<?php
/**
 * Old id to new id mapping.
 *
 * @package Transtrix
 */

namespace Transtrix\Reference;

defined( 'ABSPATH' ) || exit;

/**
 * Maps source-site ids to destination-site ids, bucketed by object type.
 *
 * Bucketing matters: post 5 and term 5 are different objects. A flat map would
 * rewrite one into the other, which is the exact bug this class exists to stop.
 */
class Id_Map {

	/**
	 * Buckets of old id => new id, keyed by object type.
	 *
	 * @var array<string,array<int,int>>
	 */
	private $map = array();

	/**
	 * Record a mapping.
	 *
	 * @param string $object_type Bucket, for example 'post' or 'term'.
	 * @param int    $old         Source-site id.
	 * @param int    $new_id      Destination-site id.
	 * @return void
	 */
	public function add( string $object_type, int $old, int $new_id ): void {
		$this->map[ $object_type ][ $old ] = $new_id;
	}

	/**
	 * Look up a mapping.
	 *
	 * @param string $object_type Bucket.
	 * @param int    $old         Source-site id.
	 * @return int|null Null when unmapped.
	 */
	public function get( string $object_type, int $old ): ?int {
		return isset( $this->map[ $object_type ][ $old ] ) ? $this->map[ $object_type ][ $old ] : null;
	}

	/**
	 * Whether a mapping exists.
	 *
	 * @param string $object_type Bucket.
	 * @param int    $old         Source-site id.
	 * @return bool
	 */
	public function has( string $object_type, int $old ): bool {
		return isset( $this->map[ $object_type ][ $old ] );
	}

	/**
	 * Number of mappings in a bucket.
	 *
	 * @param string $object_type Bucket.
	 * @return int
	 */
	public function count( string $object_type ): int {
		return isset( $this->map[ $object_type ] ) ? count( $this->map[ $object_type ] ) : 0;
	}
}