<?php

/*

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

 * Copyright (C) 2006-2008 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 used to handle and process plugin requests and loading. Singleton.

 * @package Enano

 * @author Dan Fuhry <dan@enanocms.org>

 * @copyright (C) 2006-2008 Enano Project

 * @license GNU General Public License <http://enanocms.org/Special:GNU_General_Public_License>

 */

class pluginLoader {

  /**

   * The list of hooks registered.

   * @var array

   * @access private

   */

  var $hook_list;

  /**

   * The list of plugins that should be loaded. Used only by common.php.

   * @var array

   * @access private

   */

  var $load_list;

  /**

   * The list of plugins that are loaded currently. This is only used by the loaded() method which in turn is

   * used by template files with the <!-- IFPLUGIN --> special tag.

   * @var array

   * @access private

   */

  var $loaded_plugins;

  /**

   * The list of plugins that are always loaded because they're part of the Enano core. This cannot be modified

   * by any external code because user plugins are loaded after the load_list is calculated. Can be useful in

   * alternative administration panel frameworks that need the list of system plugins.

   * @var array

   */

  var $system_plugins = Array('SpecialUserFuncs.php','SpecialUserPrefs.php','SpecialPageFuncs.php','SpecialAdmin.php','SpecialCSS.php','SpecialUpdownload.php','SpecialSearch.php','PrivateMessages.php','SpecialGroups.php', 'SpecialRecentChanges.php', 'DemoMode.php');

  /**

   * Name kept for compatibility. Effectively a constructor. Calculates the list of plugins that should be loaded

   * and puts that list in the $load_list property. Plugin developers have absolutely no use for this whatsoever.

   */

  function loadAll() 

  {

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

    $GLOBALS['plugins_cache'] = array();

    // if we're in an upgrade, just skip this step

    if ( defined('IN_ENANO_UPGRADE') )

    {

      $this->load_list = array();

      return false;

    }

    $dir = ENANO_ROOT.'/plugins/';

    $this->load_list = $this->system_plugins;

    $q = $db->sql_query('SELECT plugin_filename, plugin_version FROM ' . table_prefix . 'plugins WHERE plugin_flags & ~' . PLUGIN_DISABLED . ' = plugin_flags;');

    if ( !$q )

      $db->_die();

    while ( $row = $db->fetchrow() )

    {

      if ( file_exists(ENANO_ROOT . "/plugins/{$row['plugin_filename']}") )

      {

        $this->load_list[] = $row['plugin_filename'];

      }

    }

    $this->loaded_plugins = $this->get_plugin_list($this->load_list);

    // check for out-of-date plugins

    foreach ( $this->load_list as $i => $plugin )

    {

      if ( in_array($plugin, $this->system_plugins) )

        continue;

      if ( $this->loaded_plugins[$plugin]['status'] & PLUGIN_OUTOFDATE )

      {

        // it's out of date, don't load

        unset($this->load_list[$i]);

        unset($this->loaded_plugins[$plugin]);

      }

    }

    $this->load_list = array_unique($this->load_list);

  }

  /**

   * Name kept for compatibility. This method is used to add a new hook into the code somewhere. Plugins are encouraged

   * to set hooks and hook into other plugins in a fail-safe way, this encourages reuse of code. Returns an array, whose

   * values should be eval'ed.

   * @example <code>

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

   foreach ( $code as $cmd )

   {

     eval($cmd);

   }

   </code>

   * @param string The name of the hook.

   * @param array Deprecated.

   */

  function setHook($name, $opts = Array()) {

    if(isset($this->hook_list[$name]) && is_array($this->hook_list[$name]))

    {

      return array(implode("\n", $this->hook_list[$name]));

    }

    else

    {

      return Array();

    }

  }

  /**

   * Attaches to a hook effectively scheduling some code to be run at that point. You should try to keep hooks clean by

   * making a function that has variables that need to be modified passed by reference.

   * @example Simple example: <code>

   $plugins->attachHook('render_wikiformat_pre', '$text = str_replace("Goodbye, Mr. Chips", "Hello, Mr. Carrots", $text);');

   </code>

   * @example More complicated example: <code>

   $plugins->attachHook('render_wikiformat_pre', 'myplugin_parser_ext($text);');

   // Notice that $text is passed by reference.

   function myplugin_parser_ext(&$text)

   {

     $text = str_replace("Goodbye, Mr. Chips", "Hello, Mr. Carrots", $text);

   }

   </code>

   */

  function attachHook($name, $code) {

    if(!isset($this->hook_list[$name]))

    {

      $this->hook_list[$name] = Array();

    }

    $this->hook_list[$name][] = $code;

  }

  /**

   * Tell whether a plugin is loaded or not.

   * @param string The filename of the plugin

   * @return bool

   */

  function loaded($plugid)

  {

    return isset( $this->loaded_plugins[$plugid] );

  }

  /**

   * Parses all special comment blocks in a plugin and returns an array in the format:

   <code>

   array(

       0 => array(

           'block' => 'upgrade',

           // parsed from the block's parameters section

             'release_from' => '1.0b1',

             'release_to' => '1.0b2',

           'value' => 'foo'

         ),

       1 => array(

           ...

         )

     );

   </code>

   * @param string Path to plugin file

   * @param string Optional. The type of block to fetch. If this is specified, only the block type specified will be read, all others will be discarded.

   * @return array

   */

  public static function parse_plugin_blocks($file, $type = false)

  {

    if ( !file_exists($file) )

    {

      return array();

    }

    $blocks = array();

    $contents = @file_get_contents($file);

    if ( empty($contents) )

    {

      return array();

    }

    $regexp = '#^/\*\*!([a-z0-9_]+)'  // block header and type

            . '(([\s]+[a-z0-9_]+[\s]*=[\s]*".+?"[\s]*;)*)' // parameters

            . '[\s]*\*\*' . "\n"      // spacing and header close

            . '([\w\W]+?)' . "\n"     // value

            . '\*\*!\*/'              // closing comment

            . '#m';

    // Match out all blocks

    $results = preg_match_all($regexp, $contents, $blocks);

    $return = array();

    foreach ( $blocks[0] as $i => $_ )

    {

      if ( is_string($type) && $blocks[1][$i] !== $type )

        continue;

      $value =& $blocks[4][$i];

      // parse includes

      preg_match_all('/^!include [\'"]?(.+?)[\'"]?$/m', $value, $includes);

      foreach ( $includes[0] as $i => $replace )

      {

        $filename = ENANO_ROOT . '/' . $includes[1][$i];

        if ( @file_exists( $filename ) && @is_readable( $filename ) )

        {

          $contents = @file_get_contents($filename);

          $value = str_replace_once($replace, $contents, $value);

        }

      }

      $el = self::parse_vars($blocks[2][$i]);

      $el['block'] = $blocks[1][$i];

      $el['value'] = $value;

      $return[] = $el;

    }

    return $return;

  }

  private static function parse_vars($var_block)

  {

    preg_match_all('/[\s]+([a-z0-9_]+)[\s]*=[\s]*"(.+?)";/', $var_block, $matches);

    $return = array();

    foreach ( $matches[0] as $i => $_ )

    {

      $return[ $matches[1][$i] ] = $matches[2][$i];

    }

    return $return;

  }

  /**

   * Reads all plugins in the filesystem and cross-references them with the database, providing a very complete summary of plugins

   * on the site.

   * @param array If specified, will restrict scanned files to this list. Defaults to null, which means all PHP files will be scanned.

   * @param bool If true, allows using cached information. Defaults to true.

   * @return array

   */

  function get_plugin_list($restrict = null, $use_cache = true)

  {

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

    // Scan all plugins

    $plugin_list = array();

    $ta = 0;

    // won't load twice (failsafe automatic skip)

    $this->load_plugins_cache();

    if ( $use_cache )

    {

      global $plugins_cache;

    }

    else

    {

      // blank array - effectively skips importing the cache

      $plugins_cache = array();

    }

    if ( $dirh = @opendir( ENANO_ROOT . '/plugins' ) )

    {

      while ( $dh = @readdir($dirh) )

      {

        if ( !preg_match('/\.php$/i', $dh) )

          continue;

        if ( is_array($restrict) )

          if ( !in_array($dh, $restrict) )

            continue;

        // it's a PHP file, attempt to read metadata

        $fullpath = ENANO_ROOT . "/plugins/$dh";

        $plugin_meta = $this->get_plugin_info($fullpath, $use_cache);

        if ( is_array($plugin_meta) )

        {

          // all checks passed

          $plugin_list[$dh] = $plugin_meta;

        }

      }

    }

    // gather info about installed plugins

    $q = $db->sql_query('SELECT plugin_id, plugin_filename, plugin_version, plugin_flags FROM ' . table_prefix . 'plugins;');

    if ( !$q )

      $db->_die();

    while ( $row = $db->fetchrow() )

    {

      if ( !isset($plugin_list[ $row['plugin_filename'] ]) )

      {

        // missing plugin file, don't report (for now)

        continue;

      }

      $filename =& $row['plugin_filename'];

      $plugin_list[$filename]['installed'] = true;

      $plugin_list[$filename]['status'] = PLUGIN_INSTALLED;

      $plugin_list[$filename]['plugin id'] = $row['plugin_id'];

      if ( $row['plugin_version'] != $plugin_list[$filename]['version'] )

      {

        $plugin_list[$filename]['status'] |= PLUGIN_OUTOFDATE;

        $plugin_list[$filename]['version installed'] = $row['plugin_version'];

      }

      if ( $row['plugin_flags'] & PLUGIN_DISABLED )

      {

        $plugin_list[$filename]['status'] |= PLUGIN_DISABLED;

      }

    }

    $db->free_result();

    // sort it all out by filename

    ksort($plugin_list);

    // done

    return $plugin_list;

  }

  /**

   * Retrieves the metadata block from a plugin file

   * @param string Path to plugin file (full path)

   * @return array

   */

  function get_plugin_info($fullpath, $use_cache = true)

  {

    global $plugins_cache;

    $dh = basename($fullpath);

    // first can we use cached info?

    if ( isset($plugins_cache[$dh]) && $plugins_cache[$dh]['file md5'] === $this->md5_header($fullpath) )

    {

      $plugin_meta = $plugins_cache[$dh];

    }

    else

    {

      // the cache is out of date if we reached here -- regenerate

      if ( $use_cache )

        $this->generate_plugins_cache();

      // pass 1: try to read a !info block

      $blockdata = $this->parse_plugin_blocks($fullpath, 'info');

      if ( empty($blockdata) )

      {

        // no !info block, check for old header

        $fh = @fopen($fullpath, 'r');

        if ( !$fh )

          // can't read, bail out

          return false;

        $plugin_data = array();

        for ( $i = 0; $i < 8; $i++ )

        {

          $plugin_data[] = @fgets($fh, 8096);

        }

        // close our file handle

        fclose($fh);

        // is the header correct?

        if ( trim($plugin_data[0]) != '<?php' || trim($plugin_data[1]) != '/*' )

        {

          // nope. get out.

          return false;

        }

        // parse all the variables

        $plugin_meta = array();

        for ( $i = 2; $i <= 7; $i++ )

        {

          if ( !preg_match('/^([A-z0-9 ]+?): (.+?)$/', trim($plugin_data[$i]), $match) )

            return false;

          $plugin_meta[ strtolower($match[1]) ] = $match[2];

        }

      }

      else

      {

        // parse JSON block

        $plugin_data =& $blockdata[0]['value'];

        $plugin_data = enano_clean_json(enano_trim_json($plugin_data));

        try

        {

          $plugin_meta_uc = enano_json_decode($plugin_data);

        }

        catch ( Exception $e )

        {

          return false;

        }

        // convert all the keys to lowercase

        $plugin_meta = array();

        foreach ( $plugin_meta_uc as $key => $value )

        {

          $plugin_meta[ strtolower($key) ] = $value;

        }

      }

    }

    if ( !isset($plugin_meta) || !is_array(@$plugin_meta) )

    {

      // parsing didn't work.

      return false;

    }

    // check for required keys

    $required_keys = array('plugin name', 'plugin uri', 'description', 'author', 'version', 'author uri');

    foreach ( $required_keys as $key )

    {

      if ( !isset($plugin_meta[$key]) )

        // not set, skip this plugin

        return false;

    }

    // decide if it's a system plugin

    $plugin_meta['system plugin'] = in_array($dh, $this->system_plugins);

    // reset installed variable

    $plugin_meta['installed'] = false;

    $plugin_meta['status'] = 0;

    return $plugin_meta;

  }

  /**

   * Attempts to cache plugin information in a file to speed fetching.

   */

  function generate_plugins_cache()

  {

    if ( getConfig('cache_thumbs') != '1' )

      return;

    // fetch the most current info

    $plugin_info = $this->get_plugin_list(null, false);

    foreach ( $plugin_info as $plugin => &$info )

    {

      $info['file md5'] = $this->md5_header(ENANO_ROOT . "/plugins/$plugin");

    }

    $this->update_plugins_cache($plugin_info);

    $GLOBALS['plugins_cache'] = $plugin_info;

    return true;

  }

  /**

   * Writes an information array to the cache file.

   * @param array

   * @access private

   */

  function update_plugins_cache($plugin_info)

  {

    global $cache;

    try

    {

      $result = $cache->store('plugins', $plugin_info, -1);

    }

    catch ( Exception $e )

    {

      return false;

    }

    return $result;

  }

  /**

   * Loads the plugins cache if any.

   */

  function load_plugins_cache()

  {

    global $cache;

    if ( $data = $cache->fetch('plugins') )

    {

      $GLOBALS['plugins_cache'] = $data;

    }

  }

  /**

   * Calculates the MD5 sum of the first 10 lines of a file. Useful for caching plugin header information.

   * @param string File

   * @return string

   */