<?php
/**
 * Booking life cycle: create, change status, record payments.
 *
 * @package Rentbaik
 */

namespace Rentbaik\Booking;

use DateTimeImmutable;
use Rentbaik\Availability\Availability;
use Rentbaik\Availability\BlockRepository;
use Rentbaik\Customers\CustomerRepository;
use Rentbaik\Fleet\UnitRepository;
use Rentbaik\Notifications\Emails;
use Rentbaik\Payments\PaymentRepository;
use Rentbaik\Pricing\Calculator;
use Rentbaik\Pricing\Rules;
use Rentbaik\Settings;
use Rentbaik\Support\Format;
use Rentbaik\Support\Time;
use WP_Error;

defined( 'ABSPATH' ) || exit;

/**
 * Business rules around bookings.
 */
final class BookingService {

	/**
	 * Booking statuses in their usual order.
	 */
	public const STATUSES = array( 'pending', 'confirmed', 'active', 'returned', 'completed', 'cancelled', 'no_show' );

	/**
	 * Status labels.
	 *
	 * @return array<string, string>
	 */
	public static function status_labels(): array {
		return array(
			'pending'   => __( 'Waiting', 'rentbaik' ),
			'confirmed' => __( 'Confirmed', 'rentbaik' ),
			'active'    => __( 'On rent', 'rentbaik' ),
			'returned'  => __( 'Returned', 'rentbaik' ),
			'completed' => __( 'Completed', 'rentbaik' ),
			'cancelled' => __( 'Cancelled', 'rentbaik' ),
			'no_show'   => __( 'No-show', 'rentbaik' ),
		);
	}

	/**
	 * Labels for where a booking came from.
	 *
	 * @return array<string, string>
	 */
	public static function source_labels(): array {
		return array(
			'web'      => __( 'Website', 'rentbaik' ),
			'whatsapp' => __( 'WhatsApp', 'rentbaik' ),
			'admin'    => __( 'Staff (phone / walk-in)', 'rentbaik' ),
		);
	}

	/**
	 * Allowed next statuses.
	 *
	 * @param string $status Current status.
	 * @return string[]
	 */
	public static function next_statuses( string $status ): array {
		$map = array(
			'pending'   => array( 'confirmed', 'cancelled' ),
			'confirmed' => array( 'active', 'cancelled', 'no_show' ),
			'active'    => array( 'returned' ),
			'returned'  => array( 'completed' ),
			'completed' => array(),
			'cancelled' => array(),
			'no_show'   => array(),
		);
		return $map[ $status ] ?? array();
	}

	/**
	 * Create a booking.
	 *
	 * @param array<string, mixed> $input vehicle_id, unit_id, pickup, return (UTC DateTimeImmutable), location_id,
	 *                                    return_location_id, extras (id => qty), customer (sanitized array), status,
	 *                                    source, payment_method, customer_note, internal_note, allow_past, hold,
	 *                                    hold_minutes (optional, 0 = setting), allow_unassigned (staff only: keep
	 *                                    the booking without a unit when none is free).
	 * @return int|WP_Error Booking ID.
	 */
	public static function create( array $input ) {
		$vehicle_id = (int) ( $input['vehicle_id'] ?? 0 );
		$pickup     = $input['pickup'] ?? null;
		$return     = $input['return'] ?? null;
		if ( $vehicle_id <= 0 || ! $pickup instanceof DateTimeImmutable || ! $return instanceof DateTimeImmutable ) {
			return new WP_Error( 'rentbaik_input', __( 'Choose a vehicle, a pick-up time and a return time.', 'rentbaik' ) );
		}
		$location_id = (int) ( $input['location_id'] ?? 0 );
		$valid       = Rules::validate( $vehicle_id, $pickup, $return, $location_id, ! empty( $input['allow_past'] ) );
		if ( is_wp_error( $valid ) ) {
			return $valid;
		}

		$quote = Calculator::quote( $vehicle_id, $pickup, $return, (array) ( $input['extras'] ?? array() ), $location_id );
		if ( is_wp_error( $quote ) ) {
			return $quote;
		}

		foreach ( $quote['lines'] as $line ) {
			if ( 'extra' !== $line['type'] ) {
				continue;
			}
			$extra = \Rentbaik\Pricing\ExtraRepository::find( (int) $line['extra_id'] );
			if ( $extra && null !== $extra['stock'] ) {
				$used = BookingRepository::extra_quantity_between( (int) $extra['id'], Time::to_mysql( $pickup ), Time::to_mysql( $return ) );
				if ( $used + (int) $line['quantity'] > (int) $extra['stock'] ) {
					/* translators: 1: extra name, 2: number still available. */
					return new WP_Error( 'rentbaik_extra_stock', sprintf( __( 'Not enough “%1$s” left for these dates (%2$d available).', 'rentbaik' ), $extra['name'], max( 0, (int) $extra['stock'] - $used ) ) );
				}
			}
		}

		$customer = (array) ( $input['customer'] ?? array() );
		if ( '' === ( $customer['first_name'] ?? '' ) && '' === ( $customer['last_name'] ?? '' ) ) {
			return new WP_Error( 'rentbaik_customer', __( 'Enter the customer name.', 'rentbaik' ) );
		}
		if ( '' === ( $customer['email'] ?? '' ) && '' === ( $customer['phone'] ?? '' ) ) {
			return new WP_Error( 'rentbaik_contact', __( 'Enter an email address or a phone number for the customer.', 'rentbaik' ) );
		}
		$customer_id = CustomerRepository::find_or_create( $customer );

		$status  = in_array( $input['status'] ?? '', array( 'pending', 'confirmed' ), true ) ? $input['status'] : 'pending';
		$hold    = ! empty( $input['hold'] );
		$minutes = (int) ( $input['hold_minutes'] ?? 0 ) > 0 ? (int) $input['hold_minutes'] : (int) Settings::get( 'advanced', 'hold_minutes' );
		$start   = Time::to_mysql( $pickup );
		$end     = Time::to_mysql( $return );
		$now     = gmdate( 'Y-m-d H:i:s' );

		$booking_id = BookingRepository::insert(
			array(
				'booking_number'     => 'tmp-' . wp_generate_password( 12, false ),
				'status'             => $status,
				'source'             => in_array( $input['source'] ?? '', array( 'web', 'whatsapp', 'admin' ), true ) ? $input['source'] : 'admin',
				'customer_id'        => $customer_id,
				'pickup_location_id' => $location_id,
				'return_location_id' => (int) ( $input['return_location_id'] ?? $location_id ),
				'pickup_at'          => $start,
				'return_at'          => $end,
				'currency'           => $quote['currency'],
				'subtotal'           => $quote['rental_total'],
				'extras_total'       => $quote['extras_total'],
				'fees_total'         => $quote['fees_total'],
				'tax_total'          => $quote['tax_total'],
				'total'              => $quote['total'],
				'deposit_amount'     => $quote['deposit'],
				'deposit_status'     => $quote['deposit'] > 0 ? 'due' : 'none',
				'payment_method'     => sanitize_key( (string) ( $input['payment_method'] ?? '' ) ),
				'customer_note'      => (string) ( $input['customer_note'] ?? '' ),
				'internal_note'      => (string) ( $input['internal_note'] ?? '' ),
				'created_by'         => get_current_user_id(),
				'created_at'         => $now,
				'updated_at'         => $now,
			),
			array( '%s', '%s', '%s', '%d', '%d', '%d', '%s', '%s', '%s', '%d', '%d', '%d', '%d', '%d', '%d', '%s', '%s', '%s', '%s', '%d', '%s', '%s' )
		);
		if ( $booking_id <= 0 ) {
			return new WP_Error( 'rentbaik_db', __( 'The booking could not be saved. Please try again.', 'rentbaik' ) );
		}

		$unit_id = Availability::reserve( $vehicle_id, $start, $end, $booking_id, $hold ? 'hold' : 'booking', (int) ( $input['unit_id'] ?? 0 ), $location_id, $minutes );
		$patch   = array( 'booking_number' => self::number_for( $booking_id ) );
		if ( $unit_id <= 0 ) {
			if ( $hold || empty( $input['allow_unassigned'] ) ) {
				BookingRepository::delete( $booking_id );
				return new WP_Error( 'rentbaik_unavailable', __( 'No unit of this vehicle is free for these dates.', 'rentbaik' ) );
			}
			// Staff chose to take the booking anyway: it has no unit until one is assigned.
			$unit_id                = 0;
			$patch['internal_note'] = trim( (string) ( $input['internal_note'] ?? '' ) . "\n" . __( 'Created without a unit because no unit was free. Assign a unit before pick-up.', 'rentbaik' ) );
		}

		if ( $hold ) {
			$patch['hold_expires_at'] = Time::to_mysql( Time::now()->modify( '+' . $minutes . ' minutes' ) );
		}
		BookingRepository::patch( $booking_id, $patch );

		self::add_items( $booking_id, $quote, $vehicle_id, $unit_id );

		if ( ! $hold ) {
			Emails::booking_created( $booking_id );
		}

		/**
		 * Fires after a booking is created.
		 *
		 * @param int   $booking_id Booking ID.
		 * @param array $input      Input used to create it.
		 */
		do_action( 'rentbaik_booking_created', $booking_id, $input );

		return $booking_id;
	}

	/**
	 * Write the lines of a quote as booking items.
	 *
	 * @param int                  $booking_id Booking ID.
	 * @param array<string, mixed> $quote      Quote from Calculator::quote().
	 * @param int                  $vehicle_id Vehicle post ID.
	 * @param int                  $unit_id    Unit ID.
	 * @return void
	 */
	private static function add_items( int $booking_id, array $quote, int $vehicle_id, int $unit_id ): void {
		foreach ( $quote['lines'] as $line ) {
			BookingRepository::add_item(
				array(
					'booking_id'    => $booking_id,
					'item_type'     => $line['type'],
					'vehicle_id'    => 'vehicle' === $line['type'] ? $vehicle_id : 0,
					'unit_id'       => 'vehicle' === $line['type'] ? $unit_id : 0,
					'extra_id'      => (int) ( $line['extra_id'] ?? 0 ),
					'label'         => $line['label'],
					'quantity'      => $line['quantity'],
					'duration'      => $line['duration'],
					'duration_unit' => $line['duration_unit'],
					'unit_price'    => $line['unit_price'],
					'total'         => $line['total'],
					'meta'          => array( 'detail' => $line['detail'] ),
				)
			);
		}
	}

	/**
	 * Move the pick-up and/or return of a booking by whole days (the times of day stay the same).
	 * Checks the rental rules and availability, and recalculates the price with the same extras.
	 *
	 * @param int  $booking_id Booking ID.
	 * @param int  $start_days Days to move the pick-up (negative = earlier).
	 * @param int  $end_days   Days to move the return.
	 * @param bool $save       False = only check and describe the change.
	 * @param int  $target_unit Move to this unit of the same vehicle (0 = keep, or any free unit when needed).
	 * @return array<string, mixed>|WP_Error Old and new pick-up, return, total and unit.
	 */
	public static function reschedule( int $booking_id, int $start_days, int $end_days, bool $save, int $target_unit = 0 ) {
		$booking = BookingRepository::find( $booking_id );
		if ( ! $booking ) {
			return new WP_Error( 'rentbaik_missing', __( 'Booking not found.', 'rentbaik' ) );
		}
		$status = (string) $booking['status'];
		if ( ! in_array( $status, array( 'pending', 'confirmed', 'active' ), true ) ) {
			return new WP_Error( 'rentbaik_move_status', __( 'Only bookings that are waiting, confirmed or on rent can be moved.', 'rentbaik' ) );
		}
		if ( '' !== (string) $booking['hold_expires_at'] ) {
			return new WP_Error( 'rentbaik_move_hold', __( 'This booking is waiting for an online payment. Move it after the payment.', 'rentbaik' ) );
		}
		if ( 'active' === $status && 0 !== $start_days ) {
			return new WP_Error( 'rentbaik_move_active', __( 'The vehicle is already picked up, so only the return date can change.', 'rentbaik' ) );
		}
		$item = BookingRepository::vehicle_item( $booking_id );
		if ( $item && $target_unit === (int) $item['unit_id'] ) {
			$target_unit = 0;
		}
		if ( 0 === $start_days && 0 === $end_days && 0 === $target_unit ) {
			return new WP_Error( 'rentbaik_move_none', __( 'The dates did not change.', 'rentbaik' ) );
		}
		if ( $target_unit > 0 ) {
			if ( 'active' === $status ) {
				return new WP_Error( 'rentbaik_move_active_unit', __( 'The vehicle is already with the customer, so the booking cannot move to another unit.', 'rentbaik' ) );
			}
			$target = UnitRepository::find( $target_unit );
			if ( ! $item || ! $target || (int) $target['vehicle_id'] !== (int) $item['vehicle_id'] || ! in_array( $target['status'], array( 'available', 'rented' ), true ) ) {
				return new WP_Error( 'rentbaik_move_unit', __( 'A booking can only move to another unit of the same vehicle that is in use.', 'rentbaik' ) );
			}
		}
		$old_pickup = Time::from_utc( (string) $booking['pickup_at'] );
		$old_return = Time::from_utc( (string) $booking['return_at'] );
		if ( ! $item || ! $old_pickup || ! $old_return ) {
			return new WP_Error( 'rentbaik_missing', __( 'Booking not found.', 'rentbaik' ) );
		}

		// Move in local time so the time of day stays the same across daylight saving changes.
		$utc    = new \DateTimeZone( 'UTC' );
		$pickup = Time::local( $old_pickup )->modify( sprintf( '%+d days', $start_days ) )->setTimezone( $utc );
		$return = Time::local( $old_return )->modify( sprintf( '%+d days', $end_days ) )->setTimezone( $utc );
		if ( $return <= $pickup ) {
			return new WP_Error( 'rentbaik_period', __( 'The return time must be after the pick-up time.', 'rentbaik' ) );
		}

		$vehicle_id = (int) $item['vehicle_id'];
		$location   = (int) $booking['pickup_location_id'];
		if ( 0 !== $end_days && $return < Time::now() ) {
			return new WP_Error( 'rentbaik_move_past', __( 'The new return is in the past. To end a rental early, mark the booking as returned.', 'rentbaik' ) );
		}
		// A moved pick-up must not be in the past; an unchanged one may be (bookings already under way).
		$valid = Rules::validate( $vehicle_id, $pickup, $return, $location, 0 === $start_days );
		if ( is_wp_error( $valid ) ) {
			return new WP_Error( 'rentbaik_move_rules', implode( ' ', $valid->get_error_messages() ) );
		}

		$start   = Time::to_mysql( $pickup );
		$end     = Time::to_mysql( $return );
		$old_uid = (int) $item['unit_id'];
		$unit_id = $target_unit > 0
			? Availability::unit_for_move( $booking_id, $vehicle_id, $target_unit, $start, $end, false, $location )
			: Availability::unit_for_move( $booking_id, $vehicle_id, $old_uid, $start, $end, 'active' !== $status, $location );
		// A booking without a unit may move its dates and still have no unit.
		$keep_unassigned = 0 === $old_uid && 0 === $target_unit && $unit_id <= 0;
		if ( $unit_id <= 0 && ! $keep_unassigned ) {
			return new WP_Error(
				'rentbaik_unavailable',
				$target_unit > 0
					? __( 'That unit is not free for these dates.', 'rentbaik' )
					: ( 'active' === $status
					? __( 'This vehicle is booked by another customer in the new period.', 'rentbaik' )
					: __( 'No unit of this vehicle is free for the new dates.', 'rentbaik' ) )
			);
		}

		$extras = array();
		foreach ( BookingRepository::items( $booking_id ) as $row ) {
			if ( 'extra' === $row['item_type'] && (int) $row['extra_id'] > 0 ) {
				$extras[ (int) $row['extra_id'] ] = (int) $row['quantity'];
			}
		}
		$quote = Calculator::quote( $vehicle_id, $pickup, $return, $extras, $location );
		if ( is_wp_error( $quote ) ) {
			return $quote;
		}

		$result = array(
			'old_pickup' => (string) $booking['pickup_at'],
			'old_return' => (string) $booking['return_at'],
			'pickup'     => $start,
			'return'     => $end,
			'old_total'  => (int) $booking['total'],
			'total'      => (int) $quote['total'],
			'paid'       => (int) $booking['paid_total'],
			'currency'   => (string) $booking['currency'],
			'old_unit'   => $old_uid,
			'unit'       => $unit_id,
			'chosen'     => $target_unit > 0,
		);
		if ( ! $save ) {
			return $result;
		}

		// Check again under the lock while moving, in case someone booked the unit in the meantime.
		$unit_id = $target_unit > 0
			? Availability::unit_for_move( $booking_id, $vehicle_id, $target_unit, $start, $end, false, $location, true )
			: Availability::unit_for_move( $booking_id, $vehicle_id, $old_uid, $start, $end, 'active' !== $status, $location, true );
		if ( $unit_id <= 0 && $keep_unassigned ) {
			$unit_id = 0;
		} elseif ( $unit_id <= 0 ) {
			return new WP_Error( 'rentbaik_unavailable', __( 'No unit of this vehicle is free for the new dates.', 'rentbaik' ) );
		}
		$result['unit'] = $unit_id;

		BookingRepository::delete_items( $booking_id );
		self::add_items( $booking_id, $quote, $vehicle_id, $unit_id );

		$user = wp_get_current_user();
		$note = sprintf(
			/* translators: 1: date, 2: user name, 3: old pick-up, 4: old return, 5: new pick-up, 6: new return. */
			__( '%1$s, %2$s moved the dates: %3$s – %4$s → %5$s – %6$s.', 'rentbaik' ),
			wp_date( Format::date_format() ),
			$user->exists() ? $user->display_name : __( 'Staff', 'rentbaik' ),
			Format::datetime( (string) $booking['pickup_at'] ),
			Format::datetime( (string) $booking['return_at'] ),
			Format::datetime( $start ),
			Format::datetime( $end )
		);
		if ( $unit_id !== $old_uid ) {
			$from_unit = UnitRepository::find( $old_uid );
			$to_unit   = UnitRepository::find( $unit_id );
			/* translators: 1: old plate number, 2: new plate number. */
			$note .= ' ' . sprintf( __( 'Unit: %1$s → %2$s.', 'rentbaik' ), $from_unit ? $from_unit['plate_number'] : '?', $to_unit ? $to_unit['plate_number'] : '?' );
		}
		$patch = array(
			'pickup_at'     => $start,
			'return_at'     => $end,
			'subtotal'      => (int) $quote['rental_total'],
			'extras_total'  => (int) $quote['extras_total'],
			'fees_total'    => (int) $quote['fees_total'],
			'tax_total'     => (int) $quote['tax_total'],
			'total'         => (int) $quote['total'],
			'internal_note' => trim( (string) $booking['internal_note'] . "\n" . $note ),
		);
		// Reminders follow the new dates.
		if ( 0 !== $start_days ) {
			$patch['pickup_reminder_sent'] = 0;
		}
		if ( 0 !== $end_days ) {
			$patch['return_reminder_sent'] = 0;
		}
		BookingRepository::patch( $booking_id, $patch );
		self::refresh_totals( $booking_id );

		/**
		 * Fires after staff moved the dates of a booking.
		 *
		 * @param int                  $booking_id Booking ID.
		 * @param array<string, mixed> $result     Old and new pick-up, return, total and unit.
		 */
		do_action( 'rentbaik_booking_rescheduled', $booking_id, $result );

		return $result;
	}

	/**
	 * Public booking number for an ID.
	 *
	 * @param int $booking_id Booking ID.
	 * @return string
	 */
	public static function number_for( int $booking_id ): string {
		return Settings::get( 'advanced', 'booking_prefix' ) . ( 1000 + $booking_id );
	}

	/**
	 * Change the status of a booking and apply its side effects.
	 *
	 * @param int    $booking_id Booking ID.
	 * @param string $status     New status.
	 * @return true|WP_Error
	 */
	public static function set_status( int $booking_id, string $status ) {
		$booking = BookingRepository::find( $booking_id );
		if ( ! $booking ) {
			return new WP_Error( 'rentbaik_missing', __( 'Booking not found.', 'rentbaik' ) );
		}
		if ( ! in_array( $status, self::next_statuses( (string) $booking['status'] ), true ) ) {
			return new WP_Error( 'rentbaik_status', __( 'This status change is not allowed.', 'rentbaik' ) );
		}

		$item    = BookingRepository::vehicle_item( $booking_id );
		$unit_id = $item ? (int) $item['unit_id'] : 0;
		$now     = gmdate( 'Y-m-d H:i:s' );
		$patch   = array( 'status' => $status );

		switch ( $status ) {
			case 'confirmed':
				BlockRepository::confirm_holds( $booking_id );
				$patch['hold_expires_at'] = null;
				break;
			case 'active':
				if ( $unit_id <= 0 ) {
					return new WP_Error( 'rentbaik_no_unit', __( 'Assign a unit to this booking before handing over the vehicle.', 'rentbaik' ) );
				}
				$patch['actual_pickup_at'] = $now;
				UnitRepository::set_status( $unit_id, 'rented' );
				break;
			case 'returned':
				$patch['actual_return_at'] = $now;
				UnitRepository::set_status( $unit_id, 'available' );
				if ( $now < $booking['return_at'] ) {
					// Early return frees the rest of the period.
					BlockRepository::set_booking_end( $booking_id, $now );
				}
				break;
			case 'cancelled':
			case 'no_show':
				BlockRepository::delete_for_booking( $booking_id );
				break;
		}

		$patch = array_filter(
			$patch,
			static function ( $value ) {
				return null !== $value;
			}
		);
		BookingRepository::patch( $booking_id, $patch );
		if ( 'confirmed' === $status ) {
			self::clear_hold_expiry( $booking_id );
		}

		Emails::status_changed( $booking_id, $status );

		/**
		 * Fires after a booking status changes.
		 *
		 * @param int    $booking_id Booking ID.
		 * @param string $status     New status.
		 * @param string $old_status Previous status.
		 */
		do_action( 'rentbaik_booking_status_changed', $booking_id, $status, (string) $booking['status'] );

		return true;
	}

	/**
	 * Remove the checkout hold expiry of a booking.
	 *
	 * @param int $booking_id Booking ID.
	 * @return void
	 */
	public static function clear_hold_expiry( int $booking_id ): void {
		BookingRepository::clear_hold_expiry( $booking_id );
	}

	/**
	 * Record a payment, refund or deposit and update the booking totals.
	 *
	 * @param int                  $booking_id Booking ID.
	 * @param array<string, mixed> $payment    payment_type, method, amount (minor), reference, note.
	 * @return int|WP_Error Payment ID.
	 */
	public static function add_payment( int $booking_id, array $payment ) {
		$booking = BookingRepository::find( $booking_id );
		if ( ! $booking ) {
			return new WP_Error( 'rentbaik_missing', __( 'Booking not found.', 'rentbaik' ) );
		}
		if ( (int) ( $payment['amount'] ?? 0 ) <= 0 ) {
			return new WP_Error( 'rentbaik_amount', __( 'Enter an amount greater than zero.', 'rentbaik' ) );
		}

		$payment_id = PaymentRepository::add(
			array_merge(
				$payment,
				array(
					'booking_id' => $booking_id,
					'currency'   => $booking['currency'],
					'status'     => 'paid',
				)
			)
		);

		self::refresh_totals( $booking_id );

		/**
		 * Fires after staff recorded a payment, refund or deposit on a booking.
		 *
		 * @param int                  $booking_id Booking ID.
		 * @param array<string, mixed> $payment    Payment data (method, amount, payment_type).
		 */
		do_action( 'rentbaik_payment_added', $booking_id, $payment );

		return $payment_id;
	}

	/**
	 * Recalculate the paid total and deposit status of a booking from its payments.
	 *
	 * @param int $booking_id Booking ID.
	 * @return void
	 */
	public static function refresh_totals( int $booking_id ): void {
		$booking = BookingRepository::find( $booking_id );
		if ( ! $booking ) {
			return;
		}
		$totals  = PaymentRepository::totals_for_booking( $booking_id );
		$deposit = (int) $booking['deposit_amount'];
		$dstatus = 'none';
		if ( $deposit > 0 ) {
			$dstatus = $totals['deposit'] >= $deposit ? 'held' : 'due';
			foreach ( PaymentRepository::for_booking( $booking_id ) as $row ) {
				if ( 'deposit_refund' === $row['payment_type'] && $totals['deposit'] <= 0 ) {
					$dstatus = 'returned';
				}
			}
		}
		BookingRepository::patch(
			$booking_id,
			array(
				'paid_total'     => $totals['paid'],
				'deposit_status' => $dstatus,
			)
		);
	}

	/**
	 * Payment state of a booking: unpaid, partial or paid.
	 *
	 * @param array<string, mixed> $booking Booking row.
	 * @return string
	 */
	public static function payment_state( array $booking ): string {
		$paid  = (int) $booking['paid_total'];
		$total = (int) $booking['total'];
		if ( $paid <= 0 ) {
			return 'unpaid';
		}
		return $paid >= $total ? 'paid' : 'partial';
	}

	/**
	 * Payment state labels.
	 *
	 * @return array<string, string>
	 */
	public static function payment_state_labels(): array {
		return array(
			'unpaid'  => __( 'Unpaid', 'rentbaik' ),
			'partial' => __( 'Part paid', 'rentbaik' ),
			'paid'    => __( 'Paid', 'rentbaik' ),
		);
	}
}