refactor: structured track layout per scene

apps/web/src/lib/commands/timeline/track/add-track.ts

@@ -1,5 +1,5 @@
 import { Command, type CommandResult } from "@/lib/commands/base-command";
-import type { TrackType, TimelineTrack } from "@/lib/timeline";
+import type { SceneTracks, TrackType } from "@/lib/timeline";
 import { generateUUID } from "@/utils/id";
 import { EditorCore } from "@/core";
 import {
@@ -9,7 +9,7 @@ import {
 
 export class AddTrackCommand extends Command {
 	private trackId: string;
-	private savedState: TimelineTrack[] | null = null;
+	private savedState: SceneTracks | null = null;
 
 	constructor(
 		private type: TrackType,
@@ -21,21 +21,28 @@ export class AddTrackCommand extends Command {
 
 	execute(): CommandResult | undefined {
 		const editor = EditorCore.getInstance();
-		this.savedState = editor.timeline.getTracks();
+		this.savedState = editor.scenes.getActiveScene().tracks;
 
-		const newTrack: TimelineTrack = buildEmptyTrack({
-			id: this.trackId,
-			type: this.type,
-		});
-
-		const updatedTracks = [...(this.savedState || [])];
 		const insertIndex =
 			this.index ??
 			getDefaultInsertIndexForTrack({
-				tracks: updatedTracks,
+				tracks: this.savedState,
 				trackType: this.type,
 			});
-		updatedTracks.splice(insertIndex, 0, newTrack);
+
+		const updatedTracks =
+			this.type === "audio"
+				? buildAudioTrackState({
+						tracks: this.savedState,
+						insertIndex,
+						trackId: this.trackId,
+					})
+				: buildOverlayTrackState({
+						tracks: this.savedState,
+						insertIndex,
+						trackId: this.trackId,
+						trackType: this.type,
+					});
 
 		editor.timeline.updateTracks(updatedTracks);
 		return undefined;
@@ -52,3 +59,60 @@ export class AddTrackCommand extends Command {
 		return this.trackId;
 	}
 }
+
+function buildAudioTrackState({
+	tracks,
+	insertIndex,
+	trackId,
+}: {
+	tracks: SceneTracks;
+	insertIndex: number;
+	trackId: string;
+}): SceneTracks {
+	const audioInsertIndex = Math.max(
+		0,
+		insertIndex - tracks.overlay.length - 1,
+	);
+	const newTrack = buildEmptyTrack({
+		id: trackId,
+		type: "audio",
+	});
+	return {
+		...tracks,
+		audio: [
+			...tracks.audio.slice(0, audioInsertIndex),
+			newTrack,
+			...tracks.audio.slice(audioInsertIndex),
+		],
+	};
+}
+
+function buildOverlayTrackState({
+	tracks,
+	insertIndex,
+	trackId,
+	trackType,
+}: {
+	tracks: SceneTracks;
+	insertIndex: number;
+	trackId: string;
+	trackType: Exclude<TrackType, "audio">;
+}): SceneTracks {
+	const overlayInsertIndex = Math.min(insertIndex, tracks.overlay.length);
+	const newTrack =
+		trackType === "video"
+			? buildEmptyTrack({ id: trackId, type: "video" })
+			: trackType === "text"
+				? buildEmptyTrack({ id: trackId, type: "text" })
+				: trackType === "graphic"
+					? buildEmptyTrack({ id: trackId, type: "graphic" })
+					: buildEmptyTrack({ id: trackId, type: "effect" });
+	return {
+		...tracks,
+		overlay: [
+			...tracks.overlay.slice(0, overlayInsertIndex),
+			newTrack,
+			...tracks.overlay.slice(overlayInsertIndex),
+		],
+	};
+}