<?php
namespace Advently\Security;

defined( 'ABSPATH' ) || exit;

/**
 * Rate-limit counters in transients (object cache when the site has one).
 *
 * The window's end is stored with the count so later hits keep the original
 * expiry instead of sliding it forward on every request.
 */
final class TransientStore implements Store {

	public function get( string $key ): int {
		$entry = $this->entry( $key );
		return $entry ? $entry['count'] : 0;
	}

	public function incr( string $key, int $ttl ): int {
		$entry = $this->entry( $key ) ?? [
			'count'   => 0,
			'expires' => time() + $ttl,
		];
		++$entry['count'];
		set_transient( self::name( $key ), $entry, max( 1, $entry['expires'] - time() ) );
		return $entry['count'];
	}

	private function entry( string $key ): ?array {
		$entry = get_transient( self::name( $key ) );
		if ( ! is_array( $entry ) || ! isset( $entry['count'], $entry['expires'] ) || $entry['expires'] <= time() ) {
			return null;
		}
		return $entry;
	}

	private static function name( string $key ): string {
		return 'advently_rl_' . md5( $key );
	}
}