<?php
// +----------------------------------------------------------------------
// | YwxApp [ WE CAN DO IT JUST THINK ]
// +----------------------------------------------------------------------
// | Copyright (c) 2026-2036 http://ywxapp.cn All rights reserved.
// +----------------------------------------------------------------------
// | Author: ywxapp<admin@ywxapp.cn>
// +----------------------------------------------------------------------
declare(strict_types=1);

namespace ywxapp\middleware;

use Closure;
use think\App;
use think\exception\HttpException;
use think\facade\Cache;
use think\Request;
use think\Response;

/**
 * API 限流中间件（固定窗口计数，按 IP 维度）。
 *
 * - 规则读取 config/ratelimit.php：rules 为「正则 => {limit, window}」，
 *   按声明顺序匹配 pathinfo，命中即用；未命中走 default 兜底。
 * - 存储驱动跟随 config/cache.php：配了 Redis 自动分布式生效，
 *   File 驱动单机生效。
 * - 注册位置：app/api/middleware.php（放在 CrossDomain 之后，
 *   预检 OPTIONS 由 CrossDomain 提前返回，不计入配额）。
 */
class RateLimit
{
    public function __construct(protected App $app)
    {
    }

    public function handle(Request $request, Closure $next): Response
    {
        $default = (array) $this->app->config->get('ratelimit.default', ['limit' => 120, 'window' => 60]);
        $bucket  = 'default';
        $limit   = (int) ($default['limit'] ?? 120);
        $window  = max(1, (int) ($default['window'] ?? 60));

        $path = strtolower($request->pathinfo());
        foreach ((array) $this->app->config->get('ratelimit.rules', []) as $pattern => $rule) {
            if (!is_string($pattern) || !is_array($rule)) {
                continue;
            }
            if (preg_match($pattern, $path)) {
                $bucket = $pattern;
                $limit  = (int) ($rule['limit'] ?? 0);
                $window = max(1, (int) ($rule['window'] ?? 60));
                break;
            }
        }

        if ($limit <= 0) {
            return $next($request); // 0 = 该桶不限流
        }

        $key = 'ratelimit:' . ($this->app->http->getName() ?: 'index') . ':' . md5($bucket) . ':' . $request->ip();
        $hit = (int) Cache::get($key, 0);
        if ($hit >= $limit) {
            return $this->deny($request, $window, $hit);
        }
        Cache::set($key, $hit + 1, $window);

        return $next($request);
    }

    /**
     * 超限响应：api 应用或 Ajax 统一 JSON（结构与 Result 一致），其余抛 HttpException。
     */
    protected function deny(Request $request, int $window, int $hit): Response
    {
        $appName = $this->app->http->getName() ?: '';
        $isApi   = $appName === 'api' || $request->isAjax();

        if (!$isApi) {
            throw new HttpException(429, '请求过于频繁，请稍后再试');
        }

        $payload = [
            'code'      => 429,
            'message'   => '请求过于频繁，请稍后再试',
            'timestamp' => time(),
        ];

        return Response::create($payload, 'json', 429)->header([
            'Retry-After' => (string) $window,
            'X-RateLimit-Limit' => (string) $hit,
        ]);
    }
}