AssetManager.php

<?php
/**
 * Piwik - Open source web analytics
 *
 * @link http://piwik.org
 * @license http://www.gnu.org/licenses/gpl-3.0.html GPL v3 or later
 *
 * @category Piwik
 * @package Piwik
 */
namespace Piwik;

use Exception;
use JSMin;
use lessc;
use Piwik\Translate;

/**
 * @see libs/jsmin/jsmin.php
 */
require_once PIWIK_INCLUDE_PATH . '/libs/jsmin/jsmin.php';

/**
 * AssetManager is the class used to manage the inclusion of UI assets:
 * JavaScript and CSS files.
 *
 * It performs the following actions:
 *  - Identifies required assets
 *  - Includes assets in the rendered HTML page
 *  - Manages asset merging and minifying
 *  - Manages server-side cache
 *
 * Whether assets are included individually or as merged files is defined by
 * the global option 'disable_merged_assets'. When set to 1, files will be
 * included individually.
 * When set to 0, files will be included within a pair of files: 1 JavaScript
 * and 1 css file.
 *
 * @package Piwik
 */
class AssetManager
{
    const MERGED_CSS_FILE = "asset_manager_global_css.css";
    const MERGED_JS_FILE = "asset_manager_global_js.js";
    const TRANSLATIONS_JS_FILE = "asset_manager_translations_js.js";
    const CSS_IMPORT_EVENT = "AssetManager.getStylesheetFiles";
    const JS_IMPORT_EVENT = "AssetManager.getJsFiles";
    const MERGED_FILE_DIR = "tmp/assets/";
    const CSS_IMPORT_DIRECTIVE = "<link rel=\"stylesheet\" type=\"text/css\" href=\"%s\" />\n";
    const JS_IMPORT_DIRECTIVE = "<script type=\"text/javascript\" src=\"%s\"></script>\n";
    const GET_CSS_MODULE_ACTION = "index.php?module=Proxy&action=getCss";
    const GET_JS_MODULE_ACTION = "index.php?module=Proxy&action=getJs";
    const MINIFIED_JS_RATIO = 100;

    /**
     * Returns CSS file inclusion directive(s) using the markup <link>
     *
     * @return string
     */
    public static function getCssAssets()
    {
        return sprintf(self::CSS_IMPORT_DIRECTIVE, self::GET_CSS_MODULE_ACTION);
    }

    /**
     * Returns JS file inclusion directive(s) using the markup <script>
     *
     * @return string
     */
    public static function getJsAssets()