<?php
namespace QWSpeedCache\Cache;

defined( 'ABSPATH' ) || exit;

/**
 * Optional early page-cache bootstrap via wp-content/advanced-cache.php.
 */
class AdvancedCache {

	const DROPIN_MARKER = 'QW Optimize advanced-cache';

	public function __construct() {
		add_action( 'update_option_qwsc_settings', array( $this, 'on_settings_update' ), 20, 2 );
		add_action( 'admin_init', array( $this, 'maybe_sync' ), 5 );
		add_action( 'admin_post_qwsc_fix_wp_cache', array( $this, 'handle_wp_cache_repair' ) );
	}

	/**
	 * Path to drop-in.
	 *
	 * @return string
	 */
	public static function dropin_path() {
		return WP_CONTENT_DIR . '/advanced-cache.php';
	}

	/**
	 * Path to plugin-provided drop-in source.
	 *
	 * @return string
	 */
	public static function source_path() {
		return QWSC_PATH . 'includes/Cache/advanced-cache-dropin.php';
	}

	/**
	 * @return bool
	 */
	public static function is_installed() {
		$path = self::dropin_path();
		if ( ! file_exists( $path ) ) {
			return false;
		}
		// phpcs:ignore WordPress.WP.AlternativeFunctions.file_get_contents_file_get_contents -- Inspecting the local wp-content/advanced-cache.php drop-in for ownership.
		$contents = (string) file_get_contents( $path );
		return false !== strpos( $contents, self::DROPIN_MARKER );
	}

	/**
	 * Install drop-in if enabled and missing/ours.
	 *
	 * @return bool Success.
	 */
	public static function install() {
		$src = self::source_path();
		if ( ! file_exists( $src ) ) {
			return false;
		}
		$dest = self::dropin_path();
		if ( file_exists( $dest ) && ! self::is_installed() ) {
			// Do not overwrite third-party advanced-cache.php.
			return false;
		}
		$ok = @copy( $src, $dest );
		if ( $ok ) {
			self::write_dropin_config();
		}
		return (bool) $ok;
	}

	/**
	 * Lightweight JSON config for advanced-cache.php (no WP bootstrap).
	 */
	public static function write_dropin_config() {
		$settings = array();
		if ( class_exists( '\QWSpeedCache\Plugin' ) ) {
			$settings = \QWSpeedCache\Plugin::instance()->get_all_settings();
		}
		$hours = isset( $settings['cache_lifespan'] ) ? (int) $settings['cache_lifespan'] : 10;
		$hours = max( 0, min( 720, $hours ) );
		$max_age = $hours > 0 ? $hours * \HOUR_IN_SECONDS : ( 10 * \HOUR_IN_SECONDS );
		$rules = array();
		if ( class_exists( '\QWSpeedCache\Cache\Exclusions' ) ) {
			$rules = Exclusions::dropin_rules( is_array( $settings ) ? $settings : array() );
		}
		$data = array(
			// Bind early cache reads to the configured site, never an arbitrary Host header.
			'site_host'       => strtolower( (string) wp_parse_url( home_url( '/' ), PHP_URL_HOST ) ),
			'cache_mobile'    => ! empty( $settings['cache_mobile'] ) || ! isset( $settings['cache_mobile'] ),
			'max_age'         => $max_age,
			'reject_uris'     => $rules['reject_uris'] ?? array(),
			'never_paths'     => $rules['never_paths'] ?? array(),
			'reject_cookies'  => $rules['reject_cookies'] ?? array(),
			'ignore_qs'       => $rules['ignore_qs'] ?? array(),
			'v'               => 2,
		);
		$dir = ( defined( 'QWSC_CACHE_DIR' ) ? QWSC_CACHE_DIR : WP_CONTENT_DIR . '/cache/qw-speed-cache/' );
		if ( ! is_dir( $dir ) ) {
			wp_mkdir_p( $dir );
		}
		// phpcs:ignore WordPress.WP.AlternativeFunctions.file_system_operations_file_put_contents,PluginCheck.CodeAnalysis.WriteFile.PluginDirectoryWrite -- Runtime cache config is stored under wp-content/cache, not the plugin directory.
		@file_put_contents( $dir . 'dropin-config.json', wp_json_encode( $data ), LOCK_EX );
	}

	/**
	 * Remove our drop-in only.
	 *
	 * @return bool
	 */
	public static function uninstall() {
		if ( ! self::is_installed() ) {
			return true;
		}
		$path = self::dropin_path();
		if ( ! file_exists( $path ) ) {
			return true;
		}
		wp_delete_file( $path );
		return ! file_exists( $path );
	}

	/**
	 * @param mixed $old Old value.
	 * @param mixed $new New value.
	 */
	public function on_settings_update( $old, $new ) {
		if ( ! is_array( $new ) ) {
			return;
		}
		$enabled = ! empty( $new['advanced_cache_enabled'] );
		if ( $enabled ) {
			self::install();
			self::write_dropin_config();
		} else {
			self::uninstall();
		}
		// Keep dropin config in sync when only cache_mobile / lifespan changes.
		if ( $enabled || self::is_installed() ) {
			self::write_dropin_config();
		}
	}

	public function maybe_sync() {
		if ( ! current_user_can( 'manage_options' ) ) {
			return;
		}
		$s = \QWSpeedCache\Plugin::instance()->get_all_settings();
		if ( ! empty( $s['advanced_cache_enabled'] ) ) {
			if ( ! self::is_installed() ) {
				self::install();
			}
		}
	}


	/**
	 * Locate the active wp-config.php without guessing beyond WordPress' supported layouts.
	 *
	 * @return string Empty string when no unambiguous config file can be found.
	 */
	public static function config_path() {
		$candidates = array(
			trailingslashit( ABSPATH ) . 'wp-config.php',
			dirname( untrailingslashit( ABSPATH ) ) . '/wp-config.php',
		);
		$found = array();
		foreach ( array_unique( $candidates ) as $candidate ) {
			if ( file_exists( $candidate ) ) {
				$found[] = $candidate;
			}
		}
		return 1 === count( $found ) ? $found[0] : '';
	}

	/**
	 * Read the WP_CACHE definition from wp-config.php.
	 *
	 * @return bool|null True/false when explicitly defined, null when absent/unknown.
	 */
	public static function config_wp_cache_value() {
		$path = self::config_path();
		if ( ! $path ) {
			return null;
		}
		if ( ! function_exists( 'WP_Filesystem' ) ) {
			require_once ABSPATH . 'wp-admin/includes/file.php';
		}
		global $wp_filesystem;
		if ( ! WP_Filesystem() || ! $wp_filesystem ) {
			return null;
		}
		$contents = $wp_filesystem->get_contents( $path );
		if ( false === $contents ) {
			return null;
		}
		if ( preg_match( '/^[\\t ]*define\\s*\\(\\s*[\\\'\"]WP_CACHE[\\\'\"]\\s*,\\s*(true|false|1|0)\\s*\\)\\s*;/mi', $contents, $m ) ) {
			return in_array( strtolower( $m[1] ), array( 'true', '1' ), true );
		}
		return null;
	}

	/**
	 * Safely enable WP_CACHE in wp-config.php using WP_Filesystem.
	 * The original content is retained in memory and restored if verification fails.
	 *
	 * @return array{ok:bool,code:string,message:string}
	 */
	public static function repair_wp_cache() {
		$path = self::config_path();
		if ( ! $path ) {
			return array( 'ok' => false, 'code' => 'config_missing', 'message' => __( 'Could not locate a unique wp-config.php file.', 'qw-optimize' ) );
		}
		if ( ! wp_is_writable( $path ) ) {
			return array( 'ok' => false, 'code' => 'not_writable', 'message' => __( 'wp-config.php is not writable. Add define( \'WP_CACHE\', true ); manually.', 'qw-optimize' ) );
		}
		if ( ! function_exists( 'WP_Filesystem' ) ) {
			require_once ABSPATH . 'wp-admin/includes/file.php';
		}
		global $wp_filesystem;
		if ( ! WP_Filesystem() || ! $wp_filesystem ) {
			return array( 'ok' => false, 'code' => 'filesystem', 'message' => __( 'WordPress could not initialize filesystem access for wp-config.php.', 'qw-optimize' ) );
		}
		$original = $wp_filesystem->get_contents( $path );
		if ( false === $original || '' === $original ) {
			return array( 'ok' => false, 'code' => 'read_failed', 'message' => __( 'Could not read wp-config.php safely.', 'qw-optimize' ) );
		}

		// Do not edit ambiguous configurations with multiple WP_CACHE definitions.
		// Changing only the first occurrence can leave caching disabled or cause warnings.
		$definition_pattern = '/^[\t ]*define\s*\(\s*[\\\'"]WP_CACHE[\\\'"]\s*,/mi';
		$definition_count = preg_match_all( $definition_pattern, $original );
		if ( false === $definition_count || $definition_count > 1 ) {
			return array( 'ok' => false, 'code' => 'ambiguous_definitions', 'message' => __( 'Multiple WP_CACHE definitions were found. Update wp-config.php manually.', 'qw-optimize' ) );
		}
		if ( 1 === $definition_count && ! preg_match( '/^[\t ]*define\s*\(\s*[\\\'"]WP_CACHE[\\\'"]\s*,\s*(?:true|false|1|0)\s*\)\s*;/mi', $original ) ) {
			return array( 'ok' => false, 'code' => 'unsupported_definition', 'message' => __( 'WP_CACHE uses a custom expression. Update wp-config.php manually.', 'qw-optimize' ) );
		}
		$replacement = "define( 'WP_CACHE', true );";
		$pattern = '/^[\\t ]*define\\s*\\(\\s*[\\\'\"]WP_CACHE[\\\'\"]\\s*,\\s*(?:true|false|1|0)\\s*\\)\\s*;/mi';
		if ( preg_match( $pattern, $original ) ) {
			$updated = preg_replace( $pattern, $replacement, $original, 1 );
		} else {
			$markers = array(
				"/* That's all, stop editing!",
				"/** Absolute path to the WordPress directory.",
				"require_once ABSPATH . 'wp-settings.php';",
				'require_once ABSPATH . "wp-settings.php";',
			);
			$updated = $original;
			$inserted = false;
			foreach ( $markers as $marker ) {
				$pos = strpos( $updated, $marker );
				if ( false !== $pos ) {
					$updated = substr( $updated, 0, $pos ) . $replacement . "\n\n" . substr( $updated, $pos );
					$inserted = true;
					break;
				}
			}
			if ( ! $inserted ) {
				return array( 'ok' => false, 'code' => 'layout_unknown', 'message' => __( 'wp-config.php uses an unfamiliar layout, so QW Optimize did not modify it.', 'qw-optimize' ) );
			}
		}
		if ( ! is_string( $updated ) ) {
			return array( 'ok' => false, 'code' => 'update_failed', 'message' => __( 'Could not prepare a safe wp-config.php update.', 'qw-optimize' ) );
		}
		if ( $updated === $original ) {
			return array( 'ok' => true, 'code' => 'already_set', 'message' => __( 'WP_CACHE is already enabled in wp-config.php.', 'qw-optimize' ) );
		}
		$chmod = defined( 'FS_CHMOD_FILE' ) ? FS_CHMOD_FILE : 0644;
		if ( ! $wp_filesystem->put_contents( $path, $updated, $chmod ) ) {
			return array( 'ok' => false, 'code' => 'write_failed', 'message' => __( 'Could not update wp-config.php.', 'qw-optimize' ) );
		}
		$verify = $wp_filesystem->get_contents( $path );
		if ( false === $verify || ! preg_match( '/^[\\t ]*define\\s*\\(\\s*[\\\'\"]WP_CACHE[\\\'\"]\\s*,\\s*(?:true|1)\\s*\\)\\s*;/mi', $verify ) ) {
			$wp_filesystem->put_contents( $path, $original, $chmod );
			return array( 'ok' => false, 'code' => 'verify_failed', 'message' => __( 'WP_CACHE verification failed; the original wp-config.php content was restored.', 'qw-optimize' ) );
		}
		return array( 'ok' => true, 'code' => 'updated', 'message' => __( 'WP_CACHE was enabled successfully. Reload WordPress to activate early page caching.', 'qw-optimize' ) );
	}

	/**
	 * Admin-post handler for the explicit WP_CACHE repair action.
	 */
	public function handle_wp_cache_repair() {
		\QWSpeedCache\Admin\ActionGuard::require_manage( 'qwsc_fix_wp_cache' );
		$result = self::repair_wp_cache();
		$key = 'qwsc_wp_cache_fix_' . get_current_user_id();
		set_transient( $key, $result, 60 );
		wp_safe_redirect( admin_url( 'admin.php?page=qw-speed-cache-cache&qwsc_wp_cache_fix=1' ) );
		exit;
	}

	/**
	 * Status labels for admin UI.
	 *
	 * @return array{installed:bool,ours:bool,wp_cache:bool}
	 */
	public static function status() {
		$config_path = self::config_path();
		$config_value = self::config_wp_cache_value();
		return array(
			'installed'       => file_exists( self::dropin_path() ),
			'ours'            => self::is_installed(),
			'wp_cache'        => defined( 'WP_CACHE' ) && WP_CACHE,
			'config_found'    => (bool) $config_path,
			'config_writable' => $config_path ? wp_is_writable( $config_path ) : false,
			'config_wp_cache' => $config_value,
			'repairable'      => (bool) ( $config_path && wp_is_writable( $config_path ) && true !== $config_value ),
		);
	}
}