<?php

/**
 * The plugin purge class for X-LiteSpeed-Purge
 *
 * @since       1.1.3
 * @since       2.2 Refactored. Changed access from public to private for most func and class variables.
 */

namespace LiteSpeed;

defined('WPINC') || exit();

class Purge extends Base {

	const LOG_TAG = '🧹';

	protected $_pub_purge    = array();
	protected $_pub_purge2   = array();
	protected $_priv_purge   = array();
	protected $_purge_single = false;

	const X_HEADER  = 'X-LiteSpeed-Purge';
	const X_HEADER2 = 'X-LiteSpeed-Purge2';
	const DB_QUEUE  = 'queue';
	const DB_QUEUE2 = 'queue2';

	const TYPE_PURGE_ALL          = 'purge_all';
	const TYPE_PURGE_ALL_LSCACHE  = 'purge_all_lscache';
	const TYPE_PURGE_ALL_CSSJS    = 'purge_all_cssjs';
	const TYPE_PURGE_ALL_LOCALRES = 'purge_all_localres';
	const TYPE_PURGE_ALL_CCSS     = 'purge_all_ccss';
	const TYPE_PURGE_ALL_UCSS     = 'purge_all_ucss';
	const TYPE_PURGE_ALL_LQIP     = 'purge_all_lqip';
	const TYPE_PURGE_ALL_AVATAR   = 'purge_all_avatar';
	const TYPE_PURGE_ALL_OBJECT   = 'purge_all_object';
	const TYPE_PURGE_ALL_OPCACHE  = 'purge_all_opcache';

	const TYPE_PURGE_FRONT     = 'purge_front';
	const TYPE_PURGE_UCSS      = 'purge_ucss';
	const TYPE_PURGE_FRONTPAGE = 'purge_frontpage';
	const TYPE_PURGE_PAGES     = 'purge_pages';
	const TYPE_PURGE_ERROR     = 'purge_error';

	/**
	 * Init hooks
	 *
	 * @since  3.0
	 */
	public function init() {
		// Register purge actions.
		// Most used values: edit_post, save_post, delete_post, wp_trash_post, clean_post_cache, wp_update_comment_count
		$purge_post_events = apply_filters('litespeed_purge_post_events', array(
			'delete_post',
			'wp_trash_post',
			// 'clean_post_cache', // This will disable wc's not purge product when stock status not change setting
			'wp_update_comment_count', // TODO: check if needed for non ESI
		));

		foreach ($purge_post_events as $event) {
			// this will purge all related tags
			add_action($event, array( $this, 'purge_post' ));
		}

		// Purge post only when status is/was publish
		add_action('transition_post_status', array( $this, 'purge_publish' ), 10, 3);

		add_action('wp_update_comment_count', array( $this, 'purge_feeds' ));

		if ($this->conf(self::O_OPTM_UCSS)) {
			add_action('edit_post', __NAMESPACE__ . '\Purge::purge_ucss');
		}
	}

	/**
	 * Only purge publish related status post
	 *
	 * @since 3.0
	 * @access public
	 */
	public function purge_publish( $new_status, $old_status, $post ) {
		if ($new_status != 'publish' && $old_status != 'publish') {
			return;
		}

		$this->purge_post($post->ID);
	}

	/**
	 * Handle all request actions from main cls
	 *
	 * @since  1.8
	 * @access public
	 */
	public function handler() {
		$type = Router::verify_type();

		switch ($type) {
			case self::TYPE_PURGE_ALL:
            $this->_purge_all();
				break;

			case self::TYPE_PURGE_ALL_LSCACHE:
            $this->_purge_all_lscache();
				break;

			case self::TYPE_PURGE_ALL_CSSJS:
            $this->_purge_all_cssjs();
				break;

			case self::TYPE_PURGE_ALL_LOCALRES:
            $this->_purge_all_localres();
				break;

			case self::TYPE_PURGE_ALL_CCSS:
            $this->_purge_all_ccss();
				break;

			case self::TYPE_PURGE_ALL_UCSS:
            $this->_purge_all_ucss();
				break;

			case self::TYPE_PURGE_ALL_LQIP:
            $this->_purge_all_lqip();
				break;

			case self::TYPE_PURGE_ALL_AVATAR:
            $this->_purge_all_avatar();
				break;

			case self::TYPE_PURGE_ALL_OBJECT:
            $this->_purge_all_object();
				break;

			case self::TYPE_PURGE_ALL_OPCACHE:
            $this->purge_all_opcache();
				break;

			case self::TYPE_PURGE_FRONT:
            $this->_purge_front();
				break;

			case self::TYPE_PURGE_UCSS:
            $this->_purge_ucss();
				break;

			case self::TYPE_PURGE_FRONTPAGE:
            $this->_purge_frontpage();
				break;

			case self::TYPE_PURGE_PAGES:
            $this->_purge_pages();
				break;

			case strpos($type, self::TYPE_PURGE_ERROR) === 0:
            $this->_purge_error(substr($type, strlen(self::TYPE_PURGE_ERROR)));
				break;

			default:
				break;
		}

		Admin::redirect();
	}

	/**
	 * Shortcut to purge all lscache
	 *
	 * @since 1.0.0
	 * @access public
	 */
	public static function purge_all( $reason = false ) {
		self::cls()->_purge_all($reason);
	}

	/**
	 * Purge all caches (lscache/op/oc)
	 *
	 * @since 2.2
	 * @access private
	 */
	private function _purge_all( $reason = false ) {
		// if ( defined( 'LITESPEED_CLI' ) ) {
		// Can't send, already has output, need to save and wait for next run
		// self::update_option( self::DB_QUEUE, $curr_built );
		// self::debug( 'CLI request, queue stored: ' . $curr_built );
		// }
		// else {
		$this->_purge_all_lscache(true);
		$this->_purge_all_cssjs(true);
		$this->_purge_all_localres(true);
		// $this->_purge_all_ccss( true );
		// $this->_purge_all_lqip( true );
		$this->_purge_all_object(true);
		$this->purge_all_opcache(true);
		// }

		if ($this->conf(self::O_CDN_CLOUDFLARE_CLEAR)) {
			CDN\Cloudflare::purge_all('Purge All');
		}

		if (!is_string($reason)) {
			$reason = false;
		}

		if ($reason) {
			$reason = "( $reason )";
		}

		self::debug('Purge all ' . $reason, 3);

		$msg = __('Purged all caches successfully.', 'litespeed-cache');
		!defined('LITESPEED_PURGE_SILENT') && Admin_Display::success($msg);

		do_action('litespeed_purged_all');
	}

	/**
	 * Alerts LiteSpeed Web Server to purge all pages.
	 *
	 * For multisite installs, if this is called by a site admin (not network admin),
	 * it will only purge all posts associated with that site.
	 *
	 * @since 2.2
	 * @access public
	 */
	private function _purge_all_lscache( $silence = false ) {
		$this->_add('*');

		// Action to run after server was notified to delete LSCache entries.
		do_action('litespeed_purged_all_lscache');

		if (!$silence) {
			$msg = __('Notified LiteSpeed Web Server to purge all LSCache entries.', 'litespeed-cache');
			!defined('LITESPEED_PURGE_SILENT') && Admin_Display::success($msg);
		}
	}

	/**
	 * Delete all critical css
	 *
	 * @since    2.3
	 * @access   private
	 */
	private function _purge_all_ccss( $silence = false ) {
		do_action('litespeed_purged_all_ccss');

		$this->cls('CSS')->rm_cache_folder('ccss');

		$this->cls('Data')->url_file_clean('ccss');

		if (!$silence) {
			$msg = __('Cleaned all Critical CSS files.', 'litespeed-cache');
			!defined('LITESPEED_PURGE_SILENT') && Admin_Display::success($msg);
		}
	}

	/**
	 * Delete all unique css
	 *
	 * @since    2.3
	 * @access   private
	 */
	private function _purge_all_ucss( $silence = false ) {
		do_action('litespeed_purged_all_ucss');

		$this->cls('CSS')->rm_cache_folder('ucss');

		$this->cls('Data')->url_file_clean('ucss');

		if (!$silence) {
			$msg = __('Cleaned all Unique CSS files.', 'litespeed-cache');
			!defined('LITESPEED_PURGE_SILENT') && Admin_Display::success($msg);
		}
	}

	/**
	 * Purge one UCSS by URL
	 *
	 * @since 4.5
	 * @access public
	 */
	public static function purge_ucss( $post_id_or_url ) {
		self::debug('Purge a single UCSS: ' . $post_id_or_url);
		// If is post_id, generate URL
		if (!preg_match('/\D/', $post_id_or_url)) {
			$post_id_or_url = get_permalink($post_id_or_url);
		}
		$post_id_or_url = untrailingslashit($post_id_or_url);

		$existing_url_files = Data::cls()->mark_as_expired($post_id_or_url, true);
		if ($existing_url_files) {
			// Add to UCSS Q
			self::cls('UCSS')->add_to_q($existing_url_files);
		}
	}

	/**
	 * Delete all LQIP images
	 *
	 * @since    3.0
	 * @access   private
	 */
	private function _purge_all_lqip( $silence = false ) {
		do_action('litespeed_purged_all_lqip');

		$this->cls('Placeholder')->rm_cache_folder('lqip');

		if (!$silence) {
			$msg = __('Cleaned all LQIP files.', 'litespeed-cache');
			!defined('LITESPEED_PURGE_SILENT') && Admin_Display::success($msg);
		}
	}

	/**
	 * Delete all avatar images
	 *
	 * @since    3.0
	 * @access   private
	 */
	private function _purge_all_avatar( $silence = false ) {
		do_action('litespeed_purged_all_avatar');

		$this->cls('Avatar')->rm_cache_folder('avatar');

		if (!$silence) {
			$msg = __('Cleaned all Gravatar files.', 'litespeed-cache');
			!defined('LITESPEED_PURGE_SILENT') && Admin_Display::success($msg);
		}
	}

	/**
	 * Delete all localized JS
	 *
	 * @since    3.3
	 * @access   private
	 */
	private function _purge_all_localres( $silence = false ) {
		do_action('litespeed_purged_all_localres');

		$this->_add(Tag::TYPE_LOCALRES);

		if (!$silence) {
			$msg = __('Cleaned all localized resource entries.', 'litespeed-cache');
			!defined('LITESPEED_PURGE_SILENT') && Admin_Display::success($msg);
		}
	}

	/**
	 * Alerts LiteSpeed Web Server to purge pages.
	 *
	 * @since    1.2.2
	 * @access   private
	 */
	private function _purge_all_cssjs( $silence = false ) {
		if (wp_doing_cron() || defined('LITESPEED_DID_send_headers')) {
			self::debug('❌ Bypassed cssjs delete as header sent (lscache purge after this point will fail) or doing cron');
			return;
		}
		$this->_purge_all_lscache($silence); // Purge CSSJS must purge lscache too to avoid 404

		do_action('litespeed_purged_all_cssjs');

		Optimize::update_option(Optimize::ITEM_TIMESTAMP_PURGE_CSS, time());

		$this->_add(Tag::TYPE_MIN);

		$this->cls('CSS')->rm_cache_folder('css');
		$this->cls('CSS')->rm_cache_folder('js');

		$this->cls('Data')->url_file_clean('css');
		$this->cls('Data')->url_file_clean('js');

		// Clear UCSS queue as it used combined CSS to generate
		$this->clear_q('ucss', true);

		if (!$silence) {
			$msg = __('Notified LiteSpeed Web Server to purge CSS/JS entries.', 'litespeed-cache');
			!defined('LITESPEED_PURGE_SILENT') && Admin_Display::success($msg);
		}
	}

	/**
	 * Purge opcode cache
	 *
	 * @since  1.8.2
	 * @since  7.3 added test for opcode cache restriction
	 * @access public
	 */
	public function purge_all_opcache( $silence = false ) {
		if (!Router::opcache_enabled()) {
			self::debug('❌ Failed to reset OPcache due to OPcache not enabled');

			if (!$silence) {
				$msg = __('OPcache is not enabled.', 'litespeed-cache');
				!defined('LITESPEED_PURGE_SILENT') && Admin_Display::error($msg);
			}

			return false;
		}

		if (Router::opcache_restricted(__FILE__)) {
			self::debug('❌ Failed to reset OPcache due to OPcache is restricted. File requesting the clear is not allowed.');

			if (!$silence) {
				$msg = sprintf(__('OPcache is restricted by %s setting.', 'litespeed-cache'), '<code>restrict_api</code>');
				!defined('LITESPEED_PURGE_SILENT') && Admin_Display::error($msg);
			}

			return false;
		}

		// Purge opcode cache
		if (!opcache_reset()) {
			self::debug('❌ Reset OPcache not worked');

			if (!$silence) {
				$msg = __('Reset the OPcache failed.', 'litespeed-cache');
				!defined('LITESPEED_PURGE_SILENT') && Admin_Display::success($msg);
			}

			return false;
		}

		// Action to run after opcache purge.
		do_action('litespeed_purged_all_opcache');

		self::debug('Reset OPcache');

		if (!$silence) {
			$msg = __('Reset the entire OPcache successfully.', 'litespeed-cache');
			!defined('LITESPEED_PURGE_SILENT') && Admin_Display::success($msg);
		}

		return true;
	}

	/**
	 * Purge object cache
	 *
	 * @since  3.4
	 * @access public
	 */
	public static function purge_all_object( $silence = true ) {
		self::cls()->_purge_all_object($silence);
	}

	/**
	 * Purge object cache
	 *
	 * @since  1.8
	 * @access private
	 */
	private function _purge_all_object( $silence = false ) {
		if (!defined('LSCWP_OBJECT_CACHE')) {
			self::debug('Failed to flush object cache due to object cache not enabled');

			if (!$silence) {
				$msg = __('Object cache is not enabled.', 'litespeed-cache');
				Admin_Display::error($msg);
			}

			return false;
		}

		do_action('litespeed_purged_all_object');

		$this->cls('Object_Cache')->flush();
		self::debug('Flushed object cache');

		if (!$silence) {
			$msg = __('Purge all object caches successfully.', 'litespeed-cache');
			!defined('LITESPEED_PURGE_SILENT') && Admin_Display::success($msg);
		}

		return true;
	}

	/**
	 * Adds new public purge tags to the array of purge tags for the request.
	 *
	 * @since 1.1.3
	 * @access public
	 * @param mixed $tags Tags to add to the list.
	 */
	public static function add( $tags, $purge2 = false ) {
		self::cls()->_add($tags, $purge2);
	}

	/**
	 * Add tags to purge
	 *
	 * @since 2.2
	 * @access private
	 */
	private function _add( $tags, $purge2 = false ) {
		if (!is_array($tags)) {
			$tags = array( $tags );
		}

		$tags = $this->_prepend_bid($tags);

		if (!array_diff($tags, $purge2 ? $this->_pub_purge2 : $this->_pub_purge)) {
			return;
		}

		if ($purge2) {
			$this->_pub_purge2 = array_merge($this->_pub_purge2, $tags);
			$this->_pub_purge2 = array_unique($this->_pub_purge2);
		} else {
			$this->_pub_purge = array_merge($this->_pub_purge, $tags);
			$this->_pub_purge = array_unique($this->_pub_purge);
		}
		self::debug('added ' . implode(',', $tags) . ($purge2 ? ' [Purge2]' : ''), 8);

		// Send purge header immediately
		$curr_built = $this->_build($purge2);
		if (defined('LITESPEED_CLI')) {
			// Can't send, already has output, need to save and wait for next run
			self::update_option($purge2 ? self::DB_QUEUE2 : self::DB_QUEUE, $curr_built);
			self::debug('CLI request, queue stored: ' . $curr_built);
		} else {
			@header($curr_built);
			if (wp_doing_cron() || defined('LITESPEED_DID_send_headers') || apply_filters('litespeed_delay_purge', false)) {
				self::update_option($purge2 ? self::DB_QUEUE2 : self::DB_QUEUE, $curr_built);
				self::debug('Output existed, queue stored: ' . $curr_built);
			}
			self::debug($curr_built);
		}
	}

	/**
	 * Adds new private purge tags to the array of purge tags for the request.
	 *
	 * @since 1.1.3
	 * @access public
	 * @param mixed $tags Tags to add to the list.
	 */
	public static function add_private( $tags ) {
		self::cls()->_add_private($tags);
	}

	/**
	 * Add private ESI tag to purge list
	 *
	 * @since 3.0
	 * @access public
	 */
	public static function add_private_esi( $tag ) {
		self::add_private(Tag::TYPE_ESI . $tag);
	}

	/**
	 * Add private all tag to purge list
	 *
	 * @since 3.0
	 * @access public
	 */
	public static function add_private_all() {
		self::add_private('*');
	}

	/**
	 * Add tags to private purge
	 *
	 * @since 2.2
	 * @access private
	 */
	private function _add_private( $tags ) {
		if (!is_array($tags)) {
			$tags = array( $tags );
		}

		$tags = $this->_prepend_bid($tags);

		if (!array_diff($tags, $this->_priv_purge)) {
			return;
		}

		self::debug('added [private] ' . implode(',', $tags), 3);

		$this->_priv_purge = array_merge($this->_priv_purge, $tags);
		$this->_priv_purge = array_unique($this->_priv_purge);

		// Send purge header immediately
		@header($this->_build());
	}

	/**
	 * Incorporate blog_id into purge tags for multisite
	 *
	 * @since 4.0
	 * @access private
	 * @param mixed $tags Tags to add to the list.
	 */
	private function _prepend_bid( $tags ) {
		if (in_array('*', $tags)) {
			return array( '*' );
		}

		$curr_bid = is_multisite() ? get_current_blog_id() : '';

		foreach ($tags as $k => $v) {
			$tags[$k] = $curr_bid . '_' . $v;
		}
		return $tags;
	}

	/**
	 * Activate `purge related tags` for Admin QS.
	 *
	 * @since    1.1.3
	 * @access   public
	 * @deprecated @7.0 Drop @v7.5
	 */
	public static function set_purge_related() {
	}

	/**
	 * Activate `purge single url tag` for Admin QS.
	 *
	 * @since    1.1.3
	 * @access   public
	 */
	public static function set_purge_single() {
		self::cls()->_purge_single = true;
		do_action('litespeed_purged_single');
	}

	/**
	 * Purge frontend url
	 *
	 * @since 1.3
	 * @since 2.2 Renamed from `frontend_purge`; Access changed from public
	 * @access private
	 */
	private function _purge_front() {
		if (empty($_SERVER['HTTP_REFERER'])) {
			exit('no referer');
		}

		$this->purge_url($_SERVER['HTTP_REFERER']);

		do_action('litespeed_purged_front', $_SERVER['HTTP_REFERER']);
		wp_redirect($_SERVER['HTTP_REFERER']);
		exit();
	}

	/**
	 * Purge single UCSS
	 *
	 * @since 4.7
	 */
	private function _purge_ucss() {
		if (empty($_SERVER['HTTP_REFERER'])) {
			exit('no referer');
		}

		$url_tag = empty($_GET['url_tag']) ? $_SERVER['HTTP_REFERER'] : $_GET['url_tag'];

		self::debug('Purge ucss [url_tag] ' . $url_tag);

		do_action('litespeed_purge_ucss', $url_tag);
		$this->purge_url($_SERVER['HTTP_REFERER']);

		wp_redirect($_SERVER['HTTP_REFERER']);
		exit();
	}

	/**
	 * Alerts LiteSpeed Web Server to purge the front page.
	 *
	 * @since    1.0.3
	 * @since    2.2    Access changed from public to private, renamed from `_purge_front`
	 * @access   private
	 */
	private function _purge_frontpage() {
		$this->_add(Tag::TYPE_FRONTPAGE);
		if (LITESPEED_SERVER_TYPE !== 'LITESPEED_SERVER_OLS') {
			$this->_add_private(Tag::TYPE_FRONTPAGE);
		}

		$msg = __('Notified LiteSpeed Web Server to purge the front page.', 'litespeed-cache');
		!defined('LITESPEED_PURGE_SILENT') && Admin_Display::success($msg);
		do_action('litespeed_purged_frontpage');
	}

	/**
	 * Alerts LiteSpeed Web Server to purge pages.
	 *
	 * @since    1.0.15
	 * @access   private
	 */
	private function _purge_pages() {
		$this->_add(Tag::TYPE_PAGES);

		$msg = __('Notified LiteSpeed Web Server to purge all pages.', 'litespeed-cache');
		!defined('LITESPEED_PURGE_SILENT') && Admin_Display::success($msg);
		do_action('litespeed_purged_pages');
	}

	/**
	 * Alerts LiteSpeed Web Server to purge error pages.
	 *
	 * @since    1.0.14
	 * @access   private
	 */
	private function _purge_error( $type = false ) {
		$this->_add(Tag::TYPE_HTTP);

		if (!$type || !in_array($type, array( '403', '404', '500' ))) {
			return;
		}

		$this->_add(Tag::TYPE_HTTP . $type);

		$msg = __('Notified LiteSpeed Web Server to purge error pages.', 'litespeed-cache');
		!defined('LITESPEED_PURGE_SILENT') && Admin_Display::success($msg);
	}

	/**
	 * Callback to add purge tags if admin selects to purge selected category pages.
	 *
	 * @since 1.0.7
	 * @access public
	 */
	public function purge_cat( $value ) {
		$val = trim($value);
		if (empty($val)) {
			return;
		}
		if (preg_match('/^[a-zA-Z0-9-]+$/', $val) == 0) {
			self::debug("$val cat invalid");
			return;
		}
		$cat = get_category_by_slug($val);
		if ($cat == false) {
			self::debug("$val cat not existed/published");
			return;
		}

		self::add(Tag::TYPE_ARCHIVE_TERM . $cat->term_id);

		!defined('LITESPEED_PURGE_SILENT') && Admin_Display::success(sprintf(__('Purge category %s', 'litespeed-cache'), $val));

		// Action to run after category purge.
		do_action('litespeed_purged_cat', $value);
	}

	/**
	 * Callback to add purge tags if admin selects to purge selected tag pages.
	 *
	 * @since 1.0.7
	 * @access public
	 */
	public function purge_tag( $val ) {
		$val = trim($val);
		if (empty($val)) {
			return;
		}
		if (preg_match('/^[a-zA-Z0-9-]+$/', $val) == 0) {
			self::debug("$val tag invalid");
			return;
		}
		$term = get_term_by('slug', $val, 'post_tag');
		if ($term === false) {
			self::debug("$val tag not exist");
			return;
		}

		self::add(Tag::TYPE_ARCHIVE_TERM . $term->term_id);

		!defined('LITESPEED_PURGE_SILENT') && Admin_Display::success(sprintf(__('Purge tag %s', 'litespeed-cache'), $val));

		// Action to run after tag purge.
		do_action('litespeed_purged_tag', $val);
	}

	/**
	 * Callback to add purge tags if admin selects to purge selected urls.
	 *
	 * @since 1.0.7
	 * @access public
	 */
	public function purge_url( $url, $purge2 = false, $quite = false ) {
		$val = trim($url);
		if (empty($val)) {
			return;
		}

		if (strpos($val, '<') !== false) {
			self::debug("$val url contains <");
			return;
		}

		$val = Utility::make_relative($val);

		$hash = Tag::get_uri_tag($val);

		if ($hash === false) {
			self::debug("$val url invalid");
			return;
		}

		self::add($hash, $purge2);

		!$quite && !defined('LITESPEED_PURGE_SILENT') && Admin_Display::success(sprintf(__('Purge url %s', 'litespeed-cache'), $val));

		// Action to run after url purge.
		do_action('litespeed_purged_link', $url);
	}

	/**
	 * Purge a list of pages when selected by admin. This method will look at the post arguments to determine how and what to purge.
	 *
	 * @since 1.0.7
	 * @access public
	 */
	public function purge_list() {
		if (!isset($_REQUEST[Admin_Display::PURGEBYOPT_SELECT]) || !isset($_REQUEST[Admin_Display::PURGEBYOPT_LIST])) {
			return;
		}
		$sel      = $_REQUEST[Admin_Display::PURGEBYOPT_SELECT];
		$list_buf = $_REQUEST[Admin_Display::PURGEBYOPT_LIST];
		if (empty($list_buf)) {
			return;
		}
		$list_buf = str_replace(',', "\n", $list_buf); // for cli
		$list     = explode("\n", $list_buf);
		switch ($sel) {
			case Admin_Display::PURGEBY_CAT:
            $cb = 'purge_cat';
				break;
			case Admin_Display::PURGEBY_PID:
            $cb = 'purge_post';
				break;
			case Admin_Display::PURGEBY_TAG:
            $cb = 'purge_tag';
				break;
			case Admin_Display::PURGEBY_URL:
            $cb = 'purge_url';
				break;

			default:
				return;
		}
		array_map(array( $this, $cb ), $list);

		// for redirection
		$_GET[Admin_Display::PURGEBYOPT_SELECT] = $sel;
	}

	/**
	 * Purge ESI
	 *
	 * @since 3.0
	 * @access public
	 */
	public static function purge_esi( $tag ) {
		self::add(Tag::TYPE_ESI . $tag);
		do_action('litespeed_purged_esi', $tag);
	}

	/**
	 * Purge a certain post type
	 *
	 * @since 3.0
	 * @access public
	 */
	public static function purge_posttype( $post_type ) {
		self::add(Tag::TYPE_ARCHIVE_POSTTYPE . $post_type);
		self::add($post_type);

		do_action('litespeed_purged_posttype', $post_type);
	}

	/**
	 * Purge all related tags to a post.
	 *
	 * @since 1.0.0
	 * @access public
	 */
	public function purge_post( $pid ) {
		$pid = intval($pid);
		// ignore the status we don't care
		if (!$pid || !in_array(get_post_status($pid), array( 'publish', 'trash', 'private', 'draft' ))) {
			return;
		}

		$purge_tags = $this->_get_purge_tags_by_post($pid);
		if (!$purge_tags) {
			return;
		}

		self::add($purge_tags);
		if ($this->conf(self::O_CACHE_REST)) {
			self::add(Tag::TYPE_REST);
		}

		// $this->cls( 'Control' )->set_stale();
		do_action('litespeed_purged_post', $pid);
	}

	/**
	 * Hooked to the load-widgets.php action.
	 * Attempts to purge a single widget from cache.
	 * If no widget id is passed in, the method will attempt to find the widget id.
	 *
	 * @since 1.1.3
	 * @access public
	 */
	public static function purge_widget( $widget_id = null ) {
		if (is_null($widget_id)) {
			$widget_id = $_POST['widget-id'];
			if (is_null($widget_id)) {
				return;
			}
		}

		self::add(Tag::TYPE_WIDGET . $widget_id);
		self::add_private(Tag::TYPE_WIDGET . $widget_id);

		do_action('litespeed_purged_widget', $widget_id);
	}

	/**
	 * Hooked to the wp_update_comment_count action.
	 * Purges the comment widget when the count is updated.
	 *
	 * @access public
	 * @since 1.1.3
	 * @global type $wp_widget_factory
	 */
	public static function purge_comment_widget() {
		global $wp_widget_factory;
		if (!isset($wp_widget_factory->widgets['WP_Widget_Recent_Comments'])) {
			return;
		}

		$recent_comments = $wp_widget_factory->widgets['WP_Widget_Recent_Comments'];
		if (!is_null($recent_comments)) {
			self::add(Tag::TYPE_WIDGET . $recent_comments->id);
			self::add_private(Tag::TYPE_WIDGET . $recent_comments->id);

			do_action('litespeed_purged_comment_widget', $recent_comments->id);
		}
	}

	/**
	 * Purges feeds on comment count update.
	 *
	 * @since 1.0.9
	 * @access public
	 */
	public function purge_feeds() {
		if ($this->conf(self::O_CACHE_TTL_FEED) > 0) {
			self::add(Tag::TYPE_FEED);
		}
		do_action('litespeed_purged_feeds');
	}

	/**
	 * Purges all private cache entries when the user logs out.
	 *
	 * @access public
	 * @since 1.1.3
	 */
	public static function purge_on_logout() {
		self::add_private_all();
		do_action('litespeed_purged_on_logout');
	}

	/**
	 * Generate all purge tags before output
	 *
	 * @access private
	 * @since 1.1.3
	 */
	private function _finalize() {
		// Make sure header output only run once
		if (!defined('LITESPEED_DID_' . __FUNCTION__)) {
			define('LITESPEED_DID_' . __FUNCTION__, true);
		} else {
			return;
		}

		do_action('litespeed_purge_finalize');

		// Append unique uri purge tags if Admin QS is `PURGESINGLE` or `PURGE`
		if ($this->_purge_single) {
			$tags             = array( Tag::build_uri_tag() );
			$this->_pub_purge = array_merge($this->_pub_purge, $this->_prepend_bid($tags));
		}

		if (!empty($this->_pub_purge)) {
			$this->_pub_purge = array_unique($this->_pub_purge);
		}

		if (!empty($this->_priv_purge)) {
			$this->_priv_purge = array_unique($this->_priv_purge);
		}
	}

	/**
	 * Gathers all the purge headers.
	 *
	 * This will collect all site wide purge tags as well as third party plugin defined purge tags.
	 *
	 * @since 1.1.0
	 * @access public
	 * @return string the built purge header
	 */
	public static function output() {
		$instance = self::cls();

		$instance->_finalize();

		return $instance->_build();
	}

	/**
	 * Build the current purge headers.
	 *
	 * @since 1.1.5
	 * @access private
	 * @return string the built purge header
	 */
	private function _build( $purge2 = false ) {
		if ($purge2) {
			if (empty($this->_pub_purge2)) {
				return;
			}
		} elseif (empty($this->_pub_purge) && empty($this->_priv_purge)) {
			return;
		}

		$purge_header = '';

		// Handle purge2 @since 4.4.1
		if ($purge2) {
			$public_tags = $this->_append_prefix($this->_pub_purge2);
			if (empty($public_tags)) {
				return;
			}
			$purge_header = self::X_HEADER2 . ': public,';
			if (Control::is_stale()) {
				$purge_header .= 'stale,';
			}
			$purge_header .= implode(',', $public_tags);
			return $purge_header;
		}

		$private_prefix = self::X_HEADER . ': private,';

		if (!empty($this->_pub_purge)) {
			$public_tags = $this->_append_prefix($this->_pub_purge);
			if (empty($public_tags)) {
				// If this ends up empty, private will also end up empty
				return;
			}
			$purge_header = self::X_HEADER . ': public,';
			if (Control::is_stale()) {
				$purge_header .= 'stale,';
			}
			$purge_header  .= implode(',', $public_tags);
			$private_prefix = ';private,';
		}

		// Handle priv purge tags
		if (!empty($this->_priv_purge)) {
			$private_tags  = $this->_append_prefix($this->_priv_purge, true);
			$purge_header .= $private_prefix . implode(',', $private_tags);
		}

		return $purge_header;
	}

	/**
	 * Append prefix to an array of purge headers
	 *
	 * @since 1.1.0
	 * @access private
	 */
	private function _append_prefix( $purge_tags, $is_private = false ) {
		$curr_bid = is_multisite() ? get_current_blog_id() : '';

		$purge_tags = apply_filters('litespeed_purge_tags', $purge_tags, $is_private);
		if (!in_array('*', $purge_tags)) {
			$tags = array();
			foreach ($purge_tags as $val) {
				$tags[] = LSWCP_TAG_PREFIX . $val;
			}
			return $tags;
		}

		// Purge All need to check if need to reset crawler or not
		if (!$is_private && $this->conf(self::O_CRAWLER)) {
			Crawler::cls()->reset_pos();
		}

		if ((defined('LSWCP_EMPTYCACHE') && LSWCP_EMPTYCACHE) || $is_private) {
			return array( '*' );
		}

		if (is_multisite() && !$this->_is_subsite_purge()) {
			$blogs = Activation::get_network_ids();
			if (empty($blogs)) {
				self::debug('build_purge_headers: blog list is empty');
				return '';
			}
			$tags = array();
			foreach ($blogs as $blog_id) {
				$tags[] = LSWCP_TAG_PREFIX . $blog_id . '_';
			}
			return $tags;
		} else {
			return array( LSWCP_TAG_PREFIX . $curr_bid . '_' );
		}
	}

	/**
	 * Check if this purge belongs to a subsite purge
	 *
	 * @since  4.0
	 */
	private function _is_subsite_purge() {
		if (!is_multisite()) {
			return false;
		}

		if (is_network_admin()) {
			return false;
		}

		if (defined('LSWCP_EMPTYCACHE') && LSWCP_EMPTYCACHE) {
			return false;
		}

		// Would only use multisite and network admin except is_network_admin is false for ajax calls, which is used by WordPress updates v4.6+
		if (Router::is_ajax() && (check_ajax_referer('updates', false, false) || check_ajax_referer('litespeed-purgeall-network', false, false))) {
			return false;
		}

		return true;
	}

	/**
	 * Gets all the purge tags correlated with the post about to be purged.
	 *
	 * If the purge all pages configuration is set, all pages will be purged.
	 *
	 * This includes site wide post types (e.g. front page) as well as any third party plugin specific post tags.
	 *
	 * @since 1.0.0
	 * @access private
	 */
	private function _get_purge_tags_by_post( $post_id ) {
		// If this is a valid post we want to purge the post, the home page and any associated tags & cats
		// If not, purge everything on the site.

		$purge_tags = array();

		if ($this->conf(self::O_PURGE_POST_ALL)) {
			// ignore the rest if purge all
			return array( '*' );
		}

		// now do API hook action for post purge
		do_action('litespeed_api_purge_post', $post_id);

		// post
		$purge_tags[] = Tag::TYPE_POST . $post_id;
		$post_status  = get_post_status($post_id);
		if (function_exists('is_post_status_viewable')) {
			$viewable = is_post_status_viewable($post_status);
			if ($viewable) {
				$purge_tags[] = Tag::get_uri_tag(wp_make_link_relative(get_permalink($post_id)));
			}
		}

		// for archive of categories|tags|custom tax
		global $post;
		$original_post = $post;
		$post          = get_post($post_id);
		$post_type     = $post->post_type;

		global $wp_widget_factory;
		// recent_posts
		$recent_posts = isset($wp_widget_factory->widgets['WP_Widget_Recent_Posts']) ? $wp_widget_factory->widgets['WP_Widget_Recent_Posts'] : null;
		if (!is_null($recent_posts)) {
			$purge_tags[] = Tag::TYPE_WIDGET . $recent_posts->id;
		}

		// get adjacent posts id as related post tag
		if ($post_type == 'post') {
			$prev_post = get_previous_post();
			$next_post = get_next_post();
			if (!empty($prev_post->ID)) {
				$purge_tags[] = Tag::TYPE_POST . $prev_post->ID;
				self::debug('--------purge_tags prev is: ' . $prev_post->ID);
			}
			if (!empty($next_post->ID)) {
				$purge_tags[] = Tag::TYPE_POST . $next_post->ID;
				self::debug('--------purge_tags next is: ' . $next_post->ID);
			}
		}

		if ($this->conf(self::O_PURGE_POST_TERM)) {
			$taxonomies = get_object_taxonomies($post_type);
			// self::debug('purge by post, check tax = ' . var_export($taxonomies, true));
			foreach ($taxonomies as $tax) {
				$terms = get_the_terms($post_id, $tax);
				if (!empty($terms)) {
					foreach ($terms as $term) {
						$purge_tags[] = Tag::TYPE_ARCHIVE_TERM . $term->term_id;
					}
				}
			}
		}

		if ($this->conf(self::O_CACHE_TTL_FEED)) {
			$purge_tags[] = Tag::TYPE_FEED;
		}

		// author, for author posts and feed list
		if ($this->conf(self::O_PURGE_POST_AUTHOR)) {
			$purge_tags[] = Tag::TYPE_AUTHOR . get_post_field('post_author', $post_id);
		}

		// archive and feed of post type
		// todo: check if type contains space
		if ($this->conf(self::O_PURGE_POST_POSTTYPE)) {
			if (get_post_type_archive_link($post_type)) {
				$purge_tags[] = Tag::TYPE_ARCHIVE_POSTTYPE . $post_type;
				$purge_tags[] = $post_type;
			}
		}

		if ($this->conf(self::O_PURGE_POST_FRONTPAGE)) {
			$purge_tags[] = Tag::TYPE_FRONTPAGE;
		}

		if ($this->conf(self::O_PURGE_POST_HOMEPAGE)) {
			$purge_tags[] = Tag::TYPE_HOME;
		}

		if ($this->conf(self::O_PURGE_POST_PAGES)) {
			$purge_tags[] = Tag::TYPE_PAGES;
		}

		if ($this->conf(self::O_PURGE_POST_PAGES_WITH_RECENT_POSTS)) {
			$purge_tags[] = Tag::TYPE_PAGES_WITH_RECENT_POSTS;
		}

		// if configured to have archived by date
		$date = $post->post_date;
		$date = strtotime($date);

		if ($this->conf(self::O_PURGE_POST_DATE)) {
			$purge_tags[] = Tag::TYPE_ARCHIVE_DATE . date('Ymd', $date);
		}

		if ($this->conf(self::O_PURGE_POST_MONTH)) {
			$purge_tags[] = Tag::TYPE_ARCHIVE_DATE . date('Ym', $date);
		}

		if ($this->conf(self::O_PURGE_POST_YEAR)) {
			$purge_tags[] = Tag::TYPE_ARCHIVE_DATE . date('Y', $date);
		}

		// Set back to original post as $post_id might affecting the global $post value
		$post = $original_post;

		return array_unique($purge_tags);
	}

	/**
	 * The dummy filter for purge all
	 *
	 * @since 1.1.5
	 * @access public
	 * @param string $val The filter value
	 * @return string     The filter value
	 */
	public static function filter_with_purge_all( $val ) {
		self::purge_all();
		return $val;
	}
}
