fix: tighten track placement type safety

apps/web/src/lib/timeline/placement/__tests__/resolve.test.ts

@@ -1,7 +1,53 @@
 import { describe, expect, test } from "bun:test";
-import type { ElementType, TimelineElement, TimelineTrack, TrackType } from "@/lib/timeline";
+import type {
+	AudioElement,
+	AudioTrack,
+	GraphicElement,
+	GraphicTrack,
+	TextElement,
+	TextTrack,
+	TimelineTrack,
+	VideoElement,
+	VideoTrack,
+} from "@/lib/timeline";
+import type { Transform } from "@/lib/rendering";
 import { resolveTrackPlacement } from "@/lib/timeline/placement";
 
+function buildTransform(): Transform {
+	return {
+		scaleX: 1,
+		scaleY: 1,
+		position: { x: 0, y: 0 },
+		rotate: 0,
+	};
+}
+
+type TestElement = AudioElement | GraphicElement | TextElement | VideoElement;
+
+function buildElement(params: {
+	id: string;
+	type: "audio";
+	startTime: number;
+	duration: number;
+}): AudioElement;
+function buildElement(params: {
+	id: string;
+	type: "graphic";
+	startTime: number;
+	duration: number;
+}): GraphicElement;
+function buildElement(params: {
+	id: string;
+	type: "text";
+	startTime: number;
+	duration: number;
+}): TextElement;
+function buildElement(params: {
+	id: string;
+	type: "video";
+	startTime: number;
+	duration: number;
+}): VideoElement;
 function buildElement({
 	id,
 	type,
@@ -9,61 +55,171 @@ function buildElement({
 	duration,
 }: {
 	id: string;
-	type: ElementType;
+	type: TestElement["type"];
 	startTime: number;
 	duration: number;
-}): TimelineElement {
+}): TestElement {
-	return {
+	switch (type) {
-		id,
+		case "audio":
-		type,
+			return {
-		name: id,
+				id,
-		startTime,
+				type: "audio",
-		duration,
+				name: id,
-		trimStart: 0,
+				startTime,
-		trimEnd: 0,
+				duration,
-	} as TimelineElement;
+				trimStart: 0,
+				trimEnd: 0,
+				volume: 1,
+				sourceType: "upload",
+				mediaId: `media-${id}`,
+			} satisfies AudioElement;
+		case "graphic":
+			return {
+				id,
+				type: "graphic",
+				name: id,
+				startTime,
+				duration,
+				trimStart: 0,
+				trimEnd: 0,
+				definitionId: `graphic-${id}`,
+				params: {},
+				transform: buildTransform(),
+				opacity: 1,
+			} satisfies GraphicElement;
+		case "text":
+			return {
+				id,
+				type: "text",
+				name: id,
+				startTime,
+				duration,
+				trimStart: 0,
+				trimEnd: 0,
+				content: id,
+				fontSize: 32,
+				fontFamily: "sans-serif",
+				color: "#ffffff",
+				background: {
+					enabled: false,
+					color: "#000000",
+				},
+				textAlign: "left",
+				fontWeight: "normal",
+				fontStyle: "normal",
+				textDecoration: "none",
+				transform: buildTransform(),
+				opacity: 1,
+			} satisfies TextElement;
+		case "video":
+			return {
+				id,
+				type: "video",
+				name: id,
+				startTime,
+				duration,
+				trimStart: 0,
+				trimEnd: 0,
+				mediaId: `media-${id}`,
+				transform: buildTransform(),
+				opacity: 1,
+			} satisfies VideoElement;
+	}
+
+	throw new Error(`Unsupported test element type: ${type}`);
 }
 
-function buildTrack({
+type BuildTrackParams =
-	id,
+	| {
-	type,
+			id: string;
-	elements = [],
+			type: "audio";
-	isMain = false,
+			elements?: AudioTrack["elements"];
-}: {
+			isMain?: boolean;
+	  }
+	| {
+			id: string;
+			type: "graphic";
+			elements?: GraphicTrack["elements"];
+			isMain?: boolean;
+	  }
+	| {
+			id: string;
+			type: "text";
+			elements?: TextTrack["elements"];
+			isMain?: boolean;
+	  }
+	| {
+			id: string;
+			type: "video";
+			elements?: VideoTrack["elements"];
+			isMain?: boolean;
+	  };
+
+function buildTrack(params: {
 	id: string;
-	type: TrackType;
+	type: "audio";
-	elements?: TimelineElement[];
+	elements?: AudioTrack["elements"];
 	isMain?: boolean;
-}): TimelineTrack {
+}): AudioTrack;
-	if (type === "video") {
+function buildTrack(params: {
-		return {
+	id: string;
-			id,
+	type: "graphic";
-			type,
+	elements?: GraphicTrack["elements"];
-			name: id,
+	isMain?: boolean;
-			elements: elements as TimelineTrack["elements"],
+}): GraphicTrack;
-			isMain,
+function buildTrack(params: {
-			muted: false,
+	id: string;
-			hidden: false,
+	type: "text";
-		};
+	elements?: TextTrack["elements"];
+	isMain?: boolean;
+}): TextTrack;
+function buildTrack(params: {
+	id: string;
+	type: "video";
+	elements?: VideoTrack["elements"];
+	isMain?: boolean;
+}): VideoTrack;
+function buildTrack(params: BuildTrackParams): TimelineTrack {
+	const { id, type, isMain = false } = params;
+
+	switch (type) {
+		case "audio":
+			return {
+				id,
+				type: "audio",
+				name: id,
+				elements: params.elements ?? [],
+				muted: false,
+			};
+		case "graphic":
+			return {
+				id,
+				type: "graphic",
+				name: id,
+				elements: params.elements ?? [],
+				hidden: false,
+			};
+		case "text":
+			return {
+				id,
+				type: "text",
+				name: id,
+				elements: params.elements ?? [],
+				hidden: false,
+			};
+		case "video":
+			return {
+				id,
+				type: "video",
+				name: id,
+				elements: params.elements ?? [],
+				isMain,
+				muted: false,
+				hidden: false,
+			};
 	}
 
-	if (type === "audio") {
+	throw new Error(`Unsupported test track type: ${type}`);
-		return {
-			id,
-			type,
-			name: id,
-			elements: elements as TimelineTrack["elements"],
-			muted: false,
-		};
-	}
-
-	return {
-		id,
-		type,
-		name: id,
-		elements: elements as TimelineTrack["elements"],
-		hidden: false,
-	};
 }
 
 function buildTimeSpan({
@@ -124,7 +280,9 @@ describe("resolveTrackPlacement", () => {
 			buildTrack({
 				id: "text-1",
 				type: "text",
-				elements: [buildElement({ id: "a", type: "text", startTime: 0, duration: 5 })],
+				elements: [
+					buildElement({ id: "a", type: "text", startTime: 0, duration: 5 }),
+				],
 			}),
 			buildTrack({ id: "text-2", type: "text" }),
 		];
@@ -256,7 +414,9 @@ describe("resolveTrackPlacement", () => {
 			buildTrack({
 				id: "text-middle",
 				type: "text",
-				elements: [buildElement({ id: "a", type: "text", startTime: 0, duration: 5 })],
+				elements: [
+					buildElement({ id: "a", type: "text", startTime: 0, duration: 5 }),
+				],
 			}),
 			buildTrack({ id: "text-source", type: "text" }),
 		];
@@ -281,12 +441,16 @@ describe("resolveTrackPlacement", () => {
 			buildTrack({
 				id: "text-top",
 				type: "text",
-				elements: [buildElement({ id: "a", type: "text", startTime: 0, duration: 5 })],
+				elements: [
+					buildElement({ id: "a", type: "text", startTime: 0, duration: 5 }),
+				],
 			}),
 			buildTrack({
 				id: "text-source",
 				type: "text",
-				elements: [buildElement({ id: "b", type: "text", startTime: 0, duration: 5 })],
+				elements: [
+					buildElement({ id: "b", type: "text", startTime: 0, duration: 5 }),
+				],
 			}),
 		];
 

apps/web/src/lib/timeline/placement/resolve.ts

@@ -44,9 +44,7 @@ function buildExistingTrackResult({
 		trackId: track.id,
 		trackIndex,
 		trackType: track.type,
-		...(adjustedStartTime !== requestedStartTime
+		...(adjustedStartTime !== requestedStartTime ? { adjustedStartTime } : {}),
-			? { adjustedStartTime }
-			: {}),
 	};
 }
 
@@ -114,6 +112,24 @@ function resolveAlwaysNewTrack({
 	});
 }
 
+function getInsertDirection({
+	hoverDirection,
+	verticalDragDirection,
+}: {
+	hoverDirection: "above" | "below";
+	verticalDragDirection?: "up" | "down" | null;
+}): "above" | "below" {
+	if (verticalDragDirection === "up") {
+		return "above";
+	}
+
+	if (verticalDragDirection === "down") {
+		return "below";
+	}
+
+	return hoverDirection;
+}
+
 export function resolveTrackPlacement({
 	tracks,
 	...placement
@@ -127,7 +143,9 @@ export function resolveTrackPlacement({
 	const { timeSpans, strategy } = placement;
 
 	if (strategy.type === "explicit") {
-		const trackIndex = tracks.findIndex((track) => track.id === strategy.trackId);
+		const trackIndex = tracks.findIndex(
+			(track) => track.id === strategy.trackId,
+		);
 		if (trackIndex < 0) {
 			return null;
 		}
@@ -182,15 +200,16 @@ export function resolveTrackPlacement({
 			});
 		}
 
-		const insertDirection =
-			!isPreferredTrackCompatible && strategy.verticalDragDirection
-				? strategy.verticalDragDirection
-				: strategy.hoverDirection;
 		const { insertIndex, insertPosition } = resolvePreferredNewTrackPlacement({
 			tracks,
 			trackType,
 			preferredIndex: strategy.trackIndex,
-			direction: insertDirection,
+			direction: getInsertDirection({
+				hoverDirection: strategy.hoverDirection,
+				verticalDragDirection: !isPreferredTrackCompatible
+					? strategy.verticalDragDirection
+					: null,
+			}),
 		});
 		return buildNewTrackResult({
 			trackType,