privly/privly-applications

/** 
 * @fileOverview This file defines functions for loading
 * Javascripts, and CSS files.  The files are specified using a custom meta tag
 *
 * `PrivlyTopCSS` defines CSS files that should be loaded when the application
 * is viewed as the top application on the page.
 *
 **/

/**
 * Loads a javascript file whose path is passed as an argument.
 * @param filename string path to the JS file that should be added to the 
 * HTML.
 */
function loadJs(filename){
  var fileref= document.createElement('script');
  fileref.setAttribute("type", "text/javascript");
  fileref.setAttribute("src", filename);
  if (typeof fileref !== "undefined"){
    document.getElementsByTagName("head")[0].appendChild(fileref);
  }
}

/**
 * Loads a CSS file whose path is passed as an argument.
 *
 * @param filename string path to the CSS file that should be added to the 
 * HTML.
 *
 */
function loadCSS(filename){
  var fileref= document.createElement('link');
  fileref.setAttribute("rel", "stylesheet");
  fileref.setAttribute("type", "text/css");
  fileref.setAttribute("href", filename);
  if (typeof fileref !== "undefined"){
    document.getElementsByTagName("head")[0].appendChild(fileref);
  }
}

/**
 * Returns the content of a meta tag whose name is passed as an argument.
 */
function getMetaValue(metaName){
  var metas = document.getElementsByTagName("meta");
  for (var i = 0; i < metas.length; i++){
    if(metas[i].getAttribute('name') == metaName){
      return metas[i].getAttribute('content');
    }
  }
  return "none";
}

/**
 * Loads all the files defined in the named meta tag and load them.
 * @param {string} meta The name of the meta tag.
 * @param {string} type The Type of the meta tag, "JS" or "CSS" are supported.
 * @return {boolean} A boolean value indicating whether
 * the any files were loaded.
 */
function loadFilesFromMeta(meta, type) {
  var filesToLoad = getMetaValue(meta);
  if (filesToLoad === "none"){
    return false;
  }
  var files = filesToLoad.split(";");

  for (var i = 0; i < files.length; i++){
    if( type === "CSS" ) {
      loadCSS(files[i]);
    } else if( type === "JS" ) {
      loadJs(files[i]);
    }
  }
  return true;
}

/**
 * Loads CSS files targeted for the top application.
 * @return {boolean} A boolean value indicating whether
 * any files were specified in meta tags.
 */
function loadTopCSS(){
  return loadFilesFromMeta("PrivlyTopCSS", "CSS");
}

/**
 * Loads JS files targeted for the top application.
 * @return {boolean} A boolean value indicating whether
 * any files were specified in meta tags.
 */
function loadTopJS(){
  return loadFilesFromMeta("PrivlyTopJS", "JS");
}

/**
 * Loads CSS files targeted for an injected application.
 * @return {boolean} A boolean value indicating whether
 * any files were specified in meta tags.
 */
function loadInjectedCSS(){
  return loadFilesFromMeta("PrivlyInjectedCSS", "CSS");
}

/**
 * Loads JS files targeted for the top application.
 * @return {boolean} A boolean value indicating whether
 * any files were specified in meta tags.
 */
function loadInjectedJS(){
  return loadFilesFromMeta("PrivlyInjectedJS", "JS");
}