Improve thread search to keyword matching across titles and content

Search now splits query into keywords and matches each against both
title and data fields (not just title prefix). Also searches child
node content and returns parent threads for matches.

remarkbox/api/views.py

@@ -150,7 +150,7 @@ def api_list_threads(request):
     require_csrf=False,
 )
 def api_search_threads(request):
-    """Search threads by title prefix within a namespace."""
+    """Search threads by keywords in title and content within a namespace."""
     namespace_name = get_param(request, "namespace")
     q = get_param(request, "q", "").strip()
 
@@ -164,13 +164,52 @@ def api_search_threads(request):
     namespace = get_or_create_namespace(request.dbsession, namespace_name)
 
     from remarkbox.models.node import Node
+    from sqlalchemy import or_
 
-    roots = (
-        namespace.visible_roots
-        .filter(Node.title.ilike("{}%".format(q.replace("%", "\\%").replace("_", "\\_"))))
-        .limit(10)
-        .all()
-    )
+    def _escape(s):
+        return s.replace("%", "\\%").replace("_", "\\_")
+
+    # Split query into keywords; each must appear in title OR content.
+    keywords = q.split()
+
+    # Search root nodes: all keywords must match title or data.
+    query = namespace.visible_roots
+    for kw in keywords:
+        pattern = "%{}%".format(_escape(kw))
+        query = query.filter(or_(
+            Node.title.ilike(pattern),
+            Node.data.ilike(pattern),
+        ))
+
+    title_matches = query.limit(10).all()
+    seen_ids = {r.id for r in title_matches}
+
+    # Also search child nodes and return their root threads.
+    remaining = 10 - len(title_matches)
+    child_roots = []
+    if remaining > 0:
+        child_query = (
+            request.dbsession.query(Node)
+            .filter(
+                Node.namespace_id == None,  # child nodes
+                Node.disabled == False,
+            )
+        )
+        for kw in keywords:
+            pattern = "%{}%".format(_escape(kw))
+            child_query = child_query.filter(Node.data.ilike(pattern))
+
+        # Get distinct root_ids from matching children, scoped to namespace.
+        children = child_query.limit(50).all()
+        for child in children:
+            root = child.root
+            if root.id not in seen_ids and root.namespace == namespace:
+                seen_ids.add(root.id)
+                child_roots.append(root)
+                if len(child_roots) >= remaining:
+                    break
+
+    all_roots = title_matches + child_roots
 
     return {
         "threads": [
@@ -181,7 +220,7 @@ def api_search_threads(request):
                 "created_ago": root.human_created_timestamp,
                 "stats": root.stats if root.cache else None,
             }
-            for root in roots
+            for root in all_roots
         ],
     }