<?php

declare(strict_types=1);

namespace RenzoJohnson\Blocks\Assets;

use RenzoJohnson\Blocks\Vendor\JShrink\Minifier;

\defined( 'ABSPATH' ) || exit;

// phpcs:disable WordPress.WP.AlternativeFunctions -- Atomic local cache creation requires same-filesystem locks and renames; WP_Filesystem may request credentials and has no flock primitive.
final class JavaScriptAssetOptimizer {
	private const CACHE_DIRECTORY   = 'blocks-js-cache';
	private const COMPILER_ID       = 'jshrink-1.8.1-blocks-prefix-2';
	private const ENABLED_OPTION    = 'blocks_perf_minify_js';
	private const EXTRA_OPTION      = 'blocks_perf_minify_js_handles';
	private const RETENTION_SECONDS = 2592000;
	private const DEFAULT_HANDLES   = array(
		'blocks-frontend',
		'blocks-analytics',
		'blocks-livechat',
		'blocks-geo-init',
	);

	public function __construct( private readonly \Blocks_Settings_Repository $settings ) {
	}

	public function register_hooks(): void {
		if ( $this->settings->get_bool( self::ENABLED_OPTION ) ) {
			\add_filter( 'script_loader_src', $this->filter_source( ... ), 9000, 2 );
		}
	}

	public function filter_source( string $src, string $handle ): string {
		if (
			\is_admin()
			|| ! $this->settings->get_bool( self::ENABLED_OPTION )
			|| '' === $src
			|| ! \in_array( $handle, $this->selected_handles(), true )
		) {
			return $src;
		}

		$resolved = $this->resolve_source( $src );
		if ( null === $resolved ) {
			return $src;
		}

		$source = $this->read_file( $resolved['path'] );
		if ( null === $source || '' === $source ) {
			return $src;
		}

		$location = self::cache_location( true );
		if ( null === $location ) {
			return $src;
		}

		$cached_url = $this->cache_source( $resolved['relative'], $source, $location );

		return '' !== $cached_url ? $cached_url : $src;
	}

	public static function uninstall(): void {
		$location = self::cache_location( false );
		if ( null === $location ) {
			return;
		}

		$entries = \array_merge(
			self::glob_paths( $location['directory'] . DIRECTORY_SEPARATOR . '*.min.js' ),
			self::glob_paths( $location['directory'] . DIRECTORY_SEPARATOR . '.lock-*' ),
			self::glob_paths( $location['directory'] . DIRECTORY_SEPARATOR . '.tmp-*' )
		);

		foreach ( $entries as $entry ) {
			$name = \basename( $entry );
			if (
				\is_link( $entry )
				|| ! \is_file( $entry )
				|| (
					1 !== \preg_match( '/\A[A-Za-z0-9._-]+-[a-f0-9]{16}-[a-f0-9]{16}\.min\.js\z/', $name )
					&& 1 !== \preg_match( '/\A\.lock-[a-f0-9]{16}\z/', $name )
					&& 1 !== \preg_match( '/\A\.tmp-[a-f0-9]{16}-[A-Za-z0-9]+\z/', $name )
				)
			) {
				continue;
			}
			self::quiet_filesystem( static fn (): bool => \unlink( $entry ) );
		}

		self::quiet_filesystem( static fn (): bool => \rmdir( $location['directory'] ) );
	}

	/** @return array<int, string> */
	private function selected_handles(): array {
		$extra = \preg_split( '/\R/', $this->settings->get_string( self::EXTRA_OPTION ) );
		$extra = false === $extra ? array() : \array_filter( \array_map( 'trim', $extra ) );

		return \array_values( \array_unique( \array_merge( self::DEFAULT_HANDLES, $extra ) ) );
	}

	/** @return array{path:string,relative:string}|null */
	private function resolve_source( string $src ): ?array {
		$source_parts  = \wp_parse_url( \html_entity_decode( $src, ENT_QUOTES | ENT_HTML5, 'UTF-8' ) );
		$content_parts = \wp_parse_url( \content_url( '/' ) );
		if ( ! \is_array( $source_parts ) || ! \is_array( $content_parts ) || ! $this->same_authority( $source_parts, $content_parts ) ) {
			return null;
		}

		$source_path  = isset( $source_parts['path'] ) && \is_string( $source_parts['path'] ) ? \rawurldecode( $source_parts['path'] ) : '';
		$content_path = isset( $content_parts['path'] ) && \is_string( $content_parts['path'] ) ? \rawurldecode( $content_parts['path'] ) : '';
		if ( '' === $source_path || '' === $content_path || \str_contains( $source_path, "\0" ) ) {
			return null;
		}

		$prefix = \trailingslashit( $content_path );
		if ( ! \str_starts_with( $source_path, $prefix ) ) {
			return null;
		}

		$relative = \ltrim( \substr( $source_path, \strlen( $prefix ) ), '/' );
		if (
			'' === $relative
			|| 1 !== \preg_match( '/\.js\z/i', $relative )
			|| 1 === \preg_match( '/\.min\.js\z/i', $relative )
		) {
			return null;
		}

		$content_root = \realpath( WP_CONTENT_DIR );
		$file         = \realpath( WP_CONTENT_DIR . DIRECTORY_SEPARATOR . \str_replace( '/', DIRECTORY_SEPARATOR, $relative ) );
		if (
			! \is_string( $content_root )
			|| ! \is_string( $file )
			|| ! \str_starts_with( $file, $content_root . DIRECTORY_SEPARATOR )
			|| ! \is_file( $file )
			|| ! \is_readable( $file )
		) {
			return null;
		}

		return array(
			'path'     => $file,
			'relative' => \str_replace( DIRECTORY_SEPARATOR, '/', \substr( $file, \strlen( $content_root ) + 1 ) ),
		);
	}

	/**
	 * @param array<string, mixed> $source Source URL parts.
	 * @param array<string, mixed> $content Content URL parts.
	 */
	private function same_authority( array $source, array $content ): bool {
		if ( isset( $source['user'] ) || isset( $source['pass'] ) ) {
			return false;
		}
		$source_scheme  = isset( $source['scheme'] ) && \is_string( $source['scheme'] ) ? \strtolower( $source['scheme'] ) : null;
		$content_scheme = isset( $content['scheme'] ) && \is_string( $content['scheme'] ) ? \strtolower( $content['scheme'] ) : null;
		if ( ! isset( $source['host'] ) ) {
			return null === $source_scheme;
		}
		if (
			null === $source_scheme
			|| null === $content_scheme
			|| ! \in_array( $source_scheme, array( 'http', 'https' ), true )
			|| ! \in_array( $content_scheme, array( 'http', 'https' ), true )
			|| $source_scheme !== $content_scheme
			|| ! isset( $content['host'] )
			|| ! \is_string( $source['host'] )
			|| ! \is_string( $content['host'] )
		) {
			return false;
		}
		if ( \strtolower( $source['host'] ) !== \strtolower( $content['host'] ) ) {
			return false;
		}

		if ( ( isset( $source['port'] ) && ! \is_int( $source['port'] ) ) || ( isset( $content['port'] ) && ! \is_int( $content['port'] ) ) ) {
			return false;
		}
		$source_port  = isset( $source['port'] ) && \is_int( $source['port'] ) ? $source['port'] : null;
		$content_port = isset( $content['port'] ) && \is_int( $content['port'] ) ? $content['port'] : null;
		if ( null === $source_port && null === $content_port ) {
			return true;
		}

		$default_port = 'http' === $content_scheme ? 80 : 443;

		return ( $source_port ?? $default_port ) === ( $content_port ?? $default_port );
	}

	private function read_file( string $path ): ?string {
		$content = self::quiet_filesystem( static fn (): string|false => \file_get_contents( $path ) );

		return \is_string( $content ) ? $content : null;
	}

	/** @return array{directory:string,url:string}|null */
	private static function cache_location( bool $create ): ?array {
		$uploads = \wp_upload_dir( null, false );
		if (
			! empty( $uploads['error'] )
			|| ! isset( $uploads['basedir'], $uploads['baseurl'] )
			|| ! \is_string( $uploads['basedir'] )
			|| ! \is_string( $uploads['baseurl'] )
		) {
			return null;
		}

		$base = \realpath( $uploads['basedir'] );
		if ( ! \is_string( $base ) ) {
			return null;
		}

		$expected = $base . DIRECTORY_SEPARATOR . self::CACHE_DIRECTORY;
		if ( $create && ! \is_dir( $expected ) && ! \wp_mkdir_p( $expected ) ) {
			return null;
		}

		$directory = \realpath( $expected );
		if ( ! \is_string( $directory ) || $directory !== $expected || ! \is_dir( $directory ) ) {
			return null;
		}

		return array(
			'directory' => $directory,
			'url'       => \trailingslashit( $uploads['baseurl'] ) . self::CACHE_DIRECTORY . '/',
		);
	}

	/** @param array{directory:string,url:string} $location */
	private function cache_source( string $relative, string $source, array $location ): string {
		$path_hash    = \substr( \hash( 'sha256', $relative ), 0, 16 );
		$content_hash = \substr( \hash( 'sha256', self::COMPILER_ID . "\0" . $relative . "\0" . $source ), 0, 16 );
		$stem         = \sanitize_file_name( \pathinfo( $relative, PATHINFO_FILENAME ) );
		$stem         = '' !== $stem ? $stem : 'script';
		$filename     = $stem . '-' . $path_hash . '-' . $content_hash . '.min.js';
		$destination  = $location['directory'] . DIRECTORY_SEPARATOR . $filename;
		$lock_path    = $location['directory'] . DIRECTORY_SEPARATOR . '.lock-' . $path_hash;

		if ( $this->valid_cache_file( $destination ) ) {
			return $location['url'] . \rawurlencode( $filename );
		}
		if ( \is_link( $destination ) || ( \file_exists( $destination ) && ! \is_file( $destination ) ) || \is_link( $lock_path ) ) {
			return '';
		}

		$lock = self::quiet_filesystem( static fn () => \fopen( $lock_path, 'c' ) );
		if ( ! \is_resource( $lock ) ) {
			return '';
		}

		$temporary = null;
		try {
			if ( ! \flock( $lock, LOCK_EX ) ) {
				return '';
			}
			if ( $this->valid_cache_file( $destination ) ) { // @phpstan-ignore if.alwaysFalse (Another process may fill the cache while this request waits for the lock.)
				return $location['url'] . \rawurlencode( $filename );
			}
			if ( \is_file( $destination ) && ! \is_link( $destination ) ) { // @phpstan-ignore booleanNot.alwaysTrue (Reject a path swapped to a symlink while this request waited.)
				self::quiet_filesystem( static fn (): bool => \unlink( $destination ) );
			}

			$vendor = BLOCKS_PLUGIN_DIR . '/includes/jshrink/src/Minifier.php';
			if ( ! \is_file( $vendor ) ) {
				return '';
			}
			require_once $vendor;

			try {
				$minified = Minifier::minify( $source, array( 'flaggedComments' => true ) );
			} catch ( \Throwable ) {
				return '';
			}
			if ( ! \is_string( $minified ) || '' === $minified || \strlen( $minified ) >= \strlen( $source ) ) {
				return '';
			}

			$temporary = self::quiet_filesystem( static fn (): string|false => \tempnam( $location['directory'], '.tmp-' . $path_hash . '-' ) );
			if ( ! \is_string( $temporary ) ) {
				return '';
			}
			$written  = self::quiet_filesystem( static fn (): int|false => \file_put_contents( $temporary, $minified, LOCK_EX ) );
			$mode_set = self::quiet_filesystem( static fn (): bool => \chmod( $temporary, 0644 ) );
			if ( \strlen( $minified ) !== $written || true !== $mode_set ) {
				return '';
			}
			if ( true !== self::quiet_filesystem( static fn (): bool => \rename( $temporary, $destination ) ) ) {
				return '';
			}
			$temporary = null;
			$this->prune_old_cache_files( $location['directory'], $filename );

			return $location['url'] . \rawurlencode( $filename );
		} finally {
			\flock( $lock, LOCK_UN );
			self::quiet_filesystem( static fn (): bool => \fclose( $lock ) );
			if ( \is_string( $temporary ) && \is_file( $temporary ) && ! \is_link( $temporary ) ) {
				self::quiet_filesystem( static fn (): bool => \unlink( $temporary ) );
			}
		}
	}

	private function valid_cache_file( string $path ): bool {
		if ( \is_link( $path ) || ! \is_file( $path ) ) {
			return false;
		}
		$size = self::quiet_filesystem( static fn (): int|false => \filesize( $path ) );

		return \is_int( $size ) && $size > 0;
	}

	private function prune_old_cache_files( string $directory, string $current ): void {
		$entries = self::glob_paths( $directory . DIRECTORY_SEPARATOR . '*.min.js' );
		$cutoff  = \time() - self::RETENTION_SECONDS;
		foreach ( $entries as $entry ) {
			$name = \basename( $entry );
			if (
				$current === $name
				|| \is_link( $entry )
				|| ! \is_file( $entry )
				|| 1 !== \preg_match( '/\A[A-Za-z0-9._-]+-[a-f0-9]{16}-[a-f0-9]{16}\.min\.js\z/', $name )
				|| $this->is_recent( $entry, $cutoff )
			) {
				continue;
			}
			self::quiet_filesystem( static fn (): bool => \unlink( $entry ) );
		}
	}

	private function is_recent( string $path, int $cutoff ): bool {
		$modified = self::quiet_filesystem( static fn (): int|false => \filemtime( $path ) );

		return false === $modified || $modified >= $cutoff;
	}

	/** @return array<int, string> */
	private static function glob_paths( string $pattern ): array {
		$paths = self::quiet_filesystem( static fn (): array|false => \glob( $pattern ) );

		return \is_array( $paths ) ? $paths : array();
	}

	private static function quiet_filesystem( callable $operation ): mixed {
		// phpcs:ignore WordPress.PHP.DevelopmentFunctions.error_log_set_error_handler -- Expected file failures must fail open without leaking warnings into frontend output.
		\set_error_handler( static fn (): bool => true );
		try {
			return $operation();
		} finally {
			\restore_error_handler();
		}
	}
}
// phpcs:enable WordPress.WP.AlternativeFunctions