<?php

/*

 * Enano - an open-source CMS capable of wiki functions, Drupal-like sidebar blocks, and everything in between

 * Version 1.0 (Banshee)

 * pageprocess.php - intelligent retrieval of pages

 * Copyright (C) 2006-2007 Dan Fuhry

 *

 * This program is Free Software; you can redistribute and/or modify it under the terms of the GNU General Public License

 * as published by the Free Software Foundation; either version 2 of the License, or (at your option) any later version.

 *

 * This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied

 * warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for details.

 */

/**

 * Class to handle fetching page text (possibly from a cache) and formatting it.

 * @package Enano

 * @subpackage UI

 * @copyright 2007 Dan Fuhry

 * @license GNU General Public License <http://www.gnu.org/licenses/gpl.html>

 */

class PageProcessor

{

  /**

   * Page ID and namespace of the page handled by this instance

   * @var string

   */

  var $page_id;

  var $namespace;

  /**

   * Tracks if the page we're loading exists in the database or not.

   * @var bool

   */

  var $page_exists = false;

  /**

   * Permissions!

   * @var object

   */

  var $perms = null;

  /**

   * Switch to track if redirects are allowed. Defaults to true.

   * @var bool

   */

  var $allow_redir = true;

  /**

   * If this is set to true, this will call the header and footer funcs on $template when render() is called.

   * @var bool

   */

  var $send_headers = false;

  /**

   * Cache the fetched text so we don't fetch it from the DB twice.

   * @var string

   */

  var $text_cache = '';

  /**

   * Debugging information to track errors. You can set enable to false to disable sending debug information.

   * @var array

   */

  var $debug = array(

      'enable' => true,

      'works'  => false

    );

  /**

   * Constructor.

   * @param string The page ID (urlname) of the page

   * @param string The namespace of the page

   */

  function __construct( $page_id, $namespace )

  {

    global $db, $session, $paths, $template, $plugins; // Common objects

    // See if we can get some debug info

    if ( function_exists('debug_backtrace') && $this->debug['enable'] )

    {

      $this->debug['works'] = true;

      $this->debug['backtrace'] = enano_debug_print_backtrace(true);

    }

    // First things first - check page existence and permissions

    if ( !isset($paths->nslist[$namespace]) )

    {

      $this->send_error('The namespace "' . htmlspecialchars($namespace) . '" does not exist.');

    }

    $this->_setup( $page_id, $namespace );

  }

  /**

   * The main method to send the page content. Also responsible for checking permissions.

   */

  function send()

  {

    global $db, $session, $paths, $template, $plugins; // Common objects

    if ( !$this->perms->get_permissions('read') )

    {

      $this->err_access_denied();

      return false;

    }

    if ( $this->namespace == 'Special' || $this->namespace == 'Admin' )

    {

      if ( !$this->page_exists )

      {

        redirect( makeUrl(getConfig('main_page')), 'Can\'t find special page', 'The special or administration page you requested does not exist. You will now be transferred to the main page.', 2 );

      }

      $func_name = "page_{$this->namespace}_{$this->page_id}";

      if ( function_exists($func_name) )

      {

        return @call_user_func($func_name);

      }

      else

      {

        $title = 'Page backend not found';

        $message = "The administration page you are looking for was properly registered using the page API, but the backend function

                    (<tt>$fname</tt>) was not found. If this is a plugin page, then this is almost certainly a bug with the plugin.";

        if ( $this->send_headers )

        {

          $template->tpl_strings['PAGE_NAME'] = $title;

          $template->header();

          echo "<p>$message</p>";

          $template->footer();

        }

        else

        {

          echo "<h2>$title</h2>

                <p>$message</p>";

        }

        return false;

      }

    }

    else if ( in_array($this->namespace, array('Article', 'User', 'Project', 'Help', 'File', 'Category')) && $this->page_exists )

    {

      // Send as regular page

      $text = $this->fetch_text();

      if ( $text == 'err_no_text_rows' )

      {

        $this->err_no_rows();

        return false;

      }

      else

      {

        $this->render();

      }

    }

    else if ( ( $this->namespace == 'Template' || $this->namespace == 'System' ) && $this->page_exists )

    {

      $this->header();

      $text = $this->fetch_text();

      $text = preg_replace('/<noinclude>(.*?)<\/noinclude>/is', '\\1', $text);

      $text = preg_replace('/<nodisplay>(.*?)<\/nodisplay>/is', '', $text);

      $text = RenderMan::render( $text );

      echo $text;

      $this->footer();

    }

    else if ( !$this->page_exists )

    {

      // Perhaps this is hooked?

      ob_start();

      $code = $plugins->setHook('page_not_found');

      foreach ( $code as $cmd )

      {

        eval($cmd);

      }

      $ob = ob_get_contents();

      if ( empty($ob) )

      {

        $this->err_page_not_existent();

      }

    }

  }

  /**

   * Sets internal variables.

   * @access private

   */

  function _setup($page_id, $namespace)

  {

    global $db, $session, $paths, $template, $plugins; // Common objects

    $page_id_cleaned = sanitize_page_id($page_id);

    $this->page_id = $page_id_cleaned;

    $this->namespace = $namespace;

    $this->perms = $session->fetch_page_acl( $page_id, $namespace );

    // Exception for Admin: pages

    if ( $this->namespace == 'Admin' )

    {

      $fname = "page_Admin_{$this->page_id}";

    }

    // Does the page "exist"?

    {

      $this->page_exists = false;

    }

    else if ( !isset( $paths->pages[ $paths->nslist[$namespace] . $page_id ] ) && ( $this->namespace == 'Admin' && !function_exists($fname) ) )

    {

      $this->page_exists = false;

    }

    else

    {

      $this->page_exists = true;

    }

  }

  /**

   * Renders it all in one go, and echoes it out. This assumes that the text is in the DB.

   * @access private

   */

  function render()

  {

    $text = $this->fetch_text();

    $this->header();

    display_page_headers();

    echo RenderMan::render($text);

    display_page_footers();

    $this->footer();

  }

  /**

   * Sends the page header, dependent on, of course, whether we're supposed to.

   */

  function header()

  {

    global $db, $session, $paths, $template, $plugins; // Common objects

    if ( $this->send_headers )

      $template->header();

  }

  /**

   * Sends the page footer, dependent on, of course, whether we're supposed to.

   */

  function footer()

  {

    global $db, $session, $paths, $template, $plugins; // Common objects

    if ( $this->send_headers )

      $template->footer();

  }

  /**

   * Fetches the raw, unfiltered page text.

   * @access public

   */

  function fetch_text()

  {

    global $db, $session, $paths, $template, $plugins; // Common objects

    if ( !empty($this->text_cache) )

    {

      return $this->text_cache;

    }

    $q = $db->sql_query('SELECT page_text, char_tag FROM '.table_prefix.'page_text WHERE page_id=\'' . $this->page_id . '\' AND namespace=\'' . $this->namespace . '\';');

    if ( !$q )

    {

      $this->send_error('Error during SQL query.', true);

    }

    if ( $db->numrows() < 1 )

    {

      $this->page_exists = false;

      return 'err_no_text_rows';

    }

    $row = $db->fetchrow();

    $db->free_result();

    if ( !empty($row['char_tag']) )

    {

      // This page text entry uses the old text-escaping format

      $from = array(

          "{APOS:{$row['char_tag']}}",

          "{QUOT:{$row['char_tag']}}",

          "{SLASH:{$row['char_tag']}}"

        );

      $to = array("'", '"',  '\\');

      $row['page_text'] = str_replace($from, $to, $row['page_text']);

    }

    $this->text_cache = $row['page_text'];

    return $row['page_text'];

  }

  /**

   * Send the error message to the user that the access to this page is denied.

   * @access private

   */

  function err_access_denied()

  {

    global $db, $session, $paths, $template, $plugins; // Common objects

    $ob = '';

    $template->tpl_strings['PAGE_NAME'] = 'Access denied';

    if ( $this->send_headers )

    {

      $ob .= $template->getHeader();

    }

    $ob .= '<div class="error-box"><b>Access to this page is denied.</b><br />This may be because you are not logged in or you have not met certain criteria for viewing this page.</div>';

    if ( $this->send_headers )

    {

      $ob .= $template->getFooter();

    }

    echo $ob;

  }

  /**

   * Send the error message to the user complaining that there weren't any rows.

   * @access private

   */

  function err_no_rows()

  {

    global $db, $session, $paths, $template, $plugins; // Common objects

    $title = 'No text rows';

    $message = 'While the page\'s existence was verified, there were no rows in the database that matched the query for the text. This may indicate a bug with the software; ask the webmaster for more information. The offending query was:<pre>' . $db->latest_query . '</pre>';

    if ( $this->send_headers )

    {

      $template->tpl_strings['PAGE_NAME'] = $title;

      $template->header();

      echo "<p>$message</p>";

      $template->footer();

    }

    else

    {

      echo "<h2>$title</h2>

            <p>$message</p>";

    }

  }

  /**

   * Tell the user the page doesn't exist, and present them with their options.

   * @access private

   */

  function err_page_not_existent()

  {

    global $db, $session, $paths, $template, $plugins; // Common objects

    $this->header();

    header('HTTP/1.1 404 Not Found');

    echo '<h3>There is no page with this title yet.</h3>

           <p>You have requested a page that doesn\'t exist yet.';

    if ( $session->get_permissions('create_page') )

    {

      echo ' You can <a href="'.makeUrlNS($this->namespace, $this->page_id, 'do=edit', true).'" onclick="ajaxEditor(); return false;">create this page</a>, or return to the <a href="'.makeUrl(getConfig('main_page')).'">homepage</a>.';

    }

    else

    {

      echo ' Return to the <a href="'.makeUrl(getConfig('main_page')).'">homepage</a>.</p>';

    }

    if ( $session->get_permissions('history_rollback') )

    {

      $e = $db->sql_query('SELECT * FROM ' . table_prefix . 'logs WHERE action=\'delete\' AND page_id=\'' . $this->page_id . '\' AND namespace=\'' . $this->namespace . '\' ORDER BY time_id DESC;');

      if ( !$e )

      {

        $db->_die('The deletion log could not be selected.');

      }

      if ( $db->numrows() > 0 )

      {

        $r = $db->fetchrow();

        echo '<p>This page also appears to have some log entries in the database - it seems that it was deleted on ' . $r['date_string'] . '. You can probably <a href="'.makeUrl($paths->page, 'do=rollback&amp;id='.$r['time_id']).'" onclick="ajaxRollback(\''.$r['time_id'].'\'); return false;">roll back</a> the deletion.</p>';

      }

      $db->free_result();

    }

    echo '<p>

            HTTP Error: 404 Not Found

          </p>';

    $this->footer();

  }

  /**

   * PHP 4 constructor.

   * @see PageProcessor::__construct()

   */

  function PageProcessor( $page_id, $namespace )

  {

    $this->__construct($page_id, $namespace);

  }

  /**

   * Send an error message and die

   * @var string Error message

   * @var bool If true, send DBAL's debugging information as well

   */

  function send_error($message, $sql = false)

  {

    global $db, $session, $paths, $template, $plugins; // Common objects

    $content = "<p>$message</p>";

    $template->tpl_strings['PAGE_NAME'] = 'General error in page fetcher';

    if ( $this->debug['works'] )

    {

      $content .= $this->debug['backtrace'];

    }

    header('HTTP/1.1 500 Internal Server Error');

    $template->header();

    echo $content;

    $template->footer();

    $db->close();

    exit;

  }

} // class PageProcessor

?>