<?php
/**
 * Rules for translation relationships (F-COMMERCE-01).
 *
 * @package ForensixDigital
 */

declare(strict_types=1);

namespace ForensixDigital\Apps\Commerce;

defined( 'ABSPATH' ) || exit;

/**
 * Finds the languages a page has no translation in. Pure.
 */
final class TranslationRules {

	/**
	 * Languages without a translation.
	 *
	 * @param array<int, string> $languages    Codes of all active languages.
	 * @param string             $own          Language code of the page; empty when the page has none.
	 * @param array<string, int> $translations Language code => id of the translated page, 0 or missing for none.
	 * @return array<int, string> Missing language codes.
	 */
	public static function missing( array $languages, string $own, array $translations ): array {
		if ( '' === $own ) {
			return array();
		}
		$missing = array();
		foreach ( $languages as $code ) {
			if ( $code === $own ) {
				continue;
			}
			if ( empty( $translations[ $code ] ) ) {
				$missing[] = $code;
			}
		}
		return $missing;
	}

	/**
	 * What a translated page left as in the original (F-COMMERCE-02).
	 *
	 * @param array{title: string, description: string} $translation Title and search description of the translated page.
	 * @param array{title: string, description: string} $original    The same of the page in the default language.
	 * @return array<int, string> Names: same_title, no_description, same_description.
	 */
	public static function untranslated( array $translation, array $original ): array {
		$found = array();
		$title = self::plain( $translation['title'] );
		$first = self::plain( $original['title'] );
		// One-word titles such as "Blog" or brand names are often the same in every language.
		if ( '' !== $title && str_contains( $title, ' ' ) && $title === $first ) {
			$found[] = 'same_title';
		}
		$description = self::plain( $translation['description'] );
		$source      = self::plain( $original['description'] );
		if ( '' !== $source && '' === $description ) {
			$found[] = 'no_description';
		} elseif ( '' !== $source && $description === $source ) {
			$found[] = 'same_description';
		}
		return $found;
	}

	/**
	 * Text for comparing: lower case, single spaces.
	 *
	 * @param string $text Text.
	 */
	private static function plain( string $text ): string {
		return mb_strtolower( trim( (string) preg_replace( '/\s+/u', ' ', $text ) ) );
	}
}