<?php
/**
 * Tax rate for a tax class.
 *
 * @package Bookline
 */

declare( strict_types=1 );

namespace Bookline\Domain\Pricing;

use Bookline\Domain\Shared\DomainException;

/**
 * Integer percent rate with inclusive/exclusive semantics per tax class.
 *
 * @since 0.1.0
 */
final class TaxRate {

	/**
	 * Constructor.
	 *
	 * @param string $tax_class Tax class key (e.g. standard, reduced, zero).
	 * @param int    $percent   Rate 0–100 inclusive.
	 * @param bool   $inclusive Whether catalogue prices already include this tax.
	 *
	 * @throws DomainException When percent is out of range or class is empty.
	 */
	public function __construct(
		private string $tax_class,
		private int $percent,
		private bool $inclusive,
	) {
		$tax_class = trim( $this->tax_class );
		if ( '' === $tax_class ) {
			throw new DomainException( 'tax.class_empty', 'Tax class must not be empty.' );
		}
		$this->tax_class = $tax_class;

		if ( $this->percent < 0 || $this->percent > 100 ) {
			throw new DomainException( 'tax.percent_range', 'Tax percent must be between 0 and 100 inclusive.' );
		}
	}

	/**
	 * Zero-rate helper.
	 *
	 * @param string $tax_class Tax class key.
	 * @param bool   $inclusive Inclusive flag.
	 *
	 * @since 0.1.0
	 */
	public static function zero( string $tax_class = 'zero', bool $inclusive = false ): self {
		return new self( $tax_class, 0, $inclusive );
	}

	/**
	 * Tax class key.
	 *
	 * @since 0.1.0
	 */
	public function tax_class(): string {
		return $this->tax_class;
	}

	/**
	 * Percent 0–100.
	 *
	 * @since 0.1.0
	 */
	public function percent(): int {
		return $this->percent;
	}

	/**
	 * Whether prices are tax-inclusive.
	 *
	 * @since 0.1.0
	 */
	public function is_inclusive(): bool {
		return $this->inclusive;
	}
}