package handler

import (
	"net/http"
	"strconv"

	"github.com/gin-gonic/gin"

	"github.com/user-management-system/internal/auth"
	"github.com/user-management-system/internal/domain"
	"github.com/user-management-system/internal/service"
)

// UserHandler handles user management requests
type UserHandler struct {
	userService *service.UserService
}

// NewUserHandler creates a new UserHandler
func NewUserHandler(userService *service.UserService) *UserHandler {
	return &UserHandler{userService: userService}
}

func (h *UserHandler) CreateUser(c *gin.Context) {
	var req struct {
		Username string `json:"username" binding:"required"`
		Email    string `json:"email"`
		Password string `json:"password"`
		Nickname string `json:"nickname"`
	}

	if err := c.ShouldBindJSON(&req); err != nil {
		c.JSON(http.StatusBadRequest, gin.H{"error": err.Error()})
		return
	}

	user := &domain.User{
		Username: req.Username,
		Email:    domain.StrPtr(req.Email),
		Nickname: req.Nickname,
		Status:   domain.UserStatusActive,
	}

	if req.Password != "" {
		hashed, err := auth.HashPassword(req.Password)
		if err != nil {
			c.JSON(http.StatusInternalServerError, gin.H{"error": "failed to hash password"})
			return
		}
		user.Password = hashed
	}

	if err := h.userService.Create(c.Request.Context(), user); err != nil {
		handleError(c, err)
		return
	}

	c.JSON(http.StatusCreated, toUserResponse(user))
}

func (h *UserHandler) ListUsers(c *gin.Context) {
	offset, _ := strconv.ParseInt(c.DefaultQuery("offset", "0"), 10, 64)
	limit, _ := strconv.ParseInt(c.DefaultQuery("limit", "20"), 10, 64)

	users, total, err := h.userService.List(c.Request.Context(), int(offset), int(limit))
	if err != nil {
		handleError(c, err)
		return
	}

	userResponses := make([]*UserResponse, len(users))
	for i, u := range users {
		userResponses[i] = toUserResponse(u)
	}

	c.JSON(http.StatusOK, gin.H{
		"users":  userResponses,
		"total":  total,
		"offset": offset,
		"limit":  limit,
	})
}

func (h *UserHandler) GetUser(c *gin.Context) {
	id, err := strconv.ParseInt(c.Param("id"), 10, 64)
	if err != nil {
		c.JSON(http.StatusBadRequest, gin.H{"error": "invalid user id"})
		return
	}

	user, err := h.userService.GetByID(c.Request.Context(), id)
	if err != nil {
		handleError(c, err)
		return
	}

	c.JSON(http.StatusOK, toUserResponse(user))
}

func (h *UserHandler) UpdateUser(c *gin.Context) {
	id, err := strconv.ParseInt(c.Param("id"), 10, 64)
	if err != nil {
		c.JSON(http.StatusBadRequest, gin.H{"error": "invalid user id"})
		return
	}

	var req struct {
		Email    *string `json:"email"`
		Nickname *string `json:"nickname"`
	}

	if err := c.ShouldBindJSON(&req); err != nil {
		c.JSON(http.StatusBadRequest, gin.H{"error": err.Error()})
		return
	}

	user, err := h.userService.GetByID(c.Request.Context(), id)
	if err != nil {
		handleError(c, err)
		return
	}

	if req.Email != nil {
		user.Email = req.Email
	}
	if req.Nickname != nil {
		user.Nickname = *req.Nickname
	}

	if err := h.userService.Update(c.Request.Context(), user); err != nil {
		handleError(c, err)
		return
	}

	c.JSON(http.StatusOK, toUserResponse(user))
}

func (h *UserHandler) DeleteUser(c *gin.Context) {
	id, err := strconv.ParseInt(c.Param("id"), 10, 64)
	if err != nil {
		c.JSON(http.StatusBadRequest, gin.H{"error": "invalid user id"})
		return
	}

	if err := h.userService.Delete(c.Request.Context(), id); err != nil {
		handleError(c, err)
		return
	}

	c.JSON(http.StatusOK, gin.H{"message": "user deleted"})
}

func (h *UserHandler) UpdatePassword(c *gin.Context) {
	id, err := strconv.ParseInt(c.Param("id"), 10, 64)
	if err != nil {
		c.JSON(http.StatusBadRequest, gin.H{"error": "invalid user id"})
		return
	}

	var req struct {
		OldPassword string `json:"old_password" binding:"required"`
		NewPassword string `json:"new_password" binding:"required"`
	}

	if err := c.ShouldBindJSON(&req); err != nil {
		c.JSON(http.StatusBadRequest, gin.H{"error": err.Error()})
		return
	}

	if err := h.userService.ChangePassword(c.Request.Context(), id, req.OldPassword, req.NewPassword); err != nil {
		handleError(c, err)
		return
	}

	c.JSON(http.StatusOK, gin.H{"message": "密码修改成功"})
}

func (h *UserHandler) UpdateUserStatus(c *gin.Context) {
	id, err := strconv.ParseInt(c.Param("id"), 10, 64)
	if err != nil {
		c.JSON(http.StatusBadRequest, gin.H{"error": "invalid user id"})
		return
	}

	var req struct {
		Status string `json:"status" binding:"required"`
	}

	if err := c.ShouldBindJSON(&req); err != nil {
		c.JSON(http.StatusBadRequest, gin.H{"error": err.Error()})
		return
	}

	var status domain.UserStatus
	switch req.Status {
	case "active", "1":
		status = domain.UserStatusActive
	case "inactive", "0":
		status = domain.UserStatusInactive
	case "locked", "2":
		status = domain.UserStatusLocked
	case "disabled", "3":
		status = domain.UserStatusDisabled
	default:
		c.JSON(http.StatusBadRequest, gin.H{"error": "invalid status"})
		return
	}

	if err := h.userService.UpdateStatus(c.Request.Context(), id, status); err != nil {
		handleError(c, err)
		return
	}

	c.JSON(http.StatusOK, gin.H{"message": "status updated"})
}

func (h *UserHandler) GetUserRoles(c *gin.Context) {
	c.JSON(http.StatusOK, gin.H{"roles": []interface{}{}})
}

func (h *UserHandler) AssignRoles(c *gin.Context) {
	c.JSON(http.StatusOK, gin.H{"message": "role assignment not implemented"})
}

func (h *UserHandler) UploadAvatar(c *gin.Context) {
	c.JSON(http.StatusOK, gin.H{"message": "avatar upload not implemented"})
}

func (h *UserHandler) ListAdmins(c *gin.Context) {
	c.JSON(http.StatusOK, gin.H{"admins": []interface{}{}})
}

func (h *UserHandler) CreateAdmin(c *gin.Context) {
	c.JSON(http.StatusOK, gin.H{"message": "admin creation not implemented"})
}

func (h *UserHandler) DeleteAdmin(c *gin.Context) {
	c.JSON(http.StatusOK, gin.H{"message": "admin deletion not implemented"})
}

type UserResponse struct {
	ID       int64  `json:"id"`
	Username string `json:"username"`
	Email    string `json:"email,omitempty"`
	Nickname string `json:"nickname,omitempty"`
	Status   string `json:"status"`
}

func toUserResponse(u *domain.User) *UserResponse {
	email := ""
	if u.Email != nil {
		email = *u.Email
	}
	return &UserResponse{
		ID:       u.ID,
		Username: u.Username,
		Email:    email,
		Nickname: u.Nickname,
		Status:   strconv.FormatInt(int64(u.Status), 10),
	}
}