<?php
/**
 * Resolve effective unit price (after sale, before coupon).
 *
 * @package Kayvandra\MarginBeacon
 */

declare(strict_types=1);

namespace Kayvandra\MarginBeacon\Application\Audit;

use Kayvandra\MarginBeacon\Domain\Money\MoneyAmount;
use Kayvandra\MarginBeacon\Domain\Money\MoneyException;
use Kayvandra\MarginBeacon\Support\Constants;

/**
 * PRD 9.3 — sale then regular, tax-exclusive via Woo helpers when possible.
 */
final class EffectivePriceResolver {

	/**
	 * @param \WC_Product $product Product or variation.
	 * @return array{amount:?MoneyAmount,basis:string,reason_code:?string,on_sale:bool}
	 */
	public function resolve( $product ) {
		if ( ! $product ) {
			return $this->fail( 'MB_PRICE_UNRESOLVED' );
		}

		$on_sale = false;
		$raw     = '';

		if ( $product->is_on_sale() ) {
			$sale = $product->get_sale_price( 'edit' );
			if ( '' !== $sale && null !== $sale ) {
				$raw     = (string) $sale;
				$on_sale = true;
			}
		}

		if ( '' === $raw ) {
			$regular = $product->get_regular_price( 'edit' );
			if ( '' === $regular || null === $regular ) {
				// Purchasable product without price.
				return $this->fail( 'MB_PRICE_UNRESOLVED' );
			}
			$raw = (string) $regular;
		}

		// Prefer Woo tax-exclusive helper when store prices include tax.
		if ( function_exists( 'wc_get_price_excluding_tax' ) && function_exists( 'get_option' )
			&& 'yes' === get_option( 'woocommerce_prices_include_tax' )
		) {
			try {
				$ex = wc_get_price_excluding_tax(
					$product,
					array(
						'qty'   => 1,
						'price' => $raw,
					)
				);
				if ( ! is_numeric( $ex ) ) {
					return $this->fail( 'MB_TAX_BASIS_UNRESOLVED' );
				}
				$raw = (string) $ex;
			} catch ( \Throwable $e ) {
				return $this->fail( 'MB_TAX_BASIS_UNRESOLVED' );
			}
		}

		try {
			$amount = MoneyAmount::from_decimal_string( $raw, Constants::DEFAULT_MONEY_SCALE );
			if ( null === $amount ) {
				return $this->fail( 'MB_PRICE_UNRESOLVED' );
			}
			return array(
				'amount'      => $amount,
				'basis'       => $on_sale ? 'sale' : 'regular',
				'reason_code' => null,
				'on_sale'     => $on_sale,
			);
		} catch ( MoneyException $e ) {
			return $this->fail( $e->error_code() );
		}
	}

	/**
	 * @param string $code Reason.
	 * @return array
	 */
	private function fail( $code ) {
		return array(
			'amount'      => null,
			'basis'       => 'unresolved',
			'reason_code' => $code,
			'on_sale'     => false,
		);
	}
}