<?php

declare(strict_types=1);

namespace App\Filters;

use CodeIgniter\Filters\FilterInterface;
use CodeIgniter\HTTP\RequestInterface;
use CodeIgniter\HTTP\ResponseInterface;

/**
 * Cache-backed sliding-window rate limiting for processing endpoints
 * (API, upload, download). Buckets: per-IP and per-session. Legit users
 * never hit these limits; abusive automation gets a clean 429.
 */
final class RateLimit implements FilterInterface
{
    public function before(RequestInterface $request, $arguments = null)
    {
        if (! $request instanceof \CodeIgniter\HTTP\IncomingRequest) {
            return null;
        }

        $site = config('Site');

        $ipBucket   = 'rl_ip_' . md5($request->getIPAddress() . '|' . date('YmdH'));
        $sessionKey = service('analytics')->sessionHash();
        $sessBucket = 'rl_ses_' . substr($sessionKey, 0, 16) . '|' . date('YmdH');

        $cache = cache();

        $ipCount = (int) ($cache->get($ipBucket) ?? 0);
        $seCount = (int) ($cache->get($sessBucket) ?? 0);

        // API tokens carry their own generous quota and bypass the IP window
        $isApi = str_starts_with(uri_string(), 'api/v1') && $request->getHeaderLine('Authorization') !== '';

        if (! $isApi && $ipCount >= $site->maxJobsPerHourIp * 3) {
            return $this->tooMany();
        }
        if ($seCount >= $site->maxJobsPerHourSession * 3) {
            return $this->tooMany();
        }

        $cache->save($ipBucket, $ipCount + 1, 3700);
        $cache->save($sessBucket, $seCount + 1, 3700);

        return null;
    }

    private function tooMany(): ResponseInterface
    {
        return response()
            ->setStatusCode(429)
            ->setBody(view('errors/rate_limited'));
    }

    public function after(RequestInterface $request, ResponseInterface $response, $arguments = null)
    {
        return null;
    }
}