<?php
/**
 * Pass-through stemmer for languages without a real implementation.
 *
 * @package Postlinkly
 * @since   1.0.0
 */

declare(strict_types=1);

namespace Postlinkly\Text\Stemmers;

use Postlinkly\Text\Stemmer;

/**
 * Pass-through stemmer used when no language-specific stemmer is available.
 *
 * Returns the word lower-cased and otherwise unchanged. This matches the
 * default behaviour expected by the suggestion engine: comparisons happen
 * on the lower-case form, but no morphological reduction is applied.
 *
 * The StemmerLoader uses this as the fallback when the site language has
 * no registered Stemmer implementation. A site running an unsupported
 * language still gets case-insensitive matching.
 *
 * @since 1.0.0
 */
final class NullStemmer implements Stemmer {

	private string $language_code;

	/**
	 * @since 1.0.0
	 *
	 * @param string $language_code Optional. Language code to report. Default `und`
	 *                              (the ISO 639-3 "undetermined" code).
	 */
	public function __construct( string $language_code = 'und' ) {
		$this->language_code = $language_code;
	}

	/**
	 * @since 1.0.0
	 */
	public function get_language_code(): string {
		return $this->language_code;
	}

	/**
	 * @since 1.0.0
	 */
	public function stem( string $word ): string {
		return mb_strtolower( $word, 'UTF-8' );
	}
}