/**
 * @class Images
 * This class loads images and keeps them stored.
 */
function Images() {
  this.images = {};
  this.callback = undefined;
}

/**
 * Set an onload callback function. This will be called each time an image
 * is loaded
 * @param {function} callback
 */
Images.prototype.setOnloadCallback = function(callback) {
  this.callback = callback;
};

/**
 *
 * @param {string} url          Url of the image
 * @param {string} url          Url of an image to use if the url image is not found
 * @return {Image} img          The image object
 */
Images.prototype.load = function(url, brokenUrl) {
  if (this.images[url] == undefined) {
    // create the image
    var me = this;
    var img = new Image();
    img.onload = function () {

      // IE11 fix -- thanks dponch!
      if (this.width == 0) {
        document.body.appendChild(this);
        this.width = this.offsetWidth;
        this.height = this.offsetHeight;
        document.body.removeChild(this);
      }

      if (me.callback) {
        me.images[url] = img;
        me.callback(this);
      }
    };

    img.onerror = function () {
      if (brokenUrl === undefined) {
        console.error("Could not load image:", url);
        delete this.src;
        if (me.callback) {
          me.callback(this);
        }
      }
      else {
        this.src = brokenUrl;
      }
    };

    img.src = url;
  }

  return img;
};

module.exports = Images;