package handlers

import (
	"encoding/json"
	"fmt"
	"net"
	"net/http"
	"strings"
	"time"

	"ezops/internal/models"

	"github.com/gin-gonic/gin"
	"github.com/go-ldap/ldap/v3"
	"golang.org/x/crypto/bcrypt"
	"gorm.io/gorm"
)

// LDAPHandler LDAP处理器
type LDAPHandler struct {
	db *gorm.DB
}

// NewLDAPHandler 创建LDAP处理器
func NewLDAPHandler(db *gorm.DB) *LDAPHandler {
	return &LDAPHandler{db: db}
}

// LDAPAuthInfo LDAP认证返回的用户信息
type LDAPAuthInfo struct {
	Username    string
	DisplayName string
	Email       string
}

// dialLDAP 连接LDAP服务器
func dialLDAP(cfg *models.LDAPConfig) (*ldap.Conn, error) {
	if cfg.LDAPHost == "" {
		return nil, fmt.Errorf("LDAP not configured")
	}
	protocol := "ldap"
	if cfg.UseLDAPS != nil && *cfg.UseLDAPS {
		protocol = "ldaps"
	}
	port := 389
	if cfg.LDAPPort != nil && *cfg.LDAPPort > 0 {
		port = *cfg.LDAPPort
	}
	uri := fmt.Sprintf("%s://%s:%d", protocol, cfg.LDAPHost, port)
	dialer := &net.Dialer{Timeout: 5 * time.Second}
	return ldap.DialURL(uri, ldap.DialWithDialer(dialer))
}

// tryLDAPAuth 尝试LDAP认证，返回用户信息
func tryLDAPAuth(db *gorm.DB, username, password string) (*LDAPAuthInfo, error) {
	var cfg models.LDAPConfig
	if err := db.Order("id").First(&cfg).Error; err != nil {
		return nil, fmt.Errorf("LDAP未配置")
	}
	if cfg.LDAPHost == "" {
		return nil, fmt.Errorf("LDAP not configured")
	}

	conn, err := dialLDAP(&cfg)
	if err != nil {
		return nil, fmt.Errorf("LDAP连接失败: %w", err)
	}
	defer conn.Close()

	// Admin bind
	if err := conn.Bind(cfg.AdminDN, cfg.AdminPassword); err != nil {
		return nil, fmt.Errorf("LDAP管理员绑定失败: %w", err)
	}

	// Build search filter
	userFilter := ""
	baseFilter := "(objectClass=inetOrgPerson)"
	if cfg.SearchFilter != nil && *cfg.SearchFilter != "" {
		sf := *cfg.SearchFilter
		if strings.Contains(sf, "%s") {
			userFilter = strings.ReplaceAll(sf, "%s", ldap.EscapeFilter(username))
		} else {
			baseFilter = sf
			userFilter = fmt.Sprintf("(&%s(uid=%s))", baseFilter, ldap.EscapeFilter(username))
		}
	} else {
		userFilter = fmt.Sprintf("(&%s(uid=%s))", baseFilter, ldap.EscapeFilter(username))
	}

	// Search user
	searchReq := ldap.NewSearchRequest(
		cfg.BaseDN,
		ldap.ScopeWholeSubtree, ldap.NeverDerefAliases,
		1, 10, false,
		userFilter,
		[]string{"uid", "cn", "mail", "telephoneNumber"},
		nil,
	)
	sr, err := conn.Search(searchReq)
	if err != nil || len(sr.Entries) == 0 {
		return nil, fmt.Errorf("LDAP用户不存在")
	}
	entry := sr.Entries[0]
	userDN := entry.DN

	// Verify password by binding as user
	if err := conn.Bind(userDN, password); err != nil {
		return nil, fmt.Errorf("LDAP密码验证失败: %w", err)
	}

	// Extract user info using mapping
	userMapping := map[string]string{
		"username":     "uid",
		"email":        "mail",
		"display_name": "cn",
	}
	if cfg.UserMapping != nil && *cfg.UserMapping != "" {
		json.Unmarshal([]byte(*cfg.UserMapping), &userMapping)
	}

	getAttr := func(key string) string {
		if v := entry.GetAttributeValue(key); v != "" {
			return v
		}
		return ""
	}

	info := &LDAPAuthInfo{
		Username:    getAttr(userMapping["username"]),
		DisplayName: getAttr(userMapping["display_name"]),
		Email:       getAttr(userMapping["email"]),
	}
	if info.Username == "" {
		info.Username = username
	}

	return info, nil
}

// GetLDAPConfig 获取LDAP配置
// GET /api/v1/admin/ldap-config
func (h *LDAPHandler) GetLDAPConfig(c *gin.Context) {
	var configs []models.LDAPConfig
	h.db.Order("id").Find(&configs)
	if len(configs) == 0 {
		c.JSON(http.StatusOK, gin.H{})
		return
	}
	cfg := configs[0]
	// mask password
	cfg.AdminPassword = "******"
	c.JSON(http.StatusOK, cfg)
}

// UpdateLDAPConfig 更新LDAP配置
// PUT /api/v1/admin/ldap-config
func (h *LDAPHandler) UpdateLDAPConfig(c *gin.Context) {
	var input map[string]interface{}
	if err := c.ShouldBindJSON(&input); err != nil {
		c.JSON(http.StatusBadRequest, models.Response{Code: 400, Message: err.Error()})
		return
	}

	var configs []models.LDAPConfig
	h.db.Order("id").Find(&configs)

	getStr := func(key string) string {
		if v, ok := input[key].(string); ok {
			return v
		}
		return ""
	}
	getInt := func(key string) int {
		if v, ok := input[key].(float64); ok {
			return int(v)
		}
		return 0
	}
	getBool := func(key string) *bool {
		if v, ok := input[key].(bool); ok {
			return &v
		}
		return nil
	}

	userMappingStr := ""
	if um, ok := input["user_mapping"]; ok {
		if bytes, err := json.Marshal(um); err == nil {
			userMappingStr = string(bytes)
		}
	}

	if len(configs) == 0 {
		// Create
		cfg := models.LDAPConfig{
			LDAPHost:      getStr("ldap_host"),
			AdminDN:       getStr("admin_dn"),
			BaseDN:        getStr("base_dn"),
			AdminPassword: getStr("admin_password"),
		}
		if sf := getStr("search_filter"); sf != "" {
			cfg.SearchFilter = &sf
		}
		if userMappingStr != "" {
			cfg.UserMapping = &userMappingStr
		}
		if port := getInt("ldap_port"); port > 0 {
			cfg.LDAPPort = &port
		}
		if b := getBool("use_ldaps"); b != nil {
			cfg.UseLDAPS = b
		}
		h.db.Create(&cfg)
		cfg.AdminPassword = "******"
		c.JSON(http.StatusOK, models.Response{Code: 200, Message: "LDAP配置已创建", Data: cfg})
	} else {
		// Update
		cfg := configs[0]
		updates := map[string]interface{}{}
		if v := getStr("ldap_host"); v != "" {
			updates["ldap_host"] = v
		}
		if v := getStr("base_dn"); v != "" {
			updates["base_dn"] = v
		}
		if v := getStr("admin_dn"); v != "" {
			updates["admin_dn"] = v
		}
		if v := getStr("search_filter"); v != "" {
			updates["search_filter"] = v
		}
		if userMappingStr != "" {
			updates["user_mapping"] = userMappingStr
		}
		if v := getStr("admin_password"); v != "" && v != "******" {
			updates["admin_password"] = v
		}
		if port := getInt("ldap_port"); port > 0 {
			updates["ldap_port"] = port
		}
		if b := getBool("use_ldaps"); b != nil {
			updates["use_ldaps"] = *b
		}
		if len(updates) > 0 {
			h.db.Model(&cfg).Updates(updates)
		}
		h.db.First(&cfg, cfg.ID)
		cfg.AdminPassword = "******"
		c.JSON(http.StatusOK, models.Response{Code: 200, Message: "LDAP配置已更新", Data: cfg})
	}
}

// TestLDAPConnection 测试LDAP连接
// POST /api/v1/admin/ldap-config/test
func (h *LDAPHandler) TestLDAPConnection(c *gin.Context) {
	var req struct {
		TestUser     string `json:"test_user"`
		TestPassword string `json:"test_password"`
	}
	c.ShouldBindJSON(&req)

	var cfg models.LDAPConfig
	if err := h.db.Order("id").First(&cfg).Error; err != nil {
		c.JSON(http.StatusOK, gin.H{"success": false, "message": "LDAP配置不存在，请先保存配置"})
		return
	}
	if cfg.LDAPHost == "" {
		c.JSON(http.StatusOK, gin.H{"success": false, "message": "LDAP未配置"})
		return
	}

	conn, err := dialLDAP(&cfg)
	if err != nil {
		c.JSON(http.StatusOK, gin.H{"success": false, "message": fmt.Sprintf("连接失败: %s", err)})
		return
	}
	defer conn.Close()

	if err := conn.Bind(cfg.AdminDN, cfg.AdminPassword); err != nil {
		c.JSON(http.StatusOK, gin.H{"success": false, "message": fmt.Sprintf("管理员绑定失败: %s", err)})
		return
	}

	// If test_user provided, search and verify
	if req.TestUser != "" && req.TestPassword != "" {
		userFilter := ""
		baseFilter := "(objectClass=inetOrgPerson)"
		if cfg.SearchFilter != nil && *cfg.SearchFilter != "" {
			sf := *cfg.SearchFilter
			if strings.Contains(sf, "%s") {
				userFilter = strings.ReplaceAll(sf, "%s", ldap.EscapeFilter(req.TestUser))
			} else {
				baseFilter = sf
				userFilter = fmt.Sprintf("(&%s(uid=%s))", baseFilter, ldap.EscapeFilter(req.TestUser))
			}
		} else {
			userFilter = fmt.Sprintf("(&%s(uid=%s))", baseFilter, ldap.EscapeFilter(req.TestUser))
		}

		sr, err := conn.Search(ldap.NewSearchRequest(
			cfg.BaseDN, ldap.ScopeWholeSubtree, ldap.NeverDerefAliases,
			1, 10, false, userFilter,
			[]string{"uid", "cn", "mail"},
			nil,
		))
		if err != nil || len(sr.Entries) == 0 {
			c.JSON(http.StatusOK, gin.H{"success": false, "message": fmt.Sprintf("用户 %s 不存在", req.TestUser)})
			return
		}
		userDN := sr.Entries[0].DN
		if err := conn.Bind(userDN, req.TestPassword); err != nil {
			c.JSON(http.StatusOK, gin.H{"success": false, "message": fmt.Sprintf("密码验证失败: %s", err)})
			return
		}
		c.JSON(http.StatusOK, gin.H{"success": true, "message": fmt.Sprintf("认证成功！用户DN: %s", userDN)})
		return
	}

	c.JSON(http.StatusOK, gin.H{"success": true, "message": "LDAP连接成功，管理员认证通过"})
}

// ListLDAPUsers 列出LDAP用户
// POST /api/v1/admin/ldap-config/users
func (h *LDAPHandler) ListLDAPUsers(c *gin.Context) {
	var req struct {
		OuDn string `json:"ou_dn"`
	}
	c.ShouldBindJSON(&req)

	var cfg models.LDAPConfig
	if err := h.db.Order("id").First(&cfg).Error; err != nil {
		c.JSON(http.StatusOK, []interface{}{})
		return
	}

	conn, err := dialLDAP(&cfg)
	if err != nil {
		c.JSON(http.StatusOK, []interface{}{})
		return
	}
	defer conn.Close()

	if err := conn.Bind(cfg.AdminDN, cfg.AdminPassword); err != nil {
		c.JSON(http.StatusOK, []interface{}{})
		return
	}

	searchBase := cfg.BaseDN
	if req.OuDn != "" {
		searchBase = req.OuDn
	}

	baseFilter := "(objectClass=inetOrgPerson)"
	if cfg.SearchFilter != nil && *cfg.SearchFilter != "" {
		sf := *cfg.SearchFilter
		if strings.Contains(sf, "%s") {
			baseFilter = strings.ReplaceAll(sf, "%s", "*")
		} else {
			baseFilter = sf
		}
	}

	sr, err := conn.Search(ldap.NewSearchRequest(
		searchBase, ldap.ScopeWholeSubtree, ldap.NeverDerefAliases,
		200, 0, false, baseFilter,
		[]string{"uid", "cn", "mail", "dn"},
		nil,
	))
	if err != nil {
		c.JSON(http.StatusOK, []interface{}{})
		return
	}

	type LdapUser struct {
		DN   string `json:"dn"`
		UID  string `json:"uid"`
		CN   string `json:"cn"`
		Mail string `json:"mail"`
	}
	var users []LdapUser
	for _, e := range sr.Entries {
		users = append(users, LdapUser{
			DN:   e.DN,
			UID:  e.GetAttributeValue("uid"),
			CN:   e.GetAttributeValue("cn"),
			Mail: e.GetAttributeValue("mail"),
		})
	}
	c.JSON(http.StatusOK, users)
}

// BatchImportLDAP 批量导入LDAP用户
// POST /api/v1/admin/ldap-config/import
func (h *LDAPHandler) BatchImportLDAP(c *gin.Context) {
	var req struct {
		Users []struct {
			UID  string `json:"uid"`
			CN   string `json:"cn"`
			Mail string `json:"mail"`
		} `json:"users"`
	}
	if err := c.ShouldBindJSON(&req); err != nil {
		c.JSON(http.StatusBadRequest, models.Response{Code: 400, Message: err.Error()})
		return
	}

	imported := 0
	skipped := 0
	for _, lu := range req.Users {
		if lu.UID == "" {
			skipped++
			continue
		}
		// Check if already exists
		var existing models.User
		if err := h.db.Where("username = ?", lu.UID).First(&existing).Error; err == nil {
			// Already exists, update info
			updates := map[string]interface{}{
				"auth_source": "ldap",
				"is_active":   true,
			}
			if lu.CN != "" {
				updates["real_name"] = lu.CN
			}
			if lu.Mail != "" {
				updates["email"] = lu.Mail
			}
			h.db.Model(&existing).Updates(updates)
			imported++
			continue
		}

		// Create new LDAP user
		user := models.User{
			Username:   lu.UID,
			Password:   "-", // LDAP users don't have local password
			RealName:   lu.CN,
			Email:      lu.Mail,
			Status:     1,
			AuthSource: "ldap",
		}
		if err := h.db.Create(&user).Error; err != nil {
			skipped++
			continue
		}
		imported++
	}

	// bcrypt import to avoid unused import error
	_ = bcrypt.MinCost

	c.JSON(http.StatusOK, models.Response{
		Code:    200,
		Message: fmt.Sprintf("导入完成: %d 个用户成功, %d 个跳过", imported, skipped),
		Data:    gin.H{"imported": imported, "skipped": skipped},
	})
}