<?php
/**
 * Language switcher inside a classic menu (themes that print wp_nav_menu() in
 * header.php). Settings > Blocklingo > Header and footer picks the menu
 * location; the languages are added as menu items, so the theme's own walker
 * and CSS render them like the other links. Nothing is stored in the menu.
 */

declare( strict_types = 1 );

namespace AddBlack\Lang\Switcher;

defined( 'ABSPATH' ) || exit;

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

final class MenuSwitcher implements Hookable {

	/** Class on every added item; the link attributes filter looks for it. */
	public const ITEM_CLASS = 'blocklingo-menu-lang';

	/** Added items get IDs below this, so they never clash with real menu items. */
	private const ID_BASE = -1000;

	/** @var array<int, array{code: string, hreflang: string, current: bool, aria: string}> item ID => link attributes. */
	private array $links = array();

	public function __construct(
		private readonly SettingsRepository $settings,
		private readonly SwitcherBlock $switcher
	) {}

	public function register(): void {
		Hooks::filter( 'wp_nav_menu_objects', array( $this, 'add_items' ), 20, 2 );
		Hooks::filter( 'nav_menu_link_attributes', array( $this, 'link_attributes' ), 20, 2 );
		Hooks::filter( 'nav_menu_item_id', array( $this, 'item_id' ), 20, 2 );
	}

	/**
	 * Nav_menu_item_id: menu-item-blocklingo-uk instead of menu-item--1001.
	 *
	 * @param mixed $id   The li id.
	 * @param mixed $item Menu item.
	 * @return mixed
	 */
	public function item_id( mixed $id, mixed $item ): mixed {
		if ( ! is_object( $item ) || ! isset( $item->ID ) || ! isset( $this->links[ (int) $item->ID ] ) ) {
			return $id;
		}
		return 'menu-item-blocklingo-' . $this->links[ (int) $item->ID ]['code'];
	}

	/**
	 * Wp_nav_menu_objects: append one item per language to the chosen location.
	 *
	 * @param mixed $items Sorted menu items.
	 * @param mixed $args  wp_nav_menu() arguments.
	 * @return mixed
	 */
	public function add_items( mixed $items, mixed $args ): mixed {
		$options = $this->settings->get()->switcher_menu();
		if ( ! is_array( $items ) || ! is_object( $args ) || '' === $options['location'] || ( $args->theme_location ?? '' ) !== $options['location'] ) {
			return $items;
		}
		$links = $this->switcher->links(
			array(
				'display'     => $options['display'],
				'hideCurrent' => $options['hide_current'],
				'hideMissing' => $options['hide_missing'],
			)
		);
		if ( ! $links ) {
			return $items;
		}
		wp_enqueue_style( 'blocklingo-switcher' );
		$order = count( $items );
		foreach ( $links as $i => $link ) {
			$id                 = self::ID_BASE - $i;
			$this->links[ $id ] = array(
				'code'     => $link['code'],
				'hreflang' => $link['hreflang'],
				'current'  => $link['current'],
				'aria'     => $link['aria'],
			);
			$items[]            = self::item( $id, ++$order, $link );
		}
		return $items;
	}

	/**
	 * Nav_menu_link_attributes: hreflang/lang, and the same aria labels as the block.
	 *
	 * @param mixed $atts Link attributes.
	 * @param mixed $item Menu item.
	 * @return mixed
	 */
	public function link_attributes( mixed $atts, mixed $item ): mixed {
		if ( ! is_array( $atts ) || ! is_object( $item ) || ! isset( $item->ID ) || ! isset( $this->links[ (int) $item->ID ] ) ) {
			return $atts;
		}
		$link             = $this->links[ (int) $item->ID ];
		$atts['hreflang'] = $link['hreflang'];
		$atts['lang']     = $link['hreflang'];
		if ( $link['current'] ) {
			$atts['aria-current'] = 'true';
		}
		if ( '' !== $link['aria'] ) {
			$atts['aria-label'] = $link['aria'];
		}
		return $atts;
	}

	/**
	 * A menu item that exists only for this request.
	 *
	 * @param array{code: string, url: string, current: bool, html: string} $link
	 */
	private static function item( int $id, int $order, array $link ): WP_Post {
		$classes = array( 'menu-item', 'menu-item-type-custom', 'menu-item-object-custom', self::ITEM_CLASS );
		if ( $link['current'] ) {
			$classes[] = 'is-current';
		}
		$classes[] = self::ITEM_CLASS . '-' . $link['code'];
		$classes[] = 'wp-exclude-emoji';

		return new WP_Post(
			(object) array(
				'ID'               => $id,
				'db_id'            => $id,
				'post_type'        => 'nav_menu_item',
				'post_status'      => 'publish',
				'post_title'       => $link['html'],
				'title'            => $link['html'],
				'url'              => $link['url'],
				'menu_item_parent' => '0',
				'menu_order'       => $order,
				'object_id'        => (string) $id,
				'object'           => 'custom',
				'type'             => 'custom',
				'type_label'       => '',
				'target'           => '',
				'attr_title'       => '',
				'description'      => '',
				'classes'          => $classes,
				'xfn'              => '',
				'current'          => false,
				'filter'           => 'raw',
			)
		);
	}
}