/*jslint browser: true, devel: true, sloppy: true, vars: true*/
/*globals Uint8Array, Promise */
var extractable = true;
var encodePrivateKey, encodePublicKey;

function wrap(text, len) {
  var length = len || 72, i, result = "";
  for (i = 0; i < text.length; i += length) {
    result += text.slice(i, i + length) + "\n";
  }
  return result;
}

function rsaPrivateKey(key) {
  return "-----BEGIN RSA PRIVATE KEY-----\n" + key + "-----END RSA PRIVATE KEY-----";
}

function arrayBufferToBase64(buffer) {
  var binary = '', i;
  var bytes = new Uint8Array(buffer);
  var len = bytes.byteLength;
  for (i = 0; i < len; i += 1) {
    binary += String.fromCharCode(bytes[i]);
  }
  return window.btoa(binary);
}

function generateKeyPair(alg, size, name) {
  return window.crypto.subtle.generateKey({
    name: "RSASSA-PKCS1-v1_5",
    modulusLength: 2048, //can be 1024, 2048, or 4096
    publicExponent: new Uint8Array([0x01, 0x00, 0x01]),
    hash: {name: "SHA-1"} //can be "SHA-1", "SHA-256", "SHA-384", or "SHA-512"
  },
    extractable,
    ["sign", "verify"]
    ).then(function (key) {
    
    var privateKey = window.crypto.subtle.exportKey(
        "jwk",
        key.privateKey
      ).then(encodePrivateKey).then(wrap).then(rsaPrivateKey);

    var publicKey = window.crypto.subtle.exportKey(
        "jwk",
        key.publicKey
      ).then(function (jwk) {
        return encodePublicKey(jwk, name);
      });
    
    return Promise.all([privateKey, publicKey]);
  });
}