import type { RenderScene2d } from './types';
import type { PackedTilePolyline } from './worker-protocol';

/** Removes tile polylines from a scene and packs them into transferable buffers. */
export function packTilePolylines(scene: RenderScene2d): PackedTilePolyline[] | undefined {
	const polylines = scene.layers.filter((layer) => layer.type === 'polyline');

	if (polylines.length === 0) return undefined;

	const packed = polylines.map(({ vertices, breaks, ...layer }) => {
		const coordinates = new Float64Array(vertices.length * 2);

		for (let index = 0; index < vertices.length; index += 1) {
			coordinates[index * 2] = vertices[index][0];
			coordinates[index * 2 + 1] = vertices[index][1];
		}

		return { coordinates, breaks: Uint32Array.from(breaks), layer };
	});

	scene.layers = scene.layers.filter((layer) => layer.type !== 'polyline');

	return packed;
}

export function packedPolylineBytes(polylines: PackedTilePolyline[] | undefined): number {
	return (polylines ?? []).reduce(
		(bytes, polyline) => bytes + polyline.coordinates.byteLength + polyline.breaks.byteLength,
		0
	);
}