<?php
namespace Admirly\Domain;

/**
 * Fixed-window rate limiter: at most $limit submissions per $window seconds.
 */
final class RateLimiter {
	/** @var StoreInterface */
	private $store;
	/** @var int */
	private $limit;
	/** @var int */
	private $window;

	public function __construct( StoreInterface $store, int $limit = 3, int $window = 60 ) {
		$this->store  = $store;
		$this->limit  = $limit;
		$this->window = $window;
	}

	/** @param string $key IP or user id; stored as a sha1 hash. */
	public function allow( string $key, ?int $now = null ): bool {
		$now  = $now ?? time();
		$k    = 'admirly_rl_' . sha1( $key );
		$data = $this->store->get( $k );

		if ( ! is_array( $data ) || ( $now - (int) $data['start'] ) >= $this->window ) {
			$this->store->set(
				$k,
				[
					'start' => $now,
					'count' => 1,
				],
				$this->window
			);
			return true;
		}
		if ( (int) $data['count'] >= $this->limit ) {
			return false;
		}
		++$data['count'];
		$remaining = max( 1, $this->window - ( $now - (int) $data['start'] ) );
		$this->store->set( $k, $data, $remaining );
		return true;
	}
}