<?php
/**
 * @package Shiftora\Support
 */

declare(strict_types=1);

namespace Shiftora\Support;

// Prevent direct file access.
if ( ! defined( 'ABSPATH' ) ) {
	exit;
}

/**
 * The protocol version two sites must agree on before files are exchanged.
 *
 * V2 requires every media write to name its transfer, so two migrations into
 * one destination cannot overwrite each other's files. The destination
 * advertises its version and the sender checks it up front.
 */
final class TransferProtocol {

	/** Any authenticated media write. No longer advertised. */
	public const V1 = 1;

	/** Owner-scoped media writes. */
	public const V2 = 2;

	/** The version this build advertises. */
	public const CURRENT = self::V2;

	/** The lowest version this build can talk to. */
	public const MINIMUM = self::V2;

	/**
	 * The version a peer advertised, or 0 when unusable.
	 *
	 * Strict on types: "yes" or a boolean does not name a protocol. Numeric strings
	 * are accepted because loosely typed peers send them.
	 */
	public static function advertised_version( mixed $advertised ): int {
		if ( is_int( $advertised ) && $advertised > 0 ) {
			return $advertised;
		}

		if ( is_string( $advertised ) && ctype_digit( $advertised ) ) {
			return (int) $advertised;
		}

		return 0;
	}

}