xref.module

<?php
// $Id$

/**
 * Implementation of hook_block().
 */
function xref_block($op = 'list', $delta = 0) {
  switch ($op) {
    case 'list':
      return array(
        'create' => array('info' => t('Crossref: Create referrer')),
        'xref' => array('info' => t('Crossref: Referrers')),
      );
    case 'view':
      switch ($delta) {
        case 'create':
          $node = menu_get_object();
          if ($node && !empty($node->nid)) {
            $xref_links = xref_links($node->type, $node->nid);
            if (!empty($xref_links)) {
              return array('subject' => t('Reference this'), 'content' => theme('links', $xref_links));
            }
          }
          break;
        case 'xref':
          $node = menu_get_object();
          if ($node) {
            $xref_view = xref_view($node->type, $node->nid);
            if (!empty($xref_view)) {
              return array('content' => $xref_view);
            }
          }
          break;
      }
      break;
  }
}

/**
 * Implemenation of hook_nodeapi().
 */
function xref_nodeapi(&$node, $op, $teaser = NULL, $page = NULL) {
  switch ($op) {
    case 'view':
      // Node page
      if ($page && !$teaser) {
        // Xref links
        if (variable_get('xref_links_'. $node->type, 'template') == 'node') {
          $xref_links = xref_links($node->type, $node->nid);
          if (!empty($xref_links)) {
            $links = theme('links', $xref_links);
            $node->content['xref_links'] = array(
              '#weight' => -10, 
              '#value' => theme('xref_links', $links, t('Reference this via')),
            );
          }
        }

        // Xref view
        if (variable_get('xref_view_'. $node->type, true)) {
          $xref_view = xref_view($node->type, $node->nid);
          if (!empty($xref_view)) {
            $node->content['xref_view'] = array('#weight' => 100, '#value' => $xref_view);
          }
        }
      }
      break;
  }
}

/**
 *  Implementation of hook_form_alter.
 *
 *  Adds xref setting to nodetype editing pages.
 */
function xref_form_alter(&$form, $form_state, $form_id) {
  if ($form_id == 'node_type_form' && isset($form['identity']['type'])) {
    $fields = xref_fields($form['#node_type']->type);
    if (!empty($fields)) {
      $types = array();
      foreach ($fields as $k => $v) {
        $types[$v['type_name']] = $v['type_name'];
      }
      $form['xref'] = array(
        '#type' => 'fieldset',
        '#title' => t('Cross reference settings'),
        '#description' => t('This type of content can be referenced by: %type', array('%type' => implode(', ', $types))),
        '#collapsible' => TRUE,
        '#collapsed' => TRUE,
      );
      $form['xref']['xref_links'] = array(
        '#type' => 'select',
        '#title' => t('Display "Reference this via" links'),
        '#options' => array(
          FALSE => '-- '. t('Don\'t display') .' --',
          'template' => t('Provide $xref_links variable in node.tpl.php'),
          'node' => t('Display in node content'),
        ),
        '#default_value' => variable_get('xref_links_'. $form['#node_type']->type, 'template'),
      );
      $form['xref']['xref_view'] = array(
        '#type' => 'checkbox',
        '#title' => t('Display summary of referencing content'),
        '#default_value' => variable_get('xref_view_'. $form['#node_type']->type, true),
      );
    }
  }
}

/**
 * Implementation of hook_theme().
 */
function xref_theme() {
  return array('xref_links' => array());
}

/**
 * Theme xref links.
 */
function theme_xref_links($links, $label) {
  return "<div class='xref clear-block'><div class='label'>$label</div>$links</div>";  
}

/**
 * Preprocessor for theme_node().
 */
function xref_preprocess_node(&$vars) {
  $node = $vars['node'];
  if (variable_get('xref_links_'. $node->type, 'template') == 'template') {
    $links = xref_links($node->type, $node->nid);
    if (!empty($links)) {
      $links = theme('links', $links);
      $vars['xref_links'] = theme('xref_links', $links, t('Reference this'));
    }
  }
}

/**
 * API function.
 */
function xref_fields($nodetype, $reset = FALSE) {
  static $fields;
  if (!isset($fields) || $reset) {
    $fields = array();
  }
  if (!isset($fields[$nodetype])) {
    $fields[$nodetype] = array();
    // Get nodereference fields that may reference this node
    foreach (content_fields() as $field) {
      if ($field['type'] == 'nodereference') {
        foreach ($field['referenceable_types'] as $type) {
          if ($type === $nodetype) {
            $fields[$nodetype][$field['field_name']] = $field;
          }
        }
      }
    }
  }
  return $fields[$nodetype];
}

/**
 * Provides links to create any nodes that could potentially reference this node.
 */
function xref_links($nodetype, $nid) {
  $fields = array_keys(xref_fields($nodetype));
  if ($fields) {
    // Wrap each field in quotes in prep for SQL IN()
    foreach ($fields as $k => $v) {
      $fields[$k] = "'$v'";
    }

    // Build link of nodetypes with instances of all valid referencing fields
    $links = array();

    $node_types = node_get_types();
    $fields = implode(',', $fields);
    $result = db_query("SELECT field_name, type_name FROM {content_node_field_instance} WHERE widget_active = 1 AND field_name IN ($fields)");
    while ($row = db_fetch_object($result)) {
      if (node_access('create', $row->type_name)) {
        $node = node_load($nid);
        $type = $row->type_name;
        $item = menu_get_item('node/add/'. str_replace('_', '-', $type));
        if ($item['access']) {
          $links[$type] = array(
            'title' => t('via @nodetype', array('@nodetype' => $item['title'])),
            'href' => $item['href'],
            'query' => "edit[{$row->field_name}][0][nid][nid]= ". check_plain($node->title) ." [nid: {$nid}]",
          );
        }
      }
    }
    return $links;
  }
  return '';
}

/**
 * Provides a view of any nodes that reference the given node.
 *
 * @param $nodetype
 *  the node type of the content to detect references to.
 *
 * @param $nid
 *  the nid of the content to detect references to.
 *
 * @param $fieldname
 *   Optional. The id of the particular field to be used to build the view. If
 *   omitted the first field returned by xref_fields() will be used.
 *
 * @param $viewname
 *   Optional.
 */
function xref_view($nodetype, $nid, $fieldname = null, $viewname = null) {
  $output = '';
  $fields = xref_fields($nodetype);

  if (empty($fields)) {
    return '';
  }

  if (!empty($fieldname)) {
    $field = $fields[$fieldname];
  }
  else {
    $field = array_shift($fields);
  }

  if (empty($viewname)) {
    $viewname = 'xref';
  }

  // Xref nodes
  if ($view = views_get_view($viewname)) {
    $field_info = content_database_info($field);
    module_load_include('inc', 'content', 'includes/views/content.views');

    $view->set_display();
    $handler = $view->display['default']->handler;
    $handler->override_option('arguments', array(
      $field['field_name'] => array(
        'default_action' => 'not found',
        'style_plugin' => 'default_summary',
        'style_options' => array(),
        'wildcard' => 'all',
        'wildcard_substitution' => 'All',
        'title' => '',
        'default_argument_type' => 'php',
        'default_argument' => '',
        'validate_type' => 'none',
        'validate_fail' => 'not found',
        'break_phrase' => 0,
        'not' => 0,
        'id' => $field['field_name'] .'_nid',
        'table' => content_views_tablename($field),
        'field' => $field['field_name'] .'_nid',
        'relationship' => 'none',
        'default_options_div_prefix' => '',
        'default_argument_user' => 0,
        'default_argument_fixed' => '',
        'default_argument_php' => '',
        'validate_argument_node_type' => array(),
        'validate_argument_node_access' => 0,
        'validate_argument_nid_type' => 'nid',
        'validate_argument_vocabulary' => array(),
        'validate_argument_type' => 'tid',
        'validate_argument_is_member' => 0,
        'validate_argument_php' => '',
      ),
    ));
    $view->pre_execute(array($nid));
    $view->execute();
    if (count($view->result)) {
      $output = $view->render();
    }
  }
  return $output;
}

/**
 * Implementation of hook_views_api().
 */
function xref_views_api() {
  return array('api' => 2);
}