aggregator.module

<?php


/**
 * @file
 * Used to aggregate syndicated content (RSS, RDF, and Atom).
 */

/**
 * Denotes that a feed's items should never expire.
 */
define('AGGREGATOR_CLEAR_NEVER', 0);

/**
 * Implements hook_help().
 */
function aggregator_help($path, $arg) {
    switch ($path) {
        case 'admin/help#aggregator':
            $output = '';
            $output .= '<h3>' . t('About') . '</h3>';
            $output .= '<p>' . t('The Aggregator module is an on-site syndicator and news reader that gathers and displays fresh content from RSS-, RDF-, and Atom-based feeds made available across the web. Thousands of sites (particularly news sites and blogs) publish their latest headlines in feeds, using a number of standardized XML-based formats. For more information, see the online handbook entry for <a href="@aggregator-module">Aggregator module</a>.', array(
                '@aggregator-module' => 'http://drupal.org/documentation/modules/aggregator',
                '@aggregator' => url('aggregator'),
            )) . '</p>';
            $output .= '<h3>' . t('Uses') . '</h3>';
            $output .= '<dl>';
            $output .= '<dt>' . t('Viewing feeds') . '</dt>';
            $output .= '<dd>' . t('Feeds contain published content, and may be grouped in categories, generally by topic. Users view feed content in the <a href="@aggregator">main aggregator display</a>, or by <a href="@aggregator-sources">their source</a> (usually via an RSS feed reader). The most recent content in a feed or category can be displayed as a block through the <a href="@admin-block">Blocks administration page</a>.', array(
                '@aggregator' => url('aggregator'),
                '@aggregator-sources' => url('aggregator/sources'),
                '@admin-block' => url('admin/structure/block'),
            )) . '</a></dd>';
            $output .= '<dt>' . t('Adding, editing, and deleting feeds') . '</dt>';
            $output .= '<dd>' . t('Administrators can add, edit, and delete feeds, and choose how often to check each feed for newly updated items on the <a href="@feededit">Feed aggregator administration page</a>.', array(
                '@feededit' => url('admin/config/services/aggregator'),
            )) . '</dd>';
            $output .= '<dt>' . t('OPML integration') . '</dt>';
            $output .= '<dd>' . t('A <a href="@aggregator-opml">machine-readable OPML file</a> of all feeds is available. OPML is an XML-based file format used to share outline-structured information such as a list of RSS feeds. Feeds can also be <a href="@import-opml">imported via an OPML file</a>.', array(
                '@aggregator-opml' => url('aggregator/opml'),
                '@import-opml' => url('admin/config/services/aggregator'),
            )) . '</dd>';
            $output .= '<dt>' . t('Configuring cron') . '</dt>';
            $output .= '<dd>' . t('A correctly configured <a href="@cron">cron maintenance task</a> is required to update feeds automatically.', array(
                '@cron' => 'http://drupal.org/cron',
            )) . '</dd>';
            $output .= '</dl>';
            return $output;
        case 'admin/config/services/aggregator':
            $output = '<p>' . t('Thousands of sites (particularly news sites and blogs) publish their latest headlines and posts in feeds, using a number of standardized XML-based formats. Formats supported by the aggregator include <a href="@rss">RSS</a>, <a href="@rdf">RDF</a>, and <a href="@atom">Atom</a>.', array(
                '@rss' => 'http://cyber.law.harvard.edu/rss/',
                '@rdf' => 'http://www.w3.org/RDF/',
                '@atom' => 'http://www.atomenabled.org',
            )) . '</p>';
            $output .= '<p>' . t('Current feeds are listed below, and <a href="@addfeed">new feeds may be added</a>. For each feed or feed category, the <em>latest items</em> block may be enabled at the <a href="@block">blocks administration page</a>.', array(
                '@addfeed' => url('admin/config/services/aggregator/add/feed'),
                '@block' => url('admin/structure/block'),
            )) . '</p>';
            return $output;
        case 'admin/config/services/aggregator/add/feed':
            return '<p>' . t('Add a feed in RSS, RDF or Atom format. A feed may only have one entry.') . '</p>';
        case 'admin/config/services/aggregator/add/category':
            return '<p>' . t('Categories allow feed items from different feeds to be grouped together. For example, several sport-related feeds may belong to a category named <em>Sports</em>. Feed items may be grouped automatically (by selecting a category when creating or editing a feed) or manually (via the <em>Categorize</em> page available from feed item listings). Each category provides its own feed page and block.') . '</p>';
        case 'admin/config/services/aggregator/add/opml':
            return '<p>' . t('<acronym title="Outline Processor Markup Language">OPML</acronym> is an XML format used to exchange multiple feeds between aggregators. A single OPML document may contain a collection of many feeds. Drupal can parse such a file and import all feeds at once, saving you the effort of adding them manually. You may either upload a local file from your computer or enter a URL where Drupal can download it.') . '</p>';
    }
}

/**
 * Implements hook_theme().
 */
function aggregator_theme() {
    return array(
        'aggregator_wrapper' => array(
            'variables' => array(
                'content' => NULL,
            ),
            'file' => 'aggregator.pages.inc',
            'template' => 'aggregator-wrapper',
        ),
        'aggregator_categorize_items' => array(
            'render element' => 'form',
            'file' => 'aggregator.pages.inc',
        ),
        'aggregator_feed_source' => array(
            'variables' => array(
                'feed' => NULL,
            ),
            'file' => 'aggregator.pages.inc',
            'template' => 'aggregator-feed-source',
        ),
        'aggregator_block_item' => array(
            'variables' => array(
                'item' => NULL,
                'feed' => 0,
            ),
        ),
        'aggregator_summary_items' => array(
            'variables' => array(
                'summary_items' => NULL,
                'source' => NULL,
            ),
            'file' => 'aggregator.pages.inc',
            'template' => 'aggregator-summary-items',
        ),
        'aggregator_summary_item' => array(
            'variables' => array(
                'item' => NULL,
            ),
            'file' => 'aggregator.pages.inc',
            'template' => 'aggregator-summary-item',
        ),
        'aggregator_item' => array(
            'variables' => array(
                'item' => NULL,
            ),
            'file' => 'aggregator.pages.inc',
            'template' => 'aggregator-item',
        ),
        'aggregator_page_opml' => array(
            'variables' => array(
                'feeds' => NULL,
            ),
            'file' => 'aggregator.pages.inc',
        ),
        'aggregator_page_rss' => array(
            'variables' => array(
                'feeds' => NULL,
                'category' => NULL,
            ),
            'file' => 'aggregator.pages.inc',
        ),
    );
}

/**
 * Implements hook_menu().
 */
function aggregator_menu() {
    $items['admin/config/services/aggregator'] = array(
        'title' => 'Feed aggregator',
        'description' => "Configure which content your site aggregates from other sites, how often it polls them, and how they're categorized.",
        'page callback' => 'aggregator_admin_overview',
        'access arguments' => array(
            'administer news feeds',
        ),
        'weight' => 10,
        'file' => 'aggregator.admin.inc',
    );
    $items['admin/config/services/aggregator/add/feed'] = array(
        'title' => 'Add feed',
        'page callback' => 'drupal_get_form',
        'page arguments' => array(
            'aggregator_form_feed',
        ),
        'access arguments' => array(
            'administer news feeds',
        ),
        'type' => MENU_LOCAL_ACTION,
        'file' => 'aggregator.admin.inc',
    );
    $items['admin/config/services/aggregator/add/category'] = array(
        'title' => 'Add category',
        'page callback' => 'drupal_get_form',
        'page arguments' => array(
            'aggregator_form_category',
        ),
        'access arguments' => array(
            'administer news feeds',
        ),
        'type' => MENU_LOCAL_ACTION,
        'file' => 'aggregator.admin.inc',
    );
    $items['admin/config/services/aggregator/add/opml'] = array(
        'title' => 'Import OPML',
        'page callback' => 'drupal_get_form',
        'page arguments' => array(
            'aggregator_form_opml',
        ),
        'access arguments' => array(
            'administer news feeds',
        ),
        'type' => MENU_LOCAL_ACTION,
        'file' => 'aggregator.admin.inc',
    );
    $items['admin/config/services/aggregator/remove/%aggregator_feed'] = array(
        'title' => 'Remove items',
        'page callback' => 'drupal_get_form',
        'page arguments' => array(
            'aggregator_admin_remove_feed',
            5,
        ),
        'access arguments' => array(
            'administer news feeds',
        ),
        'file' => 'aggregator.admin.inc',
    );
    $items['admin/config/services/aggregator/update/%aggregator_feed'] = array(
        'title' => 'Update items',
        'page callback' => 'aggregator_admin_refresh_feed',
        'page arguments' => array(
            5,
        ),
        'access arguments' => array(
            'administer news feeds',
        ),
        'file' => 'aggregator.admin.inc',
    );
    $items['admin/config/services/aggregator/list'] = array(
        'title' => 'List',
        'type' => MENU_DEFAULT_LOCAL_TASK,
        'weight' => -10,
    );
    $items['admin/config/services/aggregator/settings'] = array(
        'title' => 'Settings',
        'description' => 'Configure the behavior of the feed aggregator, including when to discard feed items and how to present feed items and categories.',
        'page callback' => 'drupal_get_form',
        'page arguments' => array(
            'aggregator_admin_form',
        ),
        'access arguments' => array(
            'administer news feeds',
        ),
        'type' => MENU_LOCAL_TASK,
        'file' => 'aggregator.admin.inc',
    );
    $items['aggregator'] = array(
        'title' => 'Feed aggregator',
        'page callback' => 'aggregator_page_last',
        'access arguments' => array(
            'access news feeds',
        ),
        'weight' => 5,
        'file' => 'aggregator.pages.inc',
    );
    $items['aggregator/sources'] = array(
        'title' => 'Sources',
        'page callback' => 'aggregator_page_sources',
        'access arguments' => array(
            'access news feeds',
        ),
        'file' => 'aggregator.pages.inc',
    );
    $items['aggregator/categories'] = array(
        'title' => 'Categories',
        'page callback' => 'aggregator_page_categories',
        'access callback' => '_aggregator_has_categories',
        'file' => 'aggregator.pages.inc',
    );
    $items['aggregator/rss'] = array(
        'title' => 'RSS feed',
        'page callback' => 'aggregator_page_rss',
        'access arguments' => array(
            'access news feeds',
        ),
        'type' => MENU_CALLBACK,
        'file' => 'aggregator.pages.inc',
    );
    $items['aggregator/opml'] = array(
        'title' => 'OPML feed',
        'page callback' => 'aggregator_page_opml',
        'access arguments' => array(
            'access news feeds',
        ),
        'type' => MENU_CALLBACK,
        'file' => 'aggregator.pages.inc',
    );
    $items['aggregator/categories/%aggregator_category'] = array(
        'title callback' => '_aggregator_category_title',
        'title arguments' => array(
            2,
        ),
        'page callback' => 'aggregator_page_category',
        'page arguments' => array(
            2,
        ),
        'access arguments' => array(
            'access news feeds',
        ),
        'file' => 'aggregator.pages.inc',
    );
    $items['aggregator/categories/%aggregator_category/view'] = array(
        'title' => 'View',
        'type' => MENU_DEFAULT_LOCAL_TASK,
        'weight' => -10,
    );
    $items['aggregator/categories/%aggregator_category/categorize'] = array(
        'title' => 'Categorize',
        'page callback' => 'drupal_get_form',
        'page arguments' => array(
            'aggregator_page_category_form',
            2,
        ),
        'access arguments' => array(
            'administer news feeds',
        ),
        'type' => MENU_LOCAL_TASK,
        'file' => 'aggregator.pages.inc',
    );
    $items['aggregator/categories/%aggregator_category/configure'] = array(
        'title' => 'Configure',
        'page callback' => 'drupal_get_form',
        'page arguments' => array(
            'aggregator_form_category',
            2,
        ),
        'access arguments' => array(
            'administer news feeds',
        ),
        'type' => MENU_LOCAL_TASK,
        'weight' => 1,
        'file' => 'aggregator.admin.inc',
    );
    $items['aggregator/sources/%aggregator_feed'] = array(
        'page callback' => 'aggregator_page_source',
        'page arguments' => array(
            2,
        ),
        'access arguments' => array(
            'access news feeds',
        ),
        'file' => 'aggregator.pages.inc',
    );
    $items['aggregator/sources/%aggregator_feed/view'] = array(
        'title' => 'View',
        'type' => MENU_DEFAULT_LOCAL_TASK,
        'weight' => -10,
    );
    $items['aggregator/sources/%aggregator_feed/categorize'] = array(
        'title' => 'Categorize',
        'page callback' => 'drupal_get_form',
        'page arguments' => array(
            'aggregator_page_source_form',
            2,
        ),
        'access arguments' => array(
            'administer news feeds',
        ),
        'type' => MENU_LOCAL_TASK,
        'file' => 'aggregator.pages.inc',
    );
    $items['aggregator/sources/%aggregator_feed/configure'] = array(
        'title' => 'Configure',
        'page callback' => 'drupal_get_form',
        'page arguments' => array(
            'aggregator_form_feed',
            2,
        ),
        'access arguments' => array(
            'administer news feeds',
        ),
        'type' => MENU_LOCAL_TASK,
        'weight' => 1,
        'file' => 'aggregator.admin.inc',
    );
    $items['admin/config/services/aggregator/edit/feed/%aggregator_feed'] = array(
        'title' => 'Edit feed',
        'page callback' => 'drupal_get_form',
        'page arguments' => array(
            'aggregator_form_feed',
            6,
        ),
        'access arguments' => array(
            'administer news feeds',
        ),
        'file' => 'aggregator.admin.inc',
    );
    $items['admin/config/services/aggregator/edit/category/%aggregator_category'] = array(
        'title' => 'Edit category',
        'page callback' => 'drupal_get_form',
        'page arguments' => array(
            'aggregator_form_category',
            6,
        ),
        'access arguments' => array(
            'administer news feeds',
        ),
        'file' => 'aggregator.admin.inc',
    );
    return $items;
}

/**
 * Title callback: Returns a title for aggregator category pages.
 *
 * @param $category
 *   An aggregator category.
 *
 * @return
 *   A string with the aggregator category title.
 */
function _aggregator_category_title($category) {
    return $category['title'];
}

/**
 * Determines whether there are any aggregator categories.
 *
 * @return
 *   TRUE if there is at least one category and the user has access to them;
 *   FALSE otherwise.
 */
function _aggregator_has_categories() {
    return user_access('access news feeds') && (bool) db_query_range('SELECT 1 FROM {aggregator_category}', 0, 1)->fetchField();
}

/**
 * Implements hook_permission().
 */
function aggregator_permission() {
    return array(
        'administer news feeds' => array(
            'title' => t('Administer news feeds'),
        ),
        'access news feeds' => array(
            'title' => t('View news feeds'),
        ),
    );
}

/**
 * Implements hook_cron().
 *
 * Queues news feeds for updates once their refresh interval has elapsed.
 */
function aggregator_cron() {
    $result = db_query('SELECT * FROM {aggregator_feed} WHERE queued = 0 AND checked + refresh < :time AND refresh <> :never', array(
        ':time' => REQUEST_TIME,
        ':never' => AGGREGATOR_CLEAR_NEVER,
    ));
    $queue = DrupalQueue::get('aggregator_feeds');
    foreach ($result as $feed) {
        if ($queue->createItem($feed)) {
            // Add timestamp to avoid queueing item more than once.
            db_update('aggregator_feed')->fields(array(
                'queued' => REQUEST_TIME,
            ))
                ->condition('fid', $feed->fid)
                ->execute();
        }
    }
    // Remove queued timestamp after 6 hours assuming the update has failed.
    db_update('aggregator_feed')->fields(array(
        'queued' => 0,
    ))
        ->condition('queued', REQUEST_TIME - 3600 * 6, '<')
        ->execute();
}

/**
 * Implements hook_cron_queue_info().
 */
function aggregator_cron_queue_info() {
    $queues['aggregator_feeds'] = array(
        'worker callback' => 'aggregator_refresh',
        'time' => 60,
    );
    return $queues;
}

/**
 * Implements hook_block_info().
 */
function aggregator_block_info() {
    $blocks = array();
    $result = db_query('SELECT cid, title FROM {aggregator_category} ORDER BY title');
    foreach ($result as $category) {
        $blocks['category-' . $category->cid]['info'] = t('!title category latest items', array(
            '!title' => $category->title,
        ));
    }
    $result = db_query('SELECT fid, title FROM {aggregator_feed} WHERE block <> 0 ORDER BY fid');
    foreach ($result as $feed) {
        $blocks['feed-' . $feed->fid]['info'] = t('!title feed latest items', array(
            '!title' => $feed->title,
        ));
    }
    return $blocks;
}

/**
 * Implements hook_block_configure().
 */
function aggregator_block_configure($delta = '') {
    list($type, $id) = explode('-', $delta);
    if ($type == 'category') {
        $value = db_query('SELECT block FROM {aggregator_category} WHERE cid = :cid', array(
            ':cid' => $id,
        ))->fetchField();
        $form['block'] = array(
            '#type' => 'select',
            '#title' => t('Number of news items in block'),
            '#default_value' => $value,
            '#options' => drupal_map_assoc(range(2, 20)),
        );
        return $form;
    }
}

/**
 * Implements hook_block_save().
 */
function aggregator_block_save($delta = '', $edit = array()) {
    list($type, $id) = explode('-', $delta);
    if ($type == 'category') {
        db_update('aggregator_category')->fields(array(
            'block' => $edit['block'],
        ))
            ->condition('cid', $id)
            ->execute();
    }
}

/**
 * Implements hook_block_view().
 *
 * Generates blocks for the latest news items in each category and feed.
 */
function aggregator_block_view($delta = '') {
    if (user_access('access news feeds')) {
        $block = array();
        list($type, $id) = explode('-', $delta);
        $result = FALSE;
        switch ($type) {
            case 'feed':
                if ($feed = db_query('SELECT fid, title, block FROM {aggregator_feed} WHERE block <> 0 AND fid = :fid', array(
                    ':fid' => $id,
                ))->fetchObject()) {
                    $block['subject'] = check_plain($feed->title);
                    $result = db_query_range("SELECT * FROM {aggregator_item} WHERE fid = :fid ORDER BY timestamp DESC, iid DESC", 0, $feed->block, array(
                        ':fid' => $id,
                    ));
                    $read_more = theme('more_link', array(
                        'url' => 'aggregator/sources/' . $feed->fid,
                        'title' => t("View this feed's recent news."),
                    ));
                }
                break;
            case 'category':
                if ($category = db_query('SELECT cid, title, block FROM {aggregator_category} WHERE cid = :cid', array(
                    ':cid' => $id,
                ))->fetchObject()) {
                    $block['subject'] = check_plain($category->title);
                    $result = db_query_range('SELECT i.* FROM {aggregator_category_item} ci LEFT JOIN {aggregator_item} i ON ci.iid = i.iid WHERE ci.cid = :cid ORDER BY i.timestamp DESC, i.iid DESC', 0, $category->block, array(
                        ':cid' => $category->cid,
                    ));
                    $read_more = theme('more_link', array(
                        'url' => 'aggregator/categories/' . $category->cid,
                        'title' => t("View this category's recent news."),
                    ));
                }
                break;
        }
        $items = array();
        if (!empty($result)) {
            foreach ($result as $item) {
                $items[] = theme('aggregator_block_item', array(
                    'item' => $item,
                ));
            }
        }
        // Only display the block if there are items to show.
        if (count($items) > 0) {
            $block['content'] = theme('item_list', array(
                'items' => $items,
            )) . $read_more;
        }
        return $block;
    }
}

/**
 * Adds/edits/deletes aggregator categories.
 *
 * @param $edit
 *   An associative array describing the category to be added/edited/deleted.
 */
function aggregator_save_category($edit) {
    $link_path = 'aggregator/categories/';
    if (!empty($edit['cid'])) {
        $link_path .= $edit['cid'];
        if (!empty($edit['title'])) {
            db_merge('aggregator_category')->key(array(
                'cid' => $edit['cid'],
            ))
                ->fields(array(
                'title' => $edit['title'],
                'description' => $edit['description'],
            ))
                ->execute();
            $op = 'update';
        }
        else {
            db_delete('aggregator_category')->condition('cid', $edit['cid'])
                ->execute();
            // Remove category from feeds.
            db_delete('aggregator_category_feed')->condition('cid', $edit['cid'])
                ->execute();
            // Remove category from feed items.
            db_delete('aggregator_category_item')->condition('cid', $edit['cid'])
                ->execute();
            // Make sure there is no active block for this category.
            if (module_exists('block')) {
                db_delete('block')->condition('module', 'aggregator')
                    ->condition('delta', 'category-' . $edit['cid'])
                    ->execute();
            }
            $edit['title'] = '';
            $op = 'delete';
        }
    }
    elseif (!empty($edit['title'])) {
        // A single unique id for bundles and feeds, to use in blocks.
        $link_path .= db_insert('aggregator_category')->fields(array(
            'title' => $edit['title'],
            'description' => $edit['description'],
            'block' => 5,
        ))
            ->execute();
        $op = 'insert';
    }
    if (isset($op)) {
        menu_link_maintain('aggregator', $op, $link_path, $edit['title']);
    }
}

/**
 * Add/edit/delete an aggregator feed.
 *
 * @param $edit
 *   An associative array describing the feed to be added/edited/deleted.
 */
function aggregator_save_feed($edit) {
    if (!empty($edit['fid'])) {
        // An existing feed is being modified, delete the category listings.
        db_delete('aggregator_category_feed')->condition('fid', $edit['fid'])
            ->execute();
    }
    if (!empty($edit['fid']) && !empty($edit['title'])) {
        db_update('aggregator_feed')->condition('fid', $edit['fid'])
            ->fields(array(
            'title' => $edit['title'],
            'url' => $edit['url'],
            'refresh' => $edit['refresh'],
            'block' => $edit['block'],
        ))
            ->execute();
    }
    elseif (!empty($edit['fid'])) {
        $iids = db_query('SELECT iid FROM {aggregator_item} WHERE fid = :fid', array(
            ':fid' => $edit['fid'],
        ))->fetchCol();
        if ($iids) {
            db_delete('aggregator_category_item')->condition('iid', $iids, 'IN')
                ->execute();
        }
        db_delete('aggregator_feed')->condition('fid', $edit['fid'])
            ->execute();
        db_delete('aggregator_item')->condition('fid', $edit['fid'])
            ->execute();
        // Make sure there is no active block for this feed.
        if (module_exists('block')) {
            db_delete('block')->condition('module', 'aggregator')
                ->condition('delta', 'feed-' . $edit['fid'])
                ->execute();
        }
    }
    elseif (!empty($edit['title'])) {
        $edit['fid'] = db_insert('aggregator_feed')->fields(array(
            'title' => $edit['title'],
            'url' => $edit['url'],
            'refresh' => $edit['refresh'],
            'block' => $edit['block'],
            'link' => '',
            'description' => '',
            'image' => '',
        ))
            ->execute();
    }
    if (!empty($edit['title'])) {
        // The feed is being saved, save the categories as well.
        if (!empty($edit['category'])) {
            foreach ($edit['category'] as $cid => $value) {
                if ($value) {
                    db_insert('aggregator_category_feed')->fields(array(
                        'fid' => $edit['fid'],
                        'cid' => $cid,
                    ))
                        ->execute();
                }
            }
        }
    }
}

/**
 * Removes all items from a feed.
 *
 * @param $feed
 *   An object describing the feed to be cleared.
 */
function aggregator_remove($feed) {
    _aggregator_get_variables();
    // Call hook_aggregator_remove() on all modules.
    module_invoke_all('aggregator_remove', $feed);
    // Reset feed.
    db_update('aggregator_feed')->condition('fid', $feed->fid)
        ->fields(array(
        'checked' => 0,
        'hash' => '',
        'etag' => '',
        'modified' => 0,
    ))
        ->execute();
}

/**
 * Gets the fetcher, parser, and processors.
 *
 * @return
 *   An array containing the fetcher, parser, and processors.
 */
function _aggregator_get_variables() {
    // Fetch the feed.
    $fetcher = variable_get('aggregator_fetcher', 'aggregator');
    if ($fetcher == 'aggregator') {
        include_once DRUPAL_ROOT . '/' . drupal_get_path('module', 'aggregator') . '/aggregator.fetcher.inc';
    }
    $parser = variable_get('aggregator_parser', 'aggregator');
    if ($parser == 'aggregator') {
        include_once DRUPAL_ROOT . '/' . drupal_get_path('module', 'aggregator') . '/aggregator.parser.inc';
    }
    $processors = variable_get('aggregator_processors', array(
        'aggregator',
    ));
    if (in_array('aggregator', $processors)) {
        include_once DRUPAL_ROOT . '/' . drupal_get_path('module', 'aggregator') . '/aggregator.processor.inc';
    }
    return array(
        $fetcher,
        $parser,
        $processors,
    );
}

/**
 * Checks a news feed for new items.
 *
 * @param $feed
 *   An object describing the feed to be refreshed.
 */
function aggregator_refresh($feed) {
    // Store feed URL to track changes.
    $feed_url = $feed->url;
    // Fetch the feed.
    list($fetcher, $parser, $processors) = _aggregator_get_variables();
    $success = module_invoke($fetcher, 'aggregator_fetch', $feed);
    // We store the hash of feed data in the database. When refreshing a
    // feed we compare stored hash and new hash calculated from downloaded
    // data. If both are equal we say that feed is not updated.
    $hash = hash('sha256', $feed->source_string);
    if ($success && $feed->hash != $hash) {
        // Parse the feed.
        if (module_invoke($parser, 'aggregator_parse', $feed)) {
            // Update feed with parsed data.
            db_merge('aggregator_feed')->key(array(
                'fid' => $feed->fid,
            ))
                ->fields(array(
                'url' => $feed->url,
                'link' => empty($feed->link) ? $feed->url : $feed->link,
                'description' => empty($feed->description) ? '' : $feed->description,
                'image' => empty($feed->image) ? '' : $feed->image,
                'hash' => $hash,
                'etag' => empty($feed->etag) ? '' : $feed->etag,
                'modified' => empty($feed->modified) ? 0 : $feed->modified,
            ))
                ->execute();
            // Log if feed URL has changed.
            if ($feed->url != $feed_url) {
                watchdog('aggregator', 'Updated URL for feed %title to %url.', array(
                    '%title' => $feed->title,
                    '%url' => $feed->url,
                ));
            }
            watchdog('aggregator', 'There is new syndicated content from %site.', array(
                '%site' => $feed->title,
            ));
            drupal_set_message(t('There is new syndicated content from %site.', array(
                '%site' => $feed->title,
            )));
            // If there are items on the feed, let all enabled processors do their work on it.
            if (@count($feed->items)) {
                foreach ($processors as $processor) {
                    module_invoke($processor, 'aggregator_process', $feed);
                }
            }
        }
    }
    else {
        drupal_set_message(t('There is no new syndicated content from %site.', array(
            '%site' => $feed->title,
        )));
    }
    // Regardless of successful or not, indicate that this feed has been checked.
    db_update('aggregator_feed')->fields(array(
        'checked' => REQUEST_TIME,
        'queued' => 0,
    ))
        ->condition('fid', $feed->fid)
        ->execute();
    // Expire old feed items.
    if (function_exists('aggregator_expire')) {
        aggregator_expire($feed);
    }
}

/**
 * Loads an aggregator feed.
 *
 * @param $fid
 *   The feed id.
 *
 * @return
 *   An object describing the feed.
 */
function aggregator_feed_load($fid) {
    $feeds =& drupal_static(__FUNCTION__);
    if (!isset($feeds[$fid])) {
        $feeds[$fid] = db_query('SELECT * FROM {aggregator_feed} WHERE fid = :fid', array(
            ':fid' => $fid,
        ))->fetchObject();
    }
    return $feeds[$fid];
}

/**
 * Loads an aggregator category.
 *
 * @param $cid
 *   The category id.
 *
 * @return
 *   An associative array describing the category.
 */
function aggregator_category_load($cid) {
    $categories =& drupal_static(__FUNCTION__);
    if (!isset($categories[$cid])) {
        $categories[$cid] = db_query('SELECT * FROM {aggregator_category} WHERE cid = :cid', array(
            ':cid' => $cid,
        ))->fetchAssoc();
    }
    return $categories[$cid];
}

/**
 * Returns HTML for an individual feed item for display in the block.
 *
 * @param $variables
 *   An associative array containing:
 *   - item: The item to be displayed.
 *   - feed: Not used.
 *
 * @ingroup themeable
 */
function theme_aggregator_block_item($variables) {
    // Display the external link to the item.
    return '<a href="' . check_url($variables['item']->link) . '">' . check_plain($variables['item']->title) . "</a>\n";
}

/**
 * Renders the HTML content safely, as allowed.
 *
 * @param $value
 *   The content to be filtered.
 *
 * @return
 *   The filtered content.
 */
function aggregator_filter_xss($value) {
    return filter_xss($value, preg_split('/\\s+|<|>/', variable_get('aggregator_allowed_html_tags', '<a> <b> <br> <dd> <dl> <dt> <em> <i> <li> <ol> <p> <strong> <u> <ul>'), -1, PREG_SPLIT_NO_EMPTY));
}

/**
 * Checks and sanitizes the aggregator configuration.
 *
 * Goes through all fetchers, parsers and processors and checks whether they
 * are available. If one is missing, resets to standard configuration.
 *
 * @return
 *   TRUE if this function resets the configuration; FALSE if not.
 */
function aggregator_sanitize_configuration() {
    $reset = FALSE;
    list($fetcher, $parser, $processors) = _aggregator_get_variables();
    if (!module_exists($fetcher)) {
        $reset = TRUE;
    }
    if (!module_exists($parser)) {
        $reset = TRUE;
    }
    foreach ($processors as $processor) {
        if (!module_exists($processor)) {
            $reset = TRUE;
            break;
        }
    }
    if ($reset) {
        variable_del('aggregator_fetcher');
        variable_del('aggregator_parser');
        variable_del('aggregator_processors');
        return TRUE;
    }
    return FALSE;
}

/**
 * Helper function for drupal_map_assoc.
 *
 * @param $count
 *   Items count.
 *
 * @return
 *   A string that is plural-formatted as "@count items".
 */
function _aggregator_items($count) {
    return format_plural($count, '1 item', '@count items');
}