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const
path = require('path'),
fs = require('fs'),
jwk = require('jwcrypto/jwk');

exports.generate = function(chars) {
  var str = "";
  const alphabet = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789";
  for (var i=0; i < chars; i++) {
    str += alphabet.charAt(Math.floor(Math.random() * alphabet.length));
  }
  return str;
}

exports.hydrateSecret = function(name, dir) {
  var p = path.join(dir, name + ".sekret");
  var fileExists = false;
  var secret = undefined;

  try{ secret = fs.readFileSync(p).toString(); } catch(e) {};

  if (secret === undefined) {
    secret = exports.generate(128);
    fs.writeFileSync(p, '');
    fs.chmodSync(p, 0600);
    fs.writeFileSync(p, secret);
  }
  return secret;
};

exports.loadSecretKey = function(name, dir) {
  var p = path.join(dir, name + ".secretkey");
  var fileExists = false;
  var secret = undefined;

  try{ secret = fs.readFileSync(p).toString(); } catch(e) {};

  if (secret === undefined) {
    return null;
  }

  // parse it
  return jwk.SecretKey.deserialize(secret);
}

exports.loadPublicKey = function(name, dir) {
  var p = path.join(dir, name + ".publickey");
  var fileExists = false;
  var secret = undefined;

  try{ secret = fs.readFileSync(p).toString(); } catch(e) {};

  if (secret === undefined) {
    return null;
  }

  // parse it
  // it should be a JSON structure with alg and serialized key
  // {alg: <ALG>, value: <SERIALIZED_KEY>}
  return jwk.PublicKey.deserialize(secret);
}