1 files changed, 32 insertions, 0 deletions
diff --git a/server/szurubooru/func/similar.py b/server/szurubooru/func/similar.py
new file mode 100644
index 0000000..a19b7d1
--- /dev/null
+++ b/server/szurubooru/func/similar.py
@@ -0,0 +1,32 @@
+from typing import List
+
+import sqlalchemy as sa
+
+from szurubooru import db, model, search
+
+_search_executor_config = search.configs.PostSearchConfig()
+_search_executor = search.Executor(_search_executor_config)
+
+
+# TODO(hunternif): this ignores the query, e.g. rating.
+# (But we're actually using a "similar" search query on the client anyway.)
+def find_similar_posts(
+    source_post: model.Post, limit: int, query_text: str = ''
+) -> List[model.Post]:
+    post_alias = sa.orm.aliased(model.Post)
+    pt_alias = sa.orm.aliased(model.PostTag)
+    result = (
+        db.session.query(post_alias)
+        .join(pt_alias, pt_alias.post_id == post_alias.post_id)
+        .filter(
+            sa.sql.or_(
+                pt_alias.tag_id == tag.tag_id for tag in source_post.tags
+            )
+        )
+        .filter(pt_alias.post_id != source_post.post_id)
+        .group_by(post_alias.post_id)
+        .order_by(sa.func.count(pt_alias.tag_id).desc())
+        .order_by(post_alias.post_id.desc())
+        .limit(limit)
+    )
+    return result