<?php
/**
 * UUID value object (RFC 4122 string form).
 *
 * @package Bookline
 */

declare( strict_types=1 );

namespace Bookline\Domain\Shared;

/**
 * Immutable UUID wrapper. Generates version-4 identifiers.
 *
 * @since 0.1.0
 */
final class Uuid {

	private const PATTERN = '/^[0-9a-f]{8}-[0-9a-f]{4}-[1-5][0-9a-f]{3}-[89ab][0-9a-f]{3}-[0-9a-f]{12}$/i';

	/**
	 * Canonical lowercase UUID string.
	 *
	 * @var string
	 */
	private string $value;

	/**
	 * Constructor.
	 *
	 * @param string $value UUID string.
	 *
	 * @throws DomainException When the value is not a valid UUID.
	 */
	public function __construct( string $value ) {
		$value = strtolower( trim( $value ) );
		if ( 1 !== preg_match( self::PATTERN, $value ) ) {
			throw new DomainException( 'uuid.invalid', 'Value is not a valid UUID.' );
		}
		$this->value = $value;
	}

	/**
	 * Generate a random UUID v4.
	 *
	 * @since 0.1.0
	 */
	public static function generate(): self {
		$bytes    = random_bytes( 16 );
		$bytes[6] = chr( ( ord( $bytes[6] ) & 0x0f ) | 0x40 );
		$bytes[8] = chr( ( ord( $bytes[8] ) & 0x3f ) | 0x80 );

		$hex = bin2hex( $bytes );
		return new self(
			sprintf(
				'%s-%s-%s-%s-%s',
				substr( $hex, 0, 8 ),
				substr( $hex, 8, 4 ),
				substr( $hex, 12, 4 ),
				substr( $hex, 16, 4 ),
				substr( $hex, 20, 12 )
			)
		);
	}

	/**
	 * Canonical string form.
	 *
	 * @since 0.1.0
	 */
	public function to_string(): string {
		return $this->value;
	}

	/**
	 * Equals.
	 *
	 * @param self $other Parameter.
	 * @since 0.1.0
	 */
	public function equals( self $other ): bool {
		return $this->value === $other->value;
	}

	/**
	 * String cast.
	 *
	 * @since 0.1.0
	 */
	public function __toString(): string {
		return $this->value;
	}
}