<?php
// $Id: apachesolr.module,v 1.1.2.12.2.136 2009-04-30 18:00:00 pwolanin Exp $

/**
 * @file
 *   Integration with the Apache Solr search application.
 */

/**
 * Implementation of hook_menu().
 */
function apachesolr_menu() {
  $items = array();
  $items['admin/settings/apachesolr'] = array(
    'title'              => 'Apache Solr',
    'description'        => 'Administer Apache Solr.',
    'page callback'      => 'drupal_get_form',
    'page arguments'     => array('apachesolr_settings'),
    'access callback'    => 'user_access',
    'access arguments'   => array('administer site configuration'),
    'file'               => 'apachesolr.admin.inc',
  );
  $items['admin/settings/apachesolr/settings'] = array(
    'title'              => 'Settings',
    'weight'             => -10,
    'access arguments'   => array('administer site configuration'),
    'file'               => 'apachesolr.admin.inc',
    'type'               => MENU_DEFAULT_LOCAL_TASK,
  );
  $items['admin/settings/apachesolr/enabled-filters'] = array(
    'title'              => 'Enabled filters',
    'page callback'      => 'drupal_get_form',
    'page arguments'     => array('apachesolr_enabled_facets_form'),
    'weight'             => -7,
    'access arguments'   => array('administer site configuration'),
    'file'               => 'apachesolr.admin.inc',
    'type'               => MENU_LOCAL_TASK,
  );
  $items['admin/settings/apachesolr/index'] = array(
    'title'              => 'Search index',
    'page callback'      => 'apachesolr_index_page',
    'access arguments'   => array('administer site configuration'),
    'weight'             => -8,
    'file'               => 'apachesolr.admin.inc',
    'type'               => MENU_LOCAL_TASK,
  );
  $items['admin/reports/apachesolr'] = array(
    'title'              => 'Apache Solr Search index',
    'page callback'      => 'apachesolr_index_report',
    'access arguments'   => array('access site reports'),
    'file'               => 'apachesolr.admin.inc',
  );
  $items['admin/reports/apachesolr/index'] = array(
    'title'              => 'Search index',
    'file'               => 'apachesolr.admin.inc',
    'type'               => MENU_DEFAULT_LOCAL_TASK,
  );
  return $items;
}

/**
 * Determines Apache Solr's behavior when searching causes an exception (e.g. Solr isn't available.)
 * Depending on the admin settings, possibly redirect to Drupal's core search.
 *
 * @param $search_name
 *   The name of the search implementation.
 *
 * @param $querystring
 *   The search query that was issued at the time of failure.
 */
function apachesolr_failure($search_name, $querystring) {
  $fail_rule = variable_get('apachesolr_failure', 'show_error');

  switch ($fail_rule) {
    case 'show_error':
      drupal_set_message(t('The Apache Solr search engine is not available. Please contact your site administrator.'), 'error');
      break;
    case 'show_drupal_results':
      drupal_set_message(t("%search_name is not available. Your search is being redirected.", array('%search_name' => $search_name)));
      drupal_goto('search/node/' . drupal_urlencode($querystring));
      break;
    case 'show_no_results':
      return;
  }
}

/**
 * Implementation of hook_requirements().
 */
function apachesolr_requirements($phase) {
  // Ensure translations don't break at install time
  $t = get_t();
  if ($phase == 'runtime') {
    $host = variable_get('apachesolr_host', 'localhost');
    $port = variable_get('apachesolr_port', 8983);
    $path = variable_get('apachesolr_path', '/solr');
    $ping = FALSE;
    try {
      $solr = apachesolr_get_solr();
      $ping = @$solr->ping(variable_get('apachesolr_ping_timeout', 4));
      // If there is no $solr object, there is no server available, so don't continue.
      if (!$ping) {
        throw new Exception(t('No Solr instance available when checking requirements.'));
      }
    }
    catch (Exception $e) {
      watchdog('Apache Solr', $e->getMessage(), NULL, WATCHDOG_ERROR);
    }
    $value =  $ping ? $t('Your site has contacted the Apache Solr server.') : $t('Your site was unable to contact the Apache Solr server.');
    $severity = $ping ? 0: 2;
    $description = theme('item_list', array($t('Host: %host', array('%host' => $host)),
                        $t('Port: %port', array('%port' => $port)),
                        $t('Path: %path', array('%path' => $path))));
    $requirements['apachesolr'] = array(
      'title' => $t('Apache Solr'),
      'value' => $value,
      'description' => $description,
      'severity' => $severity,
    );
    return $requirements;
  }
}

/**
 * Like $site_key in _update_refresh() - returns a site-specific hash.
 */
function apachesolr_site_hash() {
  if (!($hash = variable_get('apachesolr_site_hash', FALSE))) {
    global $base_url;
    $hash = substr(md5(md5($base_url . drupal_get_private_key() . 'apachesolr')), 0, 12);
    variable_set('apachesolr_site_hash', $hash);
  }
  return $hash;
}

function apachesolr_document_id($id, $type = 'node') {
  return apachesolr_site_hash() . "/$type/" . $id;
}

/**
 * Implementation of hook_user().
 *
 * Mark nodes as needing re-indexing if the author name changes.
 */
function apachesolr_user($op, &$edit, &$account) {
  switch ($op) {
    case 'update':
      if (isset($edit['name']) && $account->name != $edit['name']) {
        db_query("UPDATE {apachesolr_search_node} SET changed = %d WHERE nid IN (SELECT nid FROM {node} WHERE uid = %d)", time(), $account->uid);
      }
      break;
  }
}

/**
 * Implementation of hook_taxonomy().
 *
 * Mark nodes as needing re-indexing if a term name changes.
 */
function apachesolr_taxonomy($op, $type, $edit) {
  if ($type == 'term' && ($op == 'update')) {
    db_query("UPDATE {apachesolr_search_node} SET changed = %d WHERE nid IN (SELECT nid FROM {term_node} WHERE tid = %d)", time(), $edit['tid']);
  }
  // TODO: the rest, such as term deletion.
}

/**
 * Implementation of hook_comment().
 *
 * Mark nodes as needing re-indexing if comments are added or changed.
 * Like search_comment().
 */
function apachesolr_comment($edit, $op) {
  $edit = (array) $edit;
  switch ($op) {
    // Reindex the node when comments are added or changed
    case 'insert':
    case 'update':
    case 'delete':
    case 'publish':
    case 'unpublish':
      apachesolr_mark_node($edit['nid']);
      break;
  }
}

/**
 * Mark one node as needing re-indexing.
 */
function apachesolr_mark_node($nid) {
  db_query("UPDATE {apachesolr_search_node} SET changed = %d WHERE nid = %d", time(), $nid);
}

/**
 * Implementation of hook_node_type().
 *
 * Mark nodes as needing re-indexing if a node type name changes.
 */
function apachesolr_node_type($op, $info) {
  if ($op != 'delete' && !empty($info->old_type) && $info->old_type != $info->type) {
    // We cannot be sure we are going before or after node module.
    db_query("UPDATE {apachesolr_search_node} SET changed = %d WHERE nid IN (SELECT nid FROM {node} WHERE type = '%s' OR type = '%s')", time(), $info->old_type, $info->type);
  }
}

/**
 * Helper function for modules implmenting hook_search's 'status' op.
 */
function apachesolr_index_status($namespace) {
  list($excluded_types, $args, $join_sql, $exclude_sql) = _apachesolr_exclude_types($namespace);

  $total = db_result(db_query("SELECT COUNT(asn.nid) FROM {apachesolr_search_node} asn ". $join_sql ."WHERE asn.status = 1 " . $exclude_sql, $excluded_types));
  $remaining = db_result(db_query("SELECT COUNT(asn.nid) FROM {apachesolr_search_node} asn ". $join_sql ."WHERE (asn.changed > %d OR (asn.changed = %d AND asn.nid > %d)) AND asn.status = 1 "  . $exclude_sql, $args));
  return array('remaining' => $remaining, 'total' => $total);
}

/**
 * Returns last changed and last nid for an indexing namespace.
 */
function apachesolr_get_last_index($namespace) {
  $stored = variable_get('apachesolr_index_last', array());
  return isset($stored[$namespace]) ? $stored[$namespace] : array('last_change' => 0, 'last_nid' => 0);
}

/**
 * Clear a specific namespace's last changed and nid, or clear all.
 */
function apachesolr_clear_last_index($namespace = '') {
  if ($namespace) {
    $stored = variable_get('apachesolr_index_last', array());
    unset($stored[$namespace]);
    variable_set('apachesolr_index_last', $stored);
  }
  else {
    variable_del('apachesolr_index_last');
  }
}

function _apachesolr_exclude_types($namespace) {
  extract(apachesolr_get_last_index($namespace));
  $excluded_types = module_invoke_all('apachesolr_types_exclude', $namespace);
  $args = array($last_change, $last_change, $last_nid);
  $join_sql = '';
  $exclude_sql = '';
  if ($excluded_types) {
    $excluded_types = array_unique($excluded_types);
    $join_sql = "INNER JOIN {node} n ON n.nid = asn.nid ";
    $exclude_sql = "AND n.type NOT IN(". db_placeholders($excluded_types, 'varchar') .") ";
    $args = array_merge($args, $excluded_types);
  }
  return array($excluded_types, $args, $join_sql, $exclude_sql);
}

/**
 * Returns a resource from a query based on an indexing namespace.
 */
function apachesolr_get_nodes_to_index($namespace, $limit) {
  list($excluded_types, $args, $join_sql, $exclude_sql) = _apachesolr_exclude_types($namespace);
  return  db_query_range("SELECT asn.nid, asn.changed FROM {apachesolr_search_node} asn ". $join_sql ."WHERE (asn.changed > %d OR (asn.changed = %d AND asn.nid > %d)) AND asn.status = 1 ". $exclude_sql ."ORDER BY asn.changed ASC, asn.nid ASC", $args, 0, $limit);
}

/**
 * Function to handle the indexing of nodes.
 *
 * The calling function must supply a name space or track/store
 * the timestamp and nid returned.
 * Returns FALSE if no nodes were indexed (none found or error).
 */
function apachesolr_index_nodes($result, $namespace = '', $callback = 'apachesolr_add_node_document') {
  try {
    // Get the $solr object
    $solr = apachesolr_get_solr();
    // If there is no server available, don't continue.
    if (!$solr->ping(variable_get('apachesolr_ping_timeout', 4))) {
      throw new Exception(t('No Solr instance available during indexing.'));
    }
  }
  catch (Exception $e) {
    watchdog('Apache Solr', $e->getMessage(), NULL, WATCHDOG_ERROR);
    return FALSE;
  }
  include_once(drupal_get_path('module', 'apachesolr') .'/apachesolr.index.inc') ;
  $documents = array();
  $old_position = apachesolr_get_last_index($namespace);
  $position = $old_position;

  while ($row = db_fetch_object($result)) {
    // Variables to track the last item changed.
    $position['last_change'] = $row->changed;
    $position['last_nid'] = $row->nid;
    $callback($documents, $row->nid, $namespace);
  }

  if (count($documents)) {
    try {
      watchdog('Apache Solr', 'Adding @count documents.', array('@count' => count($documents)));
      // Chunk the adds by 20s
      $docs_chunk = array_chunk($documents, 20);
      foreach ($docs_chunk as $docs) {
        $solr->addDocuments($docs);
      }
      // Set the timestamp to indicate an index update.
      apachesolr_index_updated(time());
    }
    catch (Exception $e) {
      watchdog('Apache Solr', $e->getMessage(), NULL, WATCHDOG_ERROR);
      return FALSE;
    }
  }

  // Save the new position in case it changed.
  if ($namespace && $position != $old_position) {
    $stored = variable_get('apachesolr_index_last', array());
    $stored[$namespace] = $position;
    variable_set('apachesolr_index_last', $stored);
  }

  return $position;
}

/**
 * Convert date from timestamp into ISO 8601 format.
 * http://lucene.apache.org/solr/api/org/apache/solr/schema/DateField.html
 */
function apachesolr_date_iso($date_timestamp) {
  return gmdate('Y-m-d\TH:i:s\Z', $date_timestamp);
}

function apachesolr_delete_node_from_index($node) {
  try {
    $solr = apachesolr_get_solr();
    $solr->deleteById(apachesolr_document_id($node->nid));
    apachesolr_index_updated(time());
    return TRUE;
  }
  catch (Exception $e) {
    watchdog('Apache Solr', $e->getMessage(), NULL, WATCHDOG_ERROR);
    return FALSE;
  }
}

/**
 * Helper function to keep track of when the index has been updated.
 */
function apachesolr_index_updated($updated = NULL) {
  if (isset($updated)) {
    if ($updated) {
      variable_set('apachesolr_index_updated', (int) $updated);
    }
    else {
      variable_del('apachesolr_index_updated');
    }
  }
  return variable_get('apachesolr_index_updated', 0);
}

/**
 * Implementation of hook_cron().
 */
function apachesolr_cron() {
  try {
    $solr = apachesolr_get_solr();
    // Check for unpublished content that wasn't deleted from the index.
    $result = db_query("SELECT n.nid, n.status FROM {apachesolr_search_node} asn INNER JOIN {node} n ON n.nid = asn.nid WHERE asn.status != n.status");
    while ($node = db_fetch_object($result)) {
      _apachesolr_nodeapi_update($node, FALSE);
    }
    // Check for deleted content that wasn't deleted from the index.
    $result = db_query("SELECT asn.nid FROM {apachesolr_search_node} asn LEFT JOIN {node} n ON n.nid = asn.nid WHERE n.nid IS NULL");
    while ($node = db_fetch_object($result)) {
      _apachesolr_nodeapi_delete($node, FALSE);
    }
    $last = variable_get('apachesolr_last_optimize', 0);
    $time = time();
    // Make sure to omtimize once per day.
    if ($time - $last > 60*60*24) {
      $solr->optimize(FALSE, FALSE);
      variable_set('apachesolr_last_optimize', $time);
      apachesolr_index_updated($time);
    }
    // Only clear the cache if the index changed, but at least once daily.
    // TODO: clear on some schedule if running multi-site.
    $updated = apachesolr_index_updated();
    if ($updated) {
      $solr->clearCache();
      // Re-populate the luke cache.
      $solr->getLuke();
      // TODO: an admin interface for setting this.  Assume for now 5 minutes.
      if ($time - $updated >= variable_get('apachesolr_cache_delay', 300)) {
        // Clear the updated flag.
        apachesolr_index_updated(FALSE);
      }
    }
  }
  catch (Exception $e) {
    watchdog('Apache Solr', $e->getMessage() . ' in apachesolr_cron', NULL, WATCHDOG_ERROR);
  }
}

/**
 * Implementation of hook_nodeapi().
 */
function apachesolr_nodeapi(&$node, $op, $a3 = NULL, $a4 = NULL) {
  switch ($op) {
    case 'delete':
      _apachesolr_nodeapi_delete($node);
      break;
    case 'insert':
      // Make sure no node ends up with a timestamp that's in the future
      // by using time() rather than the node's changed or created timestamp.
      db_query("INSERT INTO {apachesolr_search_node} (nid, status, changed) VALUES  (%d, %d, %d)", $node->nid, $node->status, time());
      break;
    case 'update':
      _apachesolr_nodeapi_update($node);
      break;
  }
}

/**
 * Helper function for hook_nodeapi() and hook_cron().
 */
function _apachesolr_nodeapi_delete($node, $set_message = TRUE) {
  if (apachesolr_delete_node_from_index($node)) {
    // There was no exception, so delete from the table.
    db_query("DELETE FROM {apachesolr_search_node} WHERE nid = %d", $node->nid);
    if ($set_message && user_access('administer site configuration') && variable_get('apachesolr_set_nodeapi_messages', 1)) {
      apachesolr_set_stats_message('Deleted content will be removed from the Apache Solr search index in approximately @autocommit_time.');
    }
  }
}

/**
 * Helper function for hook_nodeapi() and hook_cron().
 */
function _apachesolr_nodeapi_update($node, $set_message = TRUE) {
  // Check if the node has gone from published to unpublished.
  if (!$node->status && db_result(db_query("SELECT status FROM {apachesolr_search_node} WHERE nid = %d", $node->nid))) {
    if (apachesolr_delete_node_from_index($node)) {
      // There was no exception, so update the table.
      db_query("UPDATE {apachesolr_search_node} SET changed = %d, status = %d WHERE nid  = %d", time(), $node->status, $node->nid);
      if ($set_message && user_access('administer site configuration') && variable_get('apachesolr_set_nodeapi_messages', 1)) {
        apachesolr_set_stats_message('Unpublished content will be removed from the Apache Solr search index in approximately @autocommit_time.');
      }
    }
  }
  else {
    db_query("UPDATE {apachesolr_search_node} SET changed = %d, status = %d WHERE nid  = %d", time(), $node->status, $node->nid);
  }
}

/**
 * Call drupal_set_message() with the text.
 *
 * The text is translated with t() and substituted using Solr stats.
 */
function apachesolr_set_stats_message($text, $type = 'status', $repeat = FALSE) {
  try {
    $solr = apachesolr_get_solr();
    $stats_summary = $solr->getStatsSummary();
    drupal_set_message(t($text, $stats_summary), $type, FALSE);
  }
  catch (Exception $e) {
    watchdog('apachesolr', $e->getMessage(), NULL, WATCHDOG_ERROR);
  }
}

/**
 * Return the enabled facets from the specified block array.
 *
 * @param $module
 *   The module (optional).
 * @return
 *   An array consisting info for facets that have been enabled
 *   for the specified module, or all enabled facets.
 */
function apachesolr_get_enabled_facets($module = NULL) {
  $enabled = variable_get('apachesolr_enabled_facets', array());
  if (isset($module)) {
    return isset($enabled[$module]) ? $enabled[$module] : array();
  }
  return $enabled;
}

/**
 * Implementation of hook_block().
 */
function apachesolr_block($op = 'list', $delta = 0, $edit = array()) {
  switch ($op) {
    case 'list':
      // Add the blocks
      $blocks['sort'] = array(
        'info' => t('Apache Solr Core: Sorting'),
        'cache' => BLOCK_CACHE_PER_PAGE,
      );
      return $blocks;

    case 'view':
      if (apachesolr_has_searched()) {
        // Get the query and response. Without these no blocks make sense.
        $response = apachesolr_static_response_cache();
        if (empty($response) || ($response->response->numFound < 2)) {
          return;
        }

        $query = apachesolr_current_query();

        switch ($delta) {
          case 'sort':
            $sorts = $query->get_available_sorts();

            $solrsorts = array();
            $sort_parameter = isset($_GET['solrsort']) ? check_plain($_GET['solrsort']) : FALSE;
            foreach (explode(',', $sort_parameter) as $solrsort) {
              $parts = explode(' ', $solrsort);
              if (!empty($parts[0]) && !empty($parts[1])) {
                $solrsorts[$parts[0]] = $parts[1];
              }
            }

            $sort_links = array();
            $path = $query->get_path();
            $new_query = clone $query;
            foreach ($sorts as $type => $sort) {
              $new_sort = isset($solrsorts[$type]) ? $solrsorts[$type] == 'asc' ? 'desc' : 'asc' : $sort['default'];
              $new_query->set_solrsort($type == "relevancy" ? '' : "{$type} {$new_sort}");
              $active = isset($solrsorts[$type]) || ($type == "relevancy" && !$solrsorts);
              $direction = isset($solrsorts[$type]) ? $solrsorts[$type] : '';
              $sort_links[$type] = array(
                'name' => $sort['name'],
                'path' => $path,
                'querystring' => $new_query->get_url_querystring(),
                'active' => $active,
                'direction' => $direction
              );
            }
            // Allow other modules to add or remove sorts.
            drupal_alter('apachesolr_sort_links', $sort_links);
            foreach ($sort_links as $type => $link) {
              $themed_links[$type] = theme('apachesolr_sort_link', $link['name'], $link['path'], $link['querystring'], $link['active'], $link['direction']);
            }
            return array('subject' => t('Sort by'),
                         'content' => theme('apachesolr_sort_list', $themed_links));
          default:
            break;
        }

      }
      break;
  }
}

/**
 * Helper function for displaying a facet block.
 */
function apachesolr_facet_block($response, $query, $module, $delta, $facet_field, $filter_by, $facet_callback = FALSE) {
  if (!empty($response->facet_counts->facet_fields->$facet_field)) {
    $contains_active = FALSE;
    $items = array();
    foreach ($response->facet_counts->facet_fields->$facet_field as $facet => $count) {
      $sortpre = 1000000 - $count;
      $options = array();
      $exclude = FALSE;
      // Solr sends this back if it's empty.
      if ($facet == '_empty_') {
         $exclude = TRUE;
         $facet = '[* TO *]';
         $facet_text = theme('placeholder', t('Missing this field'));
         $options['html'] = TRUE;
         // Put this just below any active facets.
         // '-' sorts before all numbers, but after '*'.
         $sortpre = '-';
       }
       else {
         $facet_text = $facet;
      }

      if ($facet_callback && function_exists($facet_callback)) {
        $facet_text = $facet_callback($facet, $options);
      }
      $unclick_link = '';
      $active = FALSE;
      $new_query = clone $query;
      if ($query->has_filter($facet_field, $facet)) {
        $contains_active = $active = TRUE;
        // '*' sorts before all numbers.
        $sortpre = '*';
        $new_query->remove_filter($facet_field, $facet);

        $path = $new_query->get_path();
        $querystring = $new_query->get_url_querystring();
        $unclick_link = theme('apachesolr_unclick_link', $path, $querystring);
      }
      else {
        $new_query->add_filter($facet_field, $facet, $exclude);
        $path = $new_query->get_path();
        $querystring = $new_query->get_url_querystring();
      }
      if ($count || $active) {
        $items[$sortpre . '*' . $facet_text] = theme('apachesolr_facet_item', $facet_text, $count, $path, $querystring, $active, $unclick_link, $response->response->numFound, $options);
      }
    }
    // Unless a facet is active only display 2 or more.
    if ($items && ($response->response->numFound > 1 || $contains_active)) {
      ksort($items, SORT_STRING);
      // Get information needed by the rest of the blocks about limits.
      $initial_limits = variable_get('apachesolr_facet_query_initial_limits', array());
      $limit = isset($initial_limits[$module][$delta]) ? $initial_limits[$module][$delta] : variable_get('apachesolr_facet_query_initial_limit_default', 10);
      $output = theme('apachesolr_facet_list', $items, $limit);
      return array('subject' => $filter_by, 'content' => $output);
    }
  }
  return NULL;
}

/**
 * Helper function for displaying a date facet block.
 *
 * TODO: Refactor with apachesolr_facet_block().
 */
function apachesolr_date_facet_block($response, $query, $module, $delta, $facet_field, $filter_by, $facet_callback = FALSE) {
  $items = array();

  $new_query = clone $query;
  foreach (array_reverse($new_query->get_filters($facet_field)) as $filter) {
    // Iteratively remove the date facets.
    $new_query->remove_filter($facet_field, $filter['#value']);
    $path = $new_query->get_path();
    $querystring = $new_query->get_url_querystring();
    $unclick_link = theme('apachesolr_unclick_link', $path, $querystring);
    if ($facet_callback && function_exists($facet_callback)) {
      $facet_text = $facet_callback($filter['#start']);
    }
    else {
      $facet_text = apachesolr_date_format_iso_by_gap(apachesolr_date_find_query_gap($filter['#start'], $filter['#end']), $filter['#start']);
    }
    array_unshift($items, theme('apachesolr_facet_item', $facet_text, 0, $path, $querystring, TRUE, $unclick_link));
  }
  // Add links for additional date filters.
  if (!empty($response->facet_counts->facet_dates->$facet_field)) {
    $field = clone $response->facet_counts->facet_dates->$facet_field;

    $end = $field->end;
    unset($field->end);

    $gap = $field->gap;
    unset($field->gap);

    // Treat each date facet as a range start, and use the next date
    // facet as range end.  Use 'end' for the final end.
    $range_end = array();
    foreach ($field as $facet => $count) {
      if (isset($prev_facet)) {
        $range_end[$prev_facet] = $facet;
      }
      $prev_facet = $facet;
    }
    $range_end[$prev_facet] = $end;

    foreach ($field as $facet => $count) {
      // Solr sends this back if it's empty.
      if ($facet == '_empty_' || $count == 0) {
        continue;
      }
      if ($facet_callback && function_exists($facet_callback)) {
        $facet_text = $facet_callback($facet);
      }
      else {
        $facet_text = apachesolr_date_format_iso_by_gap(substr($gap, 2), $facet);
      }
      $new_query = clone $query;
      $new_query->add_filter($facet_field, '['. $facet .' TO '. $range_end[$facet] .']');
      $path = $new_query->get_path();
      $querystring = $new_query->get_url_querystring();

      $items[] = theme('apachesolr_facet_item', $facet_text, $count, $path, $querystring, FALSE, '', $response->response->numFound);
    }
  }
  if (count($items) > 0) {
    // Get information needed by the rest of the blocks about limits.
    $initial_limits = variable_get('apachesolr_facet_query_initial_limits', array());
    $limit = isset($initial_limits[$module][$delta]) ? $initial_limits[$module][$delta] : variable_get('apachesolr_facet_query_initial_limit_default', 10);
    $output = theme('apachesolr_facet_list', $items, $limit);
    return array('subject' => $filter_by, 'content' => $output);
  }
  return NULL;
}

/**
 * Determine the gap in a date range query filter that we generated.
 *
 * This function assumes that the start and end dates are the
 * beginning and end of a single period: 1 year, month, day, hour,
 * minute, or second (all date range query filters we generate meet
 * this criteria).  So, if the seconds are different, it is a second
 * gap.  If the seconds are the same (incidentally, they will also be
 * 0) but the minutes are different, it is a minute gap.  If the
 * minutes are the same but hours are different, it's an hour gap.
 * etc.
 *
 * @param $start
 *   Start date as an ISO date string.
 * @param $end
 *   End date as an ISO date string.
 * @return
 *   YEAR, MONTH, DAY, HOUR, MINUTE, or SECOND.
 */
function apachesolr_date_find_query_gap($start_iso, $end_iso) {
  $gaps = array('SECOND' => 6, 'MINUTE' => 5, 'HOUR' => 4, 'DAY' => 3, 'MONTH' => 2, 'YEAR' => 1);
  $re = '@(\d{4})-(\d{2})-(\d{2})T(\d{2}):(\d{2}):(\d{2})@';
  if (preg_match($re, $start_iso, $start) && preg_match($re, $end_iso, $end)) {
    foreach ($gaps as $gap => $idx) {
      if ($start[$idx] != $end[$idx]) {
        return $gap;
      }
    }
  }
  // can't tell
  return 'YEAR';
}

/**
 * Format an ISO date string based on the gap used to generate it.
 * 
 * This function assumes that gaps less than one day will be displayed
 * in a search context in which a larger containing gap including a
 * day is already displayed.  So, HOUR, MINUTE, and SECOND gaps only
 * display time information, without date.
 *
 * @param $gap
 *   A gap.
 * @param $iso
 *   An ISO date string.
 * @return
 *   A gap-appropriate formatted date.
 */
function apachesolr_date_format_iso_by_gap($gap, $iso) {
  // TODO: If we assume that multiple search queries are formatted in
  // order, we could store a static list of all gaps we've formatted.
  // Then, if we format an HOUR, MINUTE, or SECOND without previously
  // having formatted a DAY or later, we could include date
  // information.  However, we'd need to do that per-field and I'm not
  // our callers always have field information handy.
  $unix = strtotime($iso);
  if ($unix > 0) {
    switch ($gap) {
      case 'YEAR':
        return gmdate('Y', $unix);
      case 'MONTH':
        return gmdate('F Y', $unix);
      case 'DAY':
        return gmdate('F j, Y', $unix);
      case 'HOUR':
        return gmdate('g A', $unix);
      case 'MINUTE':
        return gmdate('g:i A', $unix);
      case 'SECOND':
        return gmdate('g:i:s A', $unix);
    }
  }

  return $iso;
}

/**
 * Format the beginning of a date range query filter that we
 * generated.
 *
 * @param $start_iso
 *   The start date.
 * @param $end_iso
 *   The end date.
 * @return
 *   A display string reprepsenting the date range, such as "January
 * 2009" for "2009-01-01T00:00:00Z TO 2009-02-01T00:00:00Z"
 */
function apachesolr_date_format_range($start_iso, $end_iso) {
  $gap = apachesolr_date_find_query_gap($start_iso, $end_iso);
  return apachesolr_date_format_iso_by_gap($gap, $start_iso);
}

/**
 * Determine the best search gap to use for an arbitrary date range.
 *
 * Generally, we the maximum gap that fits between the start and end
 * date.  If they are more than a year apart, 1 year; if they are more
 * than a month apart, 1 month; etc.
 *
 * This function uses Unix timestamps for its computation and so is
 * not useful for dates outside that range.
 *
 * @param $start
 *   Start date as an ISO date string.
 * @param $end
 *   End date as an ISO date string.
 * @return
 *   YEAR, MONTH, DAY, HOUR, MINUTE, or SECOND depending on how far
 *   apart $start and $end are.
 */
function apachesolr_date_determine_gap($start, $end) {
  $start = strtotime($start);
  $end = strtotime($end);

  if ($end - $start >= 86400*365) {
    return 'YEAR';
  }

  if (date('m', $start) != date('m', $end)) {
    return 'MONTH';
  }

  if ($end - $start > 86400) {
    return 'DAY';
  }
  // For now, HOUR is a reasonable smallest gap.
  return 'HOUR';
}

/**
 * Return the next smaller date gap.
 *
 * @param $gap
 *   A gap.
 * @return
 *   The next smaller gap, or NULL if there is no smaller gap.
 */
function apachesolr_date_gap_drilldown($gap) {
  $drill = array(
    'YEAR' => 'MONTH',
    'MONTH' => 'DAY',
    'DAY' => 'HOUR',
    // For now, HOUR is a reasonable smallest gap.
    // 'HOUR' => 'MINUTE',
  );
  return isset($drill[$gap]) ? $drill[$gap] : NULL;
}


/**
 * Used by the 'configure' $op of hook_block so that modules can generically set
 * facet limits on their blocks.
 */
function apachesolr_facetcount_form($module, $delta) {
  $initial = variable_get('apachesolr_facet_query_initial_limits', array());
  $limits = variable_get('apachesolr_facet_query_limits', array());
  $facet_missing = variable_get('apachesolr_facet_missing', array());

  $limit = drupal_map_assoc(array(50, 40, 30, 20, 15, 10, 5, 3));

  $form['apachesolr_facet_query_initial_limit'] = array(
    '#type' => 'select',
    '#title' => t('Initial filter links'),
    '#options' => $limit,
    '#description' => t('The initial number of filter links to show in this block.'),
    '#default_value' => isset($initial[$module][$delta]) ? $initial[$module][$delta] : variable_get('apachesolr_facet_query_initial_limit_default', 10),
  );
  $limit = drupal_map_assoc(array(100, 75, 50, 40, 30, 20, 15, 10, 5, 3));
  $form['apachesolr_facet_query_limit'] = array(
    '#type' => 'select',
    '#title' => t('Maximum filter links'),
    '#options' => $limit,
    '#description' => t('The maximum number of filter links to show in this block.'),
    '#default_value' => isset($limits[$module][$delta]) ? $limits[$module][$delta] : variable_get('apachesolr_facet_query_limit_default', 20),
  );
  $form['apachesolr_facet_missing'] = array(
    '#type' => 'radios',
    '#title' => t('Include a facet for missing'),
    '#options' => array(0 => t('No'), 1 => t('Yes')),
    '#description' => t('A facet can be generated corresponding to all documents entirely missing this field.'),
    '#default_value' => isset($facet_missing[$module][$delta]) ? $facet_missing[$module][$delta] : 0,
  );
  return $form;
}

/**
 * Used by the 'save' $op of hook_block so that modules can generically set
 * facet limits on their blocks.
 */
function apachesolr_facetcount_save($edit) {
  // Save query limits
  $module = $edit['module'];
  $delta = $edit['delta'];
  $limits = variable_get('apachesolr_facet_query_limits', array());
  $limits[$module][$delta] = (int)$edit['apachesolr_facet_query_limit'];
  variable_set('apachesolr_facet_query_limits', $limits);
  $initial = variable_get('apachesolr_facet_query_initial_limits', array());
  $initial[$module][$delta] = (int)$edit['apachesolr_facet_query_initial_limit'];
  variable_set('apachesolr_facet_query_initial_limits', $initial);
  $facet_missing = variable_get('apachesolr_facet_missing', array());
  $facet_missing[$module][$delta] = (int)$edit['apachesolr_facet_missing'];
  variable_set('apachesolr_facet_missing', $facet_missing);
}

/**
 * This hook allows modules to modify the query and params objects.
 *
 * Example:
 *
 * function my_module_apachesolr_modify_query(&$query, &$params) {
 *   // I only want to see articles by the admin!
 *   $query->add_filter("uid", 1);
 *
 * }
 */
function apachesolr_modify_query(&$query, &$params, $caller) {

  foreach (module_implements('apachesolr_modify_query') as $module) {
    $function_name = $module . '_apachesolr_modify_query';
    $function_name($query, $params, $caller);
  }
  // Add array of fq parameters.
  if ($query && ($fq = $query->get_fq())) {
    $params['fq'] = $fq;
  }
}

/**
 * Semaphore that indicates whether a search has been done. Blocks use this
 * later to decide whether they should load or not.
 *
 * @param $searched
 *   A boolean indicating whether a search has been executed.
 *
 * @return
 *   TRUE if a search has been executed.
 *   FALSE otherwise.
 */
function apachesolr_has_searched($searched = NULL) {
  static $_searched = FALSE;
  if (is_bool($searched)) {
    $_searched = $searched;
  }
  return $_searched;
}

/**
 * Factory method for solr singleton object. Structure allows for an arbitrary
 * number of solr objects to be used based on the host, port, path combination.
 * Get an instance like this:
 *   $solr = apachesolr_get_solr();
 */
function apachesolr_get_solr($host = NULL, $port = NULL, $path = NULL) {
  static $solr_cache;
  
  if (empty($host)) {
    $host = variable_get('apachesolr_host', 'localhost');
  }
  if (empty($port)) {
    $port = variable_get('apachesolr_port', '8983');
  }
  if (empty($path)) {
    $path = variable_get('apachesolr_path', '/solr');
  }

  if (empty($solr_cache[$host][$port][$path])) {
    list($module, $filepath, $class) = variable_get('apachesolr_service_class', array('apachesolr', 'Drupal_Apache_Solr_Service.php', 'Drupal_Apache_Solr_Service'));
    include_once(drupal_get_path('module', $module) .'/'. $filepath);
    try {
      $solr_cache[$host][$port][$path] = new $class($host, $port, $path);
    }
    catch (Exception $e) {
      watchdog('Apache Solr', $e->getMessage(), NULL, WATCHDOG_ERROR);
      return;
    }
  }
  return $solr_cache[$host][$port][$path];
}

/**
 * It is important to hold on to the Solr response object for the duration of the
 * page request so that we can use it for things like building facet blocks.
 */
function apachesolr_static_response_cache($response = NULL) {
  static $_response;

  if (!empty($response)) {
    $_response = clone $response;
  }
  return $_response;
}

/**
 * Factory function for query objects.
 *
 * @param $keys
 *   The string that a user would type into the search box. Suitable input
 *   may come from search_get_keys().
 *
 * @param $filters
 *   Key and value pairs that are applied as a filter query.
 *
 * @param $solrsort
 *   Visible string telling solr how to sort.
 *
 * @param $base_path
 *   The search base path (without the keywords) for this query.
 */
function apachesolr_drupal_query($keys = '', $filters = '', $solrsort = '', $base_path = '') {
  list($module, $class) = variable_get('apachesolr_query_class', array('apachesolr', 'Solr_Base_Query'));
  include_once drupal_get_path('module', $module) .'/'. $class .'.php';
  
  try {
    $query = new $class(apachesolr_get_solr(), $keys, $filters, $solrsort, $base_path);
  }
  catch (Exception $e) {
    watchdog('Apache Solr', $e->getMessage(), NULL, WATCHDOG_ERROR);
    $query = NULL;
  }
  
  return $query;
}

/**
 * Static getter/setter for the current query
 */
function apachesolr_current_query($query = NULL) {
  static $saved_query = NULL;
  if (is_object($query)) {
    $saved_query = clone $query;
  }

  return empty($saved_query) ? $saved_query : clone $saved_query;
}

/**
 * array('index_type' => 'integer',
 *        'multiple' => TRUE,
 *        'name' => 'fieldname',
 *        ),
 */
function apachesolr_index_key($field) {
  switch ($field['index_type']) {
    case 'text':
      $type_prefix = 't';
      break;
    case 'string':
      $type_prefix = 's';
      break;
    case 'integer':
      $type_prefix = 'i';
      break;
    case 'sint':
      $type_prefix = 'si';
      break;
   case 'double':
      $type_prefix = 'p'; // reserve d for date
      break;
    case 'boolean':
      $type_prefix = 'b';
      break;
    case 'date':
      $type_prefix = 'd';
      break;
    case 'float':
      $type_prefix = 'f';
      break;
    default:
      $type_prefix = 's';
  }
  $sm = $field['multiple'] ? 'm_' : 's_';
  return $type_prefix . $sm . $field['name'];
}

/**
 * Invokes hook_apachesolr_cck_field_mappings to find out how to handle CCK fields.
 */
function apachesolr_cck_fields() {
  static $fields;

  if (is_null($fields)) {
    $fields = array();
    // If CCK isn't enabled, do nothing.
    if (module_exists('content')) {
      // A single default mapping for all text fields.
      $mappings['text'] = array(
        'optionwidgets_select' => array('callback' => '', 'index_type' => 'string'),
        'optionwidgets_buttons' => array('callback' => '', 'index_type' => 'string')
      );
      // A field-specific mapping would look like:
      // $mappings['per-field']['field_model_name'] = array('callback' => '', 'index_type' => 'string');
      // or
      // $mappings['per-field']['field_model_price'] = array('callback' => '', 'index_type' => 'float');
      // Allow other modules to add or alter mappings.
      drupal_alter('apachesolr_cck_fields', $mappings);
      $result = db_query("SELECT  i.field_name, f.multiple, f.type AS field_type, i.widget_type, i.label FROM {content_node_field_instance} i INNER JOIN {content_node_field} f ON i.field_name = f.field_name;");
      while ($row = db_fetch_object($result)) {
        // Only deal with fields that have option widgets (facets don't make sense otherwise), or fields that have specific mappings.
        if ((isset($mappings[$row->field_type][$row->widget_type]) && !isset($fields[$row->field_name])) || isset($mappings['per-field'][$row->field_name])) {
          if (isset($mappings['per-field'][$row->field_name])) {
            $row->index_type = $mappings['per-field'][$row->field_name]['index_type'];
            $row->callback = $mappings['per-field'][$row->field_name]['callback'];
          }
          else {
            $row->index_type = $mappings[$row->field_type][$row->widget_type]['index_type'];
            $row->callback = $mappings[$row->field_type][$row->widget_type]['callback'];
          }
          $row->multiple = (bool) $row->multiple;
          $row->name = 'cck_' . $row->field_name;
          $fields[$row->field_name] = (array) $row;
        }
      }
    }
  }
  return $fields;
}

/**
 * Implementation of hook_theme().
 */
function apachesolr_theme() {
  return array(
    'apachesolr_facet_item' => array(
      'arguments' => array('name' => NULL, 'count' => NULL, 'path' => NULL, 'querystring' => '', 'active' => FALSE, 'unclick_link' => NULL, 'num_found' => NULL, 'options' => NULL),
    ),
    'apachesolr_unclick_link' => array(
      'arguments' => array('url' => NULL, 'querystring' => ''),
    ),
    'apachesolr_facet_list' => array(
      'arguments' => array('items' => NULL),
    ),
    'apachesolr_sort_list' => array(
      'arguments' => array('items' => NULL),
    ),
    'apachesolr_sort_link' => array(
      'arguments' => array('text' => NULL, 'path' => NULL, 'querystring' => '', 'active' => FALSE, 'direction' => ''),
    ),
  );
}

function theme_apachesolr_facet_item($name, $count, $path, $querystring = '', $active = FALSE, $unclick_link = NULL, $num_found = NULL, $options = array()) {

  if ($active) {
    if (isset($options['attributes']['class'])) {
      $options['attributes']['class'] .= ' active';
    }
    else {
      $options['attributes']['class'] = 'active';
    }
  }
  if ($unclick_link) {
    if (empty($options['html'])) {
      $name = check_plain($name);
    }
    return $unclick_link . ' '. $name;
  }
  else {
    $options['query'] = $querystring;
    return apachesolr_l($name ." ($count)",  $path, $options);
  }
}

/**
 * A replacement for l() - very similar but doesn't add the 'active' class.
 *
 * @see http://api.drupal.org/api/function/l/6 for parameters and options.
 *
 * @return
 *   an HTML string containing a link to the given path.
 */
function apachesolr_l($text, $path, $options = array()) {
  // Merge in defaults.
  $options += array(
    'attributes' => array(),
    'html' => FALSE,
  );
  // Don't need this, and just to be safe.
  unset($options['attributes']['title']);

  return '<a href="'. check_url(url($path, $options)) .'"'. drupal_attributes($options['attributes']) .'>'. ($options['html'] ? $text : check_plain($text)) .'</a>';
}


function theme_apachesolr_unclick_link($path, $querystring = '') {
  return apachesolr_l("(-)", $path, array('query' => $querystring));
}

function theme_apachesolr_sort_link($text, $path, $querystring = '', $active = FALSE, $direction = '') {
  $icon = '';
  $attributes = array();
  if ($direction) {
    $icon = ' '. theme('tablesort_indicator', $direction);
  }
  if ($active) {
    $attributes['class'] = 'active';
  }
  return $icon . apachesolr_l($text, $path, array('attributes' => $attributes, 'query' => $querystring));
}

function theme_apachesolr_facet_list($items, $display_limit = 0) {
  // theme('item_list') expects a numerically indexed array.
  $items = array_values($items);
  // If there is a limit and the facet count is over the limit, hide the rest.
  if (($display_limit > 0) && (count($items) > $display_limit)) {
    // Show/hide extra facets.
    drupal_add_js(drupal_get_path('module', 'apachesolr') . '/apachesolr.js');
    // Split items array into displayed and hidden.
    $hidden_items = array_splice($items, $display_limit);
    foreach ($hidden_items as $link) {
      $items[] = array('data' => $link, 'class' => 'apachesolr-hidden-facet');
    }
  }
  $admin_link = '';
  if (user_access('administer site configuration')) {
    $admin_link = l(t('Configure enabled filters'), 'admin/settings/apachesolr/enabled-filters');
  }
  return theme('item_list', $items) . $admin_link;
}

function theme_apachesolr_sort_list($items) {
  return theme('item_list', $items);
}

/**
 * The interface for all 'query' objects.
 */
interface Drupal_Solr_Query_Interface {
  /**
   * Checks to see if a specific filter is already present.
   *
   * @param string $field
   * the facet field to check
   *
   * @param string $value
   * The facet value to check against
   */
  function has_filter($field, $value);
  
  /**
   * Remove a filter from the query
   *
   * @param string $field
   * the facet field to remove
   *
   * @param string $value
   * The facet value to remove
   * This value can be NULL
   */
  function remove_filter($field, $value = NULL);
  
  /**
   * Add a filter to a query
   *
   * @param string $field
   *   the facet field to apply to this query
   *
   * @param string value
   *   the value of the facet to apply
   *
   * @param boolean $exclude
   *   Optional paramter.  If TRUE, the filter will be negative,
   *   meaning that matching values will be excluded from the
   *   result set.
   */
  function add_filter($field, $value, $exclude = FALSE);
  
  /**
   * Return the search path (including the search keywords).
   */
  function get_path();
  
  /**
   * Return any query string for use in the l function.
   *
   * @see l()
   */
  function get_url_querystring();
  
  /**
   * return the basic string query
   */
  function get_query_basic();
  
  /**
   * Set the solrsort.
   *
   * @param string raw string to set the sort to
   */
  function set_solrsort($sortstring);
  
  /**
   * Return an array of all filters.
   */
  function get_filters($name = NULL);
  
  /**
   * Add a subquery to the query.
   *
   * @param Drupal_Solr_Query_Interface $query
   *   The query to add to the orginal query - may have keywords or filters.
   *
   * @param string $fq_operator
   *   The operator to use within the filter part of the subquery
   *
   * @param string $q_operator
   *   The operator to use in joining the subquery to
   *   the main keywords.  Note - this is unlikely to work
   *   with the Dismax handler when the main query is only
   *   keywords.
   */
  function add_subquery(Drupal_Solr_Query_Interface $query, $fq_operator = 'OR', $q_operator = 'AND');
  
  /**
   * return the sorts that are provided by the query object
   *
   * @return array all the sorts provided
   */
  function get_available_sorts();
  
  /**
   * Remove a specific subquery
   *
   * @param Drupal_Solr_Query_Interface $query
   * the query to remove
   */
  function remove_subquery(Drupal_Solr_Query_Interface $query);
  
  /**
   * remove all subqueries
   */
  function remove_subqueries();
  
  /**
   * make a sort available
   */
  function set_available_sort($field, $sort);
}