<?php
/**
 * WP_MatchesMapRegex helper class
 *
 * @package WordPress
 * @since 4.7.0
 */

/**
 * Helper class to remove the need to use eval to replace $matches[] in query strings.
 *
 * @since 2.9.0
 */
#[AllowDynamicProperties]
class WP_MatchesMapRegex {
    /**
     * store for matches
     *
     * @var array
     */
    private $_matches;

    /**
     * store for mapping result
     *
     * @var string
     */
    public $output;

    /**
     * subject to perform mapping on (query string containing $matches[] references
     *
     * @var string
     */
    private $_subject;

    /**
     * regexp pattern to match $matches[] references
     *
     * @var string
     */
    public $_pattern = '(\$matches\[[1-9]+[0-9]*\])'; // Magic number.

    /**
     * constructor
     *
     * @param string $subject subject if regex
     * @param array  $matches data to use in map
     */
    public function __construct( $subject, $matches ) {
        $this->_subject = $subject;
        $this->_matches = $matches;
        $this->output   = $this->_map();
    }

    /**
     * Substitute substring matches in subject.
     *
     * static helper function to ease use
     *
     * @param string $subject subject
     * @param array  $matches data used for substitution
     * @return string
     */
    public static function apply( $subject, $matches ) {
        $result = new WP_MatchesMapRegex( $subject, $matches );
        return $result->output;
    }

    /**
     * do the actual mapping
     *
     * @return string
     */
    private function _map() {
        $callback = array( $this, 'callback' );
        return preg_replace_callback( $this->_pattern, $callback, $this->_subject );
    }

    /**
     * preg_replace_callback hook
     *
     * @param array $matches preg_replace regexp matches
     * @return string
     */
    public function callback( $matches ) {
        $index = (int) substr( $matches[0], 9, -1 );
        return ( isset( $this->_matches[ $index ] ) ? urlencode( $this->_matches[ $index ] ) : '' );
    }
}