<?php
/**
 * Serves language URLs without extra rewrite rules.
 *
 * - do_parse_request: the prefix (/uk) is cut from the request, so WordPress
 *   resolves /uk/pro-nas/ as /pro-nas/; parse_request puts it back for
 *   canonical checks and links.
 * - home_url('/') on a page in another language points to that language's home.
 * - page_on_front / page_for_posts return the version in the current language,
 *   so /uk/ shows the Ukrainian home with the front-page template (also in the
 *   preview of a draft translation).
 */

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;

final class Router implements Hookable {

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

	public function register(): void {
		Hooks::filter( 'do_parse_request', array( $this, 'strip_prefix' ), 1 );
		Hooks::action( 'parse_request', array( $this, 'restore_uri' ), 1 );
		Hooks::filter( 'home_url', array( $this, 'home_url' ), 20, 2 );
		Hooks::filter( 'option_page_on_front', array( $this, 'special_page' ), 20 );
		Hooks::filter( 'option_page_for_posts', array( $this, 'special_page' ), 20 );
	}

	/** Do_parse_request: cut "/uk" so WordPress resolves the rest as usual. */
	public function strip_prefix( mixed $parse ): mixed {
		$lang = $this->current->prefix_in_url();
		if ( ! $lang ) {
			return $parse;
		}
		$slug     = (string) $this->settings->get()->language( $lang )?->slug;
		$original = isset( $_SERVER['REQUEST_URI'] ) ? (string) $_SERVER['REQUEST_URI'] : '/'; // phpcs:ignore WordPress.Security.ValidatedSanitizedInput -- kept byte for byte and put back in restore_uri(), so other plugins see the request unchanged; never output or queried.
		$this->current->mark_prefix_cut( $original );
		$_SERVER['REQUEST_URI'] = $this->urls->strip_prefix( wp_unslash( $original ), $slug );
		$this->raw->enter(); // WordPress reads home_url() while parsing: give it the real one.
		return $parse;
	}

	/** Parse_request: put the original URL back for canonical checks and links. */
	public function restore_uri(): void {
		$original = $this->current->take_original_uri();
		if ( null !== $original ) {
			$_SERVER['REQUEST_URI'] = $original;
			$this->raw->leave();
		}
	}

	/**
	 * Home_url( '/' ) on a UK page -> /uk/ (logo, search form, "home" links).
	 * Other paths (wp-json, assets, sitemaps) are left alone.
	 */
	public function home_url( mixed $url, mixed $path = '' ): mixed {
		if ( ! is_string( $url ) || $this->raw->active() || ! $this->urls->pretty() || ! in_array( (string) $path, array( '', '/' ), true ) ) {
			return $url;
		}
		return $this->current->is_other_than_default() ? $this->urls->lang_home( $this->current->get() ) : $url;
	}

	/** Page_on_front / page_for_posts: the published version in the current language. */
	public function special_page( mixed $value ): mixed {
		if ( $this->raw->active() || ! $value ) {
			return $value;
		}
		$lang = $this->current->get();
		if ( '' === $lang ) {
			return $value;
		}
		$id = $this->posts->published_in( (int) $value, $lang );
		if ( ! $id ) {
			$id = $this->previewed_in( (int) $value, $lang );
		}
		return $id ? $id : $value;
	}

	/**
	 * Preview of the unpublished translation of the home (or posts page):
	 * use it as the special page, so the preview gets the front-page template
	 * and looks like the page will look once published.
	 */
	private function previewed_in( int $post_id, string $lang ): int {
		// phpcs:disable WordPress.Security.NonceVerification.Recommended -- read-only, WordPress shows draft previews the same way.
		if ( empty( $_GET['preview'] ) || ! did_action( 'init' ) ) {
			return 0;
		}
		$asked = isset( $_GET['page_id'] ) ? absint( $_GET['page_id'] ) : ( isset( $_GET['p'] ) ? absint( $_GET['p'] ) : 0 );
		// phpcs:enable WordPress.Security.NonceVerification.Recommended
		$id = $this->posts->in_language( $post_id, $lang );
		return $id && $id === $asked && current_user_can( 'edit_post', $id ) ? $id : 0;
	}
}