<?php
/**
 * Order material-change revision hash (PRD 9.10.1).
 *
 * @package Kayvandra\MarginBeacon
 */

declare(strict_types=1);

namespace Kayvandra\MarginBeacon\Application\MaterialChange;

/**
 * Stable hash over material order fields only.
 * Non-material fields (notes, addresses, shipping/fee/tax lines, MarginBeacon meta) are excluded.
 */
final class OrderMaterialHasher {

	/**
	 * Hash from a WC_Order.
	 *
	 * @param \WC_Order $order Order.
	 * @return string
	 */
	public static function hash_order( $order ) {
		$payload = array(
			'currency' => (string) $order->get_currency(),
			'items'    => array(),
			'coupons'  => array(),
		);

		foreach ( $order->get_items( 'line_item' ) as $item_id => $item ) {
			$payload['items'][] = array(
				'id'            => (int) $item_id,
				'product_id'    => (int) $item->get_product_id(),
				'variation_id'  => (int) $item->get_variation_id(),
				'qty'           => self::norm_decimal( (string) $item->get_quantity() ),
				'line_total'    => self::norm_decimal( (string) $item->get_total() ),
				'line_subtotal' => self::norm_decimal( (string) $item->get_subtotal() ),
			);
		}

		foreach ( $order->get_items( 'coupon' ) as $item_id => $item ) {
			$payload['coupons'][] = array(
				'id'       => (int) $item_id,
				'code'     => (string) $item->get_code(),
				'discount' => self::norm_decimal( (string) $item->get_discount() ),
			);
		}

		return self::hash_payload( $payload );
	}

	/**
	 * Hash from a normalized payload (unit tests / fixtures).
	 *
	 * @param array $payload Material payload.
	 * @return string
	 */
	public static function hash_payload( array $payload ) {
		$normalized = self::normalize_payload( $payload );
		return hash( 'sha256', (string) wp_json_encode( $normalized ) );
	}

	/**
	 * Deterministic sort + decimal normalization.
	 *
	 * @param array $payload Raw.
	 * @return array
	 */
	public static function normalize_payload( array $payload ) {
		$items   = isset( $payload['items'] ) && is_array( $payload['items'] ) ? $payload['items'] : array();
		$coupons = isset( $payload['coupons'] ) && is_array( $payload['coupons'] ) ? $payload['coupons'] : array();

		$norm_items = array();
		foreach ( $items as $item ) {
			if ( ! is_array( $item ) ) {
				continue;
			}
			$norm_items[] = array(
				'id'            => isset( $item['id'] ) ? (int) $item['id'] : 0,
				'product_id'    => isset( $item['product_id'] ) ? (int) $item['product_id'] : 0,
				'variation_id'  => isset( $item['variation_id'] ) ? (int) $item['variation_id'] : 0,
				'qty'           => self::norm_decimal( isset( $item['qty'] ) ? (string) $item['qty'] : '0' ),
				'line_total'    => self::norm_decimal( isset( $item['line_total'] ) ? (string) $item['line_total'] : '0' ),
				'line_subtotal' => self::norm_decimal( isset( $item['line_subtotal'] ) ? (string) $item['line_subtotal'] : '0' ),
			);
		}
		usort(
			$norm_items,
			static function ( $a, $b ) {
				return $a['id'] <=> $b['id'];
			}
		);

		$norm_coupons = array();
		foreach ( $coupons as $c ) {
			if ( ! is_array( $c ) ) {
				continue;
			}
			$norm_coupons[] = array(
				'id'       => isset( $c['id'] ) ? (int) $c['id'] : 0,
				'code'     => isset( $c['code'] ) ? (string) $c['code'] : '',
				'discount' => self::norm_decimal( isset( $c['discount'] ) ? (string) $c['discount'] : '0' ),
			);
		}
		usort(
			$norm_coupons,
			static function ( $a, $b ) {
				return $a['id'] <=> $b['id'];
			}
		);

		return array(
			'currency' => isset( $payload['currency'] ) ? (string) $payload['currency'] : '',
			'items'    => $norm_items,
			'coupons'  => $norm_coupons,
		);
	}

	/**
	 * Normalize decimal strings so "10.0" === "10.00".
	 *
	 * @param string $value Raw.
	 * @return string
	 */
	public static function norm_decimal( $value ) {
		$value = trim( (string) $value );
		if ( '' === $value || ! is_numeric( $value ) ) {
			return $value;
		}
		if ( function_exists( 'bcadd' ) ) {
			$normalized = bcadd( $value, '0', 6 );
			$normalized = rtrim( rtrim( $normalized, '0' ), '.' );
			return '' === $normalized ? '0' : $normalized;
		}
		// Fallback only when BCMath unavailable (plugin requires ext-bcmath at runtime).
		$raw = trim( (string) $value );
		if ( ! preg_match( '/^-?\d+(?:\.\d+)?$/', $raw ) ) {
			return '0';
		}
		$neg   = '-' === $raw[0];
		$clean = ltrim( $raw, '-' );
		if ( false === strpos( $clean, '.' ) ) {
			$clean .= '.000000';
		}
		$parts  = explode( '.', $clean, 2 );
		$whole  = $parts[0];
		$frac   = str_pad( substr( $parts[1], 0, 6 ), 6, '0', STR_PAD_RIGHT );
		$result = $whole . '.' . $frac;
		return ( $neg ? '-' : '' ) . $result;
	}
}