<?php
/**
 * Domain-layer exception for invariant violations.
 *
 * @package Bookline
 */

declare( strict_types=1 );

namespace Bookline\Domain\Shared;

use DomainException as PhpDomainException;

/**
 * Thrown when a domain invariant is violated.
 *
 * Presentation layers map the stable `code()` to translated copy.
 * Not final — specialised domain exceptions (e.g. SlotTakenException) may extend it.
 *
 * @since 0.1.0
 */
class DomainException extends PhpDomainException {

	/**
	 * Stable machine-readable error code.
	 *
	 * @var string
	 */
	private string $error_code;

	/**
	 * Constructor.
	 *
	 * @param string $error_code Stable code (e.g. money.currency_mismatch).
	 * @param string $message    British-English developer message.
	 *
	 * @throws \Bookline\Domain\Shared\DomainException When invariants fail.
	 */
	public function __construct( string $error_code, string $message ) {
		parent::__construct( $message );
		$this->error_code = $error_code;
	}

	/**
	 * Stable error code for presentation mapping.
	 *
	 * @since 0.1.0
	 */
	public function code(): string {
		return $this->error_code;
	}
}