1 files changed, 66 insertions, 0 deletions
diff --git a/third_party/python/fluent.migrate/fluent/migrate/changesets.py b/third_party/python/fluent.migrate/fluent/migrate/changesets.py
new file mode 100644
index 0000000000..e687175550
--- /dev/null
+++ b/third_party/python/fluent.migrate/fluent/migrate/changesets.py
@@ -0,0 +1,66 @@
+from __future__ import annotations
+from typing import Set, Tuple, TypedDict
+
+import time
+
+from .blame import BlameResult
+
+Changes = Set[Tuple[str, str]]
+
+
+class Changeset(TypedDict):
+    author: str
+    first_commit: float
+    changes: Changes
+
+
+def by_first_commit(item: Changeset):
+    """Order two changesets by their first commit date."""
+    return item["first_commit"]
+
+
+def convert_blame_to_changesets(blame_json: BlameResult) -> list[Changeset]:
+    """Convert a blame dict into a list of changesets.
+
+    The blame information in `blame_json` should be a dict of the following
+    structure:
+
+        {
+            'authors': [
+                'A.N. Author <author@example.com>',
+            ],
+            'blame': {
+                'path/one': {
+                    'key1': [0, 1346095921.0],
+                },
+            }
+        }
+
+    It will be transformed into a list of changesets which can be fed into
+    `InternalContext.serialize_changeset`:
+
+        [
+            {
+                'author': 'A.N. Author <author@example.com>',
+                'first_commit': 1346095921.0,
+                'changes': {
+                    ('path/one', 'key1'),
+                }
+            },
+        ]
+
+    """
+    now = time.time()
+    changesets: list[Changeset] = [
+        {"author": author, "first_commit": now, "changes": set()}
+        for author in blame_json["authors"]
+    ]
+
+    for path, keys_info in blame_json["blame"].items():
+        for key, (author_index, timestamp) in keys_info.items():
+            changeset = changesets[author_index]
+            changeset["changes"].add((path, key))
+            if timestamp < changeset["first_commit"]:
+                changeset["first_commit"] = timestamp
+
+    return sorted(changesets, key=by_first_commit)