<?php
/**
 * Merge tags.
 *
 * @package HostKhata
 */

namespace HostKhata\Domain\Email;

defined( 'ABSPATH' ) || exit;

/**
 * Replaces `{tag}` placeholders in email text.
 *
 * Unknown tags become empty, so a typo never leaks a raw placeholder to a customer.
 *
 * @since 0.1.0
 */
final class MergeTags {

	/**
	 * Replaces the tags in a text.
	 *
	 * @since 0.1.0
	 *
	 * @param string                $text Text with `{tag}` placeholders.
	 * @param array<string, scalar> $vars Values keyed by tag name.
	 * @return string
	 */
	public static function apply( string $text, array $vars ): string {
		return (string) preg_replace_callback(
			'/\{([a-z0-9_]+)\}/',
			static function ( array $found ) use ( $vars ) {
				return isset( $vars[ $found[1] ] ) && is_scalar( $vars[ $found[1] ] ) ? (string) $vars[ $found[1] ] : '';
			},
			$text
		);
	}

	/**
	 * Tags used in a text.
	 *
	 * @since 0.1.0
	 *
	 * @param string $text Text.
	 * @return string[] Tag names without braces, each once.
	 */
	public static function used( string $text ): array {
		preg_match_all( '/\{([a-z0-9_]+)\}/', $text, $matches );

		return array_values( array_unique( $matches[1] ) );
	}
}