/application/controllers/media.php

<?php
/**
 * Media Controller
 * A controller used to serve css, images and js files from the media directory.
 *
 * This class also compresses js and css files with gzip compression (if the browser supports it) and correctly handles
 * ETag/Last-Modified headers to prevent sending unmodified files to the client.
 *
 * //// GZIP Compression has been disabled in this controller and is handled
 * by settings in the config.php file where it can be enabled/disabled ////
 *
 * PHP version 5
 * LICENSE: This source file is subject to LGPL license
 * that is available through the world-wide-web at the following URI:
 * http://www.gnu.org/copyleft/lesser.html
 * @author     Ushahidi Team <team@ushahidi.com>
 * @package    Ushahidi - http://source.ushahididev.com
 * @subpackage Controllers
 * @copyright  Ushahidi - http://www.ushahidi.com
 * @license    http://www.gnu.org/copyleft/lesser.html GNU Lesser General Public License (LGPL)
*/

class Media_Controller extends Controller {

    // Javascript URI
    public function js()
    {
        $this->_send();
    }

    // CSS URI
    public function css()
    {
        $this->_send();
    }

    // Image URI
    public function img()
    {
        $this->_send();
    }

    // Method retrieves file data via file_get_contents
    public function _send()
    {
        $gzip = false;  // Enable/Disable GZip Compression

        $segments = $this->uri->segment_array();    // URI Segments
        $file = array_pop($segments);
        $file_path = implode("/", $segments);

        $pos = strrpos($file, '.');
        if ($pos === false)
        {
            $ext = '';
        }
        else
        {
            $ext = substr($file,$pos+1);
            $file = substr($file,0,$pos);
        }

        $file = $file_path."/".$file.".".$ext;
        if ( ! file_exists($file)) {

            // If the file doesn't exist, just pass an empty file.
            $file = false;
            $file_data = '';

        }
        else
        {

            $mtime = filemtime($file);
            $file_data = file_get_contents($file);

        }

        if ($ext == "css")
        { // Compress CSS data
            $file_data = $this->_css_compress($file_data);
        }

        // HTTP Headers
        $expiry_time = 613200;  // 1 Week
        $mime = ($ext == 'css') ? 'text/css' : 'application/javascript';
        header('Content-type: '.$mime);
        header('Cache-Control: must-revalidate');
        header('Expires: '.gmdate("D, d M Y H:i:s", time() + $expiry_time).' GMT');
        if (isset($mtime))
        {
          header('ETag: '.$mtime);
        }
        header("Last-Modified: ".gmdate("D, d M Y H:i:s", $mtime)." GMT");

        $oldetag = isset($_SERVER['HTTP_IF_NONE_MATCH'])?trim($_SERVER['HTTP_IF_NONE_MATCH']):'';
        $oldmtime = isset($_SERVER['HTTP_IF_MODIFIED_SINCE'])?$_SERVER['HTTP_IF_MODIFIED_SINCE']:'';
        $accencoding = isset($_SERVER['HTTP_ACCEPT_ENCODING'])?$_SERVER['HTTP_ACCEPT_ENCODING']:'';

        if (($oldmtime AND strtotime($_SERVER['HTTP_IF_MODIFIED_SINCE']) == $oldmtime) OR $oldetag == $mtime)
        {
            header($_SERVER['SERVER_PROTOCOL'] . ' 304 Not Modified');
        }
        else
        {
            if (strpos($accencoding, 'gzip') !== false AND $gzip)
            {
                header('Content-Encoding: gzip');
                echo gzencode($file_data);
            }
            else echo $file_data;
        }
    }

    private function _css_compress($data)
    {
        // Remove comments
        $data = preg_replace('~/\*[^*]*\*+([^/][^*]*\*+)*/~', '', $data);

        // Replace all whitespace by single spaces
        $data = preg_replace('~\s+~', ' ', $data);

        // Remove needless whitespace
        $data = preg_replace('~ *+([{}+>:;,]) *~', '$1', trim($data));

        // Remove ; that closes last property of each declaration
        $data = str_replace(';}', '}', $data);

        // Remove empty CSS declarations
        $data = preg_replace('~[^{}]++\{\}~', '', $data);

        return $data;
    }

    private function _js_compress($data)
    {
        $packer = new JavaScriptPacker($data, $this->pack_js);
        return $packer->pack();
    }

}
?>