<?php
/**
 * Page-cache purging.
 *
 * The plugin's head snippet and runtime config are printed into every page,
 * so the moment a test starts, stops, or changes its rules, every cached
 * copy of every page is stale: a visitor served from the cache sees no test
 * (or a test that has already ended). Nothing in WordPress core purges page
 * caches, so this asks the popular cache layers directly and exposes an
 * action for everything else.
 *
 * @package ImproveAB
 */

defined( 'ABSPATH' ) || exit;

/**
 * Purges full-page caches after runtime-affecting changes.
 */
class ImproveAB_Cache {

	/**
	 * Whether a purge is already queued for this request.
	 *
	 * @var bool
	 */
	private static $queued = false;

	/**
	 * Purge full-page caches once, at the end of the current request.
	 *
	 * Several writes often land in one request (a test started, then edited),
	 * so the purge is debounced to shutdown and runs only once.
	 * The object-cache flush of running tests happens separately and
	 * immediately (ImproveAB_Tests::flush_cache()); this is only about HTML
	 * cached by plugins, hosts and reverse proxies.
	 *
	 * @param string $reason Short machine-readable cause, passed to the action.
	 * @return void
	 */
	public static function purge_pages( $reason = '' ) {
		/**
		 * Filter whether the plugin may purge full-page caches automatically.
		 * Return false to disable and handle `improveab_purge_caches` yourself.
		 *
		 * @param bool   $enabled Default true.
		 * @param string $reason  Cause of the purge.
		 */
		if ( ! apply_filters( 'improveab_auto_purge_caches', true, $reason ) ) {
			return;
		}
		if ( self::$queued ) {
			return;
		}
		self::$queued = true;
		if ( did_action( 'shutdown' ) ) {
			self::run( $reason );
			return;
		}
		add_action(
			'shutdown',
			function () use ( $reason ) {
				ImproveAB_Cache::run( $reason );
			},
			1
		);
	}

	/**
	 * Purge every cache layer we know how to talk to. Each integration is
	 * guarded so a missing plugin costs one function_exists() check.
	 *
	 * @param string $reason Cause of the purge.
	 * @return void
	 */
	public static function run( $reason = '' ) {
		// Nginx Helper (rtCamp) — also what many managed hosts use.
		do_action( 'rt_nginx_helper_purge_all' ); // phpcs:ignore WordPress.NamingConventions.PrefixAllGlobals.NonPrefixedHooknameFound -- another plugin's purge hook, invoked on purpose.

		// WP Rocket.
		if ( function_exists( 'rocket_clean_domain' ) ) {
			rocket_clean_domain();
		}

		// W3 Total Cache.
		if ( function_exists( 'w3tc_flush_posts' ) ) {
			w3tc_flush_posts();
		} elseif ( function_exists( 'w3tc_pgcache_flush' ) ) {
			w3tc_pgcache_flush();
		}

		// WP Super Cache: its own "delete cache" function, loaded with the
		// plugin on every request. On a network, this site's pages only.
		if ( function_exists( 'wp_cache_clear_cache' ) ) {
			wp_cache_clear_cache( is_multisite() ? get_current_blog_id() : 0 );
		}

		// LiteSpeed Cache.
		do_action( 'litespeed_purge_all' ); // phpcs:ignore WordPress.NamingConventions.PrefixAllGlobals.NonPrefixedHooknameFound -- another plugin's purge hook, invoked on purpose.

		// WP Fastest Cache.
		if ( isset( $GLOBALS['wp_fastest_cache'] ) && is_object( $GLOBALS['wp_fastest_cache'] ) && method_exists( $GLOBALS['wp_fastest_cache'], 'deleteCache' ) ) {
			$GLOBALS['wp_fastest_cache']->deleteCache( true );
		}

		// Cache Enabler.
		do_action( 'cache_enabler_clear_complete_cache' ); // phpcs:ignore WordPress.NamingConventions.PrefixAllGlobals.NonPrefixedHooknameFound -- another plugin's purge hook, invoked on purpose.

		// Hummingbird.
		do_action( 'wphb_clear_page_cache' ); // phpcs:ignore WordPress.NamingConventions.PrefixAllGlobals.NonPrefixedHooknameFound -- another plugin's purge hook, invoked on purpose.

		// Breeze (Cloudways).
		do_action( 'breeze_clear_all_cache' ); // phpcs:ignore WordPress.NamingConventions.PrefixAllGlobals.NonPrefixedHooknameFound -- another plugin's purge hook, invoked on purpose.

		// Autoptimize: its public "clear all" (which tells the page caches it
		// knows about in turn). Its autoptimize_action_cachepurged action is
		// what it announces after a purge, not a way to ask for one.
		if ( class_exists( 'autoptimizeCache' ) && is_callable( array( 'autoptimizeCache', 'clearall' ) ) ) {
			autoptimizeCache::clearall();
		}

		// SiteGround Optimizer.
		if ( function_exists( 'sg_cachepress_purge_cache' ) ) {
			sg_cachepress_purge_cache();
		}

		// WP Engine.
		if ( class_exists( 'WpeCommon' ) && method_exists( 'WpeCommon', 'purge_varnish_cache' ) ) {
			WpeCommon::purge_varnish_cache();
		}

		// Kinsta.
		if ( isset( $GLOBALS['kinsta_cache'] ) && is_object( $GLOBALS['kinsta_cache'] ) && ! empty( $GLOBALS['kinsta_cache']->kinsta_cache_purge ) && method_exists( $GLOBALS['kinsta_cache']->kinsta_cache_purge, 'purge_complete_caches' ) ) {
			$GLOBALS['kinsta_cache']->kinsta_cache_purge->purge_complete_caches();
		}

		// Pantheon.
		if ( function_exists( 'pantheon_wp_clear_edge_all' ) ) {
			pantheon_wp_clear_edge_all();
		}

		// Cloudflare plugin (their own "purge everything" hook).
		if ( class_exists( 'CF\WordPress\Hooks' ) ) {
			do_action( 'cloudflare_purge_everything' ); // phpcs:ignore WordPress.NamingConventions.PrefixAllGlobals.NonPrefixedHooknameFound -- the Cloudflare plugin's own purge hook.
		}

		/**
		 * Fires after the plugin asked page caches to purge. Hook this to purge
		 * a CDN or host cache the plugin does not know about.
		 *
		 * @param string $reason Cause: test_status, test_update, test_delete,
		 *                       settings, or '' when unspecified.
		 */
		do_action( 'improveab_purge_caches', $reason );
	}
}