<?php
/**
 * The blocklingo_lang field on translatable post types in the core wp/v2 endpoints:
 * the block editor reads and writes a post's language through it.
 */

declare( strict_types = 1 );

namespace AddBlack\Lang\Rest;

defined( 'ABSPATH' ) || exit;

use AddBlack\Lang\Hookable;
use AddBlack\Lang\Hooks;
use AddBlack\Lang\Settings\SettingsRepository;
use AddBlack\Lang\Translation\PostTranslations;
use AddBlack\Lang\Translation\TranslationRepository;
use WP_Error;

final class PostLanguageField implements Hookable {

	public const FIELD = 'blocklingo_lang';

	public function __construct(
		private readonly SettingsRepository $settings,
		private readonly TranslationRepository $translations,
		private readonly PostTranslations $posts
	) {}

	public function register(): void {
		Hooks::action( 'rest_api_init', array( $this, 'register_field' ) );
	}

	public function register_field(): void {
		$settings = $this->settings->get();
		foreach ( $settings->post_types() as $type ) {
			register_rest_field(
				$type,
				self::FIELD,
				array(
					'get_callback'    => array( $this, 'get_value' ),
					'update_callback' => array( $this, 'update_value' ),
					'schema'          => array(
						'type'        => 'string',
						'description' => __( 'Language code', 'blocklingo' ),
						'enum'        => array_keys( $settings->languages() ),
						'context'     => array( 'view', 'edit' ),
					),
				)
			);
		}
	}

	/**
	 * @param array<string, mixed> $post Prepared post data.
	 */
	public function get_value( array $post ): string {
		return $this->posts->language_of( (int) $post['id'] );
	}

	public function update_value( mixed $value, mixed $post ): bool|WP_Error {
		$post_id = $post instanceof \WP_Post ? $post->ID : 0;
		$lang    = (string) $value;
		if ( $this->posts->language_of( $post_id ) === $lang && $this->translations->find( $post_id ) ) {
			return true;
		}
		if ( ! $this->settings->get()->is_language( $lang ) ) {
			return new WP_Error( 'blocklingo_bad_lang', __( 'Unknown language.', 'blocklingo' ), array( 'status' => 400 ) );
		}
		$result = $this->translations->assign( $post_id, $lang );
		if ( $result instanceof WP_Error ) {
			$result->add_data( array( 'status' => 400 ) );
		}
		return $result;
	}
}