<?php

/*

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

 * Copyright (C) 2006-2009 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.

 */

/**

 * Framework for parsing and rendering various formats. In Enano by default, this is MediaWiki-style wikitext being

 * rendered to XHTML, but this framework allows other formats to be supported as well.

 *

 * @package Enano

 * @subpackage Content

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

 * @copyright (C) 2009 Enano CMS Project

 * @license GNU General Public License, version 2 or later <http://www.gnu.org/licenses/gpl-2.0.html>

 */

class Carpenter

{

  /**

   * Parser token

   * @const string

   */

  const PARSER_TOKEN = "\xFF";

  /**

   * Parsing engine

   * @var string

   */

  private $parser = 'mediawiki';

  /**

   * Rendering engine

   * @var string

   */

  private $renderer = 'xhtml';

  /**

   * Rendering flags

   */

  public $flags = RENDER_WIKI_DEFAULT;

  /**

   * List of rendering rules

   * @var array

   */

  private $rules = array(

      'lang',

      'templates',

      'blockquote',

      'code',

      'tables',

      'heading',

      'hr',

      // note: can't be named list ("list" is a PHP language construct)

      'multilist',

      'bold',

      'italic',

      'underline',

      'externalwithtext',

      'externalnotext',

      'mailtowithtext',

      'mailtonotext',

      'image',

      'internallink',

      'paragraph',

      'blockquotepost'

    );

  /**

   * List of render hooks

   * @var array

   */

  private $hooks = array();

  /* private $rules = array('prefilter', 'delimiter', 'code', 'function', 'html', 'raw', 'include', 'embed', 'anchor',

           'heading', 'toc', 'horiz', 'break', 'blockquote', 'list', 'deflist', 'table', 'image',

           'phplookup', 'center', 'newline', 'paragraph', 'url', 'freelink', 'interwiki',

           'wikilink', 'colortext', 'strong', 'bold', 'emphasis', 'italic', 'underline', 'tt',

           'superscript', 'subscript', 'revise', 'tighten'); */

  /**

   * Render the text!

   * @param string Text to render

   * @return string

   */

  public function render($text)

  {

    $parser_class = "Carpenter_Parse_" . ucwords($this->parser);

    $renderer_class = "Carpenter_Render_" . ucwords($this->renderer);

    // empty?

    if ( trim($text) === '' )

      return $text;

    // include files, if we haven't already

    if ( !class_exists($parser_class) )

    {

      require_once( ENANO_ROOT . "/includes/wikiengine/parse_{$this->parser}.php");

    }

    if ( !class_exists($renderer_class) )

    {

      require_once( ENANO_ROOT . "/includes/wikiengine/render_{$this->renderer}.php");

    }

    $parser = new $parser_class;

    $renderer = new $renderer_class;

    // run prehooks

    foreach ( $this->hooks as $hook )

    {

      if ( $hook['when'] === PO_FIRST )

      {

        $text = call_user_func($hook['callback'], $text);

        if ( !is_string($text) || empty($text) )

        {

          trigger_error("Hook returned empty/invalid text: " . print_r($hook['callback'], true), E_USER_WARNING);

          // *sigh*

          $text = '';

        }

      }

    }

    // perform render

    foreach ( $this->rules as $rule )

    {

      // run prehooks

      foreach ( $this->hooks as $hook )

      {

        if ( $hook['when'] === PO_BEFORE && $hook['rule'] === $rule )

        {

          $text = call_user_func($hook['callback'], $text);

          if ( !is_string($text) || empty($text) )

          {

            trigger_error("Hook returned empty/invalid text: " . print_r($hook['callback'], true), E_USER_WARNING);

            // *sigh*

            $text = '';

          }

        }

      }

      // execute rule

      $text_before = $text;

      $text = $this->perform_render_step($text, $rule, $parser, $renderer);

      if ( empty($text) )

      {

        trigger_error("Wikitext was empty after rule \"$rule\"; restoring backup", E_USER_WARNING);

        $text = $text_before;

      }

      unset($text_before);

      // run posthooks

      foreach ( $this->hooks as $hook )

      {

        if ( $hook['when'] === PO_AFTER && $hook['rule'] === $rule )

        {

          $text = call_user_func($hook['callback'], $text);

          if ( !is_string($text) || empty($text) )

          {

            trigger_error("Hook returned empty/invalid text: " . print_r($hook['callback'], true), E_USER_WARNING);

            // *sigh*

            $text = '';

          }

        }

      }

    }

    // run posthooks

    foreach ( $this->hooks as $hook )

    {

      if ( $hook['when'] === PO_LAST )

      {

        $text = call_user_func($hook['callback'], $text);

        if ( !is_string($text) || empty($text) )

        {

          trigger_error("Hook returned empty/invalid text: " . print_r($hook['callback'], true), E_USER_WARNING);

          // *sigh*

          $text = '';

        }

      }

    }

    return (( defined('ENANO_DEBUG') && isset($_GET['parserdebug']) ) ? '<pre>' . htmlspecialchars($text) . '</pre>' : $text) . "\n\n";

  }

  /**

   * Performs a step in the rendering process.

   * @param string Text to render

   * @param string Rule to execute

   * @param object Parser instance

   * @param object Renderer instance

   * @return string

   * @access private

   */

  private function perform_render_step($text, $rule, $parser, $renderer)

  {

    // First look for a direct function

    if ( function_exists("parser_{$this->parser}_{$this->renderer}_{$rule}") )

    {

      return call_user_func("parser_{$this->parser}_{$this->renderer}_{$rule}", $text, $this->flags);

    }

    // We don't have that, so start looking for other ways or means of doing this

    if ( method_exists($parser, $rule) && method_exists($renderer, $rule) )

    {

      // Both the parser and render have callbacks they want to use.

      $pieces = $parser->$rule($text);

      $text = call_user_func(array($renderer, $rule), $text, $pieces);

    }

    else if ( method_exists($parser, $rule) && !method_exists($renderer, $rule) && isset($renderer->rules[$rule]) )

    {

      // The parser has a callback, but the renderer does not

      $pieces = $parser->$rule($text);

      $text = $this->generic_render($text, $pieces, $renderer->rules[$rule]);

    }

    else if ( !method_exists($parser, $rule) && isset($parser->rules[$rule]) && method_exists($renderer, $rule) )

    {

      // The parser has no callback, but the renderer does

      $text = preg_replace_callback($parser->rules[$rule], array($renderer, $rule), $text);

    }

    else if ( isset($parser->rules[$rule]) && isset($renderer->rules[$rule]) )

    {

      // This is a straight-up regex only rule

      $text = preg_replace($parser->rules[$rule], $renderer->rules[$rule], $text);

    }

    else

    {

      // Either the renderer or parser does not support this rule, ignore it

    }

    return $text;

  }

  /**

   * Generic renderer

   * @access protected

   */

  protected function generic_render($text, $pieces, $rule)

  {

    foreach ( $pieces as $i => $piece )

    {

      $replacement = $rule;

      // if the piece is an array, replace $1, $2, etc. in the rule with each value in the piece

      if ( is_array($piece) )

      {

        $j = 0;

        foreach ( $piece as $part )

        {

          $j++;

          $replacement = str_replace(array("\\$j", "\${$j}"), $part, $replacement);

        }

      }

      // else, just replace \\1 or $1 in the rule with the piece

      else

      {

        $replacement = str_replace(array("\\1", "\$1"), $piece, $replacement);

      }

      $text = str_replace(self::generate_token($i), $replacement, $text);

    }

    return $text;

  }

  /**

   * Add a hook into the parser.

   * @param callback Function to call

   * @param int PO_* constant

   * @param string If PO_{BEFORE,AFTER} used, rule

   */

  public function hook($callback, $when, $rule = false)

  {

    if ( !is_int($when) )

      return null;

    if ( ($when == PO_BEFORE || $when == PO_AFTER) && !is_string($rule) )

      return null;

    if ( ( is_string($callback) && !function_exists($callback) ) || ( is_array($callback) && !method_exists($callback[0], $callback[1]) ) || ( !is_string($callback) && !is_array($callback) ) )

    {

      trigger_error("Attempt to hook with undefined function/method " . print_r($callback, true), E_USER_ERROR);

      return null;

    }

    $this->hooks[] = array(

        'callback' => $callback,

        'when'     => $when,

        'rule'     => $rule

      );

  }

  /**

   * Disable a render stage

   * @param string stage

   * @return null

   */

  public function disable_rule($rule)

  {

    foreach ( $this->rules as $i => $current_rule )

    {

      if ( $current_rule === $rule )

      {

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

        return null;

      }

    }

    return null;

  }

  /**

   * Disables all rules.

   * @return null

   */

  public function disable_all_rules()

  {

    $this->rules = array();

    return null;

  }

  /**

   * Enables a rule

   * @param string rule

   * @return null

   */

  public function enable_rule($rule)

  {

    $this->rules[] = $rule;

    return null;

  }

  /**

   * Make a rule exclusive (the only one called)

   * @param string stage

   * @return null

   */

  public function exclusive_rule($rule)

  {

    if ( is_string($rule) )

      $this->rules = array($rule);

    return null;

  }

  /**

   * Generate a token

   * @param int Token index

   * @return string

   * @static

   */

  public static function generate_token($i)

  {

    return self::PARSER_TOKEN . $i . self::PARSER_TOKEN;

  }

  /**

   * Tokenize string

   * @param string

   * @param array Matches

   * @return string

   * @static

   */

  public static function tokenize($text, $matches)

  {

    $matches = array_values($matches);

    foreach ( $matches as $i => $match )

    {

      $text = str_replace_once($match, self::generate_token($i), $text);

    }

    return $text;

  }

}