const crypto = require('crypto');

const memo = new Map();

const fakePeerId = (addr) => {
  const hash = crypto.createHash('sha1');
  hash.update(addr);
  return hash.digest('hex').slice(0, 20);
};

// not super expensive, but probably worth memoizing
module.exports = (addr) => {
  if (memo.size >= 300000) {
    memo.clear();
  }
  if (!memo.has(addr)) {
    memo.set(addr, fakePeerId(addr));
  }
  return memo.get(addr);
};