From 7bf0984698e43b9aa2dd879f65951318ed410390 Mon Sep 17 00:00:00 2001
From: Maze <167211895+mazeincoding@users.noreply.github.com>
Date: Sat, 31 Jan 2026 00:20:04 +0100
Subject: codebase overhaul (#697)

---
 .../timeline/element/duplicate-elements.ts         | 114 +++++++++++++++++++++
 1 file changed, 114 insertions(+)
 create mode 100644 apps/web/src/lib/commands/timeline/element/duplicate-elements.ts

(limited to 'apps/web/src/lib/commands/timeline/element/duplicate-elements.ts')

diff --git a/apps/web/src/lib/commands/timeline/element/duplicate-elements.ts b/apps/web/src/lib/commands/timeline/element/duplicate-elements.ts
new file mode 100644
index 00000000..4bec6444
--- /dev/null
+++ b/apps/web/src/lib/commands/timeline/element/duplicate-elements.ts
@@ -0,0 +1,114 @@
+import { Command } from "@/lib/commands/base-command";
+import type { TimelineElement, TimelineTrack } from "@/types/timeline";
+import { generateUUID } from "@/utils/id";
+import { EditorCore } from "@/core";
+import {
+	buildEmptyTrack,
+	getHighestInsertIndexForTrack,
+} from "@/lib/timeline/track-utils";
+
+interface DuplicateElementsParams {
+	elements: { trackId: string; elementId: string }[];
+}
+
+export class DuplicateElementsCommand extends Command {
+	private duplicatedElements: { trackId: string; elementId: string }[] = [];
+	private savedState: TimelineTrack[] | null = null;
+	private previousSelection: { trackId: string; elementId: string }[] = [];
+	private elements: DuplicateElementsParams["elements"];
+
+	constructor({ elements }: DuplicateElementsParams) {
+		super();
+		this.elements = elements;
+	}
+
+	execute(): void {
+		const editor = EditorCore.getInstance();
+		this.savedState = editor.timeline.getTracks();
+		this.previousSelection = editor.selection.getSelectedElements();
+		this.duplicatedElements = [];
+
+		const updatedTracks = [...this.savedState];
+
+		for (const track of this.savedState) {
+			const elementsToDuplicate = this.elements.filter(
+				(el) => el.trackId === track.id,
+			);
+
+			if (elementsToDuplicate.length === 0) {
+				continue;
+			}
+
+			const elementIdsToDuplicate = new Set(
+				elementsToDuplicate.map((element) => element.elementId),
+			);
+			const newTrackElements: TimelineElement[] = [];
+
+			const newTrackId = generateUUID();
+			const newTrackBase = buildEmptyTrack({
+				id: newTrackId,
+				type: track.type,
+			});
+
+			for (const element of track.elements) {
+				if (!elementIdsToDuplicate.has(element.id)) {
+					continue;
+				}
+
+				const newId = generateUUID();
+				this.duplicatedElements.push({
+					trackId: newTrackId,
+					elementId: newId,
+				});
+				newTrackElements.push(
+					buildDuplicateElement({
+						element,
+						id: newId,
+						startTime: element.startTime,
+					}),
+				);
+			}
+
+			const newTrack = {
+				...newTrackBase,
+				elements: newTrackElements,
+			} as TimelineTrack;
+
+			const insertIndex = getHighestInsertIndexForTrack({
+				tracks: updatedTracks,
+				trackType: track.type,
+			});
+			updatedTracks.splice(insertIndex, 0, newTrack);
+		}
+
+		editor.timeline.updateTracks(updatedTracks);
+
+		if (this.duplicatedElements.length > 0) {
+			editor.selection.setSelectedElements({ elements: this.duplicatedElements });
+		}
+	}
+
+	undo(): void {
+		if (this.savedState) {
+			const editor = EditorCore.getInstance();
+			editor.timeline.updateTracks(this.savedState);
+			editor.selection.setSelectedElements({ elements: this.previousSelection });
+		}
+	}
+
+	getDuplicatedElements(): { trackId: string; elementId: string }[] {
+		return this.duplicatedElements;
+	}
+}
+
+function buildDuplicateElement({
+	element,
+	id,
+	startTime,
+}: {
+	element: TimelineElement;
+	id: string;
+	startTime: number;
+}): TimelineElement {
+	return { ...element, id, name: `${element.name} (copy)`, startTime };
+}
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