<?php
namespace QWSpeedCache\Optimization;

defined( 'ABSPATH' ) || exit;

/**
 * JavaScript minify/combine + basic safe defer for the Free package.
 */
class Js {

	/** @var array */
	private $settings;

	/** @var string */
	private $cache_dir;

	public function __construct() {
		if ( ! \QWSpeedCache\Plugin::should_optimize() ) {
			return;
		}
		$this->settings  = \QWSpeedCache\Plugin::instance()->get_all_settings();
		$this->cache_dir = QWSC_CACHE_DIR . 'js/';

		$needed = ! empty( $this->settings['minify_js'] )
			|| ! empty( $this->settings['combine_js'] )
			|| ! empty( $this->settings['defer_js'] );

		if ( ! $needed ) {
			return;
		}

		if ( ! is_dir( $this->cache_dir ) ) {
			wp_mkdir_p( $this->cache_dir );
		}

		add_action( 'wp_print_scripts', array( $this, 'process' ), 999 );
		add_filter( 'script_loader_tag', array( $this, 'filter_tag' ), 10, 3 );
	}

	/**
	 * Exclusions for minify/combine (and shared baseline).
	 *
	 * @return string[]
	 */
	private function get_base_excludes() {
		$rules = JsExclusions::parse_list( $this->settings['exclude_js'] ?? '' );
		$safe  = ! empty( $this->settings['js_safe_mode'] );
		return JsExclusions::merge_safe( $rules, $safe || true ); // always protect jquery family at least via merge when safe; when not safe still add jquery in process.
	}

	/**
	 * Exclusions for defer only.
	 *
	 * @return string[]
	 */
	private function get_defer_excludes() {
		$base  = JsExclusions::parse_list( $this->settings['exclude_js'] ?? '' );
		$defer = JsExclusions::parse_list( $this->settings['defer_js_exclusions'] ?? '' );
		$safe  = ! empty( $this->settings['js_safe_mode'] );
		return JsExclusions::merge_safe( array_merge( $base, $defer ), $safe );
	}

	public function process() {
		if ( ! \QWSpeedCache\Plugin::should_optimize() || is_admin() || is_customize_preview() ) {
			return;
		}
		// Per-post "Disable minify/combine" is evaluated here, after the main query.
		if ( \QWSpeedCache\Admin\PostMetabox::flag( 'no_minify' ) ) {
			return;
		}
		global $wp_scripts;
		if ( empty( $wp_scripts->queue ) ) {
			return;
		}

		$to_process = array();
		$excludes   = $this->get_base_excludes();
		// Always skip jquery family for minify/combine.
		$excludes = JsExclusions::merge_safe( $excludes, true );

		foreach ( $wp_scripts->queue as $handle ) {
			if ( empty( $wp_scripts->registered[ $handle ] ) ) {
				continue;
			}
			$obj = $wp_scripts->registered[ $handle ];
			$src = isset( $obj->src ) ? (string) $obj->src : '';
			if ( JsExclusions::is_excluded( $handle, $src, $excludes ) ) {
				continue;
			}
			if ( '' === $src ) {
				continue;
			}
			$to_process[ $handle ] = $obj;
		}

		if ( empty( $to_process ) ) {
			return;
		}
		if ( \QWSpeedCache\Optimization\CombineSafety::allow( $this->settings, 'js' ) ) {
			$to_combine = \QWSpeedCache\Optimization\CombineSafety::filter_items( $to_process, $this->settings, array( $this, 'get_local_path_public' ), 'js' );
			if ( count( $to_combine ) >= 2 ) {
				$this->combine( $to_combine );
			}
		} elseif ( ! empty( $this->settings['minify_js'] ) ) {
			$this->minify_individual( $to_process );
		}
	}


	/**
	 * Whether a script tag should never be delayed (modules, already delayed, ld+json, etc.).
	 *
	 * @param string $tag Script HTML.
	 * @return bool
	 */
	public static function should_skip_defer_tag( $tag ) {
		$tag = (string) $tag;
		if ( '' === $tag ) {
			return true;
		}
		if ( false !== stripos( $tag, 'type="qwsc/delayed"' ) || false !== stripos( $tag, "type='qwsc/delayed'" ) ) {
			return true;
		}
		if ( false !== stripos( $tag, 'type="module"' ) || false !== stripos( $tag, "type='module'" ) ) {
			return true;
		}
		if ( false !== stripos( $tag, 'type="application/ld+json"' ) || false !== stripos( $tag, "type='application/ld+json'" ) ) {
			return true;
		}
		if ( false !== stripos( $tag, 'type="importmap"' ) || false !== stripos( $tag, "type='importmap'" ) ) {
			return true;
		}
		return false;
	}

	/**
	 * Add defer attribute if missing (pure).
	 *
	 * @param string $tag Tag HTML.
	 * @return string
	 */
	public static function make_deferred_tag( $tag ) {
		$tag = (string) $tag;
		if ( false !== stripos( $tag, ' defer' ) || false !== stripos( $tag, ' async' ) ) {
			return $tag;
		}
		if ( self::should_skip_defer_tag( $tag ) ) {
			return $tag;
		}
		$out = preg_replace( '/\s+src=/i', ' defer src=', $tag, 1 );
		return is_string( $out ) ? $out : $tag;
	}

	public function filter_tag( $tag, $handle, $src ) {
		if ( ! \QWSpeedCache\Plugin::should_optimize() || is_admin() || empty( $this->settings['defer_js'] ) ) {
			return $tag;
		}
		$src = (string) $src;
		if ( JsExclusions::is_excluded( $handle, $src, $this->get_defer_excludes() ) ) {
			return $tag;
		}
		return self::make_deferred_tag( $tag );
	}

	/**
	 * Generate an asset safely: never replace a registered original if this
	 * file is absent, empty or could not be written to the cache directory.
	 *
	 * @param string $path Cache file path.
	 * @param string $data Generated asset bytes.
	 * @return bool Whether the generated file is ready for use.
	 */
	private static function ensure_cache_asset( $path, $data ) {
		if ( ! is_string( $data ) || '' === $data ) {
			return false;
		}
		$expected = strlen( $data );
		clearstatcache( true, $path );
		if ( is_file( $path ) && is_readable( $path ) && filesize( $path ) === $expected ) {
			return true;
		}
		// phpcs:ignore WordPress.WP.AlternativeFunctions.file_system_operations_file_put_contents -- Generated local cache under wp-content/cache; verify the complete write.
		$written = @file_put_contents( $path, $data, LOCK_EX );
		clearstatcache( true, $path );
		return $written === $expected && is_file( $path ) && is_readable( $path ) && filesize( $path ) === $expected;
	}

	private function minify_individual( $items ) {
		global $wp_scripts;
		foreach ( $items as $handle => $obj ) {
			$src = $this->get_local_path( $obj->src );
			if ( ! $src || ! file_exists( $src ) ) {
				continue;
			}
			// phpcs:ignore WordPress.WP.AlternativeFunctions.file_get_contents_file_get_contents -- Reading a validated local enqueued JS asset, never fetching a remote URL.
			$content = file_get_contents( $src );
			if ( false === $content ) {
				continue;
			}
			$min     = $this->minify( $content );
			$hash    = substr( md5( $min ), 0, 12 );
			// A registered asset handle is extension-controlled; never use it directly as a filesystem component.
			$safe_handle = sanitize_file_name( (string) $handle );
			if ( '' === $safe_handle ) {
				$safe_handle = 'asset';
			}
			$out     = $this->cache_dir . $safe_handle . '-' . $hash . '.js';
			if ( self::ensure_cache_asset( $out, $min ) ) {
				$wp_scripts->registered[ $handle ]->src = $this->url_from_path( $out );
			}
		}
	}

	private function combine( $items ) {
		global $wp_scripts;
		$combined = '';
		$handles  = array();
		foreach ( $items as $handle => $obj ) {
			$src = $this->get_local_path( $obj->src );
			if ( ! $src || ! file_exists( $src ) ) {
				continue;
			}
			// phpcs:ignore WordPress.WP.AlternativeFunctions.file_get_contents_file_get_contents -- Reading a validated local enqueued JS asset, never fetching a remote URL.
			$content = file_get_contents( $src );
			if ( false === $content ) {
				continue;
			}
			if ( ! empty( $this->settings['minify_js'] ) ) {
				$content = $this->minify( $content );
			}
			$combined .= "/* {$handle} */\n" . $content . ";\n";
			$handles[] = $handle;
		}
		if ( '' === $combined ) {
			return;
		}
		$hash = substr( md5( $combined ), 0, 12 );
		$out  = $this->cache_dir . 'combined-' . $hash . '.js';
		$was_ready = is_file( $out ) && is_readable( $out ) && filesize( $out ) === strlen( $combined );
		if ( ! self::ensure_cache_asset( $out, $combined ) ) {
			return; // Originals stay queued if the generated JS cannot be served.
		}
		if ( ! $was_ready ) {
			do_action( 'qwsc_combined_js_written', $out );
		}
		foreach ( $handles as $handle ) {
			wp_dequeue_script( $handle );
		}
		wp_enqueue_script( 'qwsc-combined-js', $this->url_from_path( $out ), array( 'jquery' ), QWSC_VERSION, true );
	}

	private function minify( $js ) {
		return \QWSpeedCache\Optimization\Minify\Engine::js( $js );
	}

	public function get_local_path_public( $src ) {
		return $this->get_local_path( $src );
	}

	private function get_local_path( $src ) {
		return LocalAssetPath::resolve( $src );
	}

	private function url_from_path( $path ) {
		return content_url( 'cache/qw-speed-cache/js/' . basename( $path ) );
	}
}