wp-cdn-rewrite.php

<?php
/*
Plugin Name: WP CDN Rewrite
Plugin URI: http://voceconnect.com/
Description: Rewrites asset URLs to CDN
Version: 0.1.5
Author: Chris Scott, Michael Pretty, Kevin Langley
Author URI: http://voceconnect.com/
*/

if(file_exists( dirname( __FILE__ ) . DIRECTORY_SEPARATOR . 'vendor' . DIRECTORY_SEPARATOR . 'autoload.php' ) )
    include_once( dirname( __FILE__ ) . DIRECTORY_SEPARATOR . 'vendor' . DIRECTORY_SEPARATOR . 'autoload.php' );

if( !class_exists( 'CDN_Rewrite' ) ){

	class CDN_Rewrite {

		const OPTION_GENERAL = 'cdn_general';

		private $cdn_root_url;
		private $file_extensions;

		private $css_file_extensions;
		private $css_cdn_root_url;

		private $js_file_extensions;
		private $js_cdn_root_url;

		private $blog_details;

		public function __construct() {
			$this->cdn_root_url = $this->css_cdn_root_url = $this->js_cdn_root_url = untrailingslashit($this->get_setting('root_url'));

			if ($css_url = trim($this->get_setting('css_root_url'))) {
				$this->css_cdn_root_url = untrailingslashit($css_url);
			}

			if ($js_url = trim($this->get_setting('js_root_url'))) {
				$this->js_cdn_root_url = untrailingslashit($js_url);
			}

			$this->file_extensions = $this->get_setting('file_extensions');
			$this->css_file_extensions = $this->get_setting('css_file_extensions');
			$this->js_file_extensions = $this->get_setting('js_file_extensions');
		}

		public function initialize() {
			if( !class_exists( 'Voce_Settings_API' ) )
	 			return _doing_it_wrong( __CLASS__, 'The Voce Settings API plugin must be active for the CDN Rewrite plugin to work', NULL );

			$this->add_options_page();
			if ('' == $this->file_extensions || '' == $this->cdn_root_url) {
				add_action('admin_notices', array($this, 'settings_warning'));
				return;
			}

			if('/' != $this->cdn_root_url) {
				$action = (defined('XMLRPC_REQUEST') && XMLRPC_REQUEST) ? 'xmlrpc_call' : 'template_redirect';
				add_action($action, array($this, 'start_buffer'), 1);
			}
		}

		/**
		 * get general setting
		 *
		 * @param string $setting setting name
		 * @return mixed setting value or false if not set
		 */
		private function get_setting($setting) {
			$settings = get_option(self::OPTION_GENERAL);
			if(!$settings || !is_array($settings)) {
				$settings = array(
					'file_extensions' => 'bmp|bz2|gif|ico|gz|jpg|jpeg|mp3|pdf|png|rar|rtf|swf|tar|tgz|txt|wav|zip',
					'css_file_extensions' => 'css',
					'js_file_extensions' => 'js'
				);
				update_option(self::OPTION_GENERAL, $settings);
			}
			return (isset($settings[$setting])) ? $settings[$setting] : false;
		}

		public function settings_warning() {
			echo "<div class='update-nag'>The CDN Rewrite plugin is missing some required settings.</div>";
		}

		/**
		 * adds the options page
		 *
		 * @return void
		 */
		public function add_options_page() {
			Voce_Settings_API::GetInstance()->add_page('CDN Rewrite', 'CDN Rewrite', self::OPTION_GENERAL, 'manage_options', '', 'options-general.php' )
				->add_group( 'CDN Rewrite Settings', 'cdn_general' )
					->add_setting( 'CDN Root URL (required)', 'root_url', array( 'description' => 'The base URL of the CDN.' ) )->group
					->add_setting( 'File Extensions (required)', 'file_extensions' )->group
					->add_setting( 'CDN Root URL for CSS Files (optional)', 'css_root_url', array( 'description' => 'The base URL of the CDN for CSS Files.' ) )->group
					->add_setting( 'File Extensions for CSS Files (optional)', 'css_file_extensions' )->group
					->add_setting( 'CDN Root URL for JS Files (optional, defaults to Root URL)', 'js_root_url', array( 'description' => 'The base URL of the CDN for JS Files.' ) )->group
					->add_setting( 'File Extensions for JS Files (optional, defaults to Root URL)', 'js_file_extensions' );
		}

		/**
		 * start output buffering.
		 *
		 */
		public function start_buffer() {
			ob_start(array($this, 'filter_urls'));
		}

		/**
		 * Callback for output buffering.  Search content for urls to replace
		 *
		 * @param string $content
		 * @return string
		 */
		public function filter_urls($content) {

			$root_url = $this->get_site_root_url();
			$xml_begin = $xml_end = '';
			if (defined('XMLRPC_REQUEST') && XMLRPC_REQUEST) {
				$xml_begin = '>';
				$xml_end = '<';
			}
			$extensions = join('|', array_filter(array($this->file_extensions, $this->css_file_extensions, $this->js_file_extensions)));
			$regex = '#(?<=[(\"\''.$xml_begin.'])'.quotemeta($root_url).'(?:(/[^\"\''.$xml_end.')]+\.('.$extensions.')))#';
			$content = preg_replace_callback($regex, array($this, 'url_rewrite'), $content);

			return $content;
		}

		/**
		 * Returns the root url of the current site
		 *
		 * @return string
		 */
		public function get_site_root_url() {
			if(is_multisite() && !is_subdomain_install()) {
				$root_blog = get_blog_details(1);
				$root_url = $root_blog->siteurl;
			} else {
				$root_url = site_url();
			}
			return $root_url;
		}

		/**
		 * Returns the details for the current blog
		 *
		 * @return object
		 */
		public function get_this_blog_details() {
			if(!isset($this->blog_details)) {
				global $blog_id;
				$this->blog_details = get_blog_details($blog_id);
			}
			return $this->blog_details;
		}

		/**
		 * Callback for url preg_replace_callback.  Returns corrected URL
		 *
		 * @param array $match
		 * @return string
		 */
		public function url_rewrite($match) {
			global $blog_id;
			$path = $match[1];
			//if is subfolder install and isn't root blog and path starts with site_url and isnt uploads dir
			if(is_multisite() && !is_subdomain_install() && $blog_id !== 1) {
				$bloginfo = $this->get_this_blog_details();
				if((0 === strpos($path, $bloginfo->path)) && (0 !== strpos($path, $bloginfo->path.'files/'))) {
					$path = '/'.substr($path, strlen($bloginfo->path));
				}
			}
			if('/' !== $this->css_cdn_root_url && preg_match("/^.*\.(".$this->css_file_extensions.")$/i", $path) ) {
				return $this->css_cdn_root_url . $path;
			}
			if('/' !== $this->js_cdn_root_url && preg_match("/^.*\.(".$this->js_file_extensions.")$/i", $path) ) {
				return $this->js_cdn_root_url . $path;
			}
			return $this->cdn_root_url . $path;
		}

	}
	add_action('init', array(new CDN_Rewrite(), 'initialize'));

	class CDN_VersionAssets {

		private $default_version = '';
		private $root_url;

		public function __construct() {
			$this->root_url = site_url();
		}

		public function initialize() {
			add_filter('style_loader_src', array($this, 'replace_version'), 10);
			add_filter('script_loader_src', array($this, 'replace_version'), 10);
			add_filter('stylesheet_uri', array($this, 'replace_version'), 10);
		}

		public function on_template_redirect() {
			$this->default_version = @filemtime(get_stylesheet_directory().'/style.css');
		}

		private function get_version($url) {
			$version = false;

			if(0 === strpos($url, $this->root_url)) {
				$parts = parse_url($url);
				foreach( array( 'scheme', 'host', 'path' ) as $part ){
					if( !isset( $parts[$part] ) )
						return false;
				}

				$file_path = str_replace( site_url('/'), ABSPATH, $parts['scheme'] . '://' . $parts['host'] . $parts['path'] );

				if( file_exists( $file_path ) && !($version = @filemtime($file_path)) ) {
					$version = $this->default_version;
				}
			}
			return $version;
		}

		public function replace_version($src) {
			if( $new_version = $this->get_version($src) ) {
				return add_query_arg('ver', $new_version, $src);
			}
			return $src;
		}
	}
	add_action('init', array(new CDN_VersionAssets(), 'initialize'));
}