<?php
/**
 * A single template variable definition.
 *
 * @package Bookline
 */

declare( strict_types=1 );

namespace Bookline\Domain\Notification;

use Closure;

/**
 * Palette entry + resolver for the replacement pipeline.
 *
 * @since 0.1.0
 */
final class VariableDefinition {

	/**
	 * Constructor.
	 *
	 * @param string                          $key         Dot key (e.g. booking.start_time).
	 * @param string                          $group       Group label.
	 * @param string                          $label       Admin label.
	 * @param string                          $description Admin description.
	 * @param Closure(VariableContext):string $resolver    Resolver.
	 */
	public function __construct(
		private readonly string $key,
		private readonly string $group,
		private readonly string $label,
		private readonly string $description,
		private readonly Closure $resolver,
	) {}

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

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

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

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

	/**
	 * Resolve against a context.
	 *
	 * @param VariableContext $context Context.
	 *
	 * @since 0.1.0
	 */
	public function resolve( VariableContext $context ): string {
		$resolver = $this->resolver;
		$value    = $resolver( $context );
		return is_scalar( $value ) || null === $value ? (string) ( $value ?? '' ) : '';
	}
}