<?php
/**
 * One URL per page and language (301):
 * - a page reached under the wrong language (/golovna/ for a UK page) -> its own URL (/uk/);
 * - the posts page in a language it has no version in (/uk/journal/) -> its URL;
 * - the default language's prefix in the URL (/en/about/) -> without it (/about/).
 */

declare( strict_types = 1 );

namespace AddBlack\Lang\Routing;

defined( 'ABSPATH' ) || exit;

use AddBlack\Lang\Hookable;
use AddBlack\Lang\Hooks;
use AddBlack\Lang\Settings\SettingsRepository;
use AddBlack\Lang\Translation\PostTranslations;
use WP_Post;

final class Redirects implements Hookable {

	public function __construct(
		private readonly CurrentLanguage $current,
		private readonly Urls $urls,
		private readonly SettingsRepository $settings,
		private readonly PostTranslations $posts
	) {}

	public function register(): void {
		Hooks::action( 'template_redirect', array( $this, 'redirect' ), 2 );
	}

	public function redirect(): void {
		$target = $this->target();
		if ( '' !== $target ) {
			wp_safe_redirect( $target, 301 );
			exit;
		}
	}

	/** Where the current request should go instead, or ''. */
	public function target(): string {
		$lang = $this->current->get();
		if ( ! $this->urls->pretty() || is_preview() || is_admin() || is_feed() || is_embed() || '' === $lang ) {
			return '';
		}
		$settings = $this->settings->get();

		// A page or post (also the posts page, e.g. /uk/journal/ when Journal has no UK version).
		if ( is_singular() || ( is_home() && ! is_front_page() ) ) {
			$post = get_queried_object();
			if ( $post instanceof WP_Post && 'publish' === $post->post_status && $settings->is_translatable_type( $post->post_type ) ) {
				if ( $this->posts->language_of( $post->ID ) !== $lang ) {
					return (string) get_permalink( $post );
				}
			}
		}

		// Prefix of the default language in the URL: drop it.
		$prefix_lang = $this->current->prefix_in_url();
		if ( '' !== $prefix_lang && $settings->default_code() === $prefix_lang ) {
			$uri = Urls::request_uri();
			$uri = '' !== $uri ? $uri : '/';
			return $this->urls->raw_home() . $this->urls->strip_prefix( $uri, (string) $settings->language( $prefix_lang )?->slug );
		}
		return '';
	}
}