1 files changed, 133 insertions, 0 deletions
diff --git a/apps/web/src/lib/commands/timeline/element/split-elements.ts b/apps/web/src/lib/commands/timeline/element/split-elements.ts
new file mode 100644
index 00000000..13d4d730
--- /dev/null
+++ b/apps/web/src/lib/commands/timeline/element/split-elements.ts
@@ -0,0 +1,133 @@
+import { Command } from "@/lib/commands/base-command";
+import type { TimelineTrack } from "@/types/timeline";
+import { generateUUID } from "@/utils/id";
+import { EditorCore } from "@/core";
+
+export class SplitElementsCommand extends Command {
+	private savedState: TimelineTrack[] | null = null;
+	private rightSideElements: { trackId: string; elementId: string }[] = [];
+	private previousSelection: { trackId: string; elementId: string }[] = [];
+
+	constructor(
+		private elements: { trackId: string; elementId: string }[],
+		private splitTime: number,
+		private retainSide: "both" | "left" | "right" = "both",
+	) {
+		super();
+	}
+
+	getRightSideElements(): { trackId: string; elementId: string }[] {
+		return this.rightSideElements;
+	}
+
+	execute(): void {
+		const editor = EditorCore.getInstance();
+		this.savedState = editor.timeline.getTracks();
+		this.previousSelection = editor.selection.getSelectedElements();
+		this.rightSideElements = [];
+
+		const updatedTracks = this.savedState.map((track) => {
+			const elementsToSplit = this.elements.filter(
+				(el) => el.trackId === track.id,
+			);
+
+			if (elementsToSplit.length === 0) {
+				return track;
+			}
+
+			return {
+				...track,
+				elements: track.elements.flatMap((element) => {
+					const shouldSplit = elementsToSplit.some(
+						(el) => el.elementId === element.id,
+					);
+
+					if (!shouldSplit) {
+						return [element];
+					}
+
+					const effectiveStart = element.startTime;
+					const effectiveEnd = element.startTime + element.duration;
+
+					if (
+						this.splitTime <= effectiveStart ||
+						this.splitTime >= effectiveEnd
+					) {
+						return [element];
+					}
+
+					const relativeTime = this.splitTime - element.startTime;
+					const leftVisibleDuration = relativeTime;
+					const rightVisibleDuration = element.duration - relativeTime;
+
+					if (this.retainSide === "left") {
+						return [
+							{
+								...element,
+								duration: leftVisibleDuration,
+								trimEnd: element.trimEnd + rightVisibleDuration,
+								name: `${element.name} (left)`,
+							},
+						];
+					}
+
+					if (this.retainSide === "right") {
+						const newId = generateUUID();
+						this.rightSideElements.push({
+							trackId: track.id,
+							elementId: newId,
+						});
+						return [
+							{
+								...element,
+								id: newId,
+								startTime: this.splitTime,
+								duration: rightVisibleDuration,
+								trimStart: element.trimStart + leftVisibleDuration,
+								name: `${element.name} (right)`,
+							},
+						];
+					}
+
+					// "both" - split into two pieces
+					const secondElementId = generateUUID();
+					this.rightSideElements.push({
+						trackId: track.id,
+						elementId: secondElementId,
+					});
+
+					return [
+						{
+							...element,
+							duration: leftVisibleDuration,
+							trimEnd: element.trimEnd + rightVisibleDuration,
+							name: `${element.name} (left)`,
+						},
+						{
+							...element,
+							id: secondElementId,
+							startTime: this.splitTime,
+							duration: rightVisibleDuration,
+							trimStart: element.trimStart + leftVisibleDuration,
+							name: `${element.name} (right)`,
+						},
+					];
+				}),
+			} as typeof track;
+		});
+
+		editor.timeline.updateTracks(updatedTracks);
+
+		if (this.rightSideElements.length > 0) {
+			editor.selection.setSelectedElements({ elements: this.rightSideElements });
+		}
+	}
+
+	undo(): void {
+		if (this.savedState) {
+			const editor = EditorCore.getInstance();
+			editor.timeline.updateTracks(this.savedState);
+			editor.selection.setSelectedElements({ elements: this.previousSelection });
+		}
+	}
+}