action.php

<?php
/**
 * Action Plugin:   Redirects page requests based on content
 *
 * @license    GPL 2 (http://www.gnu.org/licenses/gpl.html)
 * @author     Elan Ruusamäe <glen@delfi.ee>
 * @author     David Lorentsen <zyberdog@quakenet.org>
 */

if(!defined('DOKU_INC')) die();

if(!defined('DOKU_PLUGIN')) define('DOKU_PLUGIN',DOKU_INC.'lib/plugins/');
require_once(DOKU_PLUGIN.'action.php');

/**
 * All DokuWiki action plugins need to inherit from this class
 */
class action_plugin_pageredirect extends DokuWiki_Action_Plugin {
	function register(&$controller) {
		$controller->register_hook('DOKUWIKI_STARTED', 'BEFORE', $this, 'handle_pageredirect_redirect');
		$controller->register_hook('TPL_ACT_RENDER', $this->getConf('show_note'), $this, 'handle_pageredirect_note');
		$controller->register_hook('PARSER_METADATA_RENDER','BEFORE', $this, 'handle_pageredirect_metadata');

		// This plugin goes first
		$hooks =& $controller->_hooks[TPL_ACT_RENDER_BEFORE];
		if ($hooks[0][0] != $this) {
			array_unshift($hooks, array_pop($hooks));
		}
	}

	function handle_pageredirect_redirect(&$event, $param) {
		global $ID, $ACT, $REV;

		if (($ACT == 'show' || $ACT == '') && empty($REV)) {
			$page = p_get_metadata($ID,'relation isreplacedby');

			// return if no redirection data
			if (empty($page)) { return; }

			if (isset($_GET['redirect'])) {
				// return if redirection is temporarily disabled,
				// or we have been redirected 5 times in a row
				if ($_GET['redirect'] == 'no' || $_GET['redirect'] > 4) { return; }
				elseif ($_GET['redirect'] > 0) { $redirect = $_GET['redirect'] +1; }
				else { $redirect = 1; }
			} else {
				$redirect = 1;
			}

			// verify metadata currency
			if (@filemtime(metaFN($ID,'.meta')) < @filemtime(wikiFN($ID))) { return; }

			if (!headers_sent() && $this->getConf('show_note')) {
				// remember to show note about being redirected from another page
				session_start();
				$_SESSION[DOKU_COOKIE]['redirect'] = $ID;
			}

			// preserve #section from $page
			list($page, $section) = explode('#', $page, 2);
			if (isset($section)) {
				$section = '#' . $section;
			} else {
				$section = '';
			}

			// redirect
			header("HTTP/1.1 301 Moved Permanently");
			header("Location: ".wl($page, Array('redirect' => $redirect), TRUE, '&'). $section);
			exit();
		}
	}

	function handle_pageredirect_note(&$event, $param) {
		global $ID, $ACT;

		if ($ACT == 'show' || $ACT == '') {
			if (!$this->getConf('show_note')) { return; }
			if (isset($_GET['redirect']) && $_GET['redirect'] > 0 && $_GET['redirect'] < 6) {
				if (isset($_SESSION[DOKU_COOKIE]['redirect']) && $_SESSION[DOKU_COOKIE]['redirect'] != '') {
					// we were redirected from another page, show it!
					$page = $_SESSION[DOKU_COOKIE]['redirect'];
					echo '<div class="noteredirect">'.sprintf($this->getLang('redirected_from'), '<a href="'.wl(':'.$page, Array('redirect' => 'no'), TRUE, '&').'" class="wikilink1" title="'.$page.'">'.$page.'</a>').'</div><br/>';
					unset($_SESSION[DOKU_COOKIE]['redirect']);

					return true;
				}
			}
		}

		return true;
	}

	function handle_pageredirect_metadata(&$event, $param) {
		if (isset($event->data->meta['relation'])) {
			unset($event->data->meta['relation']['isreplacedby']);
		}
	}
}