<?php

/**

 * Class 'WP_URL_Pattern_Prefixer'.

 *

 * @package WordPress

 * @subpackage Speculative Loading

 * @since 6.8.0

 */

/**

 * Class for prefixing URL patterns.

 *

 * This class is intended primarily for use as part of the speculative loading feature.

 *

 * @since 6.8.0

 * @access private

 */

class WP_URL_Pattern_Prefixer {

	/**

	 * Map of `$context_string => $base_path` pairs.

	 *

	 * @since 6.8.0

	 * @var array<string, string>

	 */

	private $contexts;

	/**

	 * Constructor.

	 *

	 * @since 6.8.0

	 *

	 * @param array<string, string> $contexts Optional. Map of `$context_string => $base_path` pairs. Default is the

	 *                                        contexts returned by the

	 *                                        {@see WP_URL_Pattern_Prefixer::get_default_contexts()} method.

	 */

	public function __construct( array $contexts = array() ) {

		if ( count( $contexts ) > 0 ) {

			$this->contexts = array_map(

				static function ( string $str ): string {

					return self::escape_pattern_string( trailingslashit( $str ) );

				},

				$contexts

			);

		} else {

			$this->contexts = self::get_default_contexts();

		}

	}

	/**

	 * Prefixes the given URL path pattern with the base path for the given context.

	 *

	 * This ensures that these path patterns work correctly on WordPress subdirectory sites, for example in a multisite

	 * network, or when WordPress itself is installed in a subdirectory of the hostname.

	 *

	 * The given URL path pattern is only prefixed if it does not already include the expected prefix.

	 *

	 * @since 6.8.0

	 *

	 * @param string $path_pattern URL pattern starting with the path segment.

	 * @param string $context      Optional. Context to use for prefixing the path pattern. Default 'home'.

	 * @return string URL pattern, prefixed as necessary.

	 */

	public function prefix_path_pattern( string $path_pattern, string $context = 'home' ): string {

		// If context path does not exist, the context is invalid.

		if ( ! isset( $this->contexts[ $context ] ) ) {

			_doing_it_wrong(

				__FUNCTION__,

				esc_html(

					sprintf(

						/* translators: %s: context string */

						__( 'Invalid URL pattern context %s.' ),

						$context

					)

				),

				'6.8.0'

			);

			return $path_pattern;

		}

		/*

		 * In the event that the context path contains a :, ? or # (which can cause the URL pattern parser to switch to

		 * another state, though only the latter two should be percent encoded anyway), it additionally needs to be

		 * enclosed in grouping braces. The final forward slash (trailingslashit ensures there is one) affects the

		 * meaning of the * wildcard, so is left outside the braces.

		 */

		$context_path         = $this->contexts[ $context ];

		$escaped_context_path = $context_path;

		if ( strcspn( $context_path, ':?#' ) !== strlen( $context_path ) ) {

			$escaped_context_path = '{' . substr( $context_path, 0, -1 ) . '}/';

		}

		/*

		 * If the path already starts with the context path (including '/'), remove it first

		 * since it is about to be added back.

		 */

		if ( str_starts_with( $path_pattern, $context_path ) ) {

			$path_pattern = substr( $path_pattern, strlen( $context_path ) );

		}

		return $escaped_context_path . ltrim( $path_pattern, '/' );

	}

	/**

	 * Returns the default contexts used by the class.

	 *

	 * @since 6.8.0

	 *

	 * @return array<string, string> Map of `$context_string => $base_path` pairs.

	 */

	public static function get_default_contexts(): array {

		return array(

			'home'       => self::escape_pattern_string( trailingslashit( (string) wp_parse_url( home_url( '/' ), PHP_URL_PATH ) ) ),

			'site'       => self::escape_pattern_string( trailingslashit( (string) wp_parse_url( site_url( '/' ), PHP_URL_PATH ) ) ),

			'uploads'    => self::escape_pattern_string( trailingslashit( (string) wp_parse_url( wp_upload_dir( null, false )['baseurl'], PHP_URL_PATH ) ) ),

			'content'    => self::escape_pattern_string( trailingslashit( (string) wp_parse_url( content_url(), PHP_URL_PATH ) ) ),

			'plugins'    => self::escape_pattern_string( trailingslashit( (string) wp_parse_url( plugins_url(), PHP_URL_PATH ) ) ),

			'template'   => self::escape_pattern_string( trailingslashit( (string) wp_parse_url( get_stylesheet_directory_uri(), PHP_URL_PATH ) ) ),

			'stylesheet' => self::escape_pattern_string( trailingslashit( (string) wp_parse_url( get_template_directory_uri(), PHP_URL_PATH ) ) ),

		);

	}

	/**

	 * Escapes a string for use in a URL pattern component.

	 *

	 * @since 6.8.0

	 * @see https://urlpattern.spec.whatwg.org/#escape-a-pattern-string

	 *

	 * @param string $str String to be escaped.

	 * @return string String with backslashes added where required.

	 */

	private static function escape_pattern_string( string $str ): string {

		return addcslashes( $str, '+*?:{}()\\' );

	}

}