+<?php
+/**
+ * StatusNet - the distributed open-source microblogging tool
+ * Copyright (C) 2011, StatusNet, Inc.
+ *
+ * A notice stream that filters its upstream content
+ *
+ * PHP version 5
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program. If not, see <http://www.gnu.org/licenses/>.
+ *
+ * @category Stream
+ * @package StatusNet
+ * @author Evan Prodromou <evan@status.net>
+ * @copyright 2011 StatusNet, Inc.
+ * @license http://www.fsf.org/licensing/licenses/agpl-3.0.html AGPL 3.0
+ * @link http://status.net/
+ */
+
+if (!defined('STATUSNET')) {
+ // This check helps protect against security problems;
+ // your code file can't be executed directly from the web.
+ exit(1);
+}
+
+/**
+ * A class for presenting a filtered notice stream based on an upstream stream
+ *
+ * @category Stream
+ * @package StatusNet
+ * @author Evan Prodromou <evan@status.net>
+ * @copyright 2011 StatusNet, Inc.
+ * @license http://www.fsf.org/licensing/licenses/agpl-3.0.html AGPL 3.0
+ * @link http://status.net/
+ */
+
+abstract class FilteringNoticeStream extends NoticeStream
+{
+ protected $upstream;
+
+ function __construct($upstream)
+ {
+ $this->upstream = $upstream;
+ }
+
+ abstract function filter($notice);
+
+ function getNotices($offset, $limit, $sinceId, $maxId)
+ {
+ // "offset" is virtual; we have to get a lot
+ $total = $offset + $limit;
+
+ $filtered = array();
+
+ $startAt = 0;
+ $askFor = $total;
+
+ // Keep going till we have $total notices in $notices array,
+ // or we get nothing from upstream.
+
+ $results = null;
+
+ do {
+
+ $raw = $this->upstream->getNotices($startAt, $askFor, $sinceId, $maxId);
+
+ $results = $raw->N;
+
+ if ($results == 0) {
+ break;
+ }
+
+ while ($raw->fetch()) {
+ if ($this->filter($raw)) {
+ $filtered[] = clone($raw);
+ if (count($filtered >= $total)) {
+ break;
+ }
+ }
+ }
+
+ // XXX: make these smarter; factor hit rate into $askFor
+
+ $startAt += $askFor;
+ $askFor = max($total - count($filtered), NOTICES_PER_PAGE);
+
+ } while (count($filtered) < $total && $results !== 0);
+
+ return new ArrayWrapper(array_slice($filtered, $offset, $limit));
+ }
+
+ function getNoticeIds($offset, $limit, $sinceId, $maxId)
+ {
+ $notices = $this->getNotices($offset, $limit, $sinceId, $maxId);
+
+ $ids = array();
+
+ while ($notices->fetch()) {
+ $ids[] = $notice->id;
+ }
+
+ return $ids;
+ }
+}