link_node.module

<?php
// $Id: link_node.module,v 1.2.2.6 2010/05/28 23:55:08 tomchiverton Exp $

/*
@file Allows users to link a node to another node.

Copyright (c) 2004 Mark Howell
Copyright (c) 2007 Tom Chiverton

This program is free software; you can redistribute it 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 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 more details.

You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.

*/

/**
 * Hook which handles filtering.
 */
function link_node_filter($op, $delta = 0, $format = -1, $text = '') {
  //drupal_set_message("attached_node_filter invoked with \$op=$op");
  switch ($op) {
    case 'list':
      return array(t("Link Node Filter"));
    case 'name':
      return t("Link Node Filter");
    case 'description':
      return t("Allows you to create meta tags that link to other nodes.");
    case 'settings':
      return link_node_filter_settings();
    case 'process':
      return link_node_filter_process($text);
    default:
      return $text;
  }
}

/**
 * Function used to discover what filters are supplied by this module.
 */
function link_node_filter_settings() {
  $form['filter_link_node'] = array(
    '#type' => 'fieldset',
    '#title' => t("Link Node codes"),
    '#collapsible' => TRUE,
    '#collapsed' => FALSE
  );
  $form['filter_link_node']['link_node'] = array(
    '#type' => 'item',
    '#title' => t('Instructions'),
    '#value' => t('This filter translates special node tags into links to other nodes. 
      Syntax: [node:node_id,title="val2"]; every param but node_id is optional.
      Each list below should be a comma separated list (no spaces) of what node properties users are
      allowed to override for the purposes of displaying a node.  E.g. <em>title,border</em>')
  );
  foreach (node_get_types() as $type => $name) {
    $form['filter_link_node']["link_node_allowed_vars_$type"] = array(
      '#type' => 'textfield',
      '#title' => t("Allowed parameters for %type nodes", array('%type' => $type)),
      '#default_value' => variable_get("link_node_allowed_vars_$type", ""),
      '#size' => 40,
      '#maxlength' => 256
    );
  }
  return $form;
}

/**
 * Actually execute filter on given text.
 *  Parse text for all meta tags.
 *  Lookup each specified node.
 *  Parse all parameters specified in each meta tag and apply them to the corresponding node.
 *  Replace meta tag with themed thumbnail view of the referrent node.
 */
function link_node_filter_process($text, $show_error_msgs=1) {
  if (variable_get("link_node_enabled", 1)) {
    // *** [node:NID,a="b",c="d",width="40",etc="foo"] ***
    // first we find every tag
    $meta_tag_regexp = '/\[node:(\d+)([^\]]*)\]/i';

    if (preg_match_all($meta_tag_regexp, $text, $match)) {
      // then we make the html
      foreach ($match[1] as $key => $nid) {
        if (module_exists('i18n') && module_exists('translation')) {
	  $lang = i18n_get_lang();
          $transnids = translation_node_get_translations($nid);
          if ($transnids[$lang]) {
            $nid = $transnids[$lang]->nid;
          }
        }

        $node = node_load(array("nid" => $nid));
        if ($node) {
          // check here to see if user has permissions to access this node
          if (!node_access("view", $node)) {
            $matches_html[$key] = t('You do not have access to view this node');
            continue;
          }

          $meta_tag_params_regexp = '/,\s*([\w_-]+)\s*=\s*"([^"]+)"\s*/';
          $meta_tag_params_regexp2 = '/,\s*([\w_-]+)\s*=\s*&quot;([^,]+)&quot;\s*/';

          if ( preg_match_all($meta_tag_params_regexp, $match[2][$key], $parm_match) == 0 ) {
            $meta_tag_params_regexp=$meta_tag_params_regexp2 ;
          }
          
          if (preg_match_all($meta_tag_params_regexp, $match[2][$key], $parm_match)) {
            $allowed_vars = explode(',', variable_get("link_node_allowed_vars_$node->type", ""));
            for ($i=0; $i<count($parm_match[1]); $i++) {  
              //$parm_match[1] contains the param names, $parm_match[2] contains values
              $parm = $parm_match[1][$i];
              $val = $parm_match[2][$i];
              
              // check the name ($parm) to make sure it's an allowable value (like "align" or "border" or something)
              if (in_array($parm, $allowed_vars)) {
                $node->$parm = $val;
              }
              else {
                if ($show_error_msgs) {
                  drupal_set_message("ignoring param '$parm' for ". $node->type ." as it is not valid.  Possible values are '<code>". variable_get("link_node_allowed_vars_$node->type", "") ."</code>'.");
                }
              }
            }      
          }

          #$matches_html[$key] = theme("link_node_thumbnail", $node);
	  # issue 772894 workaround for broken PHP5.3 ?
	  $matches_html[$key] = theme_link_node_thumbnail($node);
        }
        else {
          if ($show_error_msgs) {
            $matches_html[$key] = theme("link_node_format", t("Nonexistent node nid: ") ."$nid.");
          }
          else {
            $matches_html[$key] = "";
          }
        }
      }
      
      // PHP (4.3.2) str_replace appears to use some internal order
      // rather than array index when finding replace elements
      // corresponding to search elements.  To make sure that the
      // order of the arrays correspond, we make new copies here.
      foreach ($match[1] as $key => $value) {
        $mtch[] = $match[0][$key];
        $repl[] = $matches_html[$key];
      }
      $text = str_replace($mtch, $repl, $text);
    }
  }
  return $text;
}

/**
 * Generates a thumbnail view of a node.
 */
function theme_link_node_thumbnail(&$node) {

  $main = TRUE;
  
  if ($node->type == "image") {
    
    // offer theme developers and module developers to override this
    if (function_exists("image_link_node_thumbnail")) {
      return image_link_node_thumbnail($node);
    }
  }
  
  $output = l($node->title, drupal_get_path_alias('node/'. $node->nid), array('absolute' => TRUE) );
 
  return $output;
}

/**
 * Puts a box around the attached_node's content
 */
function theme_link_node_format($content) {
  return '<div class="link_node">'. $content ."</div>\n";
}

/**
 * Clears the filter cache when any node is updated
 */
function link_node_nodeapi(&$node, $op) {
  if ($op == "update") {
    // since this is a node-specific filter, clear the cache when nodes are updated
    cache_clear_all('*', 'cache_filter',TRUE);
  }
}

/**
 * Generates help text for this module
 */
function link_node_help($path, $arg) {
  $output = "";

  switch ($path) {
    case 'admin/help#link_node':
      $output = t('<p><strong>Nodes That Link To Other Nodes</strong></p>
      <p>
      You can link nodes to other nodes using the following syntax:<br>
      [node:<em>node_id</em>,title="val1"]<br><br>
      </p>
      <p>
      Some examples:<br>
      [node:123]<br>
      [node:123,title="original"]<br>
      </p><p>Currently available parameters:<table border="1">');
      foreach (node_get_types() as $type => $name) {
        $output .= "<tr><td>". t("Allowed parameters for <strong>$type</strong> nodes: ") ."</td><td>". variable_get("link_node_allowed_vars_$type", "") ."</td></tr>\n";
      }
      $output .= t('</table></p><p>
      Site admin: If there are properties of a node that you want to allow your users to modify when referring to them,
      you can specify those in the filter configuration.
      </p>');
      break;
  }
  return $output;
}

/**
 * Implementation of hook_filter_tips().
 */
function link_node_filter_tips($delta, $format, $long = FALSE) {
  if ($long) {
    $txt = t('<strong>Linking Nodes To Other Nodes</strong>
      <p>
      You can link nodes to other nodes using the following syntax:<br>
      [node:<em>node_id</em>,title="val2"]<br><br>
      </p>
      <p>
      Some examples:<br>
      [node:123]<br>
      [node:123,title="original"]<br>
      </p><p>Currently available parameters:<table border="1">');
    foreach (node_get_types() as $type => $name) {
      $txt .= "<tr><td>". t("Allowed parameters for <strong>$type</strong> nodes: ") ."</td><td>". variable_get("link_node_allowed_vars_$type", "") ."</td></tr>\n";
    }

    $txt .= t('</table></p><p>
      Site admin: If there are properties of a node that you want to allow your users to modify when referring to them,
      you can specify those in the filter configuration.
      
      </p>');
    return $txt;
  }
  else {
    return t('You can link nodes to other nodes using the following syntax:<br>
    [node:<em>node_id</em>,title="val2"]');
  }
}

/**
 * Implementation of hook_theme().
 */
function link_node_theme() {
  return array(
    'link_node_thumbnail' => array(
      'arguments' => array('node' => NULL),
    ),
    'link_node_format' => array(
      'arguments' => array('content' => NULL),
    ),
  );
}