package api

import (
	"crypto/rand"
	"crypto/subtle"
	"crypto/tls"
	"encoding/json"
	"fmt"
	"net"
	"net/http"
	"strconv"
	"strings"
	"sync"
	"time"

	"github.com/gin-gonic/gin"
	"github.com/go-ldap/ldap/v3"
	"github.com/pquerna/otp"
	"github.com/pquerna/otp/totp"
	"golang.org/x/crypto/bcrypt"

	"vpn-platform/backend/internal/model"
	"vpn-platform/backend/internal/service/ikev2"
	"vpn-platform/backend/internal/service/l2tp"
	"vpn-platform/backend/internal/service/openvpn"
	"vpn-platform/backend/internal/store"
)

type pendingMFA struct {
	secret  string
	backups []string
	expires time.Time
}

var (
	pendingMFAMu sync.Mutex
	pendingMFAs  = map[uint]pendingMFA{}
)

func requireRole(roles ...string) gin.HandlerFunc {
	return func(c *gin.Context) {
		role := c.GetString("role")
		for _, allowed := range roles {
			if role == allowed {
				c.Next()
				return
			}
		}
		c.AbortWithStatusJSON(http.StatusForbidden, gin.H{"error": "权限不足"})
	}
}

func (s *Server) authenticateUser(username, password string) (*model.User, error) {
	var user model.User
	err := store.DB.Where("username = ?", username).First(&user).Error
	if err == nil && user.Source != "ldap" {
		if bcrypt.CompareHashAndPassword([]byte(user.Password), []byte(password)) == nil {
			return &user, nil
		}
		return nil, fmt.Errorf("invalid password")
	}
	if user.Source == "ldap" || err != nil {
		return s.authenticateLDAP(username, password)
	}
	return nil, err
}

func ldapSettings() (*model.LDAPConfig, error) {
	var cfg model.LDAPConfig
	if err := store.DB.First(&cfg).Error; err != nil || !cfg.Enabled {
		return nil, fmt.Errorf("LDAP 未启用")
	}
	plain, err := store.DecryptSecret(cfg.BindPassword)
	if err != nil {
		return nil, fmt.Errorf("LDAP 配置密钥无效")
	}
	cfg.BindPassword = plain
	if cfg.UsernameAttribute == "" {
		cfg.UsernameAttribute = "uid"
	}
	if cfg.UserFilter == "" {
		cfg.UserFilter = "(objectClass=inetOrgPerson)"
	}
	return &cfg, nil
}

func ldapConnect(cfg *model.LDAPConfig) (*ldap.Conn, error) {
	url := cfg.URL
	if !strings.HasPrefix(url, "ldap://") && !strings.HasPrefix(url, "ldaps://") {
		// 安全默认：未显式指定协议时按 ldaps，避免口令明文过网
		url = "ldaps://" + url
	}
	conn, err := ldap.DialURL(url)
	if err != nil {
		return nil, err
	}
	if cfg.StartTLS && strings.HasPrefix(url, "ldap://") {
		host := strings.TrimPrefix(url, "ldap://")
		if h, _, err := net.SplitHostPort(host); err == nil {
			host = h
		}
		if err := conn.StartTLS(&tls.Config{ServerName: host}); err != nil {
			conn.Close()
			return nil, fmt.Errorf("StartTLS 升级失败: %w", err)
		}
	} else if strings.HasPrefix(url, "ldap://") {
		conn.Close()
		return nil, fmt.Errorf("明文 ldap:// 存在口令泄露风险，请改用 ldaps:// 或开启 StartTLS")
	}
	if cfg.BindDN != "" {
		if err := conn.Bind(cfg.BindDN, cfg.BindPassword); err != nil {
			conn.Close()
			return nil, err
		}
	}
	return conn, nil
}

func (s *Server) authenticateLDAP(username, password string) (*model.User, error) {
	cfg, err := ldapSettings()
	if err != nil || password == "" {
		return nil, fmt.Errorf("LDAP 认证不可用")
	}
	conn, err := ldapConnect(cfg)
	if err != nil {
		return nil, err
	}
	defer conn.Close()
	filter := fmt.Sprintf("(&%s(%s=%s))", cfg.UserFilter, cfg.UsernameAttribute, ldap.EscapeFilter(username))
	result, err := conn.Search(ldap.NewSearchRequest(cfg.BaseDN, ldap.ScopeWholeSubtree, ldap.NeverDerefAliases, 1, 5, false, filter, []string{"dn", cfg.UsernameAttribute, "cn", "mail"}, nil))
	if err != nil || len(result.Entries) != 1 {
		return nil, fmt.Errorf("LDAP 用户不存在")
	}
	entry := result.Entries[0]
	if err := conn.Bind(entry.DN, password); err != nil {
		return nil, fmt.Errorf("LDAP 密码错误")
	}
	var user model.User
	err = store.DB.Where("username = ?", username).First(&user).Error
	if err != nil {
		user = model.User{Username: username, Email: entry.GetAttributeValue("mail"), Source: "ldap", Role: "viewer", Enabled: true}
		if err := store.DB.Create(&user).Error; err != nil {
			return nil, err
		}
	}
	return &user, nil
}

func verifyMFA(user *model.User, code string) error {
	var device model.MFADevice
	if err := store.DB.Where("user_id = ? AND enabled = ?", user.ID, true).First(&device).Error; err != nil {
		return nil
	}
	code = strings.TrimSpace(code)
	if code == "" {
		return fmt.Errorf("需要有效的 MFA 验证码")
	}
	secret, err := store.DecryptSecret(device.Secret)
	if err != nil {
		return fmt.Errorf("MFA 配置无效")
	}
	if totp.Validate(code, secret) {
		return nil
	}
	// 备用码一次性消费（丢失验证器时恢复）
	if consumeAdminBackupCode(&device, code) {
		store.Audit(user.Username, "mfa_backup_used", user.Username, "使用备用码登录")
		return nil
	}
	return fmt.Errorf("需要有效的 MFA 验证码")
}

func consumeAdminBackupCode(device *model.MFADevice, code string) bool {
	plain, err := store.DecryptSecret(device.BackupCodes)
	if err != nil || plain == "" {
		return false
	}
	var codes []string
	if json.Unmarshal([]byte(plain), &codes) != nil {
		return false
	}
	normalized := strings.ToUpper(strings.ReplaceAll(strings.TrimSpace(code), " ", ""))
	for i, bc := range codes {
		if subtle.ConstantTimeCompare([]byte(strings.ToUpper(bc)), []byte(normalized)) == 1 {
			codes = append(codes[:i], codes[i+1:]...)
			raw, _ := json.Marshal(codes)
			if enc, err := store.EncryptSecret(string(raw)); err == nil {
				store.DB.Model(device).Update("backup_codes", enc)
			}
			return true
		}
	}
	return false
}

func (s *Server) mfaStatus(c *gin.Context) {
	var device model.MFADevice
	err := store.DB.Where("user_id = ?", c.GetUint("user_id")).First(&device).Error
	c.JSON(200, gin.H{"enabled": err == nil && device.Enabled})
}

func backupCodes() []string {
	codes := make([]string, 10)
	for i := range codes {
		raw := make([]byte, 5)
		_, _ = rand.Read(raw)
		codes[i] = fmt.Sprintf("%X", raw)
	}
	return codes
}

func (s *Server) mfaSetup(c *gin.Context) {
	var user model.User
	if err := store.DB.First(&user, c.GetUint("user_id")).Error; err != nil {
		c.JSON(404, gin.H{"error": "用户不存在"})
		return
	}
	key, err := totp.Generate(totp.GenerateOpts{Issuer: "OPSX VPN", AccountName: user.Username})
	if err != nil {
		c.JSON(500, gin.H{"error": err.Error()})
		return
	}
	pendingMFAMu.Lock()
	pendingMFAs[user.ID] = pendingMFA{secret: key.Secret(), backups: backupCodes(), expires: time.Now().Add(15 * time.Minute)}
	pendingMFAMu.Unlock()
	c.JSON(200, gin.H{"otpauth_url": key.URL(), "secret": key.Secret(), "expires_in": 900})
}

func (s *Server) mfaEnable(c *gin.Context) {
	var req struct {
		Code string `json:"code"`
	}
	if c.ShouldBindJSON(&req) != nil {
		c.JSON(400, gin.H{"error": "参数错误"})
		return
	}
	userID := c.GetUint("user_id")
	pendingMFAMu.Lock()
	pending, ok := pendingMFAs[userID]
	delete(pendingMFAs, userID)
	pendingMFAMu.Unlock()
	if !ok || time.Now().After(pending.expires) || !totp.Validate(req.Code, pending.secret) {
		c.JSON(400, gin.H{"error": "验证码无效或设置已过期"})
		return
	}
	secret, _ := store.EncryptSecret(pending.secret)
	raw, _ := json.Marshal(pending.backups)
	backups, _ := store.EncryptSecret(string(raw))
	device := model.MFADevice{UserID: userID, Secret: secret, BackupCodes: backups, Enabled: true}
	store.DB.Where("user_id = ?", userID).Assign(device).FirstOrCreate(&device)
	store.Audit(c.GetString("username"), "enable_mfa", c.GetString("username"), "")
	c.JSON(200, gin.H{"ok": true, "backup_codes": pending.backups})
}

func (s *Server) mfaDisable(c *gin.Context) {
	store.DB.Where("user_id = ?", c.GetUint("user_id")).Delete(&model.MFADevice{})
	store.Audit(c.GetString("username"), "disable_mfa", c.GetString("username"), "")
	c.JSON(200, gin.H{"ok": true})
}

func (s *Server) listUsers(c *gin.Context) {
	var users []model.User
	store.DB.Order("id").Find(&users)
	c.JSON(200, users)
}

func (s *Server) createUser(c *gin.Context) {
	var req struct {
		Username, Password, Email, Role string
		Enabled                         bool `json:"enabled"`
	}
	if c.ShouldBindJSON(&req) != nil || req.Username == "" || len(req.Password) < 8 {
		c.JSON(400, gin.H{"error": "用户名及至少 8 位的密码必填"})
		return
	}
	if req.Role == "" {
		req.Role = "viewer"
	}
	if req.Role != "admin" && req.Role != "operator" && req.Role != "viewer" {
		c.JSON(400, gin.H{"error": "角色无效"})
		return
	}
	hash, _ := bcrypt.GenerateFromPassword([]byte(req.Password), bcrypt.DefaultCost)
	user := model.User{Username: req.Username, Password: string(hash), Email: req.Email, Role: req.Role, Source: "local", Enabled: req.Enabled}
	if err := store.DB.Create(&user).Error; err != nil {
		c.JSON(400, gin.H{"error": "用户创建失败：" + err.Error()})
		return
	}
	store.Audit(c.GetString("username"), "create_user", user.Username, "")
	c.JSON(200, user)
}

func (s *Server) updateUser(c *gin.Context) {
	id, _ := strconv.Atoi(c.Param("id"))
	var user model.User
	if store.DB.First(&user, id).Error != nil {
		c.JSON(404, gin.H{"error": "用户不存在"})
		return
	}
	var req struct {
		Email, Role, Password string
		Enabled               *bool `json:"enabled"`
	}
	if c.ShouldBindJSON(&req) != nil {
		c.JSON(400, gin.H{"error": "参数错误"})
		return
	}
	if req.Email != "" {
		user.Email = req.Email
	}
	if req.Role != "" {
		user.Role = req.Role
	}
	if req.Enabled != nil {
		user.Enabled = *req.Enabled
	}
	if req.Password != "" {
		if len(req.Password) < 8 {
			c.JSON(400, gin.H{"error": "密码至少 8 位"})
			return
		}
		hash, _ := bcrypt.GenerateFromPassword([]byte(req.Password), bcrypt.DefaultCost)
		user.Password = string(hash)
		user.MustChangePassword = true // 管理员重置后强制改密
	}
	store.DB.Save(&user)
	c.JSON(200, user)
}

func (s *Server) deleteUser(c *gin.Context) {
	id, _ := strconv.Atoi(c.Param("id"))
	if uint(id) == c.GetUint("user_id") {
		c.JSON(400, gin.H{"error": "不能删除当前用户"})
		return
	}
	store.DB.Delete(&model.User{}, id)
	c.JSON(200, gin.H{"ok": true})
}

func (s *Server) getLDAPConfig(c *gin.Context) {
	var cfg model.LDAPConfig
	if store.DB.First(&cfg).Error != nil {
		c.JSON(200, gin.H{"enabled": false})
		return
	}
	c.JSON(200, cfg)
}

func (s *Server) saveLDAPConfig(c *gin.Context) {
	var req struct {
		URL               string `json:"url"`
		BindDN            string `json:"bind_dn"`
		BindPassword      string `json:"bind_password"`
		BaseDN            string `json:"base_dn"`
		UserFilter        string `json:"user_filter"`
		UsernameAttribute string `json:"username_attribute"`
		StartTLS          bool   `json:"starttls"`
		Enabled           bool   `json:"enabled"`
	}
	if c.ShouldBindJSON(&req) != nil || (req.Enabled && (req.URL == "" || req.BaseDN == "")) {
		c.JSON(400, gin.H{"error": "LDAP 地址与 Base DN 必填"})
		return
	}
	var cfg model.LDAPConfig
	store.DB.First(&cfg)
	cfg.URL, cfg.BindDN, cfg.BaseDN, cfg.UserFilter, cfg.UsernameAttribute, cfg.StartTLS, cfg.Enabled =
		req.URL, req.BindDN, req.BaseDN, req.UserFilter, req.UsernameAttribute, req.StartTLS, req.Enabled
	if req.BindPassword != "" {
		cfg.BindPassword, _ = store.EncryptSecret(req.BindPassword)
	}
	store.DB.Save(&cfg)
	c.JSON(200, gin.H{"ok": true})
}

func (s *Server) testLDAP(c *gin.Context) {
	cfg, err := ldapSettings()
	if err == nil {
		conn, connErr := ldapConnect(cfg)
		if connErr == nil {
			conn.Close()
			c.JSON(200, gin.H{"ok": true})
			return
		}
		err = connErr
	}
	c.JSON(400, gin.H{"error": "LDAP 连接失败: " + err.Error()})
}

func (s *Server) listVPNUsers(c *gin.Context) {
	var users []model.VPNUser
	q := store.DB.Order("id desc")
	if id := c.Query("tunnel_id"); id != "" {
		q = q.Where("tunnel_id = ?", id)
	}
	q.Find(&users)
	c.JSON(200, users)
}
func (s *Server) createVPNUser(c *gin.Context) {
	var req struct {
		TunnelID    uint   `json:"tunnel_id"`
		Username    string `json:"username"`
		DisplayName string `json:"display_name"`
		Email       string `json:"email"`
		Source      string `json:"source"`
		LDAPDN      string `json:"ldap_dn"`
		Password    string `json:"password"`
		Enabled     *bool  `json:"enabled"`
	}
	if c.ShouldBindJSON(&req) != nil || req.TunnelID == 0 || req.Username == "" {
		c.JSON(400, gin.H{"error": "隧道和用户名必填"})
		return
	}
	if req.Source == "" {
		req.Source = "local"
	}
	if req.Source != "local" && req.Source != "ldap" {
		c.JSON(400, gin.H{"error": "来源必须为 local 或 ldap"})
		return
	}
	t, err := store.GetTunnel(req.TunnelID)
	if err != nil {
		c.JSON(404, gin.H{"error": "隧道不存在"})
		return
	}
	switch t.Protocol {
	case "openvpn", "l2tp", "ikev2":
	default:
		c.JSON(400, gin.H{"error": "该协议不支持拨号用户（支持 OpenVPN / L2TP / IKEv2）"})
		return
	}
	user := model.VPNUser{TunnelID: req.TunnelID, Username: req.Username, DisplayName: req.DisplayName, Email: req.Email, Source: req.Source, LDAPDN: req.LDAPDN, Enabled: true}
	if req.Enabled != nil {
		user.Enabled = *req.Enabled
	}
	if user.Source == "local" {
		if len(req.Password) < 8 {
			c.JSON(400, gin.H{"error": "本地拨号用户密码至少 8 位"})
			return
		}
		hash, _ := bcrypt.GenerateFromPassword([]byte(req.Password), bcrypt.DefaultCost)
		user.Password = string(hash)
		// L2TP/IKEv2 需要可逆拨号密钥；OpenVPN 仅用 bcrypt，同时存一份便于统一导出说明。
		if enc, err := store.EncryptSecret(req.Password); err == nil {
			user.DialSecret = enc
		}
	} else if user.LDAPDN == "" {
		c.JSON(400, gin.H{"error": "LDAP 拨号用户必须填写 LDAP DN"})
		return
	}
	if err := store.DB.Create(&user).Error; err != nil {
		c.JSON(400, gin.H{"error": "创建失败：" + err.Error()})
		return
	}
	_ = refreshDialAuth(t)
	c.JSON(200, user)
}
func (s *Server) updateVPNUser(c *gin.Context) {
	id, _ := strconv.Atoi(c.Param("id"))
	var user model.VPNUser
	if store.DB.First(&user, id).Error != nil {
		c.JSON(404, gin.H{"error": "拨号用户不存在"})
		return
	}
	var req struct {
		DisplayName, Email, Password string
		Enabled                      *bool `json:"enabled"`
	}
	if c.ShouldBindJSON(&req) != nil {
		c.JSON(400, gin.H{"error": "参数错误"})
		return
	}
	user.DisplayName, user.Email = req.DisplayName, req.Email
	if req.Enabled != nil {
		if !*req.Enabled && user.Enabled {
			revokeOpenVPNCert(&user)
		}
		user.Enabled = *req.Enabled
	}
	if req.Password != "" {
		hash, _ := bcrypt.GenerateFromPassword([]byte(req.Password), bcrypt.DefaultCost)
		user.Password = string(hash)
		if enc, err := store.EncryptSecret(req.Password); err == nil {
			user.DialSecret = enc
		}
	}
	store.DB.Save(&user)
	if t, err := store.GetTunnel(user.TunnelID); err == nil {
		_ = refreshDialAuth(t)
	}
	c.JSON(200, user)
}
func (s *Server) deleteVPNUser(c *gin.Context) {
	id, _ := strconv.Atoi(c.Param("id"))
	var user model.VPNUser
	if store.DB.First(&user, id).Error == nil {
		revokeOpenVPNCert(&user)
		tunnelID := user.TunnelID
		store.DB.Delete(&model.VPNUser{}, id)
		if t, err := store.GetTunnel(tunnelID); err == nil {
			_ = refreshDialAuth(t)
		}
		c.JSON(200, gin.H{"ok": true})
		return
	}
	store.DB.Delete(&model.VPNUser{}, id)
	c.JSON(200, gin.H{"ok": true})
}

func revokeOpenVPNCert(user *model.VPNUser) {
	if user.Certificate == "" {
		return
	}
	t, err := store.GetTunnel(user.TunnelID)
	if err != nil || t.Protocol != "openvpn" {
		return
	}
	if err := openvpn.New().RevokeClientCertificate(t, user); err != nil {
		store.Audit("system", "revoke_cert_failed", user.Username, err.Error())
	}
}

// vpnUserMFASetup 为 OpenVPN 拨号用户生成 TOTP 密钥（待确认）。
func (s *Server) vpnUserMFASetup(c *gin.Context) {
	id, _ := strconv.Atoi(c.Param("id"))
	var user model.VPNUser
	if store.DB.First(&user, id).Error != nil {
		c.JSON(404, gin.H{"error": "拨号用户不存在"})
		return
	}
	t, err := store.GetTunnel(user.TunnelID)
	if err != nil || t.Protocol != "openvpn" {
		c.JSON(400, gin.H{"error": "仅 OpenVPN 拨号用户支持 MFA"})
		return
	}
	// TOTP 标准参数（RFC 6238）：SHA1、30s、6 位、base32，兼容主流 Authenticator
	key, err := totp.Generate(totp.GenerateOpts{
		Issuer:      "OPSX-OpenVPN",
		AccountName: fmt.Sprintf("%s@%s", user.Username, t.Name),
		Period:      30,
		Digits:      otp.DigitsSix,
		Algorithm:   otp.AlgorithmSHA1,
	})
	if err != nil {
		c.JSON(500, gin.H{"error": err.Error()})
		return
	}
	pendingMFAMu.Lock()
	// 用 user_id 偏移避免与管理端 MFA 冲突：拨号用户用高位 key 空间
	pendingMFAs[vpnUserPendingKey(user.ID)] = pendingMFA{
		secret: key.Secret(), backups: backupCodes(), expires: time.Now().Add(15 * time.Minute),
	}
	pendingMFAMu.Unlock()
	c.JSON(200, gin.H{
		"otpauth_url": key.URL(),
		"secret":      key.Secret(),
		"period":      30,
		"digits":      6,
		"algorithm":   "SHA1",
		"encoding":    "base32",
		"expires_in":  900,
		"hint":        "兼容主流 Authenticator 应用：扫描二维码或手动输入 base32 密钥",
	})
}

func vpnUserPendingKey(vpnUserID uint) uint {
	// 管理端 MFA 用真实 user_id；拨号 MFA pending 用高位偏移隔离。
	return 1_000_000_000 + vpnUserID
}

func (s *Server) vpnUserMFAEnable(c *gin.Context) {
	id, _ := strconv.Atoi(c.Param("id"))
	var user model.VPNUser
	if store.DB.First(&user, id).Error != nil {
		c.JSON(404, gin.H{"error": "拨号用户不存在"})
		return
	}
	var req struct {
		Code string `json:"code"`
	}
	if c.ShouldBindJSON(&req) != nil || req.Code == "" {
		c.JSON(400, gin.H{"error": "请输入验证码"})
		return
	}
	pendingMFAMu.Lock()
	pending, ok := pendingMFAs[vpnUserPendingKey(user.ID)]
	delete(pendingMFAs, vpnUserPendingKey(user.ID))
	pendingMFAMu.Unlock()
	if !ok || time.Now().After(pending.expires) || !totp.Validate(strings.TrimSpace(req.Code), pending.secret) {
		c.JSON(400, gin.H{"error": "验证码无效或设置已过期，请重新扫描二维码"})
		return
	}
	secret, err := store.EncryptSecret(pending.secret)
	if err != nil {
		c.JSON(500, gin.H{"error": "加密 MFA 密钥失败"})
		return
	}
	raw, _ := json.Marshal(pending.backups)
	backups, err := store.EncryptSecret(string(raw))
	if err != nil {
		c.JSON(500, gin.H{"error": "加密备用码失败"})
		return
	}
	user.MFASecret = secret
	user.MFABackupCodes = backups
	user.MFAEnabled = true
	if err := store.DB.Save(&user).Error; err != nil {
		c.JSON(500, gin.H{"error": err.Error()})
		return
	}
	store.Audit(c.GetString("username"), "enable_vpn_user_mfa", user.Username, "")
	c.JSON(200, gin.H{"ok": true, "backup_codes": pending.backups, "mfa_enabled": true})
}

func (s *Server) vpnUserMFADisable(c *gin.Context) {
	id, _ := strconv.Atoi(c.Param("id"))
	var user model.VPNUser
	if store.DB.First(&user, id).Error != nil {
		c.JSON(404, gin.H{"error": "拨号用户不存在"})
		return
	}
	store.DB.Model(&user).Updates(map[string]interface{}{
		"mfa_enabled": false, "mfa_secret": "", "mfa_backup_codes": "",
		"mfa_pin": "", "mfa_has_pin": false, "mfa_fail_count": 0, "mfa_locked_until": nil,
		"mfa_last_counter": 0, "mfa_last_used_at": nil,
	})
	store.Audit(c.GetString("username"), "disable_vpn_user_mfa", user.Username, "")
	c.JSON(200, gin.H{"ok": true, "mfa_enabled": false})
}

// vpnUserMFAStatus OTP Manager：查看拨号用户 MFA 状态。
func (s *Server) vpnUserMFAStatus(c *gin.Context) {
	id, _ := strconv.Atoi(c.Param("id"))
	var user model.VPNUser
	if store.DB.First(&user, id).Error != nil {
		c.JSON(404, gin.H{"error": "拨号用户不存在"})
		return
	}
	locked := user.MFALockedUntil != nil && time.Now().Before(*user.MFALockedUntil)
	c.JSON(200, gin.H{
		"mfa_enabled":      user.MFAEnabled,
		"mfa_has_pin":      user.MFAHasPin,
		"mfa_fail_count":   user.MFAFailCount,
		"mfa_locked":       locked,
		"mfa_locked_until": user.MFALockedUntil,
		"mfa_last_used_at": user.MFALastUsedAt,
		"compatible":       "TOTP 标准（兼容 Google/Microsoft Authenticator，sha1:base32:6:30s）",
	})
}

// vpnUserMFAPin 设置或清除静态 PIN（连接时第二因子 = PIN+OTP）。
func (s *Server) vpnUserMFAPin(c *gin.Context) {
	id, _ := strconv.Atoi(c.Param("id"))
	var user model.VPNUser
	if store.DB.First(&user, id).Error != nil {
		c.JSON(404, gin.H{"error": "拨号用户不存在"})
		return
	}
	if !user.MFAEnabled {
		c.JSON(400, gin.H{"error": "请先启用 MFA 再设置 PIN"})
		return
	}
	var req struct {
		Pin string `json:"pin"` // 空字符串表示清除
	}
	if c.ShouldBindJSON(&req) != nil {
		c.JSON(400, gin.H{"error": "参数错误"})
		return
	}
	if err := openvpn.SetUserMFAPin(&user, req.Pin); err != nil {
		c.JSON(400, gin.H{"error": err.Error()})
		return
	}
	store.Audit(c.GetString("username"), "set_vpn_user_mfa_pin", user.Username, "")
	c.JSON(200, gin.H{"ok": true, "mfa_has_pin": user.MFAHasPin})
}

// vpnUserMFABackupCodes 重新生成备用码。
func (s *Server) vpnUserMFABackupCodes(c *gin.Context) {
	id, _ := strconv.Atoi(c.Param("id"))
	var user model.VPNUser
	if store.DB.First(&user, id).Error != nil {
		c.JSON(404, gin.H{"error": "拨号用户不存在"})
		return
	}
	codes, err := openvpn.RegenerateBackupCodes(&user)
	if err != nil {
		c.JSON(400, gin.H{"error": err.Error()})
		return
	}
	store.Audit(c.GetString("username"), "regen_vpn_user_mfa_backup", user.Username, "")
	c.JSON(200, gin.H{"ok": true, "backup_codes": codes})
}

// vpnUserMFAUnlock 清除 MFA 锁定（失败次数过多后）。
func (s *Server) vpnUserMFAUnlock(c *gin.Context) {
	id, _ := strconv.Atoi(c.Param("id"))
	var user model.VPNUser
	if store.DB.First(&user, id).Error != nil {
		c.JSON(404, gin.H{"error": "拨号用户不存在"})
		return
	}
	if err := openvpn.UnlockUserMFA(&user); err != nil {
		c.JSON(500, gin.H{"error": err.Error()})
		return
	}
	store.Audit(c.GetString("username"), "unlock_vpn_user_mfa", user.Username, "")
	c.JSON(200, gin.H{"ok": true})
}

// vpnUserOTPSecretsLine 导出 TOTP 密钥行（标准 otp-secrets 格式，便于迁移与备份）。
func (s *Server) vpnUserOTPSecretsLine(c *gin.Context) {
	id, _ := strconv.Atoi(c.Param("id"))
	var user model.VPNUser
	if store.DB.First(&user, id).Error != nil {
		c.JSON(404, gin.H{"error": "拨号用户不存在"})
		return
	}
	line, err := openvpn.GenerateOTPSecretsLine(&user)
	if err != nil {
		c.JSON(400, gin.H{"error": err.Error()})
		return
	}
	c.JSON(200, gin.H{
		"line":   line,
		"format": "user server type:hash:encoding:key:pin:udid client",
		"note":   "标准 otp-secrets 格式密钥行；密钥敏感，请妥善保管，切勿泄露",
	})
}

// refreshDialAuth 在拨号用户变更后重写 L2TP/IKEv2 认证文件。
func refreshDialAuth(t *model.Tunnel) error {
	if t == nil {
		return nil
	}
	switch t.Protocol {
	case "l2tp":
		return l2tp.New().RefreshAuth(t)
	case "ikev2":
		return ikev2.New().RefreshAuth(t)
	}
	return nil
}

// ---- 用户批量导入 / LDAP 导入 ----

// listLDAPUsers 浏览 LDAP 目录中的用户列表，供导入选择。复用 ldapSettings + ldapConnect。
func (s *Server) listLDAPUsers(c *gin.Context) {
	cfg, err := ldapSettings()
	if err != nil {
		c.JSON(400, gin.H{"error": "LDAP 未启用或配置不完整：" + err.Error()})
		return
	}
	conn, err := ldapConnect(cfg)
	if err != nil {
		c.JSON(500, gin.H{"error": "LDAP 连接失败：" + err.Error()})
		return
	}
	defer conn.Close()

	// 搜索 BaseDN 下所有匹配用户过滤器的条目
	attrs := []string{"dn", cfg.UsernameAttribute, "cn", "mail"}
	result, err := conn.Search(ldap.NewSearchRequest(
		cfg.BaseDN, ldap.ScopeWholeSubtree, ldap.NeverDerefAliases, 0, 0, false,
		cfg.UserFilter, attrs, nil,
	))
	if err != nil {
		c.JSON(500, gin.H{"error": "LDAP 搜索失败：" + err.Error()})
		return
	}

	// 查询本地已有的 LDAP 用户名，标记已导入
	var existingNames []string
	store.DB.Model(&model.User{}).Where("source = ?", "ldap").Pluck("username", &existingNames)
	existingMap := map[string]bool{}
	for _, n := range existingNames {
		existingMap[n] = true
	}

	type ldapUser struct {
		DN       string `json:"dn"`
		UID      string `json:"uid"`
		CN       string `json:"cn"`
		Mail     string `json:"mail"`
		Imported bool   `json:"imported"`
	}
	users := make([]ldapUser, 0, len(result.Entries))
	for _, entry := range result.Entries {
		uid := entry.GetAttributeValue(cfg.UsernameAttribute)
		if uid == "" {
			continue
		}
		users = append(users, ldapUser{
			DN:       entry.DN,
			UID:      uid,
			CN:       entry.GetAttributeValue("cn"),
			Mail:     entry.GetAttributeValue("mail"),
			Imported: existingMap[uid],
		})
	}
	c.JSON(200, users)
}

// batchCreateUsers 批量创建本地用户。
func (s *Server) batchCreateUsers(c *gin.Context) {
	var req struct {
		Users []struct {
			Username string `json:"username"`
			Password string `json:"password"`
			Email    string `json:"email"`
			Role     string `json:"role"`
		} `json:"users"`
		DefaultRole string `json:"default_role"`
	}
	if err := c.ShouldBindJSON(&req); err != nil {
		c.JSON(400, gin.H{"error": "参数错误"})
		return
	}
	if req.DefaultRole == "" {
		req.DefaultRole = "viewer"
	}
	type failInfo struct {
		Username string `json:"username"`
		Error    string `json:"error"`
	}
	var success, skipped, failed int
	var fails []failInfo
	for _, u := range req.Users {
		if u.Username == "" {
			failed++
			fails = append(fails, failInfo{Error: "用户名为空"})
			continue
		}
		// 检查是否已存在
		var count int64
		store.DB.Model(&model.User{}).Where("username = ?", u.Username).Count(&count)
		if count > 0 {
			skipped++
			continue
		}
		pwd := u.Password
		if len(pwd) < 8 {
			failed++
			fails = append(fails, failInfo{Username: u.Username, Error: "密码至少 8 位"})
			continue
		}
		role := u.Role
		if role == "" {
			role = req.DefaultRole
		}
		if role != "admin" && role != "operator" && role != "viewer" {
			role = "viewer"
		}
		hash, _ := bcrypt.GenerateFromPassword([]byte(pwd), bcrypt.DefaultCost)
		user := model.User{
			Username: u.Username, Password: string(hash), Email: u.Email,
			Role: role, Source: "local", Enabled: true,
		}
		if err := store.DB.Create(&user).Error; err != nil {
			failed++
			fails = append(fails, failInfo{Username: u.Username, Error: err.Error()})
			continue
		}
		store.Audit(c.GetString("username"), "batch_create_user", u.Username, "")
		success++
	}
	c.JSON(200, gin.H{
		"success": success, "skipped": skipped, "failed": failed,
		"errors": fails, "total": len(req.Users),
	})
}

// importLDAPUsers 从 LDAP 导入选中的用户到本地 DB（source=ldap）。
func (s *Server) importLDAPUsers(c *gin.Context) {
	var req struct {
		DNs []string `json:"dns"`
	}
	if err := c.ShouldBindJSON(&req); err != nil {
		c.JSON(400, gin.H{"error": "参数错误"})
		return
	}
	cfg, err := ldapSettings()
	if err != nil {
		c.JSON(400, gin.H{"error": "LDAP 未启用：" + err.Error()})
		return
	}
	conn, err := ldapConnect(cfg)
	if err != nil {
		c.JSON(500, gin.H{"error": "LDAP 连接失败：" + err.Error()})
		return
	}
	defer conn.Close()

	type failInfo struct {
		DN    string `json:"dn"`
		Error string `json:"error"`
	}
	var success, skipped, failed int
	var fails []failInfo
	for _, dn := range req.DNs {
		// 按 DN 查询单个条目
		result, err := conn.Search(ldap.NewSearchRequest(
			dn, ldap.ScopeBaseObject, ldap.NeverDerefAliases, 0, 0, false,
			"(objectClass=*)", []string{cfg.UsernameAttribute, "cn", "mail"}, nil,
		))
		if err != nil || len(result.Entries) == 0 {
			failed++
			fails = append(fails, failInfo{DN: dn, Error: "查询失败"})
			continue
		}
		entry := result.Entries[0]
		uid := entry.GetAttributeValue(cfg.UsernameAttribute)
		if uid == "" {
			failed++
			fails = append(fails, failInfo{DN: dn, Error: "无 uid 属性"})
			continue
		}
		// 检查本地是否已存在
		var count int64
		store.DB.Model(&model.User{}).Where("username = ?", uid).Count(&count)
		if count > 0 {
			skipped++
			continue
		}
		user := model.User{
			Username: uid, Email: entry.GetAttributeValue("mail"),
			Role: "viewer", Source: "ldap", Enabled: true,
		}
		if err := store.DB.Create(&user).Error; err != nil {
			failed++
			fails = append(fails, failInfo{DN: dn, Error: err.Error()})
			continue
		}
		store.Audit(c.GetString("username"), "import_ldap_user", uid, dn)
		success++
	}
	c.JSON(200, gin.H{
		"success": success, "skipped": skipped, "failed": failed,
		"errors": fails, "total": len(req.DNs),
	})
}