<?php
/**
 * Page-cache bypass for AI bots (W3 Total Cache, LiteSpeed Cache, WP Rocket, WP Super Cache).
 *
 * Proven on W3TC (see research/2026-10-24-plugins-platforms-verification.md).
 *
 * @package FlareOps
 */

namespace FlareOps;

if ( ! defined( 'ABSPATH' ) ) {
	exit;
}

final class Cache {

	public const STATE_OPTION = 'flareops_cache_bypass';

	/** Detected page-cache plugins (slugs). */
	public static function detect(): array {
		$found = array();
		if ( defined( 'W3TC' ) || class_exists( '\W3TC\Dispatcher' ) ) {
			$found[] = 'w3tc';
		}
		if ( defined( 'LSCWP_V' ) ) {
			$found[] = 'litespeed';
		}
		if ( defined( 'WP_ROCKET_VERSION' ) ) {
			$found[] = 'wp-rocket';
		}
		if ( function_exists( 'wp_cache_setting' ) || defined( 'WPCACHEHOME' ) ) {
			$found[] = 'wp-super-cache';
		}
		if ( class_exists( 'WpFastestCache' ) ) {
			$found[] = 'wp-fastest-cache';
		}
		if ( defined( 'SiteGround_Optimizer\VERSION' ) || class_exists( 'SiteGround_Optimizer\Loader\Loader' ) ) {
			$found[] = 'sg-optimizer';
		}
		if ( class_exists( 'Breeze_Admin' ) || defined( 'BREEZE_VERSION' ) ) {
			$found[] = 'breeze';
		}
		if ( defined( 'CE_VERSION' ) || class_exists( 'Cache_Enabler' ) ) {
			$found[] = 'cache-enabler';
		}
		return $found;
	}

	public static function primary(): string {
		$d = self::detect();
		return $d ? $d[0] : 'none';
	}

	/** True once the admin applied the bypass (and has not undone it). */
	public static function is_applied(): bool {
		$state = get_option( self::STATE_OPTION, array() );
		return is_array( $state ) && ! empty( $state['at'] );
	}

	/** Re-apply only after the admin opted in, when the set of cache plugins changed since last time. */
	public static function maybe_apply(): void {
		if ( ! self::is_applied() ) {
			return;
		}
		$state = get_option( self::STATE_OPTION, array() );
		$sig   = implode( ',', self::detect() ) . '|' . md5( implode( ',', Bots::cache_bypass_tokens() ) );
		if ( ( $state['sig'] ?? '' ) !== $sig ) {
			self::apply();
		}
	}

	/** Lowercased set difference: tokens not yet in $have. */
	private static function missing( array $have, array $uas ): array {
		$lower = array_map( 'strtolower', array_map( 'strval', $have ) );
		return array_values( array_filter( $uas, static fn( $t ) => ! in_array( strtolower( $t ), $lower, true ) ) );
	}

	/** Undo apply(): remove exactly the user agents we added, regenerate WP Rocket, forget the state. Never throws. */
	public static function restore(): array {
		$state = get_option( self::STATE_OPTION, array() );
		$added = is_array( $state ) && is_array( $state['added'] ?? null ) ? $state['added'] : array();
		$log   = array();
		$strip = static function ( array $list, array $remove ): array {
			$rm = array_map( 'strtolower', $remove );
			return array_values( array_filter( $list, static fn( $v ) => ! in_array( strtolower( (string) $v ), $rm, true ) ) );
		};
		if ( ! empty( $added['w3tc'] ) && class_exists( '\W3TC\Dispatcher' ) ) {
			try {
				$c = \W3TC\Dispatcher::config();
				$c->set( 'pgcache.reject.ua', $strip( (array) $c->get_array( 'pgcache.reject.ua' ), $added['w3tc'] ) );
				$c->save();
				if ( function_exists( 'w3tc_flush_all' ) ) {
					w3tc_flush_all();
				}
				$log[] = 'W3TC restored';
			} catch ( \Throwable $e ) {
				$log[] = 'W3TC restore error: ' . $e->getMessage();
			}
		}
		if ( ! empty( $added['litespeed'] ) && defined( 'LSCWP_V' ) ) {
			try {
				$cur = apply_filters( 'litespeed_conf', 'cache-exc_useragents' );
				$cur = is_array( $cur ) ? $cur : preg_split( '/[\r\n]+/', (string) $cur );
				do_action( 'litespeed_save_conf', array( 'cache-exc_useragents' => $strip( (array) $cur, $added['litespeed'] ) ) );
				$log[] = 'LiteSpeed restored';
			} catch ( \Throwable $e ) {
				$log[] = 'LiteSpeed restore error: ' . $e->getMessage();
			}
		}
		if ( ! empty( $added['wp-super-cache'] ) && function_exists( 'wp_cache_setting' ) ) {
			try {
				global $cache_rejected_user_agent;
				wp_cache_setting( 'cache_rejected_user_agent', $strip( (array) $cache_rejected_user_agent, $added['wp-super-cache'] ) );
				$log[] = 'WP Super Cache restored';
			} catch ( \Throwable $e ) {
				$log[] = 'WP Super Cache restore error: ' . $e->getMessage();
			}
		}
		delete_option( self::STATE_OPTION );
		// WP Rocket: our filter now adds nothing (not applied); regenerate its rules.
		if ( defined( 'WP_ROCKET_VERSION' ) ) {
			try {
				if ( function_exists( 'flush_rocket_htaccess' ) ) {
					flush_rocket_htaccess();
				}
				if ( function_exists( 'rocket_generate_config_file' ) ) {
					rocket_generate_config_file();
				}
				$log[] = 'WP Rocket regenerated';
			} catch ( \Throwable $e ) {
				$log[] = 'WP Rocket restore error: ' . $e->getMessage();
			}
		}
		return $log;
	}

	/** Configure every detected cache plugin. Never throws. */
	public static function apply(): array {
		$uas     = Bots::cache_bypass_tokens();
		$log     = array();
		$results = array();
		$prev    = get_option( self::STATE_OPTION, array() );
		$added   = is_array( $prev ) && is_array( $prev['added'] ?? null ) ? $prev['added'] : array();
		// Mark as applied first so the WP Rocket filter below contributes our user agents.
		update_option( self::STATE_OPTION, array_merge( is_array( $prev ) ? $prev : array(), array( 'at' => Util::iso() ) ), false );

		// W3 Total Cache.
		if ( class_exists( '\W3TC\Dispatcher' ) ) {
			try {
				$c               = \W3TC\Dispatcher::config();
				$added['w3tc']   = array_values( array_unique( array_merge( $added['w3tc'] ?? array(), self::missing( (array) $c->get_array( 'pgcache.reject.ua' ), $uas ) ) ) );
				$merged          = array_values( array_unique( array_merge( (array) $c->get_array( 'pgcache.reject.ua' ), $uas ) ) );
				$c->set( 'pgcache.reject.ua', $merged );
				$c->save();
				if ( is_admin() ) {
					$env = \W3TC\Dispatcher::component( 'Root_Environment' );
					if ( $env && method_exists( $env, 'fix_in_wpadmin' ) ) {
						$env->fix_in_wpadmin( $c, true );
					}
				}
				if ( function_exists( 'w3tc_flush_all' ) ) {
					w3tc_flush_all();
				}
				$results['w3tc'] = self::check_w3tc();
				$log[]           = 'W3TC: pgcache.reject.ua updated';
			} catch ( \Throwable $e ) {
				$results['w3tc'] = false;
				$log[]           = 'W3TC error: ' . $e->getMessage();
			}
		}

		// LiteSpeed Cache.
		if ( defined( 'LSCWP_V' ) ) {
			try {
				$current = apply_filters( 'litespeed_conf', 'cache-exc_useragents' );
				$current            = is_array( $current ) ? $current : preg_split( '/[\r\n]+/', (string) $current );
				$added['litespeed'] = array_values( array_unique( array_merge( $added['litespeed'] ?? array(), self::missing( (array) $current, $uas ) ) ) );
				$merged             = array_values( array_filter( array_unique( array_merge( (array) $current, $uas ) ) ) );
				do_action( 'litespeed_save_conf', array( 'cache-exc_useragents' => $merged ) );
				$results['litespeed'] = self::check_litespeed();
				$log[]                = 'LiteSpeed: cache-exc_useragents updated';
			} catch ( \Throwable $e ) {
				$results['litespeed'] = false;
				$log[]                = 'LiteSpeed error: ' . $e->getMessage();
			}
		}

		// WP Rocket: our rocket_cache_reject_ua filter is always registered; regenerate.
		if ( defined( 'WP_ROCKET_VERSION' ) ) {
			try {
				if ( function_exists( 'flush_rocket_htaccess' ) ) {
					flush_rocket_htaccess();
				}
				if ( function_exists( 'rocket_generate_config_file' ) ) {
					rocket_generate_config_file();
				}
				if ( function_exists( 'rocket_clean_domain' ) ) {
					rocket_clean_domain();
				}
				$results['wp-rocket'] = function_exists( 'rocket_generate_config_file' );
				$log[]                = 'WP Rocket: htaccess + config regenerated';
			} catch ( \Throwable $e ) {
				$results['wp-rocket'] = false;
				$log[]                = 'WP Rocket error: ' . $e->getMessage();
			}
		}

		// WP Super Cache: only stops storing; existing supercache files are still served. Reported as false.
		if ( function_exists( 'wp_cache_setting' ) ) {
			try {
				global $cache_rejected_user_agent;
				$added['wp-super-cache'] = array_values( array_unique( array_merge( $added['wp-super-cache'] ?? array(), self::missing( (array) $cache_rejected_user_agent, $uas ) ) ) );
				$merged                  = array_values( array_unique( array_merge( (array) $cache_rejected_user_agent, $uas ) ) );
				wp_cache_setting( 'cache_rejected_user_agent', $merged );
				$log[] = 'WP Super Cache: cache_rejected_user_agent set (partial: existing files still served)';
			} catch ( \Throwable $e ) {
				$log[] = 'WP Super Cache error: ' . $e->getMessage();
			}
			$results['wp-super-cache'] = false;
		}

		foreach ( self::detect() as $p ) {
			if ( ! array_key_exists( $p, $results ) ) {
				$results[ $p ] = false; // Unsupported cache plugin: cannot guarantee bypass.
				$log[]         = $p . ': no supported user-agent exclusion';
			}
		}

		$state = array(
			'sig'     => implode( ',', self::detect() ) . '|' . md5( implode( ',', $uas ) ),
			'at'      => Util::iso(),
			'results' => $results,
			'log'     => $log,
			'added'   => $added,
		);
		update_option( self::STATE_OPTION, $state, false );
		return $state;
	}

	public static function check_w3tc(): bool {
		try {
			if ( ! class_exists( '\W3TC\Dispatcher' ) ) {
				return false;
			}
			$have = array_map( 'strtolower', (array) \W3TC\Dispatcher::config()->get_array( 'pgcache.reject.ua' ) );
			foreach ( Bots::cache_bypass_tokens() as $t ) {
				if ( ! in_array( strtolower( $t ), $have, true ) ) {
					return false;
				}
			}
			return true;
		} catch ( \Throwable $e ) {
			return false;
		}
	}

	public static function check_litespeed(): bool {
		$cur = apply_filters( 'litespeed_conf', 'cache-exc_useragents' );
		$cur = is_array( $cur ) ? $cur : preg_split( '/[\r\n]+/', (string) $cur );
		$cur = array_map( 'strtolower', (array) $cur );
		foreach ( Bots::cache_bypass_tokens() as $t ) {
			if ( ! in_array( strtolower( $t ), $cur, true ) ) {
				return false;
			}
		}
		return true;
	}

	/** True when every detected page cache is known to let AI bots through (or there is none). */
	public static function bypass_ok(): bool {
		$detected = self::detect();
		if ( ! $detected ) {
			return true;
		}
		$state   = get_option( self::STATE_OPTION, array() );
		$results = is_array( $state ) && is_array( $state['results'] ?? null ) ? $state['results'] : array();
		foreach ( $detected as $p ) {
			if ( 'w3tc' === $p ) {
				if ( ! self::check_w3tc() ) {
					return false;
				}
				continue;
			}
			if ( 'litespeed' === $p ) {
				if ( ! self::check_litespeed() ) {
					return false;
				}
				continue;
			}
			if ( empty( $results[ $p ] ) ) {
				return false;
			}
		}
		return true;
	}

	/** Filter for WP Rocket (anchored .htaccess rule needs the leading .*). */
	public static function rocket_reject_ua( $ua ) {
		$ua = is_array( $ua ) ? $ua : array();
		if ( ! self::is_applied() ) {
			return $ua;
		}
		foreach ( Bots::cache_bypass_tokens() as $t ) {
			$ua[] = '.*' . $t;
		}
		return array_values( array_unique( $ua ) );
	}
}