import { createHash, randomBytes } from 'node:crypto';

const CHARSET = '0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ';

export function toBase62(buffer) {
  let num = BigInt('0x' + buffer.toString('hex'));
  if (num === 0n) return CHARSET[0].repeat(8);
  let res = '';
  while (num > 0n) {
    res = CHARSET[Number(num % 62n)] + res;
    num /= 62n;
  }
  return res;
}

export default function newFullHash(buffer) {
  if (buffer) {
    const digest = createHash('sha256').update(buffer).digest();
    return toBase62(digest).slice(0, 8);
  }
  const bytes = randomBytes(16);
  return toBase62(bytes).slice(0, 8);
}