var bs58 = require('bs58');

function getBytes32FromMultiash(multihash) {
  const decoded = bs58.decode(multihash);

  return {
    digest: `0x${decoded.slice(2).toString('hex')}`,
    hashFunction: decoded[0],
    size: decoded[1],
  };
}


function getMultihashFromBytes32(multihash) {
  const { digest, hashFunction, size } = multihash;
  if (size === 0) return null;

  // cut off leading "0x"
  const hashBytes = Buffer.from(digest.slice(2), 'hex');

  // prepend hashFunction and digest size
  //const multihashBytes = new (hashBytes.constructor)(2 + hashBytes.length);
  const multihashBytes = new Buffer(2 + hashBytes.length);

  console.log(hashBytes.constructor);

  multihashBytes[0] = hashFunction;
  multihashBytes[1] = size;
  multihashBytes.set(hashBytes, 2);

  return bs58.encode(multihashBytes);
}

var m = getBytes32FromMultiash(process.argv[2]);
console.log(m)