import { error } from '@sveltejs/kit';
import { getStorage } from '$lib/server/storage';
import { LocalDiskStorage } from '$lib/server/storage/local';
import type { RequestHandler } from './$types';

export const GET: RequestHandler = async ({ url }) => {
	const storage = getStorage();
	if (!(storage instanceof LocalDiskStorage)) {
		throw error(501, 'Non-local storage adapter must use its own signed URL');
	}

	let verified: { key: string; disposition: string; filename: string };
	try {
		verified = storage.verifySignedUrl(url.searchParams);
	} catch {
		throw error(403, 'Invalid or expired link');
	}

	const obj = await storage.get(verified.key).catch(() => null);
	if (!obj) throw error(404, 'Not found');

	const headers = new Headers({
		'content-type': obj.contentType,
		'content-length': String(obj.sizeBytes)
	});
	if (verified.filename) {
		const dispHeader =
			verified.disposition === 'attachment'
				? `attachment; filename="${verified.filename.replace(/"/g, '')}"`
				: `inline; filename="${verified.filename.replace(/"/g, '')}"`;
		headers.set('content-disposition', dispHeader);
	}

	return new Response(obj.stream as unknown as ReadableStream, { headers });
};