# UNDF: UNDF-2026-000001138
# UNDF: (leave blank)
# CWE-407: Algorithmic Complexity (linear scan inside loop over selected items)
# OpenShot-Qt query.py: QueryObject.filter() scans ALL objects of a type (O(N))
# and is called inside loops over selected_clips, selected_effects, etc.
#
# Defective path (src/classes/query.py line 116-160,
#                 called from src/windows/main_window.py):
#
#   # actionRemoveClip_trigger (main_window.py ~line 2140):
#   for clip_id in self.selected_clips:           # S iterations
#       clips = Clip.filter(id=clip_id)           # O(C) linear scan each time
#       for c in clips:
#           c.delete()
#
#   # QueryObject.filter() (query.py line 128):
#   for child in parent:    # scans ALL C clips
#       if child.get("id") == clip_id:
#           ...
#
# Complexity: O(S * C) where S = selected clips, C = total clips in project.
# With 100 selected clips from a 5000-clip project: 500,000 dict lookups.
#
# Same pattern in: actionRemoveTransition_trigger, actionRemoveEffect_trigger,
# keyframe update loops, and other multi-selection operations.
#
# Fix: build a {id -> object} dict once before the loop. O(C) build cost,
# then O(1) per lookup. Total O(C + S) vs O(S * C).
#
# Alternatively, add an id-keyed index to QueryObject so filter(id=x) is O(1).
# The single-call pattern Clip.filter(file_id=f.id) benefits from the index too.
#
# Severity: MEDIUM. UI responsiveness degrades quadratically when mass-deleting
# or mass-moving clips. Affects every multi-selection operation in the editor.
--- a/src/classes/query.py
+++ b/src/classes/query.py
@@ -116,6 +116,15 @@ class QueryObject:
     def filter(OBJECT_TYPE, **kwargs):
         """ Take any arguments given as filters, and find a list of matching objects """

+        # Fast path: single id lookup via index avoids O(N) scan
+        if list(kwargs.keys()) == ["id"] and hasattr(OBJECT_TYPE, "_id_index"):
+            result = OBJECT_TYPE._id_index.get(kwargs["id"])
+            return [result] if result is not None else []
+
         # Get a list of all objects of this type
         parent = get_app().project.get(OBJECT_TYPE.object_key)

+# Usage at call sites — replace inner-loop calls with index-based lookup:
+#
+#   # Before (O(S*C)):
+#   for clip_id in self.selected_clips:
+#       clips = Clip.filter(id=clip_id)
+#
+#   # After (O(C + S)):
+#   all_clips = {c.id: c for c in Clip.filter()}
+#   for clip_id in self.selected_clips:
+#       c = all_clips.get(clip_id)
+#       if c: c.delete()