<?php
/**
 * Pre-apply coupon validation for preflight simulation (WC fidelity).
 *
 * @package Kayvandra\MarginBeacon
 */

declare(strict_types=1);

namespace Kayvandra\MarginBeacon\Application\Audit;

use Kayvandra\MarginBeacon\Domain\Money\MoneyAmount;

/**
 * Validates coupon constraints that WC_Discounts skips when validate=false.
 */
final class CouponSimulationValidator {

	/**
	 * @param \WC_Coupon       $coupon        Coupon.
	 * @param MoneyAmount|null $line_subtotal Optional subtotal for min/max spend checks.
	 * @return array{valid:bool,code:?string}
	 */
	public function validate_for_simulation( $coupon, $line_subtotal = null ) {
		if ( ! $coupon || ! is_object( $coupon ) ) {
			return array(
				'valid' => false,
				'code'  => 'MB_COUPON_NOT_FOUND',
			);
		}

		// Full WC_Coupon path (runtime). Lightweight stubs used in unit fixtures skip WP checks.
		$has_id = is_callable( array( $coupon, 'get_id' ) );
		if ( $has_id ) {
			$id = (int) $coupon->get_id();
			if ( $id <= 0 ) {
				return array(
					'valid' => false,
					'code'  => 'MB_COUPON_NOT_FOUND',
				);
			}
			if ( function_exists( 'get_post_status' ) && 'publish' !== get_post_status( $id ) ) {
				return array(
					'valid' => false,
					'code'  => 'MB_COUPON_INACTIVE',
				);
			}
		}

		if ( is_callable( array( $coupon, 'get_date_expires' ) ) ) {
			$exp = $coupon->get_date_expires();
			if ( $exp && is_object( $exp ) && method_exists( $exp, 'getTimestamp' ) && $exp->getTimestamp() < time() ) {
				return array(
					'valid' => false,
					'code'  => 'MB_COUPON_EXPIRED',
				);
			}
		}

		if ( $line_subtotal instanceof MoneyAmount
			&& is_callable( array( $coupon, 'get_minimum_amount' ) )
			&& is_callable( array( $coupon, 'get_maximum_amount' ) )
		) {
			$sub_s = $line_subtotal->to_decimal_string();
			$min_s = trim( (string) $coupon->get_minimum_amount() );
			$max_s = trim( (string) $coupon->get_maximum_amount() );
			if ( '' !== $min_s && is_numeric( $min_s ) && function_exists( 'bccomp' ) ) {
				if ( bccomp( $min_s, '0', 6 ) > 0 && bccomp( $sub_s, $min_s, 6 ) < 0 ) {
					return array(
						'valid' => false,
						'code'  => 'MB_COUPON_MIN_SPEND',
					);
				}
			}
			if ( '' !== $max_s && is_numeric( $max_s ) && function_exists( 'bccomp' ) ) {
				if ( bccomp( $max_s, '0', 6 ) > 0 && bccomp( $sub_s, $max_s, 6 ) > 0 ) {
					return array(
						'valid' => false,
						'code'  => 'MB_COUPON_MAX_SPEND',
					);
				}
			}
		}

		return array(
			'valid' => true,
			'code'  => null,
		);
	}
}