["Message-ID"] = "<dummy>"
+        msg["In-Reply-To"] = " <ref-1> "
+        msg["References"] = " <ref-2> "
+        msg.set_payload("Dummy message")
+        store = Mock()
+        ref_id = kittystore.utils.get_ref_and_thread_id(
+                msg, "example-list", store)[0]
+        self.assertEqual(ref_id, "ref-1")
+
     def test_single_reference(self):
         msg = Message()
         msg["From"] = "dummy@example.com"
@@ -53,7 +77,7 @@ class TestUtils(unittest.TestCase):
         store = Mock()
         ref_id = kittystore.utils.get_ref_and_thread_id(
                 msg, "example-list", store)[0]
-        self.assertEqual(ref_id, "ref-1")
+        self.assertEqual(ref_id, "ref-2")
 
     def test_empty_reference(self):
         msg = Message()
diff --git a/kittystore/utils.py b/kittystore/utils.py
index badf5af..d98537f 100644
--- a/kittystore/utils.py
+++ b/kittystore/utils.py
@@ -110,12 +110,12 @@ def get_ref_and_thread_id(message, list_name, store):
             and not message.has_key("In-Reply-To")):
         return None, None
     # It's a reply, use the thread_id from the parent email
-    ref_id = message.get("References")
-    if ref_id is not None and ref_id.strip():
-        # There can be multiple references, use the first one
-        ref_id = ref_id.split()[0].strip()
-    else:
-        ref_id = message.get("In-Reply-To")
+    ref_id = message.get("In-Reply-To")
+    if ref_id is None or not ref_id.strip():
+        ref_id = message.get("References")
+        if ref_id is not None and ref_id.strip():
+            # There can be multiple references, use the last one
+            ref_id = ref_id.split()[-1].strip()
     if ref_id is not None:
         ref_id = IN_BRACKETS_RE.match(ref_id)
     if ref_id is None: