// 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 (var i = 0; i < buf.length; i++) {
      buf[i] = parseInt(hex.substr(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),
    );
}