// from https://github.com/advaith1/activities/blob/main/src/verify.ts

'use strict';

function hex2bin(hex: string) {
	const buf = new Uint8Array(Math.ceil(hex.length / 2));
	for (let i = 0; i < buf.length; i++) {
		buf[i] = parseInt(hex.slice(i * 2, i * 2 + 2), 16);
	}
	return buf;
}
  
const PUBLIC_KEY = crypto.subtle.importKey(
	'raw',
	hex2bin(CLIENT_PUBLIC_KEY || ''),
	{
		name: 'NODE-ED25519',
		namedCurve: 'NODE-ED25519',
	},
	true,
	['verify'],
);

const encoder = new TextEncoder();

export async function verify(request: Request) {
	const signature = hex2bin(request.headers.get('X-Signature-Ed25519') || '');
	const timestamp = request.headers.get('X-Signature-Timestamp');
	const unknown = await request.clone().text();

	return await crypto.subtle.verify(
		'NODE-ED25519',
		await PUBLIC_KEY,
		signature,
		encoder.encode(timestamp + unknown),
	);
}