<?php
// $Id: field_indexer.module,v 1.4 2008-06-22 22:49:17 davidlesieur Exp $

/**
 * @file
 * Indexes field content for use by modules that implement field search.
 */

/**
 * Implementation of hook_menu().
 */
function field_indexer_menu($may_cache) {
  $items = array();
  if ($may_cache) {
    $items[] = array(
      'path' => 'admin/settings/field_indexer',
      'title' => t('Field indexer'),
      'access' => user_access('administer search'),
      'description' => t('Enable fields for use by field searches.'),
      'callback' => 'drupal_get_form',
      'callback arguments' => array('field_indexer_admin'),
    );
  }

  return $items;
}

/**
 * Menu callback for configuring the module.
 */
function field_indexer_admin() {
  // Find all the fields available for indexing.
  $fields = field_indexer_find_fields();

  if (empty($fields)) {
    $form['message'] = array(
      '#type' => 'markup',
      '#value' => t('No fields available for indexing.'),
    );
    return $form;
  }
  
  // Find which fields were already configured.
  $known_fields = field_indexer_load_fields();

  // Assign fiid and status to fields.
  foreach ($fields as $key => $field) {
    if (isset($known_fields[$key])) {
      // Preserve the known fiid and status.
      $fields[$key]['fiid'] = $known_fields[$key]['fiid'];
      $fields[$key]['status'] = $known_fields[$key]['status'];
      // Remove from array so at the end we have a list of fields that no longer
      // exist on the system.
      unset($known_fields[$key]); 
    }
  }

  // Build the list of options.
  $options = array();
  $defaults = array();
  foreach ($fields as $key => $field) {
    // TODO: Format field label and help in a nice table instead.
    $help = check_plain($field['namespace']) . (empty($field['help']) ? '' : ' / '. check_plain($field['help']));
    $options[$key] = check_plain($field['label']) .' ('. $help .')';
    if ($field['status']) {
      $defaults[] = $key;
    }
  }
  
  // Build the settings form.
  $form['selector'] = array(
    '#type' => 'checkboxes',
    '#title' => t('Fields to index'),
    '#description' => t('Check the fields that need to be indexed.'),
    '#options' => $options,
    '#default_value' => $defaults,
  );
  $form['fields'] = array(
    '#type' => 'value',
    '#value' => $fields,
  );
  $form['lost_fields'] = array(
    '#type' => 'value',
    '#value' => $known_fields,
  );
  $form['submit'] = array(
    '#type' => 'submit',
    '#value' => t('Save configuration'),
  );
  
  return $form;
}

/**
 * Submit handler for the settings.
 */
function field_indexer_admin_submit($form_id, $form_values) {
  $enabled = FALSE;
  
  // Update or insert field selection.
  foreach ($form_values['fields'] as $key => $field) {
    $status = $form_values['selector'][$key] ? 1 : 0;
    if (isset($field['fiid'])) {
      // Update existing field if its status or label has changed.
      db_query("UPDATE {field_indexer_map} SET status = %d, label = '%s' WHERE fiid = %d AND (status != %d OR label != '%s')", $status, $field['label'], $field['fiid'], $status, $field['label']);
      
      if (db_affected_rows()) {
        if ($status) {
          $enabled = TRUE;
        }
        else {
          // Field is disabled, delete its index entries.
          field_indexer_wipe($field['fiid']);
        }
      }
    }
    else {
      // Insert newly discovered field.
      db_query("INSERT INTO {field_indexer_map} (fiid, namespace, name, extra_name, status, label) VALUES (%d, '%s', '%s', '%s', %d, '%s')", db_next_id('{field_indexer_map}_fiid'), $field['namespace'], $field['name'], $field['extra_name'], $status, $field['label']);
      if ($status) {
        $enabled = TRUE;
      }
    }
  }

  // Delete obsolete fields.
  foreach ($form_values['lost_fields'] as $field) {
    // TODO!!! test this!

    // Delete obsolete field data.
    db_query('DELETE FROM {field_indexer_map} WHERE fiid = %d', $field['fiid']);

    // Delete index entries for the field.
    field_indexer_wipe($field['fiid']);
  }

  if ($enabled) {
    field_indexer_reindex(); // Re-index all nodes.
    drupal_set_message(t('All nodes have been marked for re-indexing to ensure the indexing of the newly enabled fields. Indexing will start on the next <a href="@cron">cron</a> run.', array('@cron' => url('admin/logs/status/run-cron'))));
  }

  drupal_set_message(t('The configuration options have been saved.'));
}

/**
 * Update the full-text search index for a particular field value.
 *
 * @param $nid
 *   Id of the node containing the value.
 * @param $fiid
 *   Id of the field containing the value.
 * @param $text
 *   The content of the field. Must be a piece of HTML text.
 */
function field_indexer_index($nid, $fiid, $text) {
  search_index($nid, field_indexer_type($fiid), $text);
}

/**
 * Mark all nodes for re-indexing.
 */
function field_indexer_reindex() {
  node_search('reset');
}

/**
 * Delete index entries for the specified field.
 */
function field_indexer_wipe($fiid) {
  $type = field_indexer_type($fiid);
  db_query("DELETE FROM {search_dataset} WHERE type = '%s'", $type);
  db_query("DELETE FROM {search_index} WHERE type = '%s'", $type);
}

/**
 * Retrieve a fresh list of fields that are exposed by modules for indexing.
 */
function field_indexer_find_fields() {
  $fields = array();
  foreach (module_implements('field_indexer_list') as $module) {
    $module_fields = module_invoke($module, 'field_indexer_list');
    foreach ($module_fields as $field) {
      // Add the field.
      $fields[_field_indexer_key($field)] = $field;
    }
  }
  return $fields;
}

/**
 * Retrieve the fields settings from the database.
 *
 * @param $status
 *   Optional status of the fields to be returned (TRUE for fields that are
 *   enabled for indexing, FALSE for fields that are not being indexed). When
 *   set, only fields with the given status are returned. When not set, all
 *   indexable fields are returned.
 * @param $namespace
 *   Optional namespace of whose fields we are interested in. When not
 *   specified, all indexable fields are returned.
 * @return
 *   An array describing the fields.
 */
function field_indexer_load_fields($status = NULL, $namespace = NULL) {
  $where = array();
  $args = array();
  if (isset($status)) {
    $where[] = 'status = %d';
    $args[] = $status ? 1 : 0;
  }
  if (isset($namespace)) {
    $where[] = "namespace = '%s'";
    $args[] = $namespace;
  }
  if (count($where)) {
    $where = ' WHERE '. implode(' AND ', $where);
  }
  else {
    $where = '';
  }
  $fields = array();
  $results = db_query('SELECT * FROM {field_indexer_map}'. $where, $args);
  while ($field = db_fetch_array($results)) {
    $fields[_field_indexer_key($field)] = $field;
  }
  return $fields;
}

/**
 * Return the index type of the specified field.
 */
function field_indexer_type($fiid) {
  return 'field_'. $fiid;
}

/**
 * Return a unique key for a field. This is useful when collecting fields whose
 * fiid have not yet been assigned.
 */
function _field_indexer_key($field) {
  return $field['namespace'] .'_'. $field['name'] .'_'. $field['extra_name'];
}