<?php

namespace App\Module\OpenAPI\Middleware;

use App\Module\OpenAPI\Models\OpenApiApp;
use App\Module\OpenAPI\Services\OpenApiService;
use Closure;
use Illuminate\Http\Request;
use Illuminate\Support\Facades\Cache;
use Illuminate\Support\Facades\Log;

/**
 * API频率限制中间件
 * 
 * 用于控制API调用频率，防止滥用
 */
class RateLimitMiddleware
{
    protected OpenApiService $openApiService;

    public function __construct(OpenApiService $openApiService)
    {
        $this->openApiService = $openApiService;
    }

    /**
     * 处理请求
     *
     * @param Request $request
     * @param Closure $next
     * @param string|null $limit 限制规则，格式：60,1 表示每分钟60次
     * @return mixed
     */
    public function handle(Request $request, Closure $next, string $limit = null)
    {
        // 获取应用信息
        $app = $this->getAppFromRequest($request);
        
        if (!$app) {
            return $this->rateLimitResponse('应用信息不存在');
        }

        // 解析限制规则
        $rateLimit = $this->parseRateLimit($limit, $app);
        
        // 检查频率限制
        if (!$this->checkRateLimit($app, $rateLimit, $request)) {
            return $this->rateLimitResponse('请求频率超出限制');
        }

        // 记录请求
        $this->recordRequest($app, $request);

        return $next($request);
    }

    /**
     * 从请求中获取应用信息
     *
     * @param Request $request
     * @return OpenApiApp|null
     */
    protected function getAppFromRequest(Request $request): ?OpenApiApp
    {
        // 从请求属性中获取应用信息（由认证中间件设置）
        return $request->attributes->get('openapi_app');
    }

    /**
     * 解析限制规则
     *
     * @param string|null $limit
     * @param OpenApiApp $app
     * @return array
     */
    protected function parseRateLimit(?string $limit, OpenApiApp $app): array
    {
        // 如果没有指定限制，使用应用配置的限制
        if (!$limit) {
            $rateLimits = $app->rate_limits ?? [];
            return [
                'requests_per_minute' => $rateLimits['requests_per_minute'] ?? 60,
                'requests_per_hour' => $rateLimits['requests_per_hour'] ?? 1000,
                'requests_per_day' => $rateLimits['requests_per_day'] ?? 10000,
            ];
        }

        // 解析格式：60,1 表示每分钟60次
        $parts = explode(',', $limit);
        $maxAttempts = (int)($parts[0] ?? 60);
        $decayMinutes = (int)($parts[1] ?? 1);

        return [
            'requests_per_minute' => $decayMinutes === 1 ? $maxAttempts : 0,
            'requests_per_hour' => $decayMinutes === 60 ? $maxAttempts : 0,
            'requests_per_day' => $decayMinutes === 1440 ? $maxAttempts : 0,
        ];
    }

    /**
     * 检查频率限制
     *
     * @param OpenApiApp $app
     * @param array $rateLimit
     * @param Request $request
     * @return bool
     */
    protected function checkRateLimit(OpenApiApp $app, array $rateLimit, Request $request): bool
    {
        $ip = $request->ip();
        $appId = $app->app_id;

        // 检查每分钟限制
        if ($rateLimit['requests_per_minute'] > 0) {
            $key = "rate_limit:minute:{$appId}:{$ip}";
            if (!$this->checkLimit($key, $rateLimit['requests_per_minute'], 60)) {
                return false;
            }
        }

        // 检查每小时限制
        if ($rateLimit['requests_per_hour'] > 0) {
            $key = "rate_limit:hour:{$appId}:{$ip}";
            if (!$this->checkLimit($key, $rateLimit['requests_per_hour'], 3600)) {
                return false;
            }
        }

        // 检查每天限制
        if ($rateLimit['requests_per_day'] > 0) {
            $key = "rate_limit:day:{$appId}:{$ip}";
            if (!$this->checkLimit($key, $rateLimit['requests_per_day'], 86400)) {
                return false;
            }
        }

        return true;
    }

    /**
     * 检查单个限制
     *
     * @param string $key
     * @param int $maxAttempts
     * @param int $decaySeconds
     * @return bool
     */
    protected function checkLimit(string $key, int $maxAttempts, int $decaySeconds): bool
    {
        $attempts = Cache::get($key, 0);
        
        if ($attempts >= $maxAttempts) {
            Log::warning("Rate limit exceeded", [
                'key' => $key,
                'attempts' => $attempts,
                'max_attempts' => $maxAttempts
            ]);
            return false;
        }

        // 增加计数
        Cache::put($key, $attempts + 1, $decaySeconds);
        
        return true;
    }

    /**
     * 记录请求
     *
     * @param OpenApiApp $app
     * @param Request $request
     * @return void
     */
    protected function recordRequest(OpenApiApp $app, Request $request): void
    {
        // 这里可以记录请求日志，用于统计分析
        Log::info("API request", [
            'app_id' => $app->app_id,
            'ip' => $request->ip(),
            'uri' => $request->getRequestUri(),
            'method' => $request->getMethod(),
            'user_agent' => $request->userAgent(),
        ]);
    }

    /**
     * 返回限流响应
     *
     * @param string $message
     * @return \Illuminate\Http\JsonResponse
     */
    protected function rateLimitResponse(string $message)
    {
        return response()->json([
            'error' => 'rate_limit_exceeded',
            'message' => $message,
            'retry_after' => 60, // 建议重试时间（秒）
        ], 429);
    }
}