<?php
// $Id: feedapi.module,v 1.23 2007-07-24 16:17:40 aronnovak Exp $

/**
 * @file
 * Handle the submodules (for feed and item processing)
 * Provide a basic management of feeds
 */

/**
 * Implementation of hook_help().
 */
function feedapi_help($section) {
  switch ($section) {
    case 'admin/help#feedapi':
      return t('Provides feed management interface and handle underlying processors and parsers for any type of feeds.');
  }
}

/**
 * Implementation of hook_menu().
 */
function feedapi_menu($may_cache) {
  if ($may_cache) {
     $items[] = array(
       'path' => 'admin/content/feed',
       'title' => t('Feed'),
       'callback' => 'feedapi_management_page',
       'access' => user_access('administer feedapi'),
     );
     $items[] = array(
       'path' => 'admin/content/feed/list',
       'title' => t('List'),
       'type' => MENU_DEFAULT_LOCAL_TASK,
       'weight' => -15,
     );
     $items[] = array(
       'path' => 'feed/add',
       'title' => t('Create feed'),
       'callback' => 'drupal_get_form',
       'callback arguments' => array('feedapi_add_page'),
       'access' => user_access('handle own feeds') || user_access('administer feedapi'),
     );
     $items[] = array('path' => 'admin/settings/feedapi',
       'title' => t('FeedAPI settings'),
       'callback' => 'drupal_get_form',
       'callback arguments' => array('feedapi_admin_settings'),
       'type' => MENU_NORMAL_ITEM,
       'access' => user_access('administer feedapi'),
     );
  }
  else if (arg(0) == 'feed' && is_numeric(arg(1))) {
    global $user;
    $feed = new stdClass();
    $feed->fid = arg(1);
    feedapi_invoke_feedapi("load", $feed);
    $own_feed = $feed->uid == $user->uid && user_access('handle own feeds') ? TRUE : FALSE;
    $items[] = array('path' => 'feed/'. arg(1) .'/delete', 'title' => t('Delete'),
      'callback' => 'drupal_get_form',
      'callback arguments' => array('feedapi_delete_confirm', $feed),
      'access' => user_access('administer feedapi') || $own_feed,
      'type' => MENU_CALLBACK
    );
    $items[] = array('path' => 'feed/'. arg(1) .'/refresh', 'title' => t('Refresh'),
      'callback' => 'feedapi_invoke_feedapi',
      'callback arguments' => array("refresh", $feed),
      'access' => user_access('administer feedapi') || $own_feed,
      'type' => MENU_CALLBACK
    );
    $items[] = array('path' => 'feed/'. arg(1) .'/edit', 'title' => t('Edit'),
      'callback' => 'drupal_get_form',
      'callback arguments' => array('feedapi_edit_page', $feed),
      'access' => user_access('administer feedapi') || $own_feed,
      'type' => MENU_CALLBACK
    );
  }
  return $items;
}

/**
 * Implementation of hook_perm().
 */
function feedapi_perm() {
  return array('administer feedapi', 'handle own feeds');
}

/**
 * Do various things with feed. Handle the core data and call the
 * underyling modules (parsers/processors) too
 *
 * @param $op
 *  "load"    Load the feed. $param can be:
 *              "no" - the feed object won't have items member
 *              "info" - only the nid, fid, fiid data members will put ito each item
 *              "full" - the whole stored structure will be fetched into items
 * "refresh"  Re-download the feed and process newly arrived item
 * "purge"    Delete the feed and all connected things (eg. items)
 * "save"     Save the feed
 * "update"   Update the feed
 * 
 * FIXME: maybe split into private functions
 * 
 * @param $feed
 *  A feed object. If only the ID is known, you should pass something like this: $feed->fid = X 
 * @param $param
 *  Depends on the $op value.
 */
function feedapi_invoke_feedapi($op, &$feed, $param = NULL) {
  if (!is_object($feed)) {
    return FALSE;
  }
  $user = isset($feed->user) || isset($feed->uid) ? user_load(array('name' => $feed->user, 'uid' => $feed->uid)) : NULL;
  if (!isset($user->uid) || $user->uid == 0) {
    global $user;
  }
  _feedapi_sanitize_processors($feed);
  switch ($op) {
    case 'load':
      $load_items = $param;
      $feed = db_fetch_object(db_query("SELECT * FROM {feedapi} WHERE fid = %d", $feed->fid));
      $feed->parsers = unserialize($feed->parsers);
      $feed->processors_item = unserialize($feed->processors_item);
      $feed->processors_feed = unserialize($feed->processors_feed);
      _feedapi_sanitize_processors($feed);
      $feed->options = new stdClass();
      // Load additional elements provided by the processors
      foreach ($feed->processors_feed as $processor) {
        $feed = module_invoke($processor, "feedapi_load", $feed);
      }
      if ($load_items == "info" || $load_items == "full") {
        $feed->items = array();
        foreach ($feed->processors_item as $processor) {
          $items = module_invoke($processor, "feedapi_item_fetch_items", $feed);
          $feed->items += is_array($items) ? $items : array();
        }
      }
      if ($load_items == "full") {
        foreach ($feed->items as $key => $item) {
          foreach ($feed->processors_item as $processor) {
            $item = module_invoke($processor, "feedapi_item_load", $item);
            $feed->items[$key] = $item;
          }
        }
      }
      module_invoke_all('feedapi_after_load', $feed);
      break;

    case 'refresh':
      $cron = $param;
      $goto = user_access('administer feedapi') ? 'admin/content/feed' : drupal_init_path();
      feedapi_invoke_feedapi("load", $feed, "info");
      if (!is_array($feed->processors_item) || count($feed->processors_item) == 0) {
        if (!$cron) {
          drupal_set_message(t("This feed (%url) doesn't have any item processor. It's not possible to refresh the feed.", array('%url' => $feed->url)), "error");
          drupal_goto($goto);
        }
        return;
      }
      if (!is_array($feed->processors_feed) || count($feed->processors_feed) == 0) {
        if (!$cron) {
          drupal_set_message(t("This feed (%url) doesn't have any feed processor. It's not possible to refresh the feed.", array('%url' => $feed->url)), "error");
          drupal_goto($goto);
        }
        return;
      }
      $processors_item = $feed->processors_item;
      $processors_feed = $feed->processors_feed;
      // Force the processors to delete old items and determine the max. create elements
      $max_new_items = variable_get('feedapi_refresh_once', 10);
      foreach ($feed->processors_feed as $processor) {
        module_invoke($processor, 'feedapi_expire', $feed, $cron === TRUE ? FALSE : TRUE);
      }
      $feed = _feedapi_call_parsers($feed, $feed->parsers);
      $feed->processors_item = $processors_item;
      $feed->processors_feed = $processors_feed;
      $items = array_reverse($feed->items);
      $updated = 0;
      $new = 0;
      // Walk through the items
      foreach ($items as $item) {
        // Call each item parser
        $is_updated = FALSE;
        $is_new = FALSE;
        foreach ($feed->processors_item as $processor) {
          if (!module_invoke($processor, 'feedapi_item_unique', $item, $feed->fid)) {
            module_invoke($processor, 'feedapi_item_update', $item, $feed->fid);
            $is_updated = TRUE;
          }
          else {
            module_invoke($processor, 'feedapi_item_save', $item, $feed->fid);
            $is_new = TRUE;
          }
        }
        $new = $is_new ? $new + 1 : $new;
        $updated = ($is_updated && !$is_new) ? $updated + 1 : $updated;
        // If we consumed the max new item limit -> stop
        if ($max_new_items == $new) {
          break;
        }
      }
      db_query("UPDATE {feedapi} SET checked = %d WHERE fid = %d", time(), $feed->fid);
      module_invoke_all('feedapi_after_refresh', $feed);
      if (!$cron) {
        drupal_set_message(t("%new feed item(s) are created and %updated feed items are updated.", array("%new" => $new, "%updated" => $updated)));
        drupal_goto($goto);
      }
      break;

    case 'purge':
      feedapi_invoke_feedapi("load", $feed, "info");
      // Delete items from the processors
      foreach ($feed->items as $item) {
        foreach($feed->processors_item as $processor) {
          module_invoke($processor, 'feedapi_item_delete', $item);
        }
      }
      // Delete feed from the processors
      foreach($feed->processors_feed as $processor) {
        module_invoke($processor, 'feedapi_delete', $feed);
      }
      // Delete core data
      db_query("DELETE FROM {feedapi} WHERE fid = %d", $feed->fid);
      module_invoke_all('feedapi_after_purge', $feed);
      drupal_goto("admin/content/feed");
      break;
      
    case 'save':
      db_query("INSERT INTO {feedapi} (
        url, feed_type, processors_item, processors_feed,
        parsers, refresh, checked, uid) VALUES
        ('%s', '%s', '%s', '%s', '%s', %d, %d, %d)", 
        $feed->url, $feed->feed_type, serialize($feed->processors_item),
        serialize($feed->processors_feed), serialize($feed->parsers),
        $feed->refresh, 0, // Means that the feed have never been refreshed yet
        $user->uid
      );
      $feed->fid = db_result(db_query("SELECT fid FROM {feedapi} WHERE url = '%s'", $feed->url));
      // Parse the feed with the parsers
      $title = $feed->title;
      $description = $feed->description;
      $feed = _feedapi_call_parsers($feed, $feed->parsers);
      // If the user provided a title and a description, drop the parsers' extracted
      $feed->title = !empty($title) ? $title : $feed->title;
      $feed->description = !empty($description) ? $description : $feed->description;
      foreach ($feed->processors_feed as $processor) {
        $feed = module_invoke($processor, 'feedapi_save', $feed);
      }
      module_invoke_all('feedapi_after_save', $feed);
      drupal_set_message(t('The %feed feed (%url) was saved successfully.', array('%feed' => $feed->title, '%url' => $feed->url)));
      // Tell the user if the feed is currently not usable
      if (strlen($feed->feed_type) < 1
          || !module_exists($feed->parsers['primary']) 
          || !module_exists($feed->processors_feed[0]) 
          || !module_exists($feed->processors_item[0])) {
        drupal_set_message(t('The feed is not usable now, because there is no suitable processors and parser in the system'));
      }
      break;
      
    case 'update':
      // Store the common things
      db_query("UPDATE {feedapi} SET
        feed_type = '%s', url = '%s', processors_item = '%s',
        processors_feed = '%s', parsers = '%s', refresh = %d,
        checked = %d, uid = %d WHERE fid = %d",
        $feed->feed_type, $feed->url, serialize($feed->processors_item),
        serialize($feed->processors_feed), serialize($feed->parsers), $feed->refresh,
        $feed->checked, $user->uid, $feed->fid
      );
      // Parse the feed with the parsers
      $title = $feed->title;
      $description = $feed->description;
      $feed = _feedapi_call_parsers($feed, $feed->parsers);
      // If the user provided a title and a description, drop the parsers' extracted
      $feed->title = !empty($title) ? $title : $feed->title;
      $feed->description = !empty($description) ? $description : $feed->description;
      // Call the enabled feed processors
      foreach ($feed->processors_feed as $processor) {
        // Check if the feed processor has this feed or not
        $feed_try_load = new stdClass();
        $feed_try_load->options = new stdClass();
        $feed_try_load->fid = $feed->fid;
        if (module_invoke($processor, 'feedapi_load', $feed_try_load) === FALSE) {
          $feed = module_invoke($processor, 'feedapi_save', $feed);
        }
        else {
          $feed = module_invoke($processor, 'feedapi_update', $feed);
        }
      }
      module_invoke_all('feedapi_after_update', $feed);
      drupal_set_message(t('The %feed feed (%url) was updated successfully.', array('%feed' => $feed->title, '%url' => $feed->url)));
      break;
  }
}

/**
 * Implementation of hook_cron().
 */
function feedapi_cron() {
  $result = db_query_range("SELECT fid FROM {feedapi} ORDER BY checked ASC", 0, variable_get('feedapi_cron_max', 5));
  while ($fid = db_result($result, $row++)) {
    $feed = new stdClass();
    $feed->fid = $fid;
    feedapi_invoke_feedapi('load', $feed);
    feedapi_invoke_feedapi('refresh', $feed, TRUE);
  }
}

/**
 * Menu callback -- ask for confirmation of feed deletion
 */
function feedapi_delete_confirm($feed) {
 $form['fid'] = array('#type' => 'value', '#value' => $feed->fid);
 return confirm_form($form,
   t('Are you sure you want to delete %title?', array('%title' => $feed->title)),
   'admin/content/feed',
   t('This action cannot be undone.'),
   t('Delete'), t('Cancel'));
}

/**
 * Execute feed deletion
 */
function feedapi_delete_confirm_submit($form_id, $form_values) {
  if ($form_values['confirm']) {
    $feed = new stdClass();
    $feed->fid = $form_values['fid'];
    feedapi_invoke_feedapi("purge", $feed);
  }
}

/**
 * Provide a UI for overviewing the existing feeds
 */
function feedapi_management_page() {
  $header = array(t('URL'),
    t('Refresh interval'),
    t('Last refresh'),
    t('Title'),
    t('Commands')  
  );
  $rows = array();
  $result = db_query("SELECT fid from {feedapi}");
  while ($fid = db_result($result, $row++)) {
    $commands = array(l(t('Delete'), 'feed/'. $fid . '/delete'),
      l(t('Refresh'), 'feed/'. $fid . '/refresh'),
      l(t('Edit'), 'feed/'. $fid . '/edit'),
    );
    $ext_commands = module_invoke_all('feedapi_edit_option', $fid);
    if (count($ext_commands) > 0) {
      foreach ($ext_commands as $command) {
        $commands[] = l($command['name'], $command['link']);
      }
    } 
    $feed = new stdClass();
    $feed->fid = $fid;
    feedapi_invoke_feedapi("load", $feed);
    $rows[] = array($feed->url,
      format_interval($feed->refresh),
      $feed->checked == 0 ? t('Never') : format_interval(time() - $feed->checked) ." ". t("ago"),
      $feed->title,
      theme_item_list($commands)
    );
  }
  return theme_table($header, $rows);
}

/**
 * Provide UI for edit a feed
 */
function feedapi_edit_page($feed) {
  $form = _feedapi_common_form($feed);
  foreach (array('fid', 'feed_type', 'checked') as $value) {
    $form[$value] = array('#type' => 'hidden', '#value' => $feed->{$value});
  }
  // Select from the parsers and the processors
  $all = strlen($feed->feed_type) < 1 ? TRUE : FALSE;
  $form['processors_feed'] = array('#type' => 'checkboxes',
    '#options' => _feedapi_suitable_feed_processors($feed->feed_type, $all),
    '#default_value' => $feed->processors_feed,
    '#title' => t('Feed processor'),
  );
  $form['processors_item'] = array('#type' => 'checkboxes',
    '#options' => _feedapi_suitable_item_processors($feed->feed_type, $all),
    '#default_value' => $feed->processors_item,
    '#title' => t('Feed item processor'),
  );
  $parsers = _feedapi_suitable_parsers($feed->feed_type, $all);
  $form['primary'] = array('#type' => 'radios',
    '#title' => t('Primary parser'),
    '#options' => $parsers,
    '#default_value' => $feed->parsers['primary'],
    '#required' => TRUE,
  );
  $form['secondary'] = array('#type' => 'checkboxes',
    '#title' => t('Secondary parsers'),
    '#options' => $parsers,
    '#default_value' => $feed->parsers['secondary'],
  );
  $form['processors_settings'] = array('#type' => 'fieldset',
    '#title' => t('The currently enabled processors\' settings'),
    '#collapsible' => TRUE,
    '#collapsed' => FALSE,
  );
  $form['submit'] = array('#type' => 'submit', '#value' => t('Submit'));
  return $form;
}

/**
 * Validate as the submission
 */
function feedapi_edit_page_validate($form_id, $form_values) {
  $feed = new stdClass();
  $feed->url = $form_values['url'];
  foreach ($form_values['processors_feed'] as $processor) {
    $feed = module_invoke($processor, 'feedapi_validate', $form_id, $form_values, $feed);
  }
  // Check if the selected parser-processor configuration has a common type
  $type = module_invoke($form_values['primary'], 'feedapi_type');
  $type = is_array($type) ? $type : array();
  foreach ($form_values['processors_item'] as $processor => $turned) {
    if ($turned && !empty($processor)) {
      $type = array_intersect($type, module_invoke($processor, 'feedapi_type'));
    }
  }
  foreach ($form_values['processors_feed'] as $processor => $turned) {
    if ($turned  && !empty($processor)) {
      $type = array_intersect($type, module_invoke($processor, 'feedapi_type'));
    }
  }
  if (count($type) == 0) {
    form_set_error('feedapi', t('You have selected an invalid parser-processor configuration.'), 'error');
  }
}

/**
 * Construct parsers and processors data structures and call update
 */
function feedapi_edit_page_submit($form_id, $form_values) {
  $feed = new stdClass();
  $feed->parsers = array();
  $feed->parsers['primary'] = $form_values['primary'];
  $feed->parsers['secondary'] = array();
  foreach ($form_values['secondary'] as $parser => $turned) {
    if ($turned) {
      $feed->parsers['secondary'][] = $parser;
    }
  }
  if (strlen($form_values['feed_type']) < 1) {
    // Check the feed against the main parser to get the type
    $form_values['feed_type'] = module_invoke($feed->parsers['primary'], 'feed_compatible', $form_values['url']);
  }
  $feed->processors_item = array_values($form_values['processors_item']);
  $feed->processors_feed = array_values($form_values['processors_feed']);
  $feed = (object) array_merge($form_values, (array) $feed);
  feedapi_invoke_feedapi("update", $feed);
  drupal_goto('admin/content/feed');
}

/**
 * Provide a UI for create a feed
 */
function feedapi_add_page() {
  $form = _feedapi_common_form();
  $form['advanced'] = array('#type' => 'checkbox',
    '#title' => t('Show me the advanced parser/processor configuration'),
    '#default_value' => FALSE,
    '#description' => t('After the feed will be created, you will be able to edit the assigned parsers and processors.'),
  );
  $form['submit'] = array('#type' => 'submit', '#value' => t('Submit'));
  return $form;
}

/**
 * Let the feed processor allow or reject the given URL
 */
function feedapi_add_page_validate($form_id, $form_values) {
  $feed = new stdClass();
  $feed->url = $form_values['url'];
  $assigned = _feedapi_assign_parser_processor($feed->url);
  $feed = module_invoke($assigned['processor_feed'], 'feedapi_validate', $form_id, $form_values, $feed);
  if (db_result(db_query("SELECT fid FROM {feedapi} WHERE url = '%s'", $feed->url))) {
    form_set_error('feedapi', t('The feed URL provided already exists. Please use a different URL.'));
  }
}

/**
 * Create the feed and invoke the the assigned processor
 */
function feedapi_add_page_submit($form_id, $form_values) {
  // Assign one parser and one processor to the URL
  $assigned = _feedapi_assign_parser_processor($form_values['url']);
  $feed = new stdClass();
  $feed = (object) array_merge($form_values, (array) $feed);
  $feed->parsers = array();
  // We store it in such structures because the user will be able to assign more parsers and processors to one feed later
  $feed->parsers['primary'] = $assigned['parser'];
  $feed->parsers['secondary'] = array();
  $feed->feed_type = $assigned['type'];
  $feed->processors_item = array($assigned['processor_item']);
  $feed->processors_feed = array($assigned['processor_feed']);
  // Store the common things
  feedapi_invoke_feedapi('save', $feed);
  drupal_goto(($form_values['advanced'] == TRUE) ? 'feed/'. $feed->fid. '/edit' : drupal_init_path());
}

/**
 * Settings:
 *  Allowed HTML tags, number of feeds refreshed in one round
 */
function feedapi_admin_settings() {
  $form['feedapi_allowed_html_tags'] = array(
    '#type' => 'textfield', '#title' => t('Allowed HTML tags'), '#size' => 80, '#maxlength' => 255,
    '#default_value' => variable_get('feedapi_allowed_html_tags', '<a> <b> <br> <dd> <dl> <dt> <em> <i> <li> <ol> <p> <strong> <u> <ul>'),
    '#description' => t('The list of tags which are allowed in feeds, i.e., which will not be removed by Drupal.')
  );
  $form['feedapi_cron_max'] = array(
    '#type' => 'textfield', '#title' => t('Per-cron feeds refresh'), '#size' => 3, '#maxlength' => 10,
    '#default_value' => variable_get('feedapi_cron_max', 5),
    '#description' => t('How much feed should be refreshed in one cron run maximally')
  );
  
  $form['feedapi_refresh_once'] = array(
    '#type' => 'textfield', '#title' => t('Maximal number of items updated/created in one refresh round'), '#size' => 5, '#maxlength' => 7,
    '#default_value' => variable_get('feedapi_refresh_once', 10),
  );
  $form['advanced'] = array('#type' => 'fieldset',
    '#title' => t('Default parser and processor configuration'),
    '#description' => t('These will be used first when the detection mechanism try to assign a suitable parser and processor to the feed.
                         If these values are set to the most common situation, the feed-creation can be much faster.'),
    '#collapsible' => TRUE,
    '#collapsed' => TRUE,
  );
  
  $form['advanced']['parser'] = array('#type' => 'fieldset',
    '#title' => t('Parsers order'),
    '#description' => t('The lighter parser will be tried out earlier.'),
    '#collapsible' => TRUE,
    '#collapsed' => TRUE,
  );
  // Walk through all the possible processors - not just for one feed type's
  $parsers = _feedapi_suitable_parsers('', TRUE);
  foreach ($parsers as $parser) {
    $form['advanced']['parser']['feedapi_weight_parser_'. $parser] = array(
      '#type' => 'weight',
      '#title' => $parser,
      '#delta' => 10,
      '#default_value' => variable_get('feedapi_weight_parser_'. $parser, 0),
    );
  }
  $form['advanced']['feed_processor'] = array('#type' => 'fieldset',
    '#title' => t('Feed processors order'),
    '#description' => t('The lighter feed processor will be tried out earlier.'),
    '#collapsible' => TRUE,
    '#collapsed' => TRUE,
  );
  // Walk through all the possible processors - not just for one feed type's
  $processors = _feedapi_suitable_feed_processors('', TRUE);
  foreach ($processors as $feed_processor) {
    $form['advanced']['feed_processor']['feedapi_weight_feed_processor_'. $feed_processor] = array(
      '#type' => 'weight',
      '#title' => $feed_processor,
      '#delta' => 10,
      '#default_value' => variable_get('feedapi_weight_feed_processor_'. $feed_processor, 0),
    );
  }
  
  $form['advanced']['item_processor'] = array('#type' => 'fieldset',
    '#title' => t('Feed item processors order'),
    '#description' => t('The lighter feed item processor will be tried out earlier.'),
    '#collapsible' => TRUE,
    '#collapsed' => TRUE,
  );
  // Walk through all the possible item processors - not just for one feed type's
  $processors = _feedapi_suitable_item_processors('', TRUE);
  foreach ($processors as $item_processor) {
    $form['advanced']['item_processor']['feedapi_weight_item_processor_'. $item_processor] = array(
      '#type' => 'weight',
      '#title' => $item_processor,
      '#delta' => 10,
      '#default_value' => variable_get('feedapi_weight_item_processor_'. $item_processor, 0),
    );
  }
  return system_settings_form($form);
}

/**
 * Get the list of the parsers for the given feed type
 * 
 * @param $type
 *  The descriptor of the feed type. For eg. "XML feed"
 * @param $all
 *  If you set this to TRUE, all the parsers will be returned (not check the type)
 * @return
 *  An associative array with the names of the suitable parsers
 */
function _feedapi_suitable_parsers($type, $all = FALSE) {
  $req = array('feedapi_type', 'feedapi_parse');
  return _feedapi_check_requirement($type, $req, $all);
}

/**
 * Execute the enabled parsers and create an unified output
 *
 * @param $feed
 *  Feed object
 * @param $parsers
 *  Structure: array(
 *    "primary" => "parser_primary",
 *    "secondary" => array("parser1", "parser2", "parserN")
 *  );
 * @return
 *  The object of the parser data
 */
function _feedapi_call_parsers($feed, $parsers) {
  $fid = $feed->fid;
  if (module_exists($parsers["primary"])) {
    $parser_output =  module_invoke($parsers["primary"], "feedapi_parse", $feed);
    $feed = (object) array_merge((array) $feed, (array) $parser_output);
  }
  // Call the turned on parsers, create an union of returned options
  foreach ($parsers["secondary"] as $parser) {
    $feed_ext = module_invoke($parser, "feedapi_parse", $feed);
    $feed->options = (object) ((array) $feed->options + (array) $feed_ext->options);
  }
  $feed->fid = $fid;
  // Filter bad or not allowed tags
  $allowed = preg_split('/\s+|<|>/', variable_get('feedapi_allowed_html_tags', '<a> <b> <br> <dd> <dl> <dt> <em> <i> <li> <ol> <p> <strong> <u> <ul>'), -1, PREG_SPLIT_NO_EMPTY);
  foreach (array('title', 'description') as $property) {
    if (isset($feed->{$property})) {
      if (is_string($feed->{$property})) {
        $feed->{$property} = filter_xss($feed->{$property}, $allowed);
      }
    }
  }
  for ($i = 0; $i < count($feed->items); $i++) {
    $feed->items[$i]->title = filter_xss($feed->items[$i]->title, $allowed);
    $feed->items[$i]->description = filter_xss($feed->items[$i]->description, $allowed);
  }
  return $feed;
}

/**
 * Auto-detect one possible parser and one feed and item processor to the given URL
 * It follows the order of the modules from the module's settings page
 *
 * @param $url
 *  The fully-qualified URL of the feed
 */
function _feedapi_assign_parser_processor($url) {
  $parsers = _feedapi_suitable_parsers('', TRUE);
  // Get the parsers' weight
  $sorted_parsers = array();
  foreach ($parsers as $parser) {
    $sorted_parsers[variable_get('feedapi_weight_parser_'. $parser, 0)][] = $parser;
  }
  $success = FALSE;
  $keys = array_keys($sorted_parsers);
  if (count($keys) > 0) {
    $low = min($keys);
    $max = max($keys);
    // Call the ordered parsers to find one compatible
    for ($i = $low; $i <= $max; $i++) {
      if (isset($sorted_parsers[$i])) {
        foreach ($sorted_parsers[$i] as $parser) {
          $type = module_invoke($parser, 'feedapi_compatible', $url);
          $i =  is_string($type) ? $max + 2: $i;
          $success = is_string($type) ? TRUE : $success;
        }
      }
    }
  }
  if (!$success) {
    // We can't found a suitable parser at all
    return array('type' => '', 'parser' => '', 'processor_feed' => '', 'processor_item' => '');
  }
  // Get the feed processor's weight
  $processors_feed = _feedapi_suitable_feed_processors($type);
  foreach ($processors_feed as $processor) {
    $sorted_feed_processors[variable_get('feedapi_weight_feed_processor_'. $processor, 0)][] = $processor;
  }
  // Get the feed item processor's weight
  $processors_item = _feedapi_suitable_item_processors($type);
  foreach ($processors_item as $processor) {
    $sorted_item_processors[variable_get('feedapi_weight_item_processor_'. $processor, 0)][] = $processor;
  }
  return array(
    'type' => $type,
    'parser' => $parser,
    'processor_feed' => array_shift($sorted_feed_processors[min(array_keys($sorted_feed_processors))]),  // lightest item processor
    'processor_item' => array_shift($sorted_item_processors[min(array_keys($sorted_item_processors))])   // lightest feed processor
  );
}

/**
 * Collect a list of an arrays that fulfill the given requirements (hooks and type)
 * 
 * @param $type
 *  The descriptor of the feed type. For eg. "XML feed"
 * @param $all
 *  If you set this to TRUE, all the feed processors will be returned (not check the type)
 * @return
 *  An associative array with the names of the suitable feed processors
 */
function _feedapi_check_requirement($type, $hooks, $all) {
  $possible = array();
  $suitable = array();
  for ($i = count($hooks) - 1; $i >= 0; $i--) {
    $hooks[$i] = module_implements($hooks[$i]);
  }
  $possible = call_user_func_array('array_intersect', $hooks);
  foreach ($possible as $parser) {
    $types = module_invoke($parser, "feedapi_type");
    if (in_array($type, $types) || $all) {
      $suitable[] = $parser;
    }
  }
  return drupal_map_assoc($suitable);
}

/**
 * Get the list of the feed processors for the given feed type
 *
 * @param $type
 *  The descriptor of the feed type. For eg. "XML feed"
 * @param $all
 *  If you set this to TRUE, all the feed processors will be returned (not check the type)
 * @return
 *  An associative array with the names of the suitable feed processors
 */
function _feedapi_suitable_feed_processors($type, $all = FALSE) {
  $req = array('feedapi_type', 'feedapi_save', 'feedapi_update',
               'feedapi_delete', 'feedapi_expire', 'feedapi_load',
               'feedapi_validate', 'feedapi_get',
  );
  return _feedapi_check_requirement($type, $req, $all);
}

/**
 * Get the list of the item processors for the given feed type
 *
 * @param $type
 *  The descriptor of the feed type. For eg. "XML feed"
 * @param $all
 *  If you set this to TRUE, all the item processors will be returned (not check the type)
 * @return
 *  An associative array with the names of the suitable feed processors
 */
function _feedapi_suitable_item_processors($type, $all = FALSE) {
  $req = array('feedapi_type', 'feedapi_item_save', 'feedapi_item_update',
               'feedapi_item_delete', 'feedapi_item_load',
               'feedapi_item_unique', 'feedapi_item_fetch_items',
  );
  return _feedapi_check_requirement($type, $req, $all);
}

/**
 * Common form parts of editing/creating a feed
 */
function _feedapi_common_form($feed = FALSE) {
  $period = drupal_map_assoc(array(900, 1800, 3600, 7200, 10800, 21600, 32400, 43200, 64800, 86400, 172800, 259200, 604800, 1209600, 2419200), 'format_interval');
  $form['url'] = array('#type' => 'textfield',
    '#title' => t('URL'),
    '#description' => t('The fully-qualified URL of the feed.'),
    '#maxlength' => 255,
    '#required' => TRUE,
  );
  $form['title'] = array('#type' => 'textfield',
    '#title' => t('Title'),
    '#maxlength' => 64,
    '#description' => 'If you fill this field, the title from the feed will be overwritten by this',
    '#required' => FALSE,
  );
  $form['description'] = array('#type' => 'textarea',
    '#title' => t('Description'),
    '#description' => 'If you fill this field, the description from the feed will be overwritten by this',
  );
  $form['refresh'] = array('#type' => 'select',
    '#title' => t('Update interval'),
    '#options' => $period,
    '#description' => t('The refresh interval indicating how often you want to update this feed. Requires crontab.'),
  );
  if (user_access('administer feedapi')) {
    $form['user'] = array(
        '#type' => 'textfield',
        '#title' => t('The owner of the feed'),
        '#autocomplete_path' => 'user/autocomplete',
      );
  }
  if (is_object($feed)) {
    $form['url']['#default_value'] = isset($feed->url) ? $feed->url : '';
    $form['title']['#default_value'] = isset($feed->title) ? $feed->title : '';
    $form['description']['#default_value'] = isset($feed->description) ? $feed->description : '';
    $form['refresh']['#default_value'] = isset($feed->refresh) ? $feed->refresh : 900;
    if (user_access('administer feedapi')) {
      $user = user_load(array('uid' => $feed->uid));
      $form['user']['#default_value'] = $user->name;
    }
  }
  return $form;
}

/**
 * Remove non-existing processors from the processors arrays
 */
function _feedapi_sanitize_processors(&$feed) {
  foreach (array('processors_feed', 'processors_item') as $proc) {
    if (is_array($feed->{$proc})) {
      foreach ($feed->{$proc} as $key => $processor) {
        if (!module_exists($processor)) {
          unset($feed->{$proc}[$key]);
        }
      }
    }
  }
}