<?php
/**
 * Resolves sale-price provenance confidence for an order (TSG-015).
 *
 * @package Kayvandra\MarginBeacon
 */

declare(strict_types=1);

namespace Kayvandra\MarginBeacon\Application\Provenance;

use Kayvandra\MarginBeacon\Application\OrderRisk\QuantityNormalizer;
use Kayvandra\MarginBeacon\Domain\Money\MoneyAmount;
use Kayvandra\MarginBeacon\Domain\Money\MoneyException;
use Kayvandra\MarginBeacon\Infrastructure\Persistence\PriceRevisionRepository;

/**
 * Looks up continuous price-revision intervals for order creation time.
 */
final class SaleProvenanceResolver {

	/**
	 * @var PriceRevisionRepository
	 */
	private $repo;

	/**
	 * @param PriceRevisionRepository|null $repo Repository.
	 */
	public function __construct( $repo = null ) {
		$this->repo = $repo ? $repo : new PriceRevisionRepository();
	}

	/**
	 * Resolve sale confidence for an order.
	 *
	 * @param \WC_Order $order Order.
	 * @return array{has_sale:bool,confidence:string,evidence:array}
	 */
	public function resolve( $order ) {
		$created = $order->get_date_created();
		$at_gmt  = $created ? gmdate( 'Y-m-d H:i:s', $created->getTimestamp() ) : gmdate( 'Y-m-d H:i:s' );

		$has_sale      = false;
		$any_verified  = false;
		$any_suspected = false;
		$evidence      = array();

		foreach ( $order->get_items( 'line_item' ) as $item ) {
			$product_id   = (int) $item->get_product_id();
			$variation_id = (int) $item->get_variation_id();
			$product      = $item->get_product();

			$revision      = $this->repo->find_covering( $product_id, $variation_id, $at_gmt );
			$on_sale_now   = $product && method_exists( $product, 'is_on_sale' ) && $product->is_on_sale();
			$line_suggests = $this->line_suggests_sale( $item, $product, $revision );

			if ( $revision && PriceRevisionWriter::revision_proves_sale( $revision, $at_gmt ) ) {
				$has_sale     = true;
				$any_verified = true;
				$evidence[]   = array(
					'product_id'    => $product_id,
					'variation_id'  => $variation_id,
					'confidence'    => 'verified',
					'revision_id'   => (int) $revision['id'],
					'revision_hash' => $revision['price_revision_hash'],
					'continuity'    => $revision['continuity_state'],
				);
				continue;
			}

			// Catalog / line / gap revision — visible as sale but not Safe-eligible.
			$revision_has_sale = $revision && ( null !== $revision['sale_price'] && '' !== (string) $revision['sale_price'] );
			if ( $on_sale_now || $revision_has_sale || $line_suggests ) {
				$has_sale      = true;
				$any_suspected = true;
				$reason        = 'no_revision_observation';
				if ( $revision_has_sale || ( $revision && $on_sale_now ) ) {
					$reason = 'gap_or_schedule_mismatch';
				} elseif ( $line_suggests ) {
					$reason = 'line_price_below_regular';
				} elseif ( $on_sale_now ) {
					$reason = 'catalog_on_sale_unverified';
				}
				$evidence[] = array(
					'product_id'    => $product_id,
					'variation_id'  => $variation_id,
					'confidence'    => 'suspected',
					'revision_id'   => $revision ? (int) $revision['id'] : null,
					'revision_hash' => $revision ? $revision['price_revision_hash'] : null,
					'continuity'    => $revision ? $revision['continuity_state'] : null,
					'reason'        => $reason,
				);
			}
		}

		if ( ! $has_sale ) {
			return array(
				'has_sale'   => false,
				'confidence' => 'none',
				'evidence'   => $evidence,
			);
		}

		// All sale lines must be verified for overall verified; any suspected wins.
		$confidence = ( $any_verified && ! $any_suspected ) ? 'verified' : 'suspected';

		return array(
			'has_sale'   => true,
			'confidence' => $confidence,
			'evidence'   => $evidence,
		);
	}

	/**
	 * Heuristic: unit subtotal (pre-coupon) below known regular price.
	 *
	 * @param \WC_Order_Item_Product $item     Line item.
	 * @param \WC_Product|false|null $product  Product.
	 * @param array|null             $revision Covering revision.
	 * @return bool
	 */
	private function line_suggests_sale( $item, $product, $revision ) {
		$qty_norm = QuantityNormalizer::parse( (string) $item->get_quantity() );
		if ( ! $qty_norm['valid'] || $qty_norm['units'] <= 0 || ! is_callable( array( $item, 'get_subtotal' ) ) ) {
			return false;
		}
		$qty = $qty_norm['units'];

		$regular_amount = null;
		if ( $revision && null !== $revision['regular_price'] && '' !== (string) $revision['regular_price'] ) {
			try {
				$regular_amount = MoneyAmount::from_decimal_string( (string) $revision['regular_price'], 6 );
			} catch ( MoneyException $e ) {
				$regular_amount = null;
			}
		} elseif ( $product && is_callable( array( $product, 'get_regular_price' ) ) ) {
			$rp = $product->get_regular_price();
			if ( '' !== $rp && null !== $rp ) {
				try {
					$regular_amount = MoneyAmount::from_decimal_string( (string) $rp, 6 );
				} catch ( MoneyException $e ) {
					$regular_amount = null;
				}
			}
		}
		if ( null === $regular_amount || $regular_amount->is_zero() ) {
			return false;
		}

		// PRD 9.7: no float — compare integer units directly.
		// Unit check: line_subtotal / qty < regular
		// Multiplied to avoid fractional division:
		// line_subtotal_units < regular_units * qty
		// We allow a tiny noise tolerance by subtracting 1 (covers rounding at scale 6).
		try {
			$line_subtotal_amount = MoneyAmount::from_decimal_string( (string) $item->get_subtotal(), 6 );
			if ( null === $line_subtotal_amount ) {
				return false;
			}
		} catch ( MoneyException $e ) {
			return false;
		}
		$threshold = bcmul( (string) $regular_amount->units(), (string) $qty, 0 );
		$line      = (string) $line_subtotal_amount->units();
		// One-unit tolerance: rounding noise at scale 6 is not a sale signal.
		$gap = bcsub( $threshold, $line, 0 );
		return bccomp( $gap, '1', 0 ) > 0;
	}
}