<?php
/**
 * Computed order money breakdown.
 *
 * @package Bookline
 */

declare( strict_types=1 );

namespace Bookline\Domain\Pricing;

use Bookline\Domain\Shared\DomainException;

/**
 * Immutable totals from the pricing pipeline (docs/11 §3).
 *
 * @since 0.1.0
 */
final class OrderTotals {

	/**
	 * Constructor.
	 *
	 * @param Money $subtotal  Pre-discount, pre-tax-add (exclusive) catalogue total.
	 * @param Money $discount  Coupon discount applied.
	 * @param Money $tax       Tax component.
	 * @param Money $total     Amount the customer owes in full.
	 * @param Money $due_now   Amount charged now.
	 * @param Money $due_later Outstanding balance.
	 *
	 * @throws DomainException On currency mismatch or negative amounts.
	 */
	public function __construct(
		private Money $subtotal,
		private Money $discount,
		private Money $tax,
		private Money $total,
		private Money $due_now,
		private Money $due_later,
	) {
		$currency = $this->total->currency();
		foreach ( [ $this->subtotal, $this->discount, $this->tax, $this->due_now, $this->due_later ] as $m ) {
			if ( $m->currency() !== $currency ) {
				throw new DomainException( 'pricing.totals_currency', 'All OrderTotals money fields must share a currency.' );
			}
		}
		foreach ( [ $this->subtotal, $this->discount, $this->tax, $this->total, $this->due_now, $this->due_later ] as $m ) {
			if ( $m->is_negative() ) {
				throw new DomainException( 'pricing.totals_negative', 'OrderTotals money fields must not be negative.' );
			}
		}
		if ( $this->due_now->amount_minor() + $this->due_later->amount_minor() !== $this->total->amount_minor() ) {
			throw new DomainException( 'pricing.totals_due_split', 'due_now + due_later must equal total.' );
		}
	}

	/**
	 * Subtotal before discount.
	 *
	 * @since 0.1.0
	 */
	public function subtotal(): Money {
		return $this->subtotal;
	}

	/**
	 * Discount amount.
	 *
	 * @since 0.1.0
	 */
	public function discount(): Money {
		return $this->discount;
	}

	/**
	 * Tax component.
	 *
	 * @since 0.1.0
	 */
	public function tax(): Money {
		return $this->tax;
	}

	/**
	 * Grand total.
	 *
	 * @since 0.1.0
	 */
	public function total(): Money {
		return $this->total;
	}

	/**
	 * Amount due now.
	 *
	 * @since 0.1.0
	 */
	public function due_now(): Money {
		return $this->due_now;
	}

	/**
	 * Amount due later.
	 *
	 * @since 0.1.0
	 */
	public function due_later(): Money {
		return $this->due_later;
	}

	/**
	 * JSON payload stored on the order intent (docs/11 §3).
	 *
	 * @return array{
	 *     subtotal_minor: int,
	 *     discount_minor: int,
	 *     tax_minor: int,
	 *     total_minor: int,
	 *     due_now_minor: int,
	 *     due_later_minor: int,
	 *     currency: string
	 * }
	 */
	public function to_payload(): array {
		return [
			'subtotal_minor'  => $this->subtotal->amount_minor(),
			'discount_minor'  => $this->discount->amount_minor(),
			'tax_minor'       => $this->tax->amount_minor(),
			'total_minor'     => $this->total->amount_minor(),
			'due_now_minor'   => $this->due_now->amount_minor(),
			'due_later_minor' => $this->due_later->amount_minor(),
			'currency'        => $this->total->currency(),
		];
	}
}