<?php
/**
 * Start a preview booking session from unsaved editor draft.
 *
 * @package Bookline
 */

declare( strict_types=1 );

namespace Bookline\Application\BookingForm;

use Bookline\Application\Session\BookingSessionService;
use Bookline\Domain\BookingForm\BookingFormRepository;
use Bookline\Domain\Shared\DomainException;

/**
 * Creates ephemeral sessions for the form editor live preview.
 *
 * @since 0.1.0
 */
final class CreatePreviewSessionHandler {

	/**
	 * Constructor.
	 *
	 * @param BookingFormRepository    $forms    Form port.
	 * @param BookingSessionService    $sessions Session service.
	 * @param MutateBookingFormHandler $mutator  Draft sanitiser.
	 */
	public function __construct(
		private readonly BookingFormRepository $forms,
		private readonly BookingSessionService $sessions,
		private readonly MutateBookingFormHandler $mutator,
	) {}

	/**
	 * Build a session payload from draft editor state.
	 *
	 * @param array<string, mixed> $draft Draft body.
	 * @return array<string, mixed>
	 *
	 * @throws DomainException When invalid.
	 */
	public function handle( array $draft ): array {
		$form_id = isset( $draft['form_id'] ) ? (int) $draft['form_id'] : 0;
		if ( $form_id <= 0 ) {
			throw new DomainException( 'booking_form.preview_invalid', 'Preview requires a form id.' );
		}
		$existing = $this->forms->find_by_id( $form_id );
		if ( null === $existing ) {
			throw new DomainException( 'booking_form.not_found', 'Booking form not found.' );
		}

		$patch = [];
		foreach ( [ 'steps', 'service_ids', 'agent_ids', 'location_ids', 'category_ids', 'settings', 'theme' ] as $key ) {
			if ( array_key_exists( $key, $draft ) ) {
				$patch[ $key ] = $draft[ $key ];
			}
		}
		$merged = $this->mutator->merge_patch( $existing, $patch, false );

		return $this->sessions->create_preview_from_form(
			$merged,
			isset( $draft['timezone'] ) ? (string) $draft['timezone'] : null,
			isset( $draft['locale'] ) ? (string) $draft['locale'] : null,
		);
	}
}