drupal/modules/taxonomy/taxonomy.module

<?php
// $Id$

/**
 * @file
 * Enables the organization of content into categories.
 */

/**
 * Implementation of hook_perm().
 */
function taxonomy_perm() {
  return array('administer taxonomy');
}

/**
 * Implementation of hook_theme()
 */
function taxonomy_theme() {
  return array(
    'taxonomy_term_select' => array(
      'arguments' => array('element' => NULL),
    ),
    'taxonomy_term_page' => array(
      'arguments' => array('tids' => array(), 'result' => NULL),
    ),
  );
}

/**
 * Implementation of hook_link().
 *
 * This hook is extended with $type = 'taxonomy terms' to allow themes to
 * print lists of terms associated with a node. Themes can print taxonomy
 * links with:
 *
 * if (module_exists('taxonomy')) {
 *   $terms = taxonomy_link('taxonomy terms', $node);
 *   print theme('links', $terms);
 * }
 */
function taxonomy_link($type, $node = NULL) {
  if ($type == 'taxonomy terms' && $node != NULL) {
    $links = array();
    // If previewing, the terms must be converted to objects first.
    if ($node->build_mode == NODE_BUILD_PREVIEW) {
      $node->taxonomy = taxonomy_preview_terms($node);
    }
    if (!empty($node->taxonomy)) {
      foreach ($node->taxonomy as $term) {
        // During preview the free tagging terms are in an array unlike the
        // other terms which are objects. So we have to check if a $term 
        // is an object or not.
        if (is_object($term)) {
          $links['taxonomy_term_'. $term->tid] = array(
            'title' => $term->name,
            'href' => taxonomy_term_path($term),
            'attributes' => array('rel' => 'tag', 'title' => strip_tags($term->description))
          );
        }
        // Previewing free tagging terms; we don't link them because the
        // term-page might not exist yet.
        else {
          foreach ($term as $free_typed) {
            $typed_terms = drupal_explode_tags($free_typed);
            foreach($typed_terms as $typed_term) {
              $links['taxonomy_preview_term_'. $typed_term] = array(
                'title' => $typed_term,
              );           
            }
          }
        }
      }
    }

    // We call this hook again because some modules and themes
    // call taxonomy_link('taxonomy terms') directly.
    drupal_alter('link', $links, $node);

    return $links;
  }
}

/**
 * For vocabularies not maintained by taxonomy.module, give the maintaining
 * module a chance to provide a path for terms in that vocabulary.
 *
 * @param $term
 *   A term object.
 * @return
 *   An internal Drupal path.
 */

function taxonomy_term_path($term) {
  $vocabulary = taxonomy_vocabulary_load($term->vid);
  if ($vocabulary->module != 'taxonomy' && $path = module_invoke($vocabulary->module, 'term_path', $term)) {
    return $path;
  }
  return 'taxonomy/term/'. $term->tid;
}

/**
 * Implementation of hook_menu().
 */
function taxonomy_menu() {
  $items['admin/content/taxonomy'] = array(
    'title' => 'Categories',
    'description' => 'Create vocabularies and terms to categorize your content.',
    'page callback' => 'taxonomy_overview_vocabularies',
    'access arguments' => array('administer taxonomy'),
    'file' => 'taxonomy.admin.inc',
  );

  $items['admin/content/taxonomy/list'] = array(
    'title' => 'List',
    'type' => MENU_DEFAULT_LOCAL_TASK,
    'weight' => -10,
  );

  $items['admin/content/taxonomy/add/vocabulary'] = array(
    'title' => 'Add vocabulary',
    'page callback' => 'drupal_get_form',
    'page arguments' => array('taxonomy_form_vocabulary'),
    'type' => MENU_LOCAL_TASK,
    'parent' => 'admin/content/taxonomy',
    'file' => 'taxonomy.admin.inc',
  );

  $items['admin/content/taxonomy/edit/vocabulary/%taxonomy_vocabulary'] = array(
    'title' => 'Edit vocabulary',
    'page callback' => 'taxonomy_admin_vocabulary_edit',
    'page arguments' => array(5),
    'type' => MENU_CALLBACK,
    'file' => 'taxonomy.admin.inc',
  );

  $items['admin/content/taxonomy/edit/term'] = array(
    'title' => 'Edit term',
    'page callback' => 'taxonomy_admin_term_edit',
    'type' => MENU_CALLBACK,
    'file' => 'taxonomy.admin.inc',
  );

  $items['taxonomy/term'] = array(
    'title' => 'Taxonomy term',
    'page callback' => 'taxonomy_term_page',
    'access arguments' => array('access content'),
    'type' => MENU_CALLBACK,
    'file' => 'taxonomy.pages.inc',
  );

  $items['taxonomy/autocomplete'] = array(
    'title' => 'Autocomplete taxonomy',
    'page callback' => 'taxonomy_autocomplete',
    'access arguments' => array('access content'),
    'type' => MENU_CALLBACK,
    'file' => 'taxonomy.pages.inc',
  );
  $items['admin/content/taxonomy/%taxonomy_vocabulary'] = array(
    'title' => 'List terms',
    'page callback' => 'taxonomy_overview_terms',
    'page arguments' => array(3),
    'access arguments' => array('administer taxonomy'),
    'type' => MENU_CALLBACK,
    'file' => 'taxonomy.admin.inc',
  );

  $items['admin/content/taxonomy/%taxonomy_vocabulary/list'] = array(
    'title' => 'List',
    'type' => MENU_DEFAULT_LOCAL_TASK,
    'weight' => -10,
  );

  $items['admin/content/taxonomy/%taxonomy_vocabulary/add/term'] = array(
    'title' => 'Add term',
    'page callback' => 'taxonomy_add_term_page',
    'page arguments' => array(3),
    'type' => MENU_LOCAL_TASK,
    'parent' => 'admin/content/taxonomy/%taxonomy_vocabulary',
    'file' => 'taxonomy.admin.inc',
  );

  return $items;
}

function taxonomy_save_vocabulary(&$edit) {
  $edit['nodes'] = empty($edit['nodes']) ? array() : $edit['nodes'];

  if (!isset($edit['module'])) {
    $edit['module'] = 'taxonomy';
  }

  if (!empty($edit['vid']) && !empty($edit['name'])) {
    drupal_write_record('vocabulary', $edit, 'vid');
    db_query("DELETE FROM {vocabulary_node_types} WHERE vid = %d", $edit['vid']);
    foreach ($edit['nodes'] as $type => $selected) {
      db_query("INSERT INTO {vocabulary_node_types} (vid, type) VALUES (%d, '%s')", $edit['vid'], $type);
    }
    module_invoke_all('taxonomy', 'update', 'vocabulary', $edit);
    $status = SAVED_UPDATED;
  }
  else if (!empty($edit['vid'])) {
    $status = taxonomy_del_vocabulary($edit['vid']);
  }
  else {
    drupal_write_record('vocabulary', $edit);
    foreach ($edit['nodes'] as $type => $selected) {
      db_query("INSERT INTO {vocabulary_node_types} (vid, type) VALUES (%d, '%s')", $edit['vid'], $type);
    }
    module_invoke_all('taxonomy', 'insert', 'vocabulary', $edit);
    $status = SAVED_NEW;
  }

  cache_clear_all();

  return $status;
}

/**
 * Delete a vocabulary.
 *
 * @param $vid
 *   A vocabulary ID.
 * @return
 *   Constant indicating items were deleted.
 */
function taxonomy_del_vocabulary($vid) {
  $vocabulary = (array) taxonomy_vocabulary_load($vid);

  db_query('DELETE FROM {vocabulary} WHERE vid = %d', $vid);
  db_query('DELETE FROM {vocabulary_node_types} WHERE vid = %d', $vid);
  $result = db_query('SELECT tid FROM {term_data} WHERE vid = %d', $vid);
  while ($term = db_fetch_object($result)) {
    taxonomy_del_term($term->tid);
  }

  module_invoke_all('taxonomy', 'delete', 'vocabulary', $vocabulary);

  cache_clear_all();

  return SAVED_DELETED;
}

/**
 * Helper function for taxonomy_form_term_submit().
 *
 * @param $form_state['values']
 * @return
 *   Status constant indicating if term was inserted or updated.
 */
function taxonomy_save_term(&$form_values) {
  $form_values += array(
    'description' => '',
    'weight' => 0
  );

  if (!empty($form_values['tid']) && $form_values['name']) {
    drupal_write_record('term_data', $form_values, 'tid');
    $hook = 'update';
    $status = SAVED_UPDATED;
  }
  else if (!empty($form_values['tid'])) {
    return taxonomy_del_term($form_values['tid']);
  }
  else {
    drupal_write_record('term_data', $form_values);
    $hook = 'insert';
    $status = SAVED_NEW;
  }

  db_query('DELETE FROM {term_relation} WHERE tid1 = %d OR tid2 = %d', $form_values['tid'], $form_values['tid']);
  if (!empty($form_values['relations'])) {
    foreach ($form_values['relations'] as $related_id) {
      if ($related_id != 0) {
        db_query('INSERT INTO {term_relation} (tid1, tid2) VALUES (%d, %d)', $form_values['tid'], $related_id);
      }
    }
  }

  db_query('DELETE FROM {term_hierarchy} WHERE tid = %d', $form_values['tid']);
  if (!isset($form_values['parent']) || empty($form_values['parent'])) {
    $form_values['parent'] = array(0);
  }
  if (is_array($form_values['parent'])) {
    foreach ($form_values['parent'] as $parent) {
      if (is_array($parent)) {
        foreach ($parent as $tid) {
          db_query('INSERT INTO {term_hierarchy} (tid, parent) VALUES (%d, %d)', $form_values['tid'], $tid);
        }
      }
      else {
        db_query('INSERT INTO {term_hierarchy} (tid, parent) VALUES (%d, %d)', $form_values['tid'], $parent);
      }
    }
  }
  else {
    db_query('INSERT INTO {term_hierarchy} (tid, parent) VALUES (%d, %d)', $form_values['tid'], $form_values['parent']);
  }

  db_query('DELETE FROM {term_synonym} WHERE tid = %d', $form_values['tid']);
  if (!empty($form_values['synonyms'])) {
    foreach (explode ("\n", str_replace("\r", '', $form_values['synonyms'])) as $synonym) {
      if ($synonym) {
        db_query("INSERT INTO {term_synonym} (tid, name) VALUES (%d, '%s')", $form_values['tid'], chop($synonym));
      }
    }
  }

  if (isset($hook)) {
    module_invoke_all('taxonomy', $hook, 'term', $form_values);
  }

  cache_clear_all();

  return $status;
}

/**
 * Delete a term.
 *
 * @param $tid
 *   The term ID.
 * @return
 *   Status constant indicating deletion.
 */
function taxonomy_del_term($tid) {
  $tids = array($tid);
  while ($tids) {
    $children_tids = $orphans = array();
    foreach ($tids as $tid) {
      // See if any of the term's children are about to be become orphans:
      if ($children = taxonomy_get_children($tid)) {
        foreach ($children as $child) {
          // If the term has multiple parents, we don't delete it.
          $parents = taxonomy_get_parents($child->tid);
          if (count($parents) == 1) {
            $orphans[] = $child->tid;
          }
        }
      }

      $term = (array) taxonomy_get_term($tid);

      db_query('DELETE FROM {term_data} WHERE tid = %d', $tid);
      db_query('DELETE FROM {term_hierarchy} WHERE tid = %d', $tid);
      db_query('DELETE FROM {term_relation} WHERE tid1 = %d OR tid2 = %d', $tid, $tid);
      db_query('DELETE FROM {term_synonym} WHERE tid = %d', $tid);
      db_query('DELETE FROM {term_node} WHERE tid = %d', $tid);

      module_invoke_all('taxonomy', 'delete', 'term', $term);
    }

    $tids = $orphans;
  }

  cache_clear_all();

  return SAVED_DELETED;
}

/**
 * Generate a form element for selecting terms from a vocabulary.
 */
function taxonomy_form($vid, $value = 0, $help = NULL, $name = 'taxonomy') {
  $vocabulary = taxonomy_vocabulary_load($vid);
  $help = ($help) ? $help : $vocabulary->help;
  $blank = 0;

  if (!$vocabulary->multiple) {
    $blank = ($vocabulary->required) ? t('- Please choose -') : t('- None selected -');
  }

  return _taxonomy_term_select(check_plain($vocabulary->name), $name, $value, $vid, $help, intval($vocabulary->multiple), $blank);
}

/**
 * Generate a set of options for selecting a term from all vocabularies.
 */
function taxonomy_form_all($free_tags = 0) {
  $vocabularies = taxonomy_get_vocabularies();
  $options = array();
  foreach ($vocabularies as $vid => $vocabulary) {
    if ($vocabulary->tags && !$free_tags) { continue; }
    $tree = taxonomy_get_tree($vid);
    if ($tree && (count($tree) > 0)) {
      $options[$vocabulary->name] = array();
      foreach ($tree as $term) {
        $options[$vocabulary->name][$term->tid] = str_repeat('-', $term->depth) . $term->name;
      }
    }
  }
  return $options;
}

/**
 * Return an array of all vocabulary objects.
 *
 * @param $type
 *   If set, return only those vocabularies associated with this node type.
 */
function taxonomy_get_vocabularies($type = NULL) {
  if ($type) {
    $result = db_query(db_rewrite_sql("SELECT v.vid, v.*, n.type FROM {vocabulary} v LEFT JOIN {vocabulary_node_types} n ON v.vid = n.vid WHERE n.type = '%s' ORDER BY v.weight, v.name", 'v', 'vid'), $type);
  }
  else {
    $result = db_query(db_rewrite_sql('SELECT v.*, n.type FROM {vocabulary} v LEFT JOIN {vocabulary_node_types} n ON v.vid = n.vid ORDER BY v.weight, v.name', 'v', 'vid'));
  }

  $vocabularies = array();
  $node_types = array();
  while ($voc = db_fetch_object($result)) {
    // If no node types are associated with a vocabulary, the LEFT JOIN will
    // return a NULL value for type.
    if (isset($voc->type)) {
      $node_types[$voc->vid][] = $voc->type;
      unset($voc->type);
      $voc->nodes = $node_types[$voc->vid];
    }
    elseif (!isset($voc->nodes)) {
      $voc->nodes = array();
    }
    $vocabularies[$voc->vid] = $voc;
  }

  return $vocabularies;
}

/**
 * Implementation of hook_form_alter().
 * Generate a form for selecting terms to associate with a node.
 */
function taxonomy_form_alter(&$form, $form_state, $form_id) {
  if (isset($form['type']) && isset($form['#node']) && $form['type']['#value'] .'_node_form' == $form_id) {
    $node = $form['#node'];

    if (!isset($node->taxonomy)) {
      $terms = empty($node->nid) ? array() : taxonomy_node_get_terms($node);
    }
    else {
      // After preview the terms must be converted to objects.
      if (isset($form_state['node_preview'])) {
        $node->taxonomy = taxonomy_preview_terms($node);
      }
      $terms = $node->taxonomy;
    }

    $c = db_query(db_rewrite_sql("SELECT v.* FROM {vocabulary} v INNER JOIN {vocabulary_node_types} n ON v.vid = n.vid WHERE n.type = '%s' ORDER BY v.weight, v.name", 'v', 'vid'), $node->type);

    while ($vocabulary = db_fetch_object($c)) {
      if ($vocabulary->tags) {
        if (isset($form_state['node_preview'])) {
          // Typed string can be changed by the user before preview, 
          // so we just insert the tags directly as provided in the form.
          $typed_string = $node->taxonomy['tags'][$vocabulary->vid];
        }
        else {
          $typed_string = taxonomy_implode_tags($terms, $vocabulary->vid) . (array_key_exists('tags', $terms) ? $terms['tags'][$vocabulary->vid] : NULL);
        }
        if ($vocabulary->help) {
          $help = $vocabulary->help;
        }
        else {
          $help = t('A comma-separated list of terms describing this content. Example: funny, bungee jumping, "Company, Inc.".');
        }
        $form['taxonomy']['tags'][$vocabulary->vid] = array('#type' => 'textfield',
          '#title' => $vocabulary->name,
          '#description' => $help,
          '#required' => $vocabulary->required,
          '#default_value' => $typed_string,
          '#autocomplete_path' => 'taxonomy/autocomplete/'. $vocabulary->vid,
          '#weight' => $vocabulary->weight,
          '#maxlength' => 255,
        );
      }
      else {
        // Extract terms belonging to the vocabulary in question.
        $default_terms = array();
        foreach ($terms as $term) {     
          // Free tagging has no default terms and also no vid after preview.
          if (isset($term->vid) && $term->vid == $vocabulary->vid) {
            $default_terms[$term->tid] = $term;
          }
        }
        $form['taxonomy'][$vocabulary->vid] = taxonomy_form($vocabulary->vid, array_keys($default_terms), $vocabulary->help);
        $form['taxonomy'][$vocabulary->vid]['#weight'] = $vocabulary->weight;
        $form['taxonomy'][$vocabulary->vid]['#required'] = $vocabulary->required;
      }
    }
    if (!empty($form['taxonomy']) && is_array($form['taxonomy'])) {
      if (count($form['taxonomy']) > 1) { 
        // Add fieldset only if form has more than 1 element.
        $form['taxonomy'] += array(
          '#type' => 'fieldset',
          '#title' => t('Categories'),
          '#collapsible' => TRUE,
          '#collapsed' => FALSE,
        );
      }
      $form['taxonomy']['#weight'] = -3;
      $form['taxonomy']['#tree'] = TRUE;
    }  
  }
}

/**
 * Helper function to covert terms after a preview.
 *
 * After preview the tags are an array instead of proper objects. This function
 * converts them back to objects with the exception of 'free tagging' terms,
 * because new tags can be added by the user before preview and those do not 
 * yet exist in the database. We therefore save those tags as a string so 
 * we can fill the form again after the preview.
 */
function taxonomy_preview_terms($node) {
  $taxonomy = array();
  foreach ($node->taxonomy as $key => $term) {
    unset($node->taxonomy[$key]);
    // A 'Multiple select' and a 'Free tagging' field returns an array.
    if (is_array($term)) {
      foreach ($term as $tid) {
        if ($key == 'tags') {
          // Free tagging; the values will be saved for later as strings 
	  // instead of objects to fill the form again.
          $taxonomy['tags'] = $term;
        }
        else {
          $taxonomy[$tid] = taxonomy_get_term($tid);
        }
      }
    }
    // A 'Single select' field returns the term id.
    elseif ($term) {
      $taxonomy[$term] = taxonomy_get_term($term);
    }
  }
  return $taxonomy;
}

/**
 * Find all terms associated with the given node, within one vocabulary.
 */
function taxonomy_node_get_terms_by_vocabulary($node, $vid, $key = 'tid') {
  $result = db_query(db_rewrite_sql('SELECT t.tid, t.* FROM {term_data} t INNER JOIN {term_node} r ON r.tid = t.tid WHERE t.vid = %d AND r.vid = %d ORDER BY weight', 't', 'tid'), $vid, $node->vid);
  $terms = array();
  while ($term = db_fetch_object($result)) {
    $terms[$term->$key] = $term;
  }
  return $terms;
}

/**
 * Find all terms associated with the given node, ordered by vocabulary and term weight.
 */
function taxonomy_node_get_terms($node, $key = 'tid') {
  static $terms;

  if (!isset($terms[$node->vid][$key])) {
    $result = db_query(db_rewrite_sql('SELECT t.* FROM {term_node} r INNER JOIN {term_data} t ON r.tid = t.tid INNER JOIN {vocabulary} v ON t.vid = v.vid WHERE r.vid = %d ORDER BY v.weight, t.weight, t.name', 't', 'tid'), $node->vid);
    $terms[$node->vid][$key] = array();
    while ($term = db_fetch_object($result)) {
      $terms[$node->vid][$key][$term->$key] = $term;
    }
  }
  return $terms[$node->vid][$key];
}

/**
 * Make sure incoming vids are free tagging enabled.
 */
function taxonomy_node_validate(&$node) {
  if (!empty($node->taxonomy)) {
    $terms = $node->taxonomy;
    if (!empty($terms['tags'])) {
      foreach ($terms['tags'] as $vid => $vid_value) {
        $vocabulary = taxonomy_vocabulary_load($vid);
        if (empty($vocabulary->tags)) {
          // see form_get_error $key = implode('][', $element['#parents']);
          // on why this is the key
          form_set_error("taxonomy][tags][$vid", t('The %name vocabulary can not be modified in this way.', array('%name' => $vocabulary->name)));
        }
      }
    }
  }
}

/**
 * Save term associations for a given node.
 */
function taxonomy_node_save($node, $terms) {

  taxonomy_node_delete_revision($node);

  // Free tagging vocabularies do not send their tids in the form,
  // so we'll detect them here and process them independently.
  if (isset($terms['tags'])) {
    $typed_input = $terms['tags'];
    unset($terms['tags']);

    foreach ($typed_input as $vid => $vid_value) {
      $typed_terms = drupal_explode_tags($vid_value);

      $inserted = array();
      foreach ($typed_terms as $typed_term) {
        // See if the term exists in the chosen vocabulary
        // and return the tid; otherwise, add a new record.
        $possibilities = taxonomy_get_term_by_name($typed_term);
        $typed_term_tid = NULL; // tid match, if any.
        foreach ($possibilities as $possibility) {
          if ($possibility->vid == $vid) {
            $typed_term_tid = $possibility->tid;
          }
        }

        if (!$typed_term_tid) {
          $edit = array('vid' => $vid, 'name' => $typed_term);
          $status = taxonomy_save_term($edit);
          $typed_term_tid = $edit['tid'];
        }

        // Defend against duplicate, differently cased tags
        if (!isset($inserted[$typed_term_tid])) {
          db_query('INSERT INTO {term_node} (nid, vid, tid) VALUES (%d, %d, %d)', $node->nid, $node->vid, $typed_term_tid);
          $inserted[$typed_term_tid] = TRUE;
        }
      }
    }
  }

  if (is_array($terms)) {
    foreach ($terms as $term) {
      if (is_array($term)) {
        foreach ($term as $tid) {
          if ($tid) {
            db_query('INSERT INTO {term_node} (nid, vid, tid) VALUES (%d, %d, %d)', $node->nid, $node->vid, $tid);
          }
        }
      }
      else if (is_object($term)) {
        db_query('INSERT INTO {term_node} (nid, vid, tid) VALUES (%d, %d, %d)', $node->nid, $node->vid, $term->tid);
      }
      else if ($term) {
        db_query('INSERT INTO {term_node} (nid, vid, tid) VALUES (%d, %d, %d)', $node->nid, $node->vid, $term);
      }
    }
  }
}

/**
 * Remove associations of a node to its terms.
 */
function taxonomy_node_delete($node) {
  db_query('DELETE FROM {term_node} WHERE nid = %d', $node->nid);
}

/**
 * Remove associations of a node to its terms.
 */
function taxonomy_node_delete_revision($node) {
  db_query('DELETE FROM {term_node} WHERE vid = %d', $node->vid);
}

/**
 * Implementation of hook_node_type().
 */
function taxonomy_node_type($op, $info) {
  if ($op == 'update' && !empty($info->old_type) && $info->type != $info->old_type) {
    db_query("UPDATE {vocabulary_node_types} SET type = '%s' WHERE type = '%s'", $info->type, $info->old_type);
  }
  elseif ($op == 'delete') {
    db_query("DELETE FROM {vocabulary_node_types} WHERE type = '%s'", $info->type);
  }
}

/**
 * Find all term objects related to a given term ID.
 */
function taxonomy_get_related($tid, $key = 'tid') {
  if ($tid) {
    $result = db_query('SELECT t.*, tid1, tid2 FROM {term_relation}, {term_data} t WHERE (t.tid = tid1 OR t.tid = tid2) AND (tid1 = %d OR tid2 = %d) AND t.tid != %d ORDER BY weight, name', $tid, $tid, $tid);
    $related = array();
    while ($term = db_fetch_object($result)) {
      $related[$term->$key] = $term;
    }
    return $related;
  }
  else {
    return array();
  }
}

/**
 * Find all parents of a given term ID.
 */
function taxonomy_get_parents($tid, $key = 'tid') {
  if ($tid) {
    $result = db_query(db_rewrite_sql('SELECT t.tid, t.* FROM {term_data} t INNER JOIN {term_hierarchy} h ON h.parent = t.tid WHERE h.tid = %d ORDER BY weight, name', 't', 'tid'), $tid);
    $parents = array();
    while ($parent = db_fetch_object($result)) {
      $parents[$parent->$key] = $parent;
    }
    return $parents;
  }
  else {
    return array();
  }
}

/**
 * Find all ancestors of a given term ID.
 */
function taxonomy_get_parents_all($tid) {
  $parents = array();
  if ($tid) {
    $parents[] = taxonomy_get_term($tid);
    $n = 0;
    while ($parent = taxonomy_get_parents($parents[$n]->tid)) {
      $parents = array_merge($parents, $parent);
      $n++;
    }
  }
  return $parents;
}

/**
 * Find all children of a term ID.
 */
function taxonomy_get_children($tid, $vid = 0, $key = 'tid') {
  if ($vid) {
    $result = db_query(db_rewrite_sql('SELECT t.* FROM {term_data} t INNER JOIN {term_hierarchy} h ON h.tid = t.tid WHERE t.vid = %d AND h.parent = %d ORDER BY weight, name', 't', 'tid'), $vid, $tid);
  }
  else {
    $result = db_query(db_rewrite_sql('SELECT t.* FROM {term_data} t INNER JOIN {term_hierarchy} h ON h.tid = t.tid WHERE parent = %d ORDER BY weight, name', 't', 'tid'), $tid);
  }
  $children = array();
  while ($term = db_fetch_object($result)) {
    $children[$term->$key] = $term;
  }
  return $children;
}

/**
 * Create a hierarchical representation of a vocabulary.
 *
 * @param $vid
 *   Which vocabulary to generate the tree for.
 *
 * @param $parent
 *   The term ID under which to generate the tree. If 0, generate the tree
 *   for the entire vocabulary.
 *
 * @param $depth
 *   Internal use only.
 *
 * @param $max_depth
 *   The number of levels of the tree to return. Leave NULL to return all levels.
 *
 * @return
 *   An array of all term objects in the tree. Each term object is extended
 *   to have "depth" and "parents" attributes in addition to its normal ones.
 *   Results are statically cached.
 */
function taxonomy_get_tree($vid, $parent = 0, $depth = -1, $max_depth = NULL) {
  static $children, $parents, $terms;

  $depth++;

  // We cache trees, so it's not CPU-intensive to call get_tree() on a term
  // and its children, too.
  if (!isset($children[$vid])) {
    $children[$vid] = array();

    $result = db_query(db_rewrite_sql('SELECT t.tid, t.*, parent FROM {term_data} t INNER JOIN  {term_hierarchy} h ON t.tid = h.tid WHERE t.vid = %d ORDER BY weight, name', 't', 'tid'), $vid);
    while ($term = db_fetch_object($result)) {
      $children[$vid][$term->parent][] = $term->tid;
      $parents[$vid][$term->tid][] = $term->parent;
      $terms[$vid][$term->tid] = $term;
    }
  }

  $max_depth = (is_null($max_depth)) ? count($children[$vid]) : $max_depth;
  $tree = array();
  if (!empty($children[$vid][$parent])) {
    foreach ($children[$vid][$parent] as $child) {
      if ($max_depth > $depth) {
        $term = drupal_clone($terms[$vid][$child]);
        $term->depth = $depth;
        // The "parent" attribute is not useful, as it would show one parent only.
        unset($term->parent);
        $term->parents = $parents[$vid][$child];
        $tree[] = $term;

        if (!empty($children[$vid][$child])) {
          $tree = array_merge($tree, taxonomy_get_tree($vid, $child, $depth, $max_depth));
        }
      }
    }
  }

  return $tree;
}

/**
 * Return an array of synonyms of the given term ID.
 */
function taxonomy_get_synonyms($tid) {
  if ($tid) {
    $synonyms = array();
    $result = db_query('SELECT name FROM {term_synonym} WHERE tid = %d', $tid);
    while ($synonym = db_fetch_array($result)) {
      $synonyms[] = $synonym['name'];
    }
    return $synonyms;
  }
  else {
    return array();
  }
}

/**
 * Return the term object that has the given string as a synonym.
 */
function taxonomy_get_synonym_root($synonym) {
  return db_fetch_object(db_query("SELECT * FROM {term_synonym} s, {term_data} t WHERE t.tid = s.tid AND s.name = '%s'", $synonym));
}

/**
 * Count the number of published nodes classified by a term.
 *
 * @param $tid
 *   The term's ID
 *
 * @param $type
 *   The $node->type. If given, taxonomy_term_count_nodes only counts
 *   nodes of $type that are classified with the term $tid.
 *
 * @return int
 *   An integer representing a number of nodes.
 *   Results are statically cached.
 */
function taxonomy_term_count_nodes($tid, $type = 0) {
  static $count;

  if (!isset($count[$type])) {
    // $type == 0 always evaluates TRUE if $type is a string
    if (is_numeric($type)) {
      $result = db_query(db_rewrite_sql('SELECT t.tid, COUNT(n.nid) AS c FROM {term_node} t INNER JOIN {node} n ON t.vid = n.vid WHERE n.status = 1 GROUP BY t.tid'));
    }
    else {
      $result = db_query(db_rewrite_sql("SELECT t.tid, COUNT(n.nid) AS c FROM {term_node} t INNER JOIN {node} n ON t.vid = n.vid WHERE n.status = 1 AND n.type = '%s' GROUP BY t.tid"), $type);
    }
    while ($term = db_fetch_object($result)) {
      $count[$type][$term->tid] = $term->c;
    }
  }
  $children_count = 0;
  foreach (_taxonomy_term_children($tid) as $c) {
    $children_count += taxonomy_term_count_nodes($c, $type);
  }
  return $children_count + (isset($count[$type][$tid]) ? $count[$type][$tid] : 0);
}

/**
 * Helper for taxonomy_term_count_nodes(). Used to find out
 * which terms are children of a parent term.
 *
 * @param $tid
 *   The parent term's ID
 *
 * @return array
 *   An array of term IDs representing the children of $tid.
 *   Results are statically cached.
 *
 */
function _taxonomy_term_children($tid) {
  static $children;

  if (!isset($children)) {
    $result = db_query('SELECT tid, parent FROM {term_hierarchy}');
    while ($term = db_fetch_object($result)) {
      $children[$term->parent][] = $term->tid;
    }
  }
  return isset($children[$tid]) ? $children[$tid] : array();
}

/**
 * Try to map a string to an existing term, as for glossary use.
 *
 * Provides a case-insensitive and trimmed mapping, to maximize the
 * likelihood of a successful match.
 *
 * @param name
 *   Name of the term to search for.
 *
 * @return
 *   An array of matching term objects.
 */
function taxonomy_get_term_by_name($name) {
  $db_result = db_query(db_rewrite_sql("SELECT t.tid, t.* FROM {term_data} t WHERE LOWER(t.name) LIKE LOWER('%s')", 't', 'tid'), trim($name));
  $result = array();
  while ($term = db_fetch_object($db_result)) {
    $result[] = $term;
  }

  return $result;
}

/**
 * Return the vocabulary object matching a vocabulary ID.
 *
 * @param $vid
 *   The vocabulary's ID
 *
 * @return Object
 *   The vocabulary object with all of its metadata.
 *   Results are statically cached.
 */
function taxonomy_vocabulary_load($vid) {
  static $vocabularies = array();

  if (!array_key_exists($vid, $vocabularies)) {
    $result = db_query('SELECT v.*, n.type FROM {vocabulary} v LEFT JOIN {vocabulary_node_types} n ON v.vid = n.vid WHERE v.vid = %d', $vid);
    $node_types = array();
    while ($voc = db_fetch_object($result)) {
      if (!empty($voc->type)) {
        $node_types[] = $voc->type;
      }
      unset($voc->type);
      $voc->nodes = $node_types;
      $vocabularies[$vid] = $voc;
    }
  }

  return $vocabularies[$vid];
}

/**
 * Return the term object matching a term ID.
 *
 * @param $tid
 *   A term's ID
 *
 * @return Object
 *   A term object. Results are statically cached.
 */
function taxonomy_get_term($tid) {
  static $terms = array();

  if (!isset($terms[$tid])) {
    $terms[$tid] = db_fetch_object(db_query('SELECT * FROM {term_data} WHERE tid = %d', $tid));
  }

  return $terms[$tid];
}

function _taxonomy_term_select($title, $name, $value, $vocabulary_id, $description, $multiple, $blank, $exclude = array()) {
  $tree = taxonomy_get_tree($vocabulary_id);
  $options = array();

  if ($blank) {
    $options[''] = $blank;
  }
  if ($tree) {
    foreach ($tree as $term) {
      if (!in_array($term->tid, $exclude)) {
        $choice = new stdClass();
        $choice->option = array($term->tid => str_repeat('-', $term->depth) . $term->name);
        $options[] = $choice;
      }
    }
  }

  return array('#type' => 'select',
    '#title' => $title,
    '#default_value' => $value,
    '#options' => $options,
    '#description' => $description,
    '#multiple' => $multiple,
    '#size' => $multiple ? min(9, count($options)) : 0,
    '#weight' => -15,
    '#theme' => 'taxonomy_term_select',
  );
}

/**
 * We use the default selection field for choosing terms.
 */
function theme_taxonomy_term_select($element) {
  return theme('select', $element);
}

/**
 * Finds all nodes that match selected taxonomy conditions.
 *
 * @param $tids
 *   An array of term IDs to match.
 * @param $operator
 *   How to interpret multiple IDs in the array. Can be "or" or "and".
 * @param $depth
 *   How many levels deep to traverse the taxonomy tree. Can be a nonnegative
 *   integer or "all".
 * @param $pager
 *   Whether the nodes are to be used with a pager (the case on most Drupal
 *   pages) or not (in an XML feed, for example).
 * @param $order
 *   The order clause for the query that retrieve the nodes.
 * @return
 *   A resource identifier pointing to the query results.
 */
function taxonomy_select_nodes($tids = array(), $operator = 'or', $depth = 0, $pager = TRUE, $order = 'n.sticky DESC, n.created DESC') {
  if (count($tids) > 0) {
    // For each term ID, generate an array of descendant term IDs to the right depth.
    $descendant_tids = array();
    if ($depth === 'all') {
      $depth = NULL;
    }
    foreach ($tids as $index => $tid) {
      $term = taxonomy_get_term($tid);
      $tree = taxonomy_get_tree($term->vid, $tid, -1, $depth);
      $descendant_tids[] = array_merge(array($tid), array_map('_taxonomy_get_tid_from_term', $tree));
    }

    if ($operator == 'or') {
      $str_tids = implode(',', call_user_func_array('array_merge', $descendant_tids));
      $sql = 'SELECT DISTINCT(n.nid), n.sticky, n.title, n.created FROM {node} n INNER JOIN {term_node} tn ON n.vid = tn.vid WHERE tn.tid IN ('. $str_tids .') AND n.status = 1 ORDER BY '. $order;
      $sql_count = 'SELECT COUNT(DISTINCT(n.nid)) FROM {node} n INNER JOIN {term_node} tn ON n.vid = tn.vid WHERE tn.tid IN ('. $str_tids .') AND n.status = 1';
    }
    else {
      $joins = '';
      $wheres = '';
      foreach ($descendant_tids as $index => $tids) {
        $joins .= ' INNER JOIN {term_node} tn'. $index .' ON n.vid = tn'. $index .'.vid';
        $wheres .= ' AND tn'. $index .'.tid IN ('. implode(',', $tids) .')';
      }
      $sql = 'SELECT DISTINCT(n.nid), n.sticky, n.title, n.created FROM {node} n '. $joins .' WHERE n.status = 1 '. $wheres .' ORDER BY '. $order;
      $sql_count = 'SELECT COUNT(DISTINCT(n.nid)) FROM {node} n '. $joins .' WHERE n.status = 1 '. $wheres;
    }
    $sql = db_rewrite_sql($sql);
    $sql_count = db_rewrite_sql($sql_count);
    if ($pager) {
      $result = pager_query($sql, variable_get('default_nodes_main', 10), 0, $sql_count);
    }
    else {
      $result = db_query_range($sql, 0, variable_get('feed_default_items', 10));
    }
  }

  return $result;
}

/**
 * Accepts the result of a pager_query() call, such as that performed by
 * taxonomy_select_nodes(), and formats each node along with a pager.
*/
function taxonomy_render_nodes($result) {
  $output = '';
  $has_rows = FALSE;
  while ($node = db_fetch_object($result)) {
    $output .= node_view(node_load($node->nid), 1);
    $has_rows = TRUE;
  }
  if ($has_rows) {
    $output .= theme('pager', NULL, variable_get('default_nodes_main', 10), 0);
  }
  else {
    $output .= '<p>'. t('There are currently no posts in this category.') .'</p>';
  }
  return $output;
}

/**
 * Implementation of hook_nodeapi().
 */
function taxonomy_nodeapi($node, $op, $arg = 0) {
  switch ($op) {
    case 'load':
     $output['taxonomy'] = taxonomy_node_get_terms($node);
     return $output;

    case 'insert':
      if (!empty($node->taxonomy)) {
        taxonomy_node_save($node, $node->taxonomy);
      }
      break;

    case 'update':
      if (!empty($node->taxonomy)) {
        taxonomy_node_save($node, $node->taxonomy);
      }
      break;

    case 'delete':
      taxonomy_node_delete($node);
      break;

    case 'delete revision':
      taxonomy_node_delete_revision($node);
      break;

    case 'validate':
      taxonomy_node_validate($node);
      break;

    case 'rss item':
      return taxonomy_rss_item($node);

    case 'update index':
      return taxonomy_node_update_index($node);
  }
}

/**
 * Implementation of hook_nodeapi('update_index').
 */
function taxonomy_node_update_index(&$node) {
  $output = array();
  foreach ($node->taxonomy as $term) {
    $output[] = $term->name;
  }
  if (count($output)) {
    return '<strong>('. implode(', ', $output) .')</strong>';
  }
}

/**
 * Parses a comma or plus separated string of term IDs.
 *
 * @param $str_tids
 *   A string of term IDs, separated by plus or comma.
 *   comma (,) means AND
 *   plus (+) means OR
 *
 * @return an associative array with an operator key (either 'and'
 *   or 'or') and a tid key containing an array of the term ids.
 */
function taxonomy_terms_parse_string($str_tids) {
  $terms = array('operator' => '', 'tids' => array());
  if (preg_match('/^([0-9]+[+ ])+[0-9]+$/', $str_tids)) {
    $terms['operator'] = 'or';
    // The '+' character in a query string may be parsed as ' '.
    $terms['tids'] = preg_split('/[+ ]/', $str_tids);
  }
  else if (preg_match('/^([0-9]+,)*[0-9]+$/', $str_tids)) {
    $terms['operator'] = 'and';
    $terms['tids'] = explode(',', $str_tids);
  }
  return $terms;
}

/**
 * Provides category information for RSS feeds.
 */
function taxonomy_rss_item($node) {
  $output = array();
  foreach ($node->taxonomy as $term) {
    $output[] = array('key'   => 'category',
                      'value' => check_plain($term->name),
                      'attributes' => array('domain' => url('taxonomy/term/'. $term->tid, array('absolute' => TRUE))));
  }
  return $output;
}

/**
 * Implementation of hook_help().
 */
function taxonomy_help($path, $arg) {
  switch ($path) {
    case 'admin/help#taxonomy':
      $output = '<p>'. t('The taxonomy module is one of the most popular features because users often want to create categories to organize content by type. A simple example would be organizing a list of music reviews by musical genre.') .'</p>';
      $output .= '<p>'. t('Taxonomy is the study of classification. The taxonomy module allows you to define vocabularies (sets of categories) which are used to classify content. The module supports hierarchical classification and association between terms, allowing for truly flexible information retrieval and classification. The taxonomy module allows multiple lists of categories for classification (controlled vocabularies) and offers the possibility of creating thesauri (controlled vocabularies that indicate the relationship of terms) and taxonomies (controlled vocabularies where relationships are indicated hierarchically). To view and manage the terms of each vocabulary, click on the associated <em>list terms</em> link. To delete a vocabulary and all its terms, choose <em>edit vocabulary.</em>') .'</p>';
      $output .= '<p>'. t('A controlled vocabulary is a set of terms to use for describing content (known as descriptors in indexing lingo). Drupal allows you to describe each piece of content (blog, story, etc.) using one or many of these terms. For simple implementations, you might create a set of categories without subcategories, similar to Slashdot\'s sections. For more complex implementations, you might create a hierarchical list of categories.') .'</p>';
      $output .= '<p>'. t('For more information please read the configuration and customization handbook <a href="@taxonomy">Taxonomy page</a>.', array('@taxonomy' => 'http://drupal.org/handbook/modules/taxonomy/')) .'</p>';
      return $output;
    case 'admin/content/taxonomy':
      return '<p>'. t('The taxonomy module allows content to be classified into categories and subcategories, or vocabularies and terms. Terms may be organized in controlled vocabularies (vocabularies with multiple lists of categories), in thesauri (controlled vocabularies that indicate the relationship of terms), in taxonomies (controlled vocabularies where relationships are indicated hierarchically), or in free vocabularies (vocabularies where tags are defined during content creation). To view and manage the terms of each vocabulary, click on the associated <em>list terms</em> link. To delete a vocabulary and all its terms, choose "edit vocabulary".') .'</p>';
    case 'admin/content/taxonomy/add/vocabulary':
      return '<p>'. t("When you create a controlled vocabulary you are creating a set of terms to use for describing content (known as descriptors in indexing lingo). Drupal allows you to describe each piece of content (blog, story, etc.) using one or many of these terms. For simple implementations, you might create a set of categories without subcategories. For more complex implementations, you might create a hierarchical list of categories.") .'</p>';
  }
}

/**
 * Helper function for array_map purposes.
 */
function _taxonomy_get_tid_from_term($term) {
  return $term->tid;
}

/**
 * Implode a list of tags of a certain vocabulary into a string.
 */
function taxonomy_implode_tags($tags, $vid = NULL) {
  $typed_tags = array();
  foreach ($tags as $tag) {
    // Extract terms belonging to the vocabulary in question.
    if (is_null($vid) || $tag->vid == $vid) {

      // Commas and quotes in tag names are special cases, so encode 'em.
      if (strpos($tag->name, ',') !== FALSE || strpos($tag->name, '"') !== FALSE) {
        $tag->name = '"'. str_replace('"', '""', $tag->name) .'"';
      }

      $typed_tags[] = $tag->name;
    }
  }
  return implode(', ', $typed_tags);
}

/**
 * Implementation of hook_hook_info().
 */
function taxonomy_hook_info() {
  return array(
    'taxonomy' => array(
      'taxonomy' => array(
        'insert' => array(
          'runs when' => t('After saving a new category to the database'),
        ),
        'update' => array(
          'runs when' => t('After saving an updated category to the database'),
        ),
        'delete' => array(
          'runs when' => t('After deleting a category')
        ),
      ),
    ),
  );
}