--- a/pylib/mozreview/mozreview/diffviewer/__init__.py
+++ b/pylib/mozreview/mozreview/diffviewer/__init__.py
@@ -0,0 +1,36 @@
+from reviewboard.diffviewer.models import DiffSet
+
+
+def diffstats(diffset):
+    """Return a dictionary of diffstat information for a diffset."""
+    counts = diffset.get_total_line_counts()
+
+    # TODO: Take into account the non raw counts review board might
+    # have to display information about replacement.
+    return {
+        'insert': counts.get('raw_insert_count', 0),
+        'delete': counts.get('raw_delete_count', 0),
+    }
+
+
+def get_diffstats(review_request, user, rev=None):
+    """Return a dictionary containing diffstat information.
+
+    If no rev is provided, use the latest diffset. If the requesting
+    user is the submitter, take any draft diffsets into account.
+    """
+    # Ensure we're working with the base review request, not a draft.
+    review_request = review_request.get_review_request()
+
+    if rev is None:
+        # If the user is the submitter we might want to use the draft diffset.
+        draft = review_request.get_draft(user=user)
+        diffset = ((draft and draft.diffset) or
+                   review_request.get_latest_diffset())
+    else:
+        diffset = (
+            DiffSet.objects
+            .filter(history__pk=review_request.diffset_history_id)
+            .filter(revision=rev)).latest()
+
+    return diffstats(diffset)