<?php
/**
 * One step of a form.
 *
 * @package FormPilot
 * @since   1.0.0
 */

declare( strict_types = 1 );

namespace FormPilot\MultiStep;

use FormPilot\Models\Field;

if ( ! defined( 'ABSPATH' ) ) {
	exit;
}

/**
 * A group of fields shown together.
 *
 * @since 1.0.0
 */
final class Step {

	/**
	 * Constructor.
	 *
	 * @param int               $index       Zero based position of the step.
	 * @param string            $title       Heading shown above the step.
	 * @param string            $description Text shown under the heading.
	 * @param array<int, Field> $fields      Fields belonging to the step.
	 */
	public function __construct(
		private int $index = 0,
		private string $title = '',
		private string $description = '',
		private array $fields = array()
	) {}

	/**
	 * Returns the position of the step.
	 */
	public function index(): int {
		return $this->index;
	}

	/**
	 * Returns the heading.
	 */
	public function title(): string {
		return $this->title;
	}

	/**
	 * Returns the text under the heading.
	 */
	public function description(): string {
		return $this->description;
	}

	/**
	 * Returns the fields belonging to the step.
	 *
	 * @return array<int, Field> The fields.
	 */
	public function fields(): array {
		return $this->fields;
	}

	/**
	 * Returns the keys of the fields belonging to the step.
	 *
	 * @return array<int, string> The field keys.
	 */
	public function field_keys(): array {
		return array_map(
			static fn( Field $field ): string => $field->field_key(),
			$this->fields
		);
	}

	/**
	 * Determines whether the step holds any fields.
	 *
	 * @return bool True when the step is empty.
	 */
	public function is_empty(): bool {
		return array() === $this->fields;
	}
}