VKontakte Audio Search

vkontakte.js

goog.provide('VKontakte');

goog.require('goog.crypt.Md5');


VKontakte = function (user_id, app_id, app_secret) {
  this.user_id_ = user_id;
  this.app_id_ = app_id;
  this.app_secret_ = app_secret;
};


VKontakte.API_ENDPOINT = 'http://api.vk.com/api.php';


VKontakte.prototype.search = function (artist, track, callback) {
  var uri = this.getSearchURI_(artist, track);
  this.request_('GET', uri, function (status, response) {
    if (status === 0) {
      callback(new Error('No Internet connection'), null);
    } else {
      var result = response[1];
      if (!result) {
        callback(new Error('No audio'), null);
      } else {
        callback(null, result.audio.url);
      }
    }
  });
};

VKontakte.prototype.getSearchURI_ = function (artist, track) {
  var q = artist + ' ' + track;
  var params = {
    'method': 'audio.search',
    'q': q.toLowerCase(),
    'sort': 2,
    'test_mode': 1,
    'api_id': this.app_id_,
    'format': 'json',
    'count': 10
  };
  params['sig'] = this.generateApiRequestSignature_(params);

  return VKontakte.API_ENDPOINT + this.createSearchString_(params);
};

VKontakte.prototype.generateApiRequestSignature_ = function (params) {
  var input = this.user_id_;

  // Keys are required to be ordered alphabetically.
  Object.keys(params).sort().forEach(function (key) {
    input += key + '=' + params[key];
  });
  input += this.app_secret_;

  var md5 = new goog.crypt.Md5();
  md5.update(input);
  return md5.digest().map(function (digit) {
    return digit.toString(16);
  }).join('');
};

VKontakte.prototype.createSearchString_ = function (params) {
  var parts = [];
  var encode = window.encodeURIComponent;
  for (var key in params) {
    if (params.hasOwnProperty(key)) {
      parts.push(key + '=' + encode(params[key]));
    }
  }

  return '?' + parts.join('&');
};

VKontakte.prototype.request_ = function (method, uri, callback) {
  var xhr = new XMLHttpRequest();
  xhr.open(method, uri, true);
  xhr.onreadystatechange = function () {
    if (xhr.readyState === 4) {
      var response = {};
      try {
        response = JSON.parse(xhr.responseText);
      } finally {
        callback(xhr.statusCode, response.response || response);
      }
    }
  };
  xhr.send(null);
};