@Configuration
public class RedisConfig {
    @Bean
    public RedisTemplate<String, Object> redisTemplate(RedisConnectionFactory factory) {
        RedisTemplate<String, Object> template = new RedisTemplate<>();
        template.setConnectionFactory(factory);
        template.setKeySerializer(new StringRedisSerializer());
        template.setValueSerializer(new GenericJackson2JsonRedisSerializer());
        return template;
    }

    @Bean
    public DefaultRedisScript<Long> rateLimitScript() {
        DefaultRedisScript<Long> script = new DefaultRedisScript<>();
        script.setScriptText(
            "local key = KEYS[1]\n" +
            "local limit = tonumber(ARGV[1])\n" +
            "local expire = tonumber(ARGV[2])\n" +
            "local current = redis.call('INCR', key)\n" +
            "if current == 1 then\n" +
            "    redis.call('EXPIRE', key, expire)\n" +
            "end\n" +
            "return current > limit and 1 or 0"
        );
        script.setResultType(Long.class);
        return script;
    }
}

@Component
public class RateLimitInterceptor implements HandlerInterceptor {
    @Autowired
    private RedisTemplate<String, Object> redisTemplate;
    @Autowired
    private DefaultRedisScript<Long> rateLimitScript;

    private static final int DEFAULT_LIMIT = 60; // 每分鐘60次
    private static final int DEFAULT_TIMEOUT = 60; // 60秒過期

    @Override
    public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws IOException {
        String ip = request.getRemoteAddr();
        String uri = request.getRequestURI();
        String key = "rate_limit:" + ip + ":" + uri.split("/")[1]; // 按接口前綴分組

        Long result = redisTemplate.execute(
            rateLimitScript,
            Collections.singletonList(key),
            DEFAULT_LIMIT, DEFAULT_TIMEOUT
        );

        if (result != null && result == 1) {
            response.setStatus(HttpStatus.TOO_MANY_REQUESTS.value());
            response.getWriter().write("Too many requests");
            return false;
        }
        return true;
    }
}

@Configuration
public class WebConfig implements WebMvcConfigurer {
    @Autowired
    private RateLimitInterceptor rateLimitInterceptor;

    @Override
    public void addInterceptors(InterceptorRegistry registry) {
        registry.addInterceptor(rateLimitInterceptor)
            .addPathPatterns("/api/**")
            .excludePathPatterns("/api/login");
    }
}

public class RateLimitingInterceptor implements HandlerInterceptor {
    private final ConcurrentMap<String, Long> requestCounts = new ConcurrentHashMap<>();
    private static final long ALLOWED_REQUESTS_PER_MINUTE = 60;

    @Override
    public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
        String clientIp = request.getRemoteAddr();
        long currentTime = System.currentTimeMillis();

        // 清理過期請求
        requestCounts.entrySet().removeIf(entry -> 
            currentTime - entry.getValue() > TimeUnit.MINUTES.toMillis(1)
        );

        // 統(tǒng)計當前窗口請求數(shù)
        long count = requestCounts.values().stream()
            .filter(timestamp -> currentTime - timestamp < TimeUnit.MINUTES.toMillis(1))
            .count();

        if (count >= ALLOWED_REQUESTS_PER_MINUTE) {
            response.setStatus(HttpServletResponse.SC_TOO_MANY_REQUESTS);
            response.getWriter().write("請求過于頻繁");
            return false;
        }

        requestCounts.put(clientIp, currentTime);
        return true;
    }
}