package handlers

import (
	"encoding/json"
	"net/http"
	"strconv"
	"strings"

	"smart-customer-service/internal/models"
)

// UserHandler 用户处理器
type UserHandler struct{}

// Create 创建用户
func (h *UserHandler) Create(w http.ResponseWriter, r *http.Request) {
	var user models.User
	if err := json.NewDecoder(r.Body).Decode(&user); err != nil {
		http.Error(w, err.Error(), http.StatusBadRequest)
		return
	}

	// 验证必填字段
	if user.Username == "" || user.Email == "" {
		w.Header().Set("Content-Type", "application/json")
		w.WriteHeader(http.StatusBadRequest)
		json.NewEncoder(w).Encode(map[string]string{
			"error": "username and email are required",
		})
		return
	}

	// 密码不能为空
	if user.Password == "" {
		w.Header().Set("Content-Type", "application/json")
		w.WriteHeader(http.StatusBadRequest)
		json.NewEncoder(w).Encode(map[string]string{
			"error": "password is required",
		})
		return
	}

	// TODO: 密码加密、保存到数据库
	// user.Password = bcrypt.GenerateFromPassword(password)
	// db.Create(&user)

	w.Header().Set("Content-Type", "application/json")
	w.WriteHeader(http.StatusCreated)
	json.NewEncoder(w).Encode(map[string]interface{}{
		"message": "用户创建成功",
		"data":    user,
	})
}

// List 获取用户列表
func (h *UserHandler) List(w http.ResponseWriter, r *http.Request) {
	// 获取分页参数
	page := getPageParam(r, 1)
	perPage := getPageParam(r, 20)

	// 获取过滤参数
	tenantIDStr := r.URL.Query().Get("tenant_id")
	status := r.URL.Query().Get("status")
	keyword := r.URL.Query().Get("keyword")

	// TODO: 查询数据库
	// var users []models.User
	// query := db.Where("tenant_id = ?", tenantID)
	// if status != "" {
	//     query = query.Where("status = ?", status)
	// }
	// if keyword != "" {
	//     query = query.Where("username LIKE ? OR email LIKE ? OR full_name LIKE ?", "%"+keyword+"%", "%"+keyword+"%", "%"+keyword+"%")
	// }
	// query.Count(&total).Offset((page-1)*perPage).Limit(perPage).Preload("Tenant").Find(&users)

	var users []models.User

	w.Header().Set("Content-Type", "application/json")
	json.NewEncoder(w).Encode(map[string]interface{}{
		"total":      0,
		"page":       page,
		"per_page":   perPage,
		"total_pages": 0,
		"filters": map[string]string{
			"tenant_id": tenantIDStr,
			"status":    status,
			"keyword":   keyword,
		},
		"data": users,
	})
}

// Get 获取单个用户
func (h *UserHandler) Get(w http.ResponseWriter, r *http.Request) {
	idStr := r.URL.Query().Get("id")
	if idStr == "" {
		http.Error(w, `{"error": "id is required"}`, http.StatusBadRequest)
		return
	}

	id, err := strconv.ParseUint(idStr, 10, 32)
	if err != nil {
		http.Error(w, `{"error": "invalid id"}`, http.StatusBadRequest)
		return
	}

	// TODO: 查询数据库 (包含关联数据)
	// var user models.User
	// db.Preload("Tenant").Preload("Roles").First(&user, id)

	var user models.User

	if user.ID == 0 {
		http.Error(w, `{"error": "user not found"}`, http.StatusNotFound)
		return
	}

	w.Header().Set("Content-Type", "application/json")
	json.NewEncoder(w).Encode(user)
}

// Update 更新用户
func (h *UserHandler) Update(w http.ResponseWriter, r *http.Request) {
	idStr := r.URL.Query().Get("id")
	if idStr == "" {
		http.Error(w, `{"error": "id is required"}`, http.StatusBadRequest)
		return
	}

	id, err := strconv.ParseUint(idStr, 10, 32)
	if err != nil {
		http.Error(w, `{"error": "invalid id"}`, http.StatusBadRequest)
		return
	}

	var user models.User
	if err := json.NewDecoder(r.Body).Decode(&user); err != nil {
		http.Error(w, err.Error(), http.StatusBadRequest)
		return
	}

	// 不允许修改用户名和租户 ID
	user.Username = "" 
	user.TenantID = 0

	// TODO: 更新数据库
	// db.Model(&user).Where("id = ?", id).Updates(user)

	w.Header().Set("Content-Type", "application/json")
	json.NewEncoder(w).Encode(map[string]interface{}{
		"message": "用户更新成功",
		"data":    user,
	})
}

// Delete 删除用户
func (h *UserHandler) Delete(w http.ResponseWriter, r *http.Request) {
	idStr := r.URL.Query().Get("id")
	if idStr == "" {
		http.Error(w, `{"error": "id is required"}`, http.StatusBadRequest)
		return
	}

	id, err := strconv.ParseUint(idStr, 10, 32)
	if err != nil {
		http.Error(w, `{"error": "invalid id"}`, http.StatusBadRequest)
		return
	}

	// TODO: 软删除
	// db.Where("id = ?", id).Update("deleted_at", time.Now())

	w.Header().Set("Content-Type", "application/json")
	json.NewEncoder(w).Encode(map[string]interface{}{
		"message": "用户删除成功",
		"id":      id,
	})
}

// ChangePassword 修改密码
func (h *UserHandler) ChangePassword(w http.ResponseWriter, r *http.Request) {
	idStr := r.URL.Query().Get("id")
	if idStr == "" {
		http.Error(w, `{"error": "id is required"}`, http.StatusBadRequest)
		return
	}

	type passwordChange struct {
		OldPassword     string `json:"old_password"`
		NewPassword     string `json:"new_password"`
		ConfirmPassword string `json:"confirm_password"`
	}

	var req passwordChange
	if err := json.NewDecoder(r.Body).Decode(&req); err != nil {
		http.Error(w, err.Error(), http.StatusBadRequest)
		return
	}

	// 验证新密码
	if req.NewPassword != req.ConfirmPassword {
		http.Error(w, `{"error": "new passwords do not match"}`, http.StatusBadRequest)
		return
	}

	// 密码最小长度验证
	if len(req.NewPassword) < 8 {
		http.Error(w, `{"error": "password must be at least 8 characters"}`, http.StatusBadRequest)
		return
	}

	// TODO: 验证旧密码、更新新密码
	// 1. 查询用户旧密码
	// 2. bcrypt.CompareHashAndPassword
	// 3. 更新密码

	w.Header().Set("Content-Type", "application/json")
	json.NewEncoder(w).Encode(map[string]string{
		"message": "密码修改成功",
	})
}

// AssignRoles 分配角色
func (h *UserHandler) AssignRoles(w http.ResponseWriter, r *http.Request) {
	idStr := r.URL.Query().Get("id")
	if idStr == "" {
		http.Error(w, `{"error": "id is required"}`, http.StatusBadRequest)
		return
	}

	type roleAssignment struct {
		RoleIDs []uint `json:"role_ids"`
	}

	var req roleAssignment
	if err := json.NewDecoder(r.Body).Decode(&req); err != nil {
		http.Error(w, err.Error(), http.StatusBadRequest)
		return
	}

	// TODO: 分配角色
	// 1. 查询角色是否存在
	// 2. 更新 user_roles 关联表

	w.Header().Set("Content-Type", "application/json")
	json.NewEncoder(w).Encode(map[string]interface{}{
		"message": "角色分配成功",
		"data":    req,
	})
}

// 辅助函数：获取分页参数
func getPageParam(r *http.Request, defaultVal int) int {
	strVal := r.URL.Query().Get("page")
	if strVal == "" {
		return defaultVal
	}
	val, err := strconv.Atoi(strVal)
	if err != nil || val < 1 {
		return defaultVal
	}
	return val
}