<?php
class API extends Handler {

	const API_LEVEL  = 20;

	const STATUS_OK  = 0;
	const STATUS_ERR = 1;

	const E_API_DISABLED = "API_DISABLED";
	const E_NOT_LOGGED_IN = "NOT_LOGGED_IN";
	const E_LOGIN_ERROR = "LOGIN_ERROR";
	const E_INCORRECT_USAGE = "INCORRECT_USAGE";
	const E_UNKNOWN_METHOD = "UNKNOWN_METHOD";
	const E_OPERATION_FAILED = "E_OPERATION_FAILED";
	const E_NOT_FOUND = "E_NOT_FOUND";

	/** @var int|null */
	private $seq;

	/**
	 * @param array<int|string, mixed> $reply
	 */
	private function _wrap(int $status, array $reply): bool {
		print json_encode([
					"seq" => $this->seq,
					"status" => $status,
					"content" => $reply
				]);
		return true;
	}

	function before(string $method): bool {
		if (parent::before($method)) {
			header("Content-Type: text/json");

			if (empty($_SESSION["uid"]) && $method != "login" && $method != "isloggedin") {
				$this->_wrap(self::STATUS_ERR, array("error" => self::E_NOT_LOGGED_IN));
				return false;
			}

			if (!empty($_SESSION["uid"]) && $method != "logout" && !get_pref(Prefs::ENABLE_API_ACCESS)) {
				$this->_wrap(self::STATUS_ERR, array("error" => self::E_API_DISABLED));
				return false;
			}

			$this->seq = (int) clean($_REQUEST['seq'] ?? 0);

			return true;
		}
		return false;
	}

	function getVersion(): bool {
		$rv = array("version" => Config::get_version());
		return $this->_wrap(self::STATUS_OK, $rv);
	}

	function getApiLevel(): bool {
		$rv = array("level" => self::API_LEVEL);
		return $this->_wrap(self::STATUS_OK, $rv);
	}

	function login(): bool {

		if (session_status() == PHP_SESSION_ACTIVE) {
			session_destroy();
		}

		session_start();

		$login = clean($_REQUEST["user"]);
		$password = clean($_REQUEST["password"]);

		if (Config::get(Config::SINGLE_USER_MODE)) $login = "admin";

		if ($uid = UserHelper::find_user_by_login($login)) {
			if (get_pref(Prefs::ENABLE_API_ACCESS, $uid)) {
				if (UserHelper::authenticate($login, $password, false,  Auth_Base::AUTH_SERVICE_API)) {

					// needed for _get_config()
					UserHelper::load_user_plugins($_SESSION['uid']);

					return $this->_wrap(self::STATUS_OK, array("session_id" => session_id(),
						"config" => $this->_get_config(),
						"api_level" => self::API_LEVEL));
				} else {
					return $this->_wrap(self::STATUS_ERR, array("error" => self::E_LOGIN_ERROR));
				}
			} else {
				return $this->_wrap(self::STATUS_ERR, array("error" => self::E_API_DISABLED));
			}
		}
		return $this->_wrap(self::STATUS_ERR, array("error" => self::E_LOGIN_ERROR));
	}

	function logout(): bool {
		UserHelper::logout();
		return $this->_wrap(self::STATUS_OK, array("status" => "OK"));
	}

	function isLoggedIn(): bool {
		return $this->_wrap(self::STATUS_OK, array("status" => $_SESSION["uid"] != ''));
	}

	function getUnread(): bool {
		$feed_id = clean($_REQUEST["feed_id"] ?? "");
		$is_cat = self::_param_to_bool($_REQUEST["is_cat"] ?? false);

		if ($feed_id) {
			return $this->_wrap(self::STATUS_OK, array("unread" => Feeds::_get_counters($feed_id, $is_cat, true)));
		} else {
			return $this->_wrap(self::STATUS_OK, array("unread" => Feeds::_get_global_unread()));
		}
	}

	/* Method added for ttrss-reader for Android */
	function getCounters(): bool {
		return $this->_wrap(self::STATUS_OK, Counters::get_all());
	}

	function getFeeds(): bool {
		$cat_id = (int) clean($_REQUEST["cat_id"]);
		$unread_only = self::_param_to_bool($_REQUEST["unread_only"] ?? false);
		$limit = (int) clean($_REQUEST["limit"] ?? 0);
		$offset = (int) clean($_REQUEST["offset"] ?? 0);
		$include_nested = self::_param_to_bool($_REQUEST["include_nested"] ?? false);

		$feeds = $this->_api_get_feeds($cat_id, $unread_only, $limit, $offset, $include_nested);

		return $this->_wrap(self::STATUS_OK, $feeds);
	}

	function getCategories(): bool {
		$unread_only = self::_param_to_bool($_REQUEST["unread_only"] ?? false);
		$enable_nested = self::_param_to_bool($_REQUEST["enable_nested"] ?? false);
		$include_empty = self::_param_to_bool($_REQUEST["include_empty"] ?? false);

		// TODO do not return empty categories, return Uncategorized and standard virtual cats

		$categories = ORM::for_table('ttrss_feed_categories')
			->select_many('id', 'title', 'order_id')
			->select_many_expr([
				'num_feeds' => '(SELECT COUNT(id) FROM ttrss_feeds WHERE ttrss_feed_categories.id IS NOT NULL AND cat_id = ttrss_feed_categories.id)',
				'num_cats' => '(SELECT COUNT(id) FROM ttrss_feed_categories AS c2 WHERE c2.parent_cat = ttrss_feed_categories.id)',
			])
			->where('owner_uid', $_SESSION['uid']);

		if ($enable_nested) {
			$categories->where_null('parent_cat');
		}

		$cats = [];

		foreach ($categories->find_many() as $category) {
			if ($include_empty || $category->num_feeds > 0 || $category->num_cats > 0) {
				$unread = Feeds::_get_counters($category->id, true, true);

				if ($enable_nested)
					$unread += Feeds::_get_cat_children_unread($category->id);

				if ($unread || !$unread_only) {
					array_push($cats, [
						'id' => (int) $category->id,
						'title' => $category->title,
						'unread' => (int) $unread,
						'order_id' => (int) $category->order_id,
					]);
				}
			}
		}

		foreach ([Feeds::CATEGORY_LABELS, Feeds::CATEGORY_SPECIAL, Feeds::CATEGORY_UNCATEGORIZED] as $cat_id) {
			if ($include_empty || !$this->_is_cat_empty($cat_id)) {
				$unread = Feeds::_get_counters($cat_id, true, true);

				if ($unread || !$unread_only) {
					array_push($cats, [
						'id' => $cat_id,
						'title' => Feeds::_get_cat_title($cat_id),
						'unread' => (int) $unread,
					]);
				}
			}
		}

		return $this->_wrap(self::STATUS_OK, $cats);
	}

	function getHeadlines(): bool {
		$feed_id = clean($_REQUEST["feed_id"] ?? "");

		if (!empty($feed_id) || is_numeric($feed_id)) { // is_numeric for feed_id "0"
			$limit = (int)clean($_REQUEST["limit"] ?? 0 );

			if (!$limit || $limit >= 200) $limit = 200;

			$offset = (int)clean($_REQUEST["skip"] ?? 0);
			$filter = clean($_REQUEST["filter"] ?? "");
			$is_cat = self::_param_to_bool($_REQUEST["is_cat"] ?? false);
			$show_excerpt = self::_param_to_bool($_REQUEST["show_excerpt"] ?? false);
			$show_content = self::_param_to_bool($_REQUEST["show_content"] ?? false);
			/* all_articles, unread, adaptive, marked, updated */
			$view_mode = clean($_REQUEST["view_mode"] ?? null);
			$include_attachments = self::_param_to_bool($_REQUEST["include_attachments"] ?? false);
			$since_id = (int)clean($_REQUEST["since_id"] ?? 0);
			$include_nested = self::_param_to_bool($_REQUEST["include_nested"] ?? false);
			$sanitize_content = self::_param_to_bool($_REQUEST["sanitize"] ?? true);
			$force_update = self::_param_to_bool($_REQUEST["force_update"] ?? false);
			$has_sandbox = self::_param_to_bool($_REQUEST["has_sandbox"] ?? false);
			$excerpt_length = (int)clean($_REQUEST["excerpt_length"] ?? 0);
			$check_first_id = (int)clean($_REQUEST["check_first_id"] ?? 0);
			$include_header = self::_param_to_bool($_REQUEST["include_header"] ?? false);

			$_SESSION['hasSandbox'] = $has_sandbox;

			list($override_order, $skip_first_id_check) = Feeds::_order_to_override_query(clean($_REQUEST["order_by"] ?? ""));

			/* do not rely on params below */

			$search = clean($_REQUEST["search"] ?? "");

			list($headlines, $headlines_header) = $this->_api_get_headlines($feed_id, $limit, $offset,
				$filter, $is_cat, $show_excerpt, $show_content, $view_mode, $override_order,
				$include_attachments, $since_id, $search,
				$include_nested, $sanitize_content, $force_update, $excerpt_length, $check_first_id, $skip_first_id_check);

			if ($include_header) {
				return $this->_wrap(self::STATUS_OK, array($headlines_header, $headlines));
			} else {
				return $this->_wrap(self::STATUS_OK, $headlines);
			}
		} else {
			return $this->_wrap(self::STATUS_ERR, array("error" => self::E_INCORRECT_USAGE));
		}
	}

	function updateArticle(): bool {
		$article_ids = explode(",", clean($_REQUEST["article_ids"]));
		$mode = (int) clean($_REQUEST["mode"]);
		$data = clean($_REQUEST["data"] ?? "");
		$field_raw = (int)clean($_REQUEST["field"]);

		$field = "";
		$set_to = "";
		$additional_fields = "";

		switch ($field_raw) {
			case 0:
				$field = "marked";
				$additional_fields = ",last_marked = NOW()";
				break;
			case 1:
				$field = "published";
				$additional_fields = ",last_published = NOW()";
				break;
			case 2:
				$field = "unread";
				$additional_fields = ",last_read = NOW()";
				break;
			case 3:
				$field = "note";
				break;
			case 4:
				$field = "score";
				break;
		};

		switch ($mode) {
			case 1:
				$set_to = "true";
				break;
			case 0:
				$set_to = "false";
				break;
			case 2:
				$set_to = "NOT $field";
				break;
		}

		if ($field == "note") $set_to = $this->pdo->quote($data);
		if ($field == "score") $set_to = (int) $data;

		if ($field && $set_to && count($article_ids) > 0) {

			$article_qmarks = arr_qmarks($article_ids);

			$sth = $this->pdo->prepare("UPDATE ttrss_user_entries SET
				$field = $set_to $additional_fields
				WHERE ref_id IN ($article_qmarks) AND owner_uid = ?");
			$sth->execute([...$article_ids, $_SESSION['uid']]);

			$num_updated = $sth->rowCount();

			return $this->_wrap(self::STATUS_OK, array("status" => "OK",
				"updated" => $num_updated));

		} else {
			return $this->_wrap(self::STATUS_ERR, array("error" => self::E_INCORRECT_USAGE));
		}
	}

	function getArticle(): bool {
		$article_ids = explode(',', clean($_REQUEST['article_id'] ?? ''));
		$sanitize_content = self::_param_to_bool($_REQUEST['sanitize'] ?? true);

		// @phpstan-ignore-next-line
		if (count($article_ids)) {
			$entries = ORM::for_table('ttrss_entries')
				->table_alias('e')
				->select_many('e.id', 'e.guid', 'e.title', 'e.link', 'e.author', 'e.content', 'e.lang', 'e.comments',
					'ue.feed_id', 'ue.int_id', 'ue.marked', 'ue.unread', 'ue.published', 'ue.score', 'ue.note')
				->select_many_expr([
					'updated' => SUBSTRING_FOR_DATE.'(updated,1,16)',
					'feed_title' => '(SELECT title FROM ttrss_feeds WHERE id = ue.feed_id)',
					'site_url' => '(SELECT site_url FROM ttrss_feeds WHERE id = ue.feed_id)',
					'hide_images' => '(SELECT hide_images FROM ttrss_feeds WHERE id = feed_id)',
				])
				->join('ttrss_user_entries', [ 'ue.ref_id', '=', 'e.id'], 'ue')
				->where_in('e.id', array_map('intval', $article_ids))
				->where('ue.owner_uid', $_SESSION['uid'])
				->find_many();

			$articles = [];

			foreach ($entries as $entry) {
				$article = [
					'id' => $entry->id,
					'guid' => $entry->guid,
					'title' => $entry->title,
					'link' => $entry->link,
					'labels' => Article::_get_labels($entry->id),
					'unread' => self::_param_to_bool($entry->unread),
					'marked' => self::_param_to_bool($entry->marked),
					'published' => self::_param_to_bool($entry->published),
					'comments' => $entry->comments,
					'author' => $entry->author,
					'updated' => (int) strtotime($entry->updated ?? ''),
					'feed_id' => $entry->feed_id,
					'attachments' => Article::_get_enclosures($entry->id),
					'score' => (int) $entry->score,
					'feed_title' => $entry->feed_title,
					'note' => $entry->note,
					'lang' => $entry->lang,
				];

				if ($sanitize_content) {
					$article['content'] = Sanitizer::sanitize(
						$entry->content,
						self::_param_to_bool($entry->hide_images),
						null, $entry->site_url, null, $entry->id);
				} else {
					$article['content'] = $entry->content;
				}

				$hook_object = ['article' => &$article];

				PluginHost::getInstance()->chain_hooks_callback(PluginHost::HOOK_RENDER_ARTICLE_API,
					function ($result) use (&$article) {
						$article = $result;
					},
					$hook_object);

				$article['content'] = DiskCache::rewrite_urls($article['content']);

				array_push($articles, $article);
			}

			return $this->_wrap(self::STATUS_OK, $articles);
		} else {
			return $this->_wrap(self::STATUS_ERR, ['error' => self::E_INCORRECT_USAGE]);
		}
	}

	/**
	 * @return array<string, array<string, string>|bool|int|string>
	 */
	private function _get_config(): array {
		$config = [
			"icons_dir" => Config::get(Config::ICONS_DIR),
			"icons_url" => Config::get(Config::ICONS_URL)
		];

		$config["daemon_is_running"] = file_is_locked("update_daemon.lock");
		$config["custom_sort_types"] = $this->_get_custom_sort_types();

		$config["num_feeds"] = ORM::for_table('ttrss_feeds')
			->where('owner_uid', $_SESSION['uid'])
			->count();

		return $config;
	}

	function getConfig(): bool {
		$config = $this->_get_config();

		return $this->_wrap(self::STATUS_OK, $config);
	}

	function updateFeed(): bool {
		$feed_id = (int) clean($_REQUEST["feed_id"]);

		if (!ini_get("open_basedir")) {
			RSSUtils::update_rss_feed($feed_id);
		}

		return $this->_wrap(self::STATUS_OK, array("status" => "OK"));
	}

	function catchupFeed(): bool {
		$feed_id = clean($_REQUEST["feed_id"]);
		$is_cat = self::_param_to_bool($_REQUEST["is_cat"] ?? false);
		$mode = clean($_REQUEST["mode"] ?? "");

		if (!in_array($mode, ["all", "1day", "1week", "2week"]))
			$mode = "all";

		Feeds::_catchup($feed_id, $is_cat, $_SESSION["uid"], $mode);

		return $this->_wrap(self::STATUS_OK, array("status" => "OK"));
	}

	function getPref(): bool {
		$pref_name = clean($_REQUEST["pref_name"]);

		return $this->_wrap(self::STATUS_OK, array("value" => get_pref($pref_name)));
	}

	function getLabels(): bool {
		$article_id = (int)clean($_REQUEST['article_id'] ?? -1);

		$rv = [];

		$labels = ORM::for_table('ttrss_labels2')
			->where('owner_uid', $_SESSION['uid'])
			->order_by_asc('caption')
			->find_many();

		if ($article_id)
			$article_labels = Article::_get_labels($article_id);
		else
			$article_labels = [];

		foreach ($labels as $label) {
			$checked = false;
			foreach ($article_labels as $al) {
				if (Labels::feed_to_label_id($al[0]) == $label->id) {
					$checked = true;
					break;
				}
			}

			array_push($rv, [
				'id' => (int) Labels::label_to_feed_id($label->id),
				'caption' => $label->caption,
				'fg_color' => $label->fg_color,
				'bg_color' => $label->bg_color,
				'checked' => $checked,
			]);
		}

		return $this->_wrap(self::STATUS_OK, $rv);
	}

	function setArticleLabel(): bool {

		$article_ids = explode(",", clean($_REQUEST["article_ids"]));
		$label_id = (int) clean($_REQUEST['label_id']);
		$assign = self::_param_to_bool(clean($_REQUEST['assign']));

		$label = Labels::find_caption(Labels::feed_to_label_id($label_id), $_SESSION["uid"]);

		$num_updated = 0;

		if ($label) {

			foreach ($article_ids as $id) {

				if ($assign)
					Labels::add_article((int)$id, $label, $_SESSION["uid"]);
				else
					Labels::remove_article((int)$id, $label, $_SESSION["uid"]);

				++$num_updated;

			}
		}

		return $this->_wrap(self::STATUS_OK, array("status" => "OK",
			"updated" => $num_updated));

	}

	function index(string $method): bool {
		$plugin = PluginHost::getInstance()->get_api_method(strtolower($method));

		if ($plugin && method_exists($plugin, $method)) {
			$reply = $plugin->$method();

			return $this->_wrap($reply[0], $reply[1]);

		} else {
			return $this->_wrap(self::STATUS_ERR, array("error" => self::E_UNKNOWN_METHOD, "method" => $method));
		}
	}

	function shareToPublished(): bool {
		$title = clean($_REQUEST["title"]);
		$url = clean($_REQUEST["url"]);
		$sanitize_content = self::_param_to_bool($_REQUEST["sanitize"] ?? true);

		if ($sanitize_content)
			$content = clean($_REQUEST["content"]);
		else
			$content = $_REQUEST["content"];

		if (Article::_create_published_article($title, $url, $content, "", $_SESSION["uid"])) {
			return $this->_wrap(self::STATUS_OK, array("status" => 'OK'));
		} else {
			return $this->_wrap(self::STATUS_ERR, array("error" => self::E_OPERATION_FAILED));
		}
	}

	/**
	 * @return array<int, array{'id': int, 'title': string, 'unread': int, 'cat_id': int}>
	 */
	private static function _api_get_feeds(int $cat_id, bool $unread_only, int $limit, int $offset, bool $include_nested = false): array {
			$feeds = [];

			/* Labels */

			/* API only: -4 (Feeds::CATEGORY_ALL) All feeds, including virtual feeds */
			if ($cat_id == Feeds::CATEGORY_ALL || $cat_id == Feeds::CATEGORY_LABELS) {
				$counters = Counters::get_labels();

				foreach (array_values($counters) as $cv) {
					$unread = $cv['counter'];

					if ($unread || !$unread_only) {
						$row = [
							'id' => (int) $cv['id'],
							'title' => $cv['description'],
							'unread' => $cv['counter'],
							'cat_id' => Feeds::CATEGORY_LABELS,
						];

						array_push($feeds, $row);
					}
				}
			}

			/* Virtual feeds */

			$vfeeds = PluginHost::getInstance()->get_feeds(Feeds::CATEGORY_SPECIAL);

			if (is_array($vfeeds)) {
				foreach ($vfeeds as $feed) {
					if (!implements_interface($feed['sender'], 'IVirtualFeed'))
						continue;

					/** @var IVirtualFeed $feed['sender'] */
					$unread = $feed['sender']->get_unread($feed['id']);

					if ($unread || !$unread_only) {
						$row = [
							'id' => PluginHost::pfeed_to_feed_id($feed['id']),
							'title' => $feed['title'],
							'unread' => $unread,
							'cat_id' => Feeds::CATEGORY_SPECIAL,
						];

						array_push($feeds, $row);
					}
				}
			}

			if ($cat_id == Feeds::CATEGORY_ALL || $cat_id == Feeds::CATEGORY_SPECIAL) {
				foreach ([Feeds::FEED_STARRED, Feeds::FEED_PUBLISHED, Feeds::FEED_FRESH,
					Feeds::FEED_ALL, Feeds::FEED_RECENTLY_READ, Feeds::FEED_ARCHIVED] as $i) {
					$unread = Feeds::_get_counters($i, false, true);

					if ($unread || !$unread_only) {
						$title = Feeds::_get_title($i);

						$row = [
							'id' => $i,
							'title' => $title,
							'unread' => $unread,
							'cat_id' => Feeds::CATEGORY_SPECIAL,
						];

						array_push($feeds, $row);
					}
				}
			}

			/* Child cats */

			if ($include_nested && $cat_id) {
				$categories = ORM::for_table('ttrss_feed_categories')
					->where(['parent_cat' => $cat_id, 'owner_uid' => $_SESSION['uid']])
					->order_by_asc('order_id')
					->order_by_asc('title')
					->find_many();

				foreach ($categories as $category) {
					$unread = Feeds::_get_counters($category->id, true, true) +
						Feeds::_get_cat_children_unread($category->id);

					if ($unread || !$unread_only) {
						$row = [
							'id' => (int) $category->id,
							'title' => $category->title,
							'unread' => $unread,
							'is_cat' => true,
							'order_id' => (int) $category->order_id,
						];
						array_push($feeds, $row);
					}
				}
			}

			/* Real feeds */

			/* API only: -3 (Feeds::CATEGORY_ALL_EXCEPT_VIRTUAL) All feeds, excluding virtual feeds (e.g. Labels and such) */
			$feeds_obj = ORM::for_table('ttrss_feeds')
				->select_many('id', 'feed_url', 'cat_id', 'title', 'order_id')
				->select_expr(SUBSTRING_FOR_DATE.'(last_updated,1,19)', 'last_updated')
				->where('owner_uid', $_SESSION['uid'])
				->order_by_asc('order_id')
				->order_by_asc('title');

			if ($limit) $feeds_obj->limit($limit);
			if ($offset) $feeds_obj->offset($offset);

			if ($cat_id != Feeds::CATEGORY_ALL_EXCEPT_VIRTUAL && $cat_id != Feeds::CATEGORY_ALL) {
				$feeds_obj->where_raw('(cat_id = ? OR (? = 0 AND cat_id IS NULL))', [$cat_id, $cat_id]);
			}

			foreach ($feeds_obj->find_many() as $feed) {
				$unread = Feeds::_get_counters($feed->id, false, true);
				$has_icon = Feeds::_has_icon($feed->id);

				if ($unread || !$unread_only) {
					$row = [
						'feed_url' => $feed->feed_url,
						'title' => $feed->title,
						'id' => (int) $feed->id,
						'unread' => (int) $unread,
						'has_icon' => $has_icon,
						'cat_id' => (int) $feed->cat_id,
						'last_updated' => (int) strtotime($feed->last_updated ?? ''),
						'order_id' => (int) $feed->order_id,
					];

					array_push($feeds, $row);
				}
			}

		return $feeds;
	}

	/**
	 * @param string|int $feed_id
	 * @return array{0: array<int, array<string, mixed>>, 1: array<string, mixed>} $headlines, $headlines_header
	 */
	private static function _api_get_headlines($feed_id, int $limit, int $offset,
				string $filter, bool $is_cat, bool $show_excerpt, bool $show_content, ?string $view_mode, string $order,
				bool $include_attachments, int $since_id, string $search = "", bool $include_nested = false,
				bool $sanitize_content = true, bool $force_update = false, int $excerpt_length = 100, ?int $check_first_id = null,
				bool $skip_first_id_check = false): array {

			if ($force_update && is_numeric($feed_id) && $feed_id > 0) {
				// Update the feed if required with some basic flood control

				$feed = ORM::for_table('ttrss_feeds')
					->select_many('id', 'cache_images')
					->select_expr(SUBSTRING_FOR_DATE.'(last_updated,1,19)', 'last_updated')
					->find_one($feed_id);

				if ($feed) {
					$last_updated = strtotime($feed->last_updated ?? '');
					$cache_images = self::_param_to_bool($feed->cache_images);

					if (!$cache_images && time() - $last_updated > 120) {
						RSSUtils::update_rss_feed($feed_id, true);
					} else {
						$feed->last_updated = '1970-01-01';
						$feed->last_update_started = '1970-01-01';
						$feed->save();
					}
				}
			}

			$params = array(
				"feed" => $feed_id,
				"limit" => $limit,
				"view_mode" => $view_mode,
				"cat_view" => $is_cat,
				"search" => $search,
				"override_order" => $order,
				"offset" => $offset,
				"since_id" => $since_id,
				"include_children" => $include_nested,
				"check_first_id" => $check_first_id,
				"skip_first_id_check" => $skip_first_id_check
			);

			$qfh_ret = [];

			if (!$is_cat && is_numeric($feed_id) && $feed_id < PLUGIN_FEED_BASE_INDEX && $feed_id > LABEL_BASE_INDEX) {
				$pfeed_id = PluginHost::feed_to_pfeed_id($feed_id);

				/** @var IVirtualFeed|false $handler */
				$handler = PluginHost::getInstance()->get_feed_handler($pfeed_id);

				if ($handler) {
					$params = array(
						"feed" => $feed_id,
						"limit" => $limit,
						"view_mode" => $view_mode,
						"cat_view" => $is_cat,
						"search" => $search,
						"override_order" => $order,
						"offset" => $offset,
						"since_id" => 0,
						"include_children" => $include_nested,
						"check_first_id" => $check_first_id,
						"skip_first_id_check" => $skip_first_id_check
					);

					$qfh_ret = $handler->get_headlines($pfeed_id, $params);
				}

			} else {

				$params = array(
					"feed" => $feed_id,
					"limit" => $limit,
					"view_mode" => $view_mode,
					"cat_view" => $is_cat,
					"search" => $search,
					"override_order" => $order,
					"offset" => $offset,
					"since_id" => $since_id,
					"include_children" => $include_nested,
					"check_first_id" => $check_first_id,
					"skip_first_id_check" => $skip_first_id_check
				);

				$qfh_ret = Feeds::_get_headlines($params);
			}

			$result = $qfh_ret[0];
			$feed_title = $qfh_ret[1];
			$first_id = $qfh_ret[6];

			$headlines = array();

			$headlines_header = array(
				'id' => $feed_id,
				'first_id' => $first_id,
				'is_cat' => $is_cat);

			if (!is_numeric($result)) {
				while ($line = $result->fetch()) {
					$line["content_preview"] = truncate_string(strip_tags($line["content"]), $excerpt_length);

					PluginHost::getInstance()->chain_hooks_callback(PluginHost::HOOK_QUERY_HEADLINES,
						function ($result) use (&$line) {
							$line = $result;
						},
						$line, $excerpt_length);

					$is_updated = ($line["last_read"] == "" &&
						($line["unread"] != "t" && $line["unread"] != "1"));

					$tags = explode(",", $line["tag_cache"]);

					$label_cache = $line["label_cache"];
					$labels = false;

					if ($label_cache) {
						$label_cache = json_decode($label_cache, true);

						if ($label_cache) {
							if (($label_cache["no-labels"] ?? 0) == 1)
								$labels = [];
							else
								$labels = $label_cache;
						}
					}

					if (!is_array($labels)) $labels = Article::_get_labels($line["id"]);

					$headline_row = array(
						"id" => (int)$line["id"],
						"guid" => $line["guid"],
						"unread" => self::_param_to_bool($line["unread"]),
						"marked" => self::_param_to_bool($line["marked"]),
						"published" => self::_param_to_bool($line["published"]),
						"updated" => (int)strtotime($line["updated"] ?? ''),
						"is_updated" => $is_updated,
						"title" => $line["title"],
						"link" => $line["link"],
						"feed_id" => $line["feed_id"] ? $line['feed_id'] : 0,
						"tags" => $tags,
					);

					$enclosures = Article::_get_enclosures($line['id']);

					if ($include_attachments)
						$headline_row['attachments'] = $enclosures;

					if ($show_excerpt)
						$headline_row["excerpt"] = $line["content_preview"];

					if ($show_content) {

						if ($sanitize_content) {
							$headline_row["content"] = Sanitizer::sanitize(
								$line["content"],
								self::_param_to_bool($line['hide_images']),
								null, $line["site_url"], null, $line["id"]);
						} else {
							$headline_row["content"] = $line["content"];
						}
					}

					// unify label output to ease parsing
					if (($labels["no-labels"] ?? 0) == 1) $labels = [];

					$headline_row["labels"] = $labels;

					$headline_row["feed_title"] = isset($line["feed_title"]) ? $line["feed_title"] : $feed_title;

					$headline_row["comments_count"] = (int)$line["num_comments"];
					$headline_row["comments_link"] = $line["comments"];

					$headline_row["always_display_attachments"] = self::_param_to_bool($line["always_display_enclosures"]);

					$headline_row["author"] = $line["author"];

					$headline_row["score"] = (int)$line["score"];
					$headline_row["note"] = $line["note"];
					$headline_row["lang"] = $line["lang"];

					if ($show_content) {
						$hook_object = ["headline" => &$headline_row];

						list ($flavor_image, $flavor_stream, $flavor_kind) = Article::_get_image($enclosures,
																												$line["content"], // unsanitized
																												$line["site_url"] ?? "", // could be null if archived article
																												$headline_row);

						$headline_row["flavor_image"] = $flavor_image;
						$headline_row["flavor_stream"] = $flavor_stream;

						/* optional */
						if ($flavor_kind)
							$headline_row["flavor_kind"] = $flavor_kind;

						PluginHost::getInstance()->chain_hooks_callback(PluginHost::HOOK_RENDER_ARTICLE_API,
							function ($result) use (&$headline_row) {
								$headline_row = $result;
							},
							$hook_object);

						$headline_row["content"] = DiskCache::rewrite_urls($headline_row['content']);
					}

					array_push($headlines, $headline_row);
				}
			} else if (is_numeric($result) && $result == -1) {
				$headlines_header['first_id_changed'] = true;
			}

			return array($headlines, $headlines_header);
	}

	function unsubscribeFeed(): bool {
		$feed_id = (int) clean($_REQUEST["feed_id"]);

		$feed_exists = ORM::for_table('ttrss_feeds')
			->where(['id' => $feed_id, 'owner_uid' => $_SESSION['uid']])
			->count();

		if ($feed_exists) {
			Pref_Feeds::remove_feed($feed_id, $_SESSION['uid']);
			return $this->_wrap(self::STATUS_OK, ['status' => 'OK']);
		} else {
			return $this->_wrap(self::STATUS_ERR, ['error' => self::E_OPERATION_FAILED]);
		}
	}

	function subscribeToFeed(): bool {
		$feed_url = clean($_REQUEST["feed_url"]);
		$category_id = (int) clean($_REQUEST["category_id"]);
		$login = clean($_REQUEST["login"] ?? "");
		$password = clean($_REQUEST["password"] ?? "");

		if ($feed_url) {
			$rc = Feeds::_subscribe($feed_url, $category_id, $login, $password);

			return $this->_wrap(self::STATUS_OK, array("status" => $rc));
		} else {
			return $this->_wrap(self::STATUS_ERR, array("error" => self::E_INCORRECT_USAGE));
		}
	}

	function getFeedTree(): bool {
		$include_empty = self::_param_to_bool($_REQUEST['include_empty'] ?? false);

		$pf = new Pref_Feeds($_REQUEST);

		$_REQUEST['mode'] = 2;
		$_REQUEST['force_show_empty'] = $include_empty;

		return $this->_wrap(self::STATUS_OK,
			array("categories" => $pf->_makefeedtree()));
	}

	function getFeedIcon(): bool {
		$id = (int)$_REQUEST['id'];
		$cache = DiskCache::instance('feed-icons');

		if ($cache->exists((string)$id)) {
			return $cache->send((string)$id) > 0;
		} else {
			return $this->_wrap(self::STATUS_ERR, array("error" => self::E_NOT_FOUND));
		}
	}

	// only works for labels or uncategorized for the time being
	private function _is_cat_empty(int $id): bool {
		if ($id == Feeds::CATEGORY_LABELS) {
			$label_count = ORM::for_table('ttrss_labels2')
				->where('owner_uid', $_SESSION['uid'])
				->count();

			return $label_count == 0;
		} else if ($id == Feeds::CATEGORY_UNCATEGORIZED) {
			$uncategorized_count = ORM::for_table('ttrss_feeds')
				->where_null('cat_id')
				->where('owner_uid', $_SESSION['uid'])
				->count();

			return $uncategorized_count == 0;
		}

		return false;
	}

	/** @return array<string, string>  */
	private function _get_custom_sort_types(): array {
		$ret = [];

		PluginHost::getInstance()->run_hooks_callback(PluginHost::HOOK_HEADLINES_CUSTOM_SORT_MAP, function ($result) use (&$ret) {
			foreach ($result as $sort_value => $sort_title) {
				$ret[$sort_value] = $sort_title;
			}
		});

		return $ret;
	}
}