/* This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
;(function (exports) {
'use strict';

if (!exports.Enc) { exports.Enc = {}; }
if (!exports.SSH) { exports.SSH = {}; }

var Enc = exports.Enc;
var SSH = exports.SSH;

SSH.pack = function (opts) {
  var jwk = opts.jwk;
  var els = [];
  var ssh = {
    type: ''
  , _elements: els
  , comment: opts.comment || ''
  };
  var len;

  if ("RSA" === jwk.kty) {
    ssh.type = 'ssh-rsa';
    els.push(Enc.binToHex(ssh.type));
    els.push(SSH._padRsa(Enc.base64ToHex(jwk.e)));
    els.push(SSH._padRsa(Enc.base64ToHex(jwk.n)));
    return SSH._packElements(ssh);
  }

  if ("P-256" === jwk.crv) {
    ssh.type = 'ecdsa-sha2-nistp256';
    els.push(Enc.binToHex(ssh.type));
    els.push(Enc.binToHex('nistp256'));
    len = 32;
  } else if ("P-384" === jwk.crv) {
    ssh.type = 'ecdsa-sha2-nistp384';
    els.push(Enc.binToHex(ssh.type));
    els.push(Enc.binToHex('nistp384'));
    len = 48;
  } else {
    throw new Error("unknown key type " + (jwk.crv || jwk.kty));
  }

  els.push('04'
    + SSH._padEc(Enc.base64ToHex(jwk.x), len)
    + SSH._padEc(Enc.base64ToHex(jwk.y), len)
  );
  return SSH._packElements(ssh);
};

SSH._packElements = function (ssh) {
  var hex = ssh._elements.map(function (hex) {
    console.log(hex);
    return SSH._numToUint32Hex(hex.length/2) + hex;
  }).join('');
  return [ ssh.type, Enc.hexToBase64(hex), ssh.comment ].join(' ');
};

SSH._numToUint32Hex = function (num) {
  var hex = num.toString(16);
  while (hex.length < 8) {
    hex = '0' + hex;
  }
  console.log('length', hex);
  return hex;
};

SSH._padRsa = function (hex) {
  // BigInt is negative if the high order bit 0x80 is set,
  // so ASN1, SSH, and many other formats pad with '0x00'
  // to signifiy a positive number.
  var i = parseInt(hex.slice(0, 2), 16);
  if (0x80 & i) {
    return '00' + hex;
  }
  return hex;
};

SSH._padEc = function (hex, len) {
  while (hex.length < len * 2) {
    hex = '00' + hex;
  }
  return hex;
};

Enc.base64ToHex = function (b64) {
  var bin = atob(Enc.urlBase64ToBase64(b64));
  return Enc.binToHex(bin);
};

Enc.binToHex = function (bin) {
  return bin.split('').map(function (ch) {
    var h = ch.charCodeAt(0).toString(16);
    if (h.length % 2) { h = '0' + h; }
    return h;
  }).join('');
};

Enc.hexToBase64 = function (hex) {
  return btoa(Enc.hexToBin(hex));
};

Enc.hexToBin = function (hex) {
  return hex.match(/.{2}/g).map(function (h) {
    return String.fromCharCode(parseInt(h, 16));
  }).join('');
};

Enc.urlBase64ToBase64 = function urlsafeBase64ToBase64(str) {
  var r = str % 4;
  if (2 === r) {
    str += '==';
  } else if (3 === r) {
    str += '=';
  }
  return str.replace(/-/g, '+').replace(/_/g, '/');
};

}('undefined' !== typeof window ? window : module.exports));