package io.github.xiaoyureed.redispractice.anno;
import java.lang.annotation.*;
@Documented
@Target({ElementType.METHOD})
@Retention(RetentionPolicy.RUNTIME)
public @interface RedisLimit {
  /**
   * 标识参数名, 必须是请求参数中的一个
   */
  String identifier();
  /**
   * 在多长时间内监控, 如希望在 60s 内尝试
   * 次数限制为5次, 那么 watch=60; unit: s
   */
  long watch();
  /**
   * 锁定时长, unit: s
   */
  long lock();
  /**
   * 错误的尝试次数
   */
  int times();
}

package io.github.xiaoyureed.redispractice.aop;
@Component
@Aspect
// Ensure that current advice is outer compared with ControllerAOP
// so we can handling login limitation Exception in this aop advice.
//@Order(9)
@Slf4j
public class RedisLimitAOP {
  @Autowired
  private StringRedisTemplate stringRedisTemplate;
  @Around("@annotation(io.github.xiaoyureed.redispractice.anno.RedisLimit)")
  public Object handleLimit(ProceedingJoinPoint joinPoint) {
    MethodSignature methodSignature = (MethodSignature) joinPoint.getSignature();
    final Method   method     = methodSignature.getMethod();
    final RedisLimit redisLimitAnno = method.getAnnotation(RedisLimit.class);// 貌似可以直接在方法参数中注入 todo
    final String identifier = redisLimitAnno.identifier();
    final long  watch   = redisLimitAnno.watch();
    final int  times   = redisLimitAnno.times();
    final long  lock    = redisLimitAnno.lock();
    // final ServletRequestAttributes att       = (ServletRequestAttributes) RequestContextHolder.currentRequestAttributes();
    // final HttpServletRequest    request     = att.getRequest();
    // final String          identifierValue = request.getParameter(identifier);
    String identifierValue = null;
    try {
      final Object arg      = joinPoint.getArgs()[0];
      final Field declaredField = arg.getClass().getDeclaredField(identifier);
      declaredField.setAccessible(true);
      identifierValue = (String) declaredField.get(arg);
    } catch (NoSuchFieldException e) {
      log.error("> invalid identifier [{}], cannot find this field in request params", identifier);
    } catch (IllegalAccessException e) {
      e.printStackTrace();
    }
    if (StringUtils.isBlank(identifierValue)) {
      log.error("> the value of RedisLimit.identifier cannot be blank, invalid identifier: {}", identifier);
    }
    // check User locked
    final ValueOperations<String, String> ssOps = stringRedisTemplate.opsForValue();
    final String             flag = ssOps.get(identifierValue);
    if (flag != null && "lock".contentEquals(flag)) {
      final BaseResp result = new BaseResp();
      result.setErrMsg("user locked");
      result.setCode("1");
      return new ResponseEntity<>(result, HttpStatus.OK);
    }
    ResponseEntity result;
    try {
      result = (ResponseEntity) joinPoint.proceed();
    } catch (Throwable e) {
      result = handleLoginException(e, identifierValue, watch, times, lock);
    }
    return result;
  }
  private ResponseEntity handleLoginException(Throwable e, String identifierValue, long watch, int times, long lock) {
    final BaseResp result = new BaseResp();
    result.setCode("1");
    if (e instanceof LoginException) {
      log.info("> handle login exception...");
      final ValueOperations<String, String> ssOps = stringRedisTemplate.opsForValue();
      Boolean                exist = stringRedisTemplate.hasKey(identifierValue);
      // key doesn't exist, so it is the first login failure
      if (exist == null || !exist) {
        ssOps.set(identifierValue, "1", watch, TimeUnit.SECONDS);
        result.setErrMsg(e.getMessage());
        return new ResponseEntity<>(result, HttpStatus.OK);
      }
      String count = ssOps.get(identifierValue);
      // has been reached the limitation
      if (Integer.parseInt(count) + 1 == times) {
        log.info("> [{}] has been reached the limitation and will be locked for {}s", identifierValue, lock);
        ssOps.set(identifierValue, "lock", lock, TimeUnit.SECONDS);
        result.setErrMsg("user locked");
        return new ResponseEntity<>(result, HttpStatus.OK);
      }
      ssOps.increment(identifierValue);
      result.setErrMsg(e.getMessage() + "; you have try " + ssOps.get(identifierValue) + "times.");
    }
    log.error("> RedisLimitAOP cannot handle {}", e.getClass().getName());
    return new ResponseEntity<>(result, HttpStatus.OK);
  }
}

package io.github.xiaoyureed.redispractice.web;
@RestController
public class SessionResources {
  @Autowired
  private SessionService sessionService;
  /**
   * 1 min 之内尝试超过5次, 锁定 user 1h
   */
  @RedisLimit(identifier = "name", watch = 30, times = 5, lock = 10)
  @RequestMapping(value = "/session", method = RequestMethod.POST)
  public ResponseEntity<LoginResp> login(@Validated @RequestBody LoginReq req) {
    return new ResponseEntity<>(sessionService.login(req), HttpStatus.OK);
  }
}