<?php

use dokuwiki\Extension\ActionPlugin;
use dokuwiki\Extension\EventHandler;
use dokuwiki\Extension\Event;

/**
 * Redirect2 - DokuWiki Redirect Manager
 * 
 * @license    GPL 2 (http://www.gnu.org/licenses/gpl.html)
 * @author     Satoshi Sahara <sahara.satoshi@gmail.com>
 */
class action_plugin_redirect2 extends ActionPlugin
{
    protected $LogFile;       // log file, see function _log_redirection
    protected $debug = false; // enabled if DEBUG file exists in this plugin directory

    /**
     * Register event handlers
     */
    public function register(EventHandler $controller)
    {
        $controller->register_hook('DOKUWIKI_STARTED', 'BEFORE',    $this, 'handleReplacedBy');
        $controller->register_hook('ACTION_HEADERS_SEND', 'BEFORE', $this, 'redirectPage');
        $controller->register_hook('FETCH_MEDIA_STATUS', 'BEFORE',  $this, 'redirectMedia');
        $controller->register_hook('TPL_CONTENT_DISPLAY', 'BEFORE', $this, 'errorDocument404');
    }

    public function __construct()
    {
        global $conf;
        $this->LogFile  = $conf['cachedir'].'/redirection.log';
        if (@file_exists(dirname(__FILE__).'/DEBUG')) $this->debug = true;
    }


    /**
     * ErrorDocument404 - not found response
     * show 404 wiki page instead of inc/lang/<iso>/newpage.txt
     * TPL_CONTENT_DISPLAY:BEFORE event handler
     *
     * The code adopted from dokuwiki-plugin-notfound
     * https://www.dokuwiki.org/plugin:notfound
     * @author     Andreas Gohr <andi@splitbrain.org>
     */
     public function errorDocument404(Event $event, $param)
     {
        global $ACT, $ID, $INFO;

         if ( $INFO['exists'] || ($ACT != 'show') ) return false;
         $page = $this->getConf('404page');
         if (empty($page)) return false;

         $event->stopPropagation();
         $event->preventDefault();

         $referer = isset($_SERVER['HTTP_REFERER']) ? $_SERVER['HTTP_REFERER'] : '';
         $this->_log_redirection(404, $ID, $referer);
         echo p_wiki_xhtml($this->getConf('404page'), false);
         return true;
     }


    /**
     * Get redirect destination URL
     * 
     * @param int $status  redirect status, 301 or 302
     * @param string $dest redirect destination, absolute id or external url
     * @return mixed       url of the destination page/media, or false
     */
    protected function getRedirectURL($status = 302, $dest)
    {
        global $ID, $INFO;

        if (preg_match('@^(https?://|/)@', $dest)) {
            $url = $dest; // external url
        } else {
            list($ext, $mime) = mimetype($dest);
            if ($ext) {   // media
                $url = ml($dest);
            } else {      // page
                list($page, $section) = explode('#', $dest, 2);

                // check whether visit again using breadcrums trace
                // Note: this does not completely eliminate redirect loop.
                if ($this->_foundInBreadcrumbs($page) && $INFO['exists']) {
                    $this->_show_message('redirect_halt', $ID, $page);
                    return false;
                }

                $url = wl($page);
                if (!empty($section)) $url.= '#'.rawurlencode($section);

                // output message, to be shown at destination page (after redirect)
                $this->_show_message('redirected_from', $ID, $dest, $status);
            }
        }
        return $url;
    }

    /**
     * Check if the page found in breadcrumbs (session cookie)
     * to prevent infinite redirection loop
     *
     * @param string $id  absolute page name (id)
     * @return bool  true if id (of the page) found in breadcrumbs
     */
    private function _foundInBreadcrumbs ($id)
    {
        list($page, $section) = explode('#', $id, 2);

        if (isset($_SESSION[DOKU_COOKIE]['bc']) && 
            array_key_exists($page, $_SESSION[DOKU_COOKIE]['bc'])) {
            if ($this->debug) {
                $hist = $_SESSION[DOKU_COOKIE]['bc'];
                error_log('redirect to page['.$page.'] must stop due to prevent loop '."\n".
                          'found in breadcrumbs = '.var_export($hist, true));
            }
            return true;
        }
        return false;
    }


    /**
     * Page redirection based on metadata 'relation isreplacedby'
     * that is set by syntax component
     * DOKUWIKI_STARTED:BEFORE event handler
     */
    function handleReplacedBy(Event $event, $param)
    {
        global $ID, $ACT, $REV, $INPUT;

        if (($ACT != 'show' && $ACT != '') || $REV) return;
        if (!plugin_isdisabled('pageredirect')) return;

        // return if no redirection data
        $id = p_get_metadata($ID,'relation isreplacedby');
        if (empty($id)) return;

        // check whether redirection is temporarily disabled by url paramter
        if (is_null($INPUT->str('redirect', NULL))) {
            // Redirect current page
            $dest = $id;
            $status = 301;
            $url = $this->getRedirectURL($status, $dest);
            if ($url !== false) {
                $this->_log_redirection($status, $ID, $dest);
                http_status($status);
                send_redirect($url);
                exit;
            }
        }
        return;
    }


    /**
     * Redirection of pages based on redirect.conf file
     * ACTION_HEADERS_SEND:BEFORE event handler
     */
    function redirectPage(Event $event, $param)
    {
        global $ACT, $ID, $INPUT;

        if (!($ACT == 'show' || (!is_array($ACT) && substr($ACT, 0, 7) == 'export_')) ) return;

        // return if redirection is temporarily disabled by url paramter
        if ($INPUT->str('redirect',NULL) == 'no') return;

        // read redirect map
        $map = $this->loadHelper($this->getPluginName());
        if (empty($map)) return false;

        /*
         * Redirect based on simple prefix match of the current page
         * (Redirect Directives)
         */
        $leaf = '';  // rest of checkID ($ID = $checkID + $leaf)
        $checkID = $ID;
        do {
            if (isset($map->pattern[$checkID])) {
                $dest = $map->pattern[$checkID]['destination'];
                list($ns, $section) = explode('#', $dest, 2);
                $dest = $ns.$leaf;
                $dest.= (!empty($section)) ? '#'.rawurlencode($section) : '';

                $status = $map->pattern[$checkID]['status'];
                $url = $this->getRedirectURL($status, $dest);
                if ($url !== false) {
                    $this->_log_redirection($status, $ID, $dest);
                    http_status($status);
                    send_redirect($url);
                    exit;
                }
            }
            // check hierarchic namespace replacement
            $leaf = noNS(rtrim($checkID,':')).$leaf;
            $checkID = ($checkID == ':') ? false : getNS(rtrim($checkID,':')).':';
        } while ($checkID != false);

        /*
         * Redirect based on a regular expression match against the current page
         * (RedirectMatch Directives)
         */
        if ($this->getConf('useRedirectMatch')) {
            $redirect = $this->_RedirectMatch($ID, $map);
            if ($redirect !== false) {
                $dest = $redirect['destination'];
                $status = $redirect['status'];
                $url = $this->getRedirectURL($status, $dest);
                if ($url !== false) {
                    $this->_log_redirection($status, $ID, $dest);
                    http_status($status);
                    send_redirect($url);
                    exit;
                }
            }
        }
        return true;
    }


    /**
     * Redirect of media based on redirect.conf file
     * FETCH_MEDIA_STATUS event handler
     * @see also https://www.dokuwiki.org/devel:event:fetch_media_status
     */
    function redirectMedia(Event $event, $param)
    {
        // read redirect map
        $map = $this->loadHelper($this->getPluginName());
        if (empty($map)) return false;

        /*
         * Redirect based on simple prefix match of the current media
         * (Redirect Directives)
         */
        $leaf = '';
        // for media, $checkID need to be clean with ':' prefixed
        $checkID = ':'.ltrim($event->data['media'],':');
        do {
            if (isset($map->pattern[$checkID])) {
                $dest = $map->pattern[$checkID]['destination'];
                list($ns, $section) = explode('#', $dest, 2);
                $dest = $ns.$leaf;
                $dest.= (!empty($section)) ? '#'.rawurlencode($section) : '';

                $status = $map->pattern[$checkID]['status'];
                $url = $this->getRedirectURL($status, $dest);
                if ($url !== false) {
                    $this->_log_redirection($status, $event->data['media'], $dest);
                    $event->data['status'] = $status;
                    $event->data['statusmessage'] = $url;
                    return; // Redirect will happen at lib/exe/fetch.php
                }
            }
            // check hierarchic namespace replacement
            $leaf = noNS(rtrim($checkID,':')).$leaf;
            $checkID = ($checkID == '::') ? false : ':'.getNS(trim($checkID,':')).':';
        } while ($checkID != false);

        /*
         * Redirect based on a regular expression match against the current media
         * (RedirectMatch Directives)
         */
        if ($this->getConf('useRedirectMatch')) {
            $checkID = ':'.ltrim($event->data['media'],':');
            $redirect = $this->_RedirectMatch($checkID, $map);
            if ($redirect !== false) {
                $dest = $redirect['destination'];
                $status = $redirect['status'];
                $url = $this->getRedirectURL($status, $dest);
                if ($url !== false) {
                    $this->_log_redirection($status, $event->data['media'], $dest);
                    $event->data['status'] = $status;
                    $event->data['statusmessage'] = $url;
                    return; // Redirect will happen at lib/exe/fetch.php
                }
            }
        }
        return true;
    }


    /**
     * Resolve destination page/media id by regular expression match
     * using rediraction pattern map config file
     *
     * @param string $checkID  full and cleaned name of page or media
     *                         for the page, it must be clean id
     *                         for media, it must be clean with ':' prefixed
     * @param array $map       redirect map
     * @return array of status and destination (id), or false if no matched
     */
    protected function _RedirectMatch( $checkID, $map )
    {
        foreach ($map->pattern as $pattern => $data) {
            if (preg_match('/^%.*%$/', $pattern) !== 1) continue;
            $destID = preg_replace( $pattern, $data['destination'], $checkID, -1, $count);
            if ($count > 0) {
                $status = $data['status'];
                return array('status' => $status, 'destination' => $destID);
                break;
            }
        }
        return false;
    }


    /**
     * Show message to inform user redirection
     * 
     * @param string $format   key name for message string
     * @param string $orig     page id of redirect origin
     * @param string $dest     page id of redirect destination
     * @param int    $status   http status of the redirection
     */
    protected function _show_message($format, $orig=NULL, $dest=NULL, $status=302)
    {
        global $ID, $INFO, $INPUT;

        // check who can see the message
        $show = ( ($INFO['isadmin'] && ($this->getConf('msg_target') >= 0))
               || ($INFO['ismanager'] && ($this->getConf('msg_target') >= 1))
               || ($INPUT->server->has('REMOTE_USER') && ($this->getConf('msg_target') >= 2))
               || ($this->getConf('msg_target') >= 3) );
        if (!$show) return;
        // make links used in message
        $link = array();
        foreach (array($orig, $dest) as $id) {
            $title = hsc(p_get_metadata($id, 'title'));
            if (empty($title)) {
                $title = hsc(useHeading('navigation') ? p_get_first_heading($id) : $id);
            }
            resolve_pageid(':', $id, $exists); // absolute pagename
            $class = ($exists) ? 'wikilink1' : 'wikilink2';
            $link[$id] = '<a href="'.wl($id, array('redirect' => 'no')).'" rel="nofollow"'.
                         ' class="'.$class.'" title="'.$id.'">'.$title.'</a>';
        }

        switch ($format) {
            case 'redirect_halt':
                // "Halted redirection from %1$s to %2$s due to prevent loop."
                msg(sprintf($this->getLang($format), $link[$orig], $link[$dest]), -1);
                break;

            case 'redirected_from':
                // "You were redirected here (%2$s) from %1$s."
                if ( ($this->getConf('show_msg') == 0) ||
                    (($this->getConf('show_msg') == 1) && ($status != 301)) ) {
                    break; // no need to show message
                }
                msg(sprintf($this->getLang($format), $link[$orig], $link[$dest]), 0);
                break;

        } // end switch

    }


    /**
     * Logging of redirection
     */
    protected function _log_redirection($status, $orig, $dest='')
    {
        if (!$this->getConf('logging')) return;

        $dbg = debug_backtrace();
        $caller = $dbg[1]['function'];

        $s = date('Y-m-d H:i:s', $_SERVER['REQUEST_TIME'])."\t".$caller;
        if ($status == 404) {
            // $dest is referer of the $orig page
            $s.= "\t".$status."\t".$orig."\t".$dest;
        } else {
            // redirect from $orig to $dest
            $s.= "\t".$status."\t".$orig."\t".$dest;
        }
        io_saveFile($this->LogFile, $s."\n", true);
    }

}