<?php
/**
 * Mapping of the Kordiam slug field onto a WordPress field.
 *
 * @package Kordiam
 */

declare( strict_types=1 );

namespace Kordiam\Import;

use Kordiam\Support\MetaValue;
use Kordiam\Support\Options;

// Exit if accessed directly.
if ( ! defined( 'ABSPATH' ) ) {
	exit;
}

/**
 * Decides where a story's Slug value goes on the WordPress side.
 *
 * A site chooses one of three destinations on the Slug syncing screen: the post's
 * URL alias, its title, or an arbitrary custom field (merged into meta_input).
 */
final class SlugMapper {

	/**
	 * Option holding the destination.
	 *
	 * @var string
	 */
	public const OPTION = 'slug_syncing';

	/**
	 * Destination meaning the post's URL alias.
	 *
	 * @var string
	 */
	public const URL_ALIAS = 'url_alias';

	/**
	 * Destination meaning the post title.
	 *
	 * @var string
	 */
	public const TITLE = 'title';

	/**
	 * Blocking instantiation: this class is a namespaced function group.
	 */
	private function __construct() {
	}

	/**
	 * Getting the configured destination.
	 *
	 * @return string Destination key; URL_ALIAS when nothing is configured.
	 */
	public static function destination(): string {
		$configured = Options::get_string( self::OPTION );

		return '' === $configured ? self::URL_ALIAS : $configured;
	}

	/**
	 * Checking whether the slug is meant to become the post title (assembled elsewhere).
	 *
	 * @return bool Whether the destination is the title.
	 */
	public static function targets_title(): bool {
		return self::TITLE === self::destination();
	}

	/**
	 * Writing a slug into post data.
	 *
	 * @param array<string, mixed> $post_data Post data being assembled.
	 * @param string               $slug      Slug value from Kordiam.
	 *
	 * @return array<string, mixed> Post data with the slug applied.
	 */
	public static function apply( array $post_data, string $slug ): array {
		$slug = trim( $slug );

		if ( '' === $slug ) {
			return $post_data;
		}

		$destination = self::destination();

		if ( self::URL_ALIAS === $destination ) {
			$sanitised = sanitize_title( $slug );

			// An empty post_name would make WordPress regenerate the slug from the title.
			if ( '' !== $sanitised ) {
				$post_data['post_name'] = $sanitised;
			}

			return $post_data;
		}

		if ( self::TITLE === $destination ) {
			return $post_data;
		}

		if ( ! isset( $post_data['meta_input'] ) || ! is_array( $post_data['meta_input'] ) ) {
			$post_data['meta_input'] = array();
		}

		// WordPress does not filter arbitrary meta on the way in.
		$post_data['meta_input'][ $destination ] = MetaValue::sanitise( $slug );

		return $post_data;
	}
}