File: ../src/jsonp.js

define(['aeris/util'], function(_) {

  _.provide('aeris.jsonp');

  /*
   * Lightweight JSONP fetcher
   * Copyright 2010-2012 Erik Karlsson. All rights reserved.
   * BSD licensed
   */


  /**
   * Usage:
   *
   * JSONP.get( 'someUrl.php', {param1:'123', param2:'456'}, function(data){
   *   //do something with data, which is the JSON object you should retrieve from someUrl.php
   * });
   *
   * @class aeris.JSONP
   */
  aeris.jsonp = (function() {

    var head, window = this, config = {};

    function load(url, pfnError) {
      var script = document.createElement('script'),
        done = false;
      script.src = url;
      script.async = true;

      var errorHandler = pfnError || config.error;
      if (typeof errorHandler === 'function') {
        script.onerror = function(ex) {
          errorHandler({url: url, event: ex});
        };
      }

      script.onload = script.onreadystatechange = function() {
        if (!done && (!this.readyState || this.readyState === 'loaded' || this.readyState === 'complete')) {
          done = true;
          script.onload = script.onreadystatechange = null;
          if (script && script.parentNode) {
            script.parentNode.removeChild(script);
          }
        }
      };

      if (!head) {
        head = document.getElementsByTagName('head')[0];
      }
      head.appendChild(script);
    }

    function encode(str) {
      return encodeURIComponent(str);
    }

    function jsonp(url, params, callback, uniqueName, callbackName) {
      var query = (url || '').indexOf('?') === -1 ? '?' : '&', key;

      callbackName = (callbackName || config['callbackName'] || 'callback');
      uniqueName = uniqueName || callbackName + _.uniqueId('_aeris_jsonp_');

      params = params || {};
      for (key in params) {
        if (params.hasOwnProperty(key)) {
          query += encode(key) + '=' + encode(params[key]) + '&';
        }
      }

      window[uniqueName] = function(data) {
        callback(data);
        try {
          delete window[uniqueName];
        } catch (e) {}
        window[uniqueName] = null;
      };

      load(url + query + callbackName + '=' + uniqueName);
      return uniqueName;
    }

    function setDefaults(obj) {
      config = obj;
    }

    return {
      get: jsonp,
      init: setDefaults
    };

  }());

  return aeris.jsonp;

});