<?php
/**
 * Line item inside a cart.
 *
 * @package Bookline
 */

declare( strict_types=1 );

namespace Bookline\Domain\OrderIntent;

use Bookline\Domain\Pricing\Money;
use Bookline\Domain\Shared\DomainException;
use DateTimeImmutable;

/**
 * One appointment slot draft in a cart (docs/19 §2).
 *
 * @since 0.1.0
 */
final class CartItem {

	/**
	 * Constructor.
	 *
	 * @param int|null                  $id               Database id.
	 * @param int                       $cart_id          Parent cart.
	 * @param int                       $service_id       Service FK.
	 * @param int|null                  $duration_id      Duration FK.
	 * @param int|null                  $agent_id         Agent FK.
	 * @param int|null                  $location_id      Location FK.
	 * @param DateTimeImmutable|null    $start_utc        Start UTC.
	 * @param DateTimeImmutable|null    $end_utc          End UTC.
	 * @param DateTimeImmutable|null    $buffer_start_utc Buffer start.
	 * @param DateTimeImmutable|null    $buffer_end_utc   Buffer end.
	 * @param string|null               $timezone         IANA zone.
	 * @param int                       $attendees        Attendee count.
	 * @param array<string, mixed>|null $extras           Extras payload.
	 * @param array<string, mixed>|null $custom_fields    Custom fields.
	 * @param Money                     $price            Line price.
	 * @param int|null                  $hold_id          Soft-hold booking FK.
	 * @param int                       $sort_order       Display order.
	 *
	 * @throws DomainException When invariants fail.
	 */
	public function __construct(
		private ?int $id,
		private int $cart_id,
		private int $service_id,
		private ?int $duration_id,
		private ?int $agent_id,
		private ?int $location_id,
		private ?DateTimeImmutable $start_utc,
		private ?DateTimeImmutable $end_utc,
		private ?DateTimeImmutable $buffer_start_utc,
		private ?DateTimeImmutable $buffer_end_utc,
		private ?string $timezone,
		private int $attendees,
		private ?array $extras,
		private ?array $custom_fields,
		private Money $price,
		private ?int $hold_id,
		private int $sort_order,
	) {
		if ( $this->cart_id < 1 || $this->service_id < 1 ) {
			throw new DomainException( 'cart_item.fk', 'cart_id and service_id must be positive.' );
		}
		if ( $this->attendees < 1 ) {
			throw new DomainException( 'cart_item.attendees', 'attendees must be at least 1.' );
		}
		if ( $this->price->is_negative() ) {
			throw new DomainException( 'cart_item.price', 'price must not be negative.' );
		}
		if ( null !== $this->hold_id && $this->hold_id < 1 ) {
			throw new DomainException( 'cart_item.hold_id', 'hold_id must be positive when set.' );
		}
		if ( null !== $this->start_utc && null !== $this->end_utc && $this->end_utc <= $this->start_utc ) {
			throw new DomainException( 'cart_item.range', 'end_utc must be after start_utc.' );
		}
	}

	/**
	 * Database id.
	 *
	 * @since 0.1.0
	 */
	public function id(): ?int {
		return $this->id;
	}

	/**
	 * Cart id.
	 *
	 * @since 0.1.0
	 */
	public function cart_id(): int {
		return $this->cart_id;
	}

	/**
	 * Service id.
	 *
	 * @since 0.1.0
	 */
	public function service_id(): int {
		return $this->service_id;
	}

	/**
	 * Duration id.
	 *
	 * @since 0.1.0
	 */
	public function duration_id(): ?int {
		return $this->duration_id;
	}

	/**
	 * Agent id.
	 *
	 * @since 0.1.0
	 */
	public function agent_id(): ?int {
		return $this->agent_id;
	}

	/**
	 * Location id.
	 *
	 * @since 0.1.0
	 */
	public function location_id(): ?int {
		return $this->location_id;
	}

	/**
	 * Start UTC.
	 *
	 * @since 0.1.0
	 */
	public function start_utc(): ?DateTimeImmutable {
		return $this->start_utc;
	}

	/**
	 * End UTC.
	 *
	 * @since 0.1.0
	 */
	public function end_utc(): ?DateTimeImmutable {
		return $this->end_utc;
	}

	/**
	 * Buffer start UTC.
	 *
	 * @since 0.1.0
	 */
	public function buffer_start_utc(): ?DateTimeImmutable {
		return $this->buffer_start_utc;
	}

	/**
	 * Buffer end UTC.
	 *
	 * @since 0.1.0
	 */
	public function buffer_end_utc(): ?DateTimeImmutable {
		return $this->buffer_end_utc;
	}

	/**
	 * Timezone.
	 *
	 * @since 0.1.0
	 */
	public function timezone(): ?string {
		return $this->timezone;
	}

	/**
	 * Attendees.
	 *
	 * @since 0.1.0
	 */
	public function attendees(): int {
		return $this->attendees;
	}

	/**
	 * Extras.
	 *
	 * @return array<string, mixed>|null
	 *
	 * @since 0.1.0
	 */
	public function extras(): ?array {
		return $this->extras;
	}

	/**
	 * Custom fields.
	 *
	 * @return array<string, mixed>|null
	 *
	 * @since 0.1.0
	 */
	public function custom_fields(): ?array {
		return $this->custom_fields;
	}

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

	/**
	 * Hold booking id.
	 *
	 * @since 0.1.0
	 */
	public function hold_id(): ?int {
		return $this->hold_id;
	}

	/**
	 * Sort order.
	 *
	 * @since 0.1.0
	 */
	public function sort_order(): int {
		return $this->sort_order;
	}

	/**
	 * Assign id after insert.
	 *
	 * @param int $id New id.
	 *
	 * @throws DomainException When already assigned.
	 *
	 * @since 0.1.0
	 */
	public function assign_id( int $id ): void {
		if ( null !== $this->id ) {
			throw new DomainException( 'cart_item.id_assigned', 'Cart item id is already assigned.' );
		}
		if ( $id < 1 ) {
			throw new DomainException( 'cart_item.id_invalid', 'Cart item id must be positive.' );
		}
		$this->id = $id;
	}

	/**
	 * Attach or clear a soft hold.
	 *
	 * @param int|null $hold_id Hold booking id.
	 *
	 * @throws DomainException When hold id is invalid.
	 *
	 * @since 0.1.0
	 */
	public function set_hold_id( ?int $hold_id ): void {
		if ( null !== $hold_id && $hold_id < 1 ) {
			throw new DomainException( 'cart_item.hold_id', 'hold_id must be positive when set.' );
		}
		$this->hold_id = $hold_id;
	}
}