waf.go

package service

import (
	"bytes"
	"context"
	"crypto/tls"
	"encoding/json"
	"fmt"
	"io"
	"net/http"
	"net/url"
	"os"
	"strconv"
	"strings"

	"github.com/rs/zerolog/log"
	"gitlab.com/tensorsecurity-rd/waf-console/internal/model"
	"gitlab.com/tensorsecurity-rd/waf-console/internal/utils"
	"gitlab.com/tensorsecurity-rd/waf-console/pkg/apis/waf.security.io/v1alpha1"
	"gorm.io/gorm"
	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
	"k8s.io/apimachinery/pkg/util/sets"
)

type wafService struct {
	clusterClientManager *utils.ClusterClientManager
	db                   *gorm.DB
	gatewayUrl           string
}

func NewWafService(clusterClientManager *utils.ClusterClientManager, db *gorm.DB, gatewayUrl string) Service {
	return &wafService{clusterClientManager: clusterClientManager, db: db, gatewayUrl: gatewayUrl}
}

func (s *wafService) GetWaf(ctx context.Context, regionCode, namespace, gatewayName string) (*WafService, error) {
	wafService := &model.WafService{}
	err := s.db.Model(&model.WafService{}).Where("gateway_name = ? AND region_code = ? AND namespace = ?", gatewayName, regionCode, namespace).First(wafService).Error
	if err != nil {
		if err == gorm.ErrRecordNotFound {
			// Create new WAF service record if not found
			wafService = &model.WafService{
				RegionCode:  regionCode,
				Namespace:   namespace,
				GatewayName: gatewayName,
				Mode:        string(WafModeAlert),
			}
			if err := s.db.Create(wafService).Error; err != nil {
				return nil, fmt.Errorf("failed to create WAF service: %v", err)
			}
		} else {
			return nil, fmt.Errorf("failed to query WAF service: %v", err)
		}
	}
	listenerWafs, err := s.ListListenerWafStatus(ctx, &GatewateInfo{
		GatewayName: gatewayName,
		Namespace:   namespace,
		RegionCode:  regionCode,
	})
	if err != nil {
		return nil, fmt.Errorf("failed to list listener WAF status: %v", err)
	}
	listeners := []string{}
	for _, listener := range listenerWafs {
		hosts := strings.Join(listener.Hosts, "@")
		listeners = append(listeners, fmt.Sprintf("%s-%d", hosts, listener.Port))
	}

	return &WafService{
		GatewayName: wafService.GatewayName,
		Mode:        wafService.Mode,
		RuleNum:     wafService.RuleNum,
		AttackNum:   wafService.AttackNum,
		Listeners:   listeners,
	}, nil
}

func (s *wafService) GetWafGatewayInfo(ctx context.Context, req *GetWafGatewayInfoReq) (*WafService, error) {
	wafService := &model.WafService{}
	err := s.db.Model(&model.WafService{}).Where("gateway_name = ? AND namespace = ? AND region_code = ?", req.GatewayName, req.Namespace, req.RegionCode).First(wafService).Error
	if err != nil {
		if err == gorm.ErrRecordNotFound {
			httpRequst := http.Request{
				Method: http.MethodPost,
				URL:    &url.URL{Scheme: "https", Host: "console.tensorsecurity.com", Path: "/api/v1/waf/gateway"},
				Header: http.Header{
					"Cookie": []string{req.Cookie},
				},
				Body: io.NopCloser(strings.NewReader(fmt.Sprintf(`{"gateway_name": "%s", "namespace": "%s", "region_code": "%s"}`, req.GatewayName, req.Namespace, req.RegionCode))),
			}
			resp, err := http.DefaultClient.Do(&httpRequst)
			if err != nil {
				return nil, fmt.Errorf("failed to get WAF service: %v", err)
			}
			defer resp.Body.Close()
			body, err := io.ReadAll(resp.Body)
			if err != nil {
				return nil, fmt.Errorf("failed to read WAF service: %v", err)
			}
			var wafService model.WafService
			err = json.Unmarshal(body, &wafService)
			if err != nil {
				return nil, fmt.Errorf("failed to unmarshal WAF service: %v", err)
			}
			wafService.ID = 0
			wafService.RuleCategoryStatus = nil
			wafService.RuleNum = 0
			wafService.AttackNum = 0
			// wafService.Host = model.HostList([]string{"*"})
			wafService.Mode = string(WafModeAlert)
			err = s.db.Create(wafService).Error
			if err != nil {
				return nil, fmt.Errorf("failed to create WAF service: %v", err)
			}
		} else {
			return nil, fmt.Errorf("failed to query WAF service: %v", err)
		}
	}
	return &WafService{
		GatewayName: wafService.GatewayName,
		Mode:        wafService.Mode,
		RuleNum:     wafService.RuleNum,
		AttackNum:   wafService.AttackNum,
	}, nil
}

func (s *wafService) getRulesForService(req *CreateWafReq) ([]v1alpha1.Rule, error) {
	rules := []v1alpha1.Rule{}
	ruleCategories := []model.WafRuleCategory{}
	if err := s.db.Model(&model.WafRuleCategory{}).Where("status = ?", 0).Find(&ruleCategories).Error; err != nil {
		return nil, fmt.Errorf("failed to get rule categories: %v", err)
	}

	// Get existing WAF service config if any
	wafService := &model.WafService{}
	err := s.db.Model(&model.WafService{}).Where("gateway_name = ? AND namespace = ? AND region_code = ?", req.GatewayName, req.Namespace, req.RegionCode).First(wafService).Error
	if err != nil {
		if err == gorm.ErrRecordNotFound {
			// Create new WAF service record if not found
			wafService = &model.WafService{
				RegionCode:  req.RegionCode,
				Namespace:   req.Namespace,
				GatewayName: req.GatewayName,
				Mode:        string(WafModeAlert),
			}
			if err := s.db.Create(wafService).Error; err != nil {
				return nil, fmt.Errorf("failed to create WAF service: %v", err)
			}
		} else {
			return nil, fmt.Errorf("failed to query WAF service: %v", err)
		}
	}

	// Determine which rule categories to enable
	var enabledCategories []model.WafRuleCategory

	if wafService.RuleCategoryStatus != nil && len(wafService.RuleCategoryStatus.CategoryID) > 0 {
		// Only include categories not already enabled
		for _, category := range ruleCategories {
			for _, id := range wafService.RuleCategoryStatus.CategoryID {
				if id == category.CategoryID {
					enabledCategories = append(enabledCategories, category)
					continue
				}
			}
		}
	} else {
		// Enable all categories if none specified
		enabledCategories = ruleCategories
	}

	for _, category := range enabledCategories {
		for _, rule := range category.Rules {
			rules = append(rules, v1alpha1.Rule{
				ID:          rule.ID,
				Level:       rule.Level,
				Name:        rule.Name,
				Type:        rule.Type,
				Description: rule.Description,
				Expr:        rule.Expr,
				Mode:        rule.Mode,
			})
		}
	}

	return rules, nil
}

func (s *wafService) CreateWaf(ctx context.Context, req *CreateWafReq) (*WafService, error) {
	// Create the WAF service resource
	name := fmt.Sprintf("%s-%d", req.GatewayName, req.Port)
	service := &v1alpha1.Service{
		ObjectMeta: metav1.ObjectMeta{
			Name:      name,
			Namespace: req.Namespace,
			Labels: map[string]string{
				"apigateway_name": req.GatewayName,
			},
		},
		Spec: v1alpha1.ServiceSpec{
			HostNames:   req.Host,
			ServiceName: req.GatewayName,
			Port:        req.Port,
			Workload: v1alpha1.WorkloadRef{
				Kind:      "Deployment",
				Name:      req.GatewayName,
				Namespace: req.Namespace,
			},
			Uri: &v1alpha1.StringMatch{
				Prefix: "/",
			},
			LogConfig: &v1alpha1.LogConfig{
				Enable: 1,
				Level:  "info",
			},
			Mode: "block",
		},
	}

	rules, err := s.getRulesForService(req)
	if err != nil {
		return nil, fmt.Errorf("failed to get rules for service: %v", err)
	}
	service.Spec.Rules = rules

	if len(service.Spec.Rules) == 0 {
		return nil, fmt.Errorf("cannot create WAF service with no rules")
	}

	// Create the WAF service in Kubernetes
	client := s.clusterClientManager.GetClient(req.RegionCode)
	if client == nil {
		return nil, fmt.Errorf("failed to get cluster client for region %s", req.RegionCode)
	}
	if _, err := client.WafV1alpha1().Services(req.Namespace).Create(ctx, service, metav1.CreateOptions{}); err != nil {
		return nil, fmt.Errorf("failed to create WAF service: %v", err)
	}

	return &WafService{
		GatewayName: req.GatewayName,
		Mode:        service.Spec.Mode,
		RuleNum:     len(service.Spec.Rules),
		AttackNum:   0,
	}, nil
}

func (s *wafService) DeleteListenerWaf(ctx context.Context, req *DeleteListenerReq) error {
	client := s.clusterClientManager.GetClient(req.RegionCode)
	if client == nil {
		return fmt.Errorf("failed to get cluster client for region %s", req.RegionCode)
	}
	name := fmt.Sprintf("%s-%d", req.GatewayName, req.Port)
	if err := client.WafV1alpha1().Services(req.Namespace).Delete(ctx, name, metav1.DeleteOptions{}); err != nil {
		return fmt.Errorf("failed to delete WAF service: %v", err)
	}
	return nil
}

func (s *wafService) UpdateMode(ctx context.Context, req *UpdateModeReq) (*WafService, error) {
	// Check if WAF service exists
	wafService := &model.WafService{}
	err := s.db.Model(&model.WafService{}).Where("gateway_name = ?", req.GatewayName).First(wafService).Error
	if err != nil {
		if err == gorm.ErrRecordNotFound {
			// Create new WAF service record if not found
			wafService = &model.WafService{
				RegionCode:  req.RegionCode,
				Namespace:   req.Namespace,
				GatewayName: req.GatewayName,
				Mode:        string(req.Mode),
			}
			if err := s.db.Create(wafService).Error; err != nil {
				return nil, fmt.Errorf("failed to create WAF service: %v", err)
			}
		} else {
			return nil, fmt.Errorf("failed to query WAF service: %v", err)
		}
	} else {
		// Update mode if service exists
		if err := s.db.Model(wafService).Update("mode", string(req.Mode)).Error; err != nil {
			return nil, fmt.Errorf("failed to update WAF service mode: %v", err)
		}
	}
	return nil, nil
}

func (s *wafService) GetRuleCategories(ctx context.Context) ([]WafRuleCategory, error) {
	var categories []WafRuleCategory
	err := s.db.Table("waf_rule_categories").Find(&categories).Error
	if err != nil {
		return nil, err
	}
	return categories, nil
}

func (s *wafService) GetRules(ctx context.Context, categoryID string) ([]WafRule, error) {
	var rules []WafRule
	err := s.db.Table("waf_rules").Where("category_id = ?", categoryID).Find(&rules).Error
	if err != nil {
		return nil, err
	}
	return rules, nil
}

func (s *wafService) GetRule(ctx context.Context, ruleID int) (*WafRule, error) {
	var rule WafRule
	err := s.db.Table("waf_rules").Where("id = ?", ruleID).First(&rule).Error
	if err != nil {
		return nil, err
	}
	return &rule, nil
}

func (s *wafService) SaveRuleCategoryToDB(ctx context.Context) error {
	var categories []WafRuleCategory
	jsonFile, err := os.ReadFile("rules/waf-rules.json")
	if err != nil {
		return fmt.Errorf("error reading yaml file: %v", err)
	}

	// err = yaml.Unmarshal(yamlFile, &categories)
	err = json.Unmarshal(jsonFile, &categories)
	if err != nil {
		return fmt.Errorf("error unmarshaling yaml: %v", err)
	}

	for _, category := range categories {
		rules := []model.WafRule{}
		for _, rule := range category.Rules {
			rules = append(rules, model.WafRule{
				ID:          rule.ID,
				CategoryID:  category.CategoryID,
				Level:       rule.Level,
				Name:        rule.Name,
				Type:        rule.Type,
				Description: rule.Description,
				Expr:        rule.Expr,
				Mode:        rule.Mode,
			})
		}
		model := model.WafRuleCategory{
			CategoryID:    category.CategoryID,
			Status:        category.Status,
			CategoryEN:    category.Catagory.EN,
			CategoryZH:    category.Catagory.Zh,
			DescriptionEN: category.Description.EN,
			DescriptionZH: category.Description.Zh,
			Rules:         model.RuleList(rules),
		}
		err = s.db.Table("waf_rule_categories").Create(&model).Error
		if err != nil {
			return err
		}
	}

	return nil
}

func (s *wafService) DeleteListener(ctx context.Context, req *DeleteListenerReq) error {
	listener := &model.GatewayListener{}
	err := s.db.Model(&model.GatewayListener{}).Where("gateway_name = ? AND namespace = ? AND region_code = ?", req.GatewayName, req.Namespace, req.RegionCode).First(listener).Error
	if err != nil {
		return err
	}

	err = s.db.Model(&model.GatewayListener{}).Where("gateway_name = ? AND namespace = ? AND region_code = ?", req.GatewayName, req.Namespace, req.RegionCode).Delete(listener).Error
	if err != nil {
		return err
	}

	return nil
}

func (s *wafService) EnableListenerWaf(ctx context.Context, req *EnableListenerWafReq) error {
	// listener := &model.GatewayListener{}
	// err := s.db.Model(&model.GatewayListener{}).Where("gateway_name = ? AND namespace = ? AND region_code = ?", req.GatewayName, req.Namespace, req.RegionCode).First(listener).Error
	// if err != nil {
	// 	if err == gorm.ErrRecordNotFound {
	// 		listener = &model.GatewayListener{
	// 			GatewayName: req.GatewayName,
	// 			Namespace:   req.Namespace,
	// 			RegionCode:  req.RegionCode,
	// 			Port:        int(req.Port),
	// 			Enable:      req.Enable,
	// 			Hosts:       req.Hosts,
	// 		}
	// 		err = s.db.Model(&model.GatewayListener{}).Create(listener).Error
	// 		if err != nil {
	// 			return err
	// 		}
	// 	} else {
	// 		return err
	// 	}
	// }

	// listener.Enable = req.Enable
	// err = s.db.Model(&model.GatewayListener{}).Where("gateway_name = ? AND namespace = ? AND region_code = ?", req.GatewayName, req.Namespace, req.RegionCode).Update("enable", req.Enable).Error
	// if err != nil {
	// 	return err
	// }

	if req.Enable {
		log.Info().Msgf("Create WAF for listener %s", req.GatewayName)
		_, err := s.CreateWaf(ctx, &CreateWafReq{
			GatewateInfo: GatewateInfo{
				GatewayName: req.GatewayName,
				Namespace:   req.Namespace,
				RegionCode:  req.RegionCode,
			},
			Port: uint32(req.Port),
			Host: req.Hosts,
		})
		if err != nil {
			return err
		}
	} else {
		log.Info().Msgf("Delete WAF for listener %s", req.GatewayName)
		err := s.DeleteListenerWaf(ctx, &DeleteListenerReq{
			GatewateInfo: GatewateInfo{
				GatewayName: req.GatewayName,
				Namespace:   req.Namespace,
				RegionCode:  req.RegionCode,
			},
			Port: req.Port,
		})
		if err != nil {
			return err
		}
	}
	return nil
}

func getGatewayNameFromCrn(crn string) string {
	// crn:ucs::apigateway:lf-tst7:214613666997:instance/testaaa
	parts := strings.Split(crn, "/")
	return parts[len(parts)-1]
}

func (s *wafService) listListenerFromApiGateway(ctx context.Context, apiGatewayCrn string, regionCode string, cookie string) ([]GatewayRespListenerData, error) {
	body, err := json.Marshal(map[string]string{
		"apigateway_crn": apiGatewayCrn,
		"region_code":    regionCode,
	})
	if err != nil {
		return nil, fmt.Errorf("failed to marshal request body: %v", err)
	}
	request, err := http.NewRequestWithContext(ctx, "POST", "https://csm.console.test.tg.unicom.local/apigatewaymng/listener/lf-tst7/list_listeners", bytes.NewBuffer(body))
	if err != nil {
		return nil, fmt.Errorf("failed to create request: %v", err)
	}
	request.Header.Set("Cookie", cookie)
	// Create custom transport with TLS config
	tr := &http.Transport{
		TLSClientConfig: &tls.Config{
			InsecureSkipVerify: true, // Skip certificate verification for test environment
		},
	}
	client := &http.Client{Transport: tr}
	resp, err := client.Do(request)
	if err != nil {
		return nil, fmt.Errorf("failed to get listener list: %v", err)
	}
	defer resp.Body.Close()

	log.Info().Msgf("resp: %v", resp)
	// Parse response
	var response GatewayListenerResponseList

	if err := json.NewDecoder(resp.Body).Decode(&response); err != nil {
		return nil, fmt.Errorf("failed to parse listener list: %v", err)
	}
	log.Info().Msgf("response: %v", response)
	return response.Data, nil
}

func (s *wafService) EnableGatewayWaf(ctx context.Context, req *EnableGatewayWafReq) error {
	if req.Enable {
		listeners, err := s.listListenerFromApiGateway(ctx, req.ApiGatewayCrn, req.RegionCode, req.Cookie)
		if err != nil {
			return fmt.Errorf("failed to get listener list: %v", err)
		}
		log.Info().Msgf("listeners: %v", listeners)
		// Create WAF for each listener
		for _, listener := range listeners {
			gatewayName := getGatewayNameFromCrn(listener.ApiGatewayCrn)
			namespace := fmt.Sprintf("%s-%s", listener.CreateAccountName, listener.CreateAccountID)
			if _, err := s.CreateWaf(ctx, &CreateWafReq{
				GatewateInfo: GatewateInfo{
					GatewayName: gatewayName,
					Namespace:   namespace,
					RegionCode:  req.RegionCode,
				},
				Port: uint32(listener.Port),
				Host: listener.Hosts,
			}); err != nil {
				return fmt.Errorf("failed to create WAF for listener %d: %v", listener.Port, err)
			}
		}
	} else {
		s.DeleteGatewayWaf(ctx, &GatewateInfo{
			GatewayName: req.GatewayName,
			Namespace:   req.Namespace,
			RegionCode:  req.RegionCode,
		})
	}
	return nil
}

func (s *wafService) DeleteGatewayWaf(ctx context.Context, req *GatewateInfo) error {
	client := s.clusterClientManager.GetClient(req.RegionCode)
	if client == nil {
		return fmt.Errorf("failed to get cluster client")
	}
	labelSelector := fmt.Sprintf("apigateway_name=%s", req.GatewayName)
	if err := client.WafV1alpha1().Services(req.Namespace).DeleteCollection(ctx, metav1.DeleteOptions{}, metav1.ListOptions{LabelSelector: labelSelector}); err != nil {
		return fmt.Errorf("failed to delete WAF service: %v", err)
	}
	return nil
}

func (s *wafService) UpdateRule(ctx context.Context, req *RuleRequest) error {
	wafService := &model.WafService{}
	err := s.db.Model(&model.WafService{}).Where("gateway_name = ?", req.GatewayName).First(wafService).Error
	if err != nil {
		if err == gorm.ErrRecordNotFound {
			// Create new WAF service record if not found
			wafService = &model.WafService{
				RegionCode:  req.RegionCode,
				Namespace:   req.Namespace,
				GatewayName: req.GatewayName,
				Mode:        string(WafModeAlert),
				RuleCategoryStatus: &model.RuleCategoryStatus{
					CategoryID: req.CategoryID,
					Status:     req.Status,
				},
			}
			if err := s.db.Create(wafService).Error; err != nil {
				return fmt.Errorf("failed to create WAF service: %v", err)
			}
		} else {
			return fmt.Errorf("failed to query WAF service: %v", err)
		}
	} else {
		// Update mode if service exists
		if err := s.db.Model(wafService).Update("rule_category_status", model.RuleCategoryStatus{
			CategoryID: req.CategoryID,
			Status:     req.Status,
		}).Error; err != nil {
			return fmt.Errorf("failed to update WAF service mode: %v", err)
		}
	}
	return nil
}

func (s *wafService) ListListenerWafStatus(ctx context.Context, req *GatewateInfo) ([]*GatewayListener, error) {
	client := s.clusterClientManager.GetClient(req.RegionCode)
	if client == nil {
		return nil, fmt.Errorf("failed to get cluster client")
	}

	listenerList, err := client.WafV1alpha1().Services(req.Namespace).List(ctx, metav1.ListOptions{LabelSelector: fmt.Sprintf("apigateway_name=%s", req.GatewayName)})
	if err != nil {
		return nil, fmt.Errorf("failed to get listener list: %v", err)
	}

	listenerStatusList := []*GatewayListener{}
	for _, listener := range listenerList.Items {
		n := strings.LastIndex(listener.Name, "-")
		if n == -1 {
			return nil, fmt.Errorf("failed to get listener port: %v", listener.Name)
		}
		listenerPort := listener.Name[n+1:]
		listenerPortInt, err := strconv.Atoi(listenerPort)
		if err != nil {
			return nil, fmt.Errorf("failed to parse listener port: %v", err)
		}

		// hosts := strings.Join(listener.Spec.HostNames, "@")
		// log.Info().Msgf("hosts: %v", hosts)
		listenerStatusList = append(listenerStatusList, &GatewayListener{
			GatewayName: req.GatewayName,
			Namespace:   req.Namespace,
			RegionCode:  req.RegionCode,
			Port:        listenerPortInt,
			Hosts:       listener.Spec.HostNames,
		})
	}

	// for _, port := range portList {
	// 	listenerStatusList = append(listenerStatusList, &GatewayListener{
	// 		GatewayName: req.GatewayName,
	// 		Namespace:   req.Namespace,
	// 		RegionCode:  req.RegionCode,
	// 		Port:        port,
	// 		Enable:      true,
	// 	})
	// }

	return listenerStatusList, nil
}

func (s *wafService) EnableListenerWafs(ctx context.Context, req *EnableListenerWafsReq) error {

	client := s.clusterClientManager.GetClient(req.RegionCode)
	if client == nil {
		return fmt.Errorf("failed to get cluster client")
	}

	listenerList, err := client.WafV1alpha1().Services(req.Namespace).List(ctx, metav1.ListOptions{LabelSelector: fmt.Sprintf("apigateway_name=%s", req.GatewayName)})
	if err != nil {
		return err
	}

	portList := []int{}
	for _, listener := range listenerList.Items {
		n := strings.LastIndex(listener.Name, "-")
		if n == -1 {
			return fmt.Errorf("failed to get listener port: %v", listener.Name)
		}
		listenerPort := listener.Name[n+1:]
		listenerPortInt, err := strconv.Atoi(listenerPort)
		if err != nil {
			return fmt.Errorf("failed to parse listener port: %v", err)
		}
		portList = append(portList, listenerPortInt)
	}
	currentPortSet := sets.NewInt(portList...)

	desiredPortSet := sets.NewInt()
	wafMap := map[int][]string{}
	for _, listener := range req.Listeners {
		// get port from listener.HostsAndPort, like hosts1@127.0.0.1@abc.com-8080
		index := strings.LastIndex(listener.HostsAndPort, "-")
		if index == -1 {
			return fmt.Errorf("failed to get listener port: %v", listener)
		}
		port := listener.HostsAndPort[index+1:]
		portInt, err := strconv.Atoi(port)
		if err != nil {
			return fmt.Errorf("failed to parse listener port: %v", err)
		}
		desiredPortSet.Insert(portInt)
		log.Info().Msgf("listener: %v", listener.Name)

		hosts := strings.Split(listener.HostsAndPort, "@")
		wafMap[portInt] = hosts
	}

	// enable WAF for ports that are in the desired port set but not in the current port set
	addingPortSet := desiredPortSet.Difference(currentPortSet)
	for _, port := range addingPortSet.List() {
		err := s.EnableListenerWaf(ctx, &EnableListenerWafReq{
			GatewateInfo: GatewateInfo{
				GatewayName: req.GatewayName,
				Namespace:   req.Namespace,
				RegionCode:  req.RegionCode,
			},
			Port:   port,
			Hosts:  wafMap[port],
			Enable: true,
		})
		if err != nil {
			return fmt.Errorf("failed to enable listener WAF: %v", err)
		}
	}

	// delete WAF for ports that are not in the desired port set
	deletingPortSet := currentPortSet.Difference(desiredPortSet)
	for _, port := range deletingPortSet.List() {
		err := s.DeleteListenerWaf(ctx, &DeleteListenerReq{
			GatewateInfo: GatewateInfo{
				GatewayName: req.GatewayName,
				Namespace:   req.Namespace,
				RegionCode:  req.RegionCode,
			},
			Port: port,
		})
		if err != nil {
			return fmt.Errorf("failed to delete listener WAF: %v", err)
		}
	}
	return nil
}