<?php
/**
 * Detects native promotion signals on orders.
 *
 * @package Kayvandra\MarginBeacon
 */

declare(strict_types=1);

namespace Kayvandra\MarginBeacon\Application\OrderRisk;

use Kayvandra\MarginBeacon\Application\Provenance\SaleProvenanceResolver;

/**
 * Classifies promotion_signal and confidence per PRD 8.2 / TSG-015.
 */
final class PromotionSignalDetector {

	/**
	 * @var SaleProvenanceResolver
	 */
	private $sale_provenance;

	/**
	 * @param SaleProvenanceResolver|null $sale_provenance Resolver.
	 */
	public function __construct( $sale_provenance = null ) {
		$this->sale_provenance = $sale_provenance ? $sale_provenance : new SaleProvenanceResolver();
	}

	/**
	 * Detect promotion signal from a WC_Order.
	 *
	 * @param \WC_Order $order Order.
	 * @return array{signal:string,confidence:string,sale_evidence?:array}
	 */
	public function detect( $order ) {
		$has_coupon = false;
		foreach ( $order->get_items( 'coupon' ) as $item ) {
			$has_coupon = true;
			break;
		}

		$sale     = $this->sale_provenance->resolve( $order );
		$has_sale = ! empty( $sale['has_sale'] );

		if ( $has_coupon && $has_sale ) {
			// PRD 8.2: both → verified only when coupon AND sale are verified.
			$sale_conf = isset( $sale['confidence'] ) ? $sale['confidence'] : 'suspected';
			return array(
				'signal'        => 'both',
				'confidence'    => ( 'verified' === $sale_conf ) ? 'verified' : 'suspected',
				'sale_evidence' => isset( $sale['evidence'] ) ? $sale['evidence'] : array(),
			);
		}
		if ( $has_coupon ) {
			return array(
				'signal'     => 'coupon',
				'confidence' => 'verified',
			);
		}
		if ( $has_sale ) {
			return array(
				'signal'        => 'sale_price',
				'confidence'    => isset( $sale['confidence'] ) ? $sale['confidence'] : 'suspected',
				'sale_evidence' => isset( $sale['evidence'] ) ? $sale['evidence'] : array(),
			);
		}

		return array(
			'signal'     => 'none',
			'confidence' => 'none',
		);
	}
}