backend/handlers.go

package main

import (
	"encoding/json"
	"errors"
	"fmt"
	"io"
	"log"
	"net/http"
	"strconv"
	"time"
)

type RegisterRequest struct {
	Username  string `json:"username"`
	Passwd    string `json:"passwd"`
	TimeStamp int64  `json:"timeStamp"`
	Type      string `json:"type"`
}

type LoginRequest struct {
	Username  string `json:"username"`
	Passwd    string `json:"passwd"`
	TimeStamp int64  `json:"timeStamp"`
}

type Response struct {
	Success bool        `json:"success"`
	Message string      `json:"message,omitempty"`
	Data    interface{} `json:"data,omitempty"`
}

func RegisterHandler(w http.ResponseWriter, r *http.Request) {
	if r.Method != http.MethodPost {
		SendErrorResponse(w, http.StatusMethodNotAllowed, "invalid request method")
		return
	}

	body, err := io.ReadAll(r.Body)
	if err != nil {
		SendErrorResponse(w, http.StatusBadRequest, "failed to read request body")
		return
	}
	defer r.Body.Close()

	var req RegisterRequest
	if err := json.Unmarshal(body, &req); err != nil {
		SendErrorResponse(w, http.StatusBadRequest, "invalid request format")
		return
	}

	if req.Username == "" || req.Passwd == "" {
		SendErrorResponse(w, http.StatusBadRequest, "username and password are required")
		return
	}

	currentTime := time.Now().UnixMilli()
	if !globalConfig.Debug && (currentTime-req.TimeStamp > 3000 || req.TimeStamp-currentTime > 3000) {
		SendErrorResponse(w, http.StatusBadRequest, "timestamp out of valid range")
		return
	}

	if !isValidInput(req.Username) || !isValidInput(req.Passwd) {
		SendErrorResponse(w, http.StatusBadRequest, "invalid input: contains illegal characters")
		return
	}

	if !isValidPassword(req.Passwd) {
		SendErrorResponse(w, http.StatusBadRequest, "password does not meet complexity requirements (must contain uppercase, lowercase, digit, and special character)")
		return
	}

	userType := req.Type
	if userType == "" {
		userType = "visitor"
	}

	validTypes := map[string]bool{
		"superuser": true,
		"admin":     true,
		"visitor":   true,
	}
	if !validTypes[userType] {
		SendErrorResponse(w, http.StatusBadRequest, "invalid user type")
		return
	}

	userID, err := AddUser(req.Username, req.Passwd, userType)
	if err != nil {
		SendErrorResponse(w, http.StatusInternalServerError, err.Error())
		return
	}

	user, err := GetUserByID(userID)
	if err != nil {
		SendErrorResponse(w, http.StatusInternalServerError, "failed to retrieve user after registration")
		return
	}

	SendSuccessResponse(w, "user registered successfully", map[string]interface{}{
		"userID":   user.UserID,
		"username": user.Username,
		"type":     user.Type,
	})
}

func LoginHandler(w http.ResponseWriter, r *http.Request) {
	if r.Method != http.MethodPost {
		SendErrorResponse(w, http.StatusMethodNotAllowed, "invalid request method")
		return
	}

	body, err := io.ReadAll(r.Body)
	if err != nil {
		SendErrorResponse(w, http.StatusBadRequest, "failed to read request body")
		return
	}
	defer r.Body.Close()

	var req LoginRequest
	if err := json.Unmarshal(body, &req); err != nil {
		SendErrorResponse(w, http.StatusBadRequest, "invalid request format")
		return
	}

	if req.Username == "" || req.Passwd == "" {
		SendErrorResponse(w, http.StatusBadRequest, "username and password are required")
		return
	}

	currentTime := time.Now().UnixMilli()
	if !globalConfig.Debug && (currentTime-req.TimeStamp > 3000 || req.TimeStamp-currentTime > 3000) {
		SendErrorResponse(w, http.StatusBadRequest, "timestamp out of valid range")
		return
	}

	if !isValidInput(req.Username) || !isValidInput(req.Passwd) {
		SendErrorResponse(w, http.StatusBadRequest, "invalid input: contains illegal characters")
		return
	}

	user, err := GetUserByUsername(req.Username)
	if err != nil {
		SendErrorResponse(w, http.StatusUnauthorized, "invalid username or password")
		return
	}

	if !verifyPassword(req.Passwd, user.Passwd) {
		SendErrorResponse(w, http.StatusUnauthorized, "invalid username or password")
		return
	}

	token, err := GenerateToken(user.UserID)
	if err != nil {
		SendErrorResponse(w, http.StatusInternalServerError, "failed to generate token")
		return
	}

	SendSuccessResponse(w, "login successful", map[string]interface{}{
		"token":    token,
		"userID":   user.UserID,
		"username": user.Username,
		"type":     user.Type,
	})
}

func SendErrorResponse(w http.ResponseWriter, statusCode int, message string) {
	w.Header().Set("Content-Type", "application/json")
	w.WriteHeader(statusCode)
	resp := Response{
		Success: false,
		Message: message,
	}
	jsonResp, err := json.Marshal(resp)
	if err != nil {
		log.Printf("failed to marshal error response: %v", err)
		return
	}
	w.Write(jsonResp)
}

func SendSuccessResponse(w http.ResponseWriter, message string, data interface{}) {
	w.Header().Set("Content-Type", "application/json")
	w.WriteHeader(http.StatusOK)
	resp := Response{
		Success: true,
		Message: message,
		Data:    data,
	}
	jsonResp, err := json.Marshal(resp)
	if err != nil {
		log.Printf("failed to marshal success response: %v", err)
		return
	}
	w.Write(jsonResp)
}

func ValidateRequest(w http.ResponseWriter, r *http.Request, requiredFields ...string) (int, string, error) {
	body, err := io.ReadAll(r.Body)
	if err != nil {
		return 0, "", errors.New("failed to read request body")
	}
	defer r.Body.Close()

	return ValidateRequestWithBody(w, r, body, requiredFields...)
}

func ValidateRequestWithBody(w http.ResponseWriter, r *http.Request, body []byte, requiredFields ...string) (int, string, error) {
	var reqMap map[string]interface{}
	if err := json.Unmarshal(body, &reqMap); err != nil {
		return 0, "", errors.New("invalid request format")
	}

	token, ok := reqMap["token"].(string)
	if !ok || token == "" {
		return 0, "", errors.New("token is required")
	}

	timeStamp, ok := reqMap["timeStamp"].(float64)
	if !ok {
		return 0, "", errors.New("timeStamp is required")
	}

	currentTime := time.Now().UnixMilli()
	if !globalConfig.Debug && (currentTime-int64(timeStamp) > 3000 || int64(timeStamp)-currentTime > 3000) {
		return 0, "", errors.New("timestamp out of valid range")
	}

	userID, err := extractUserIDFromToken(token)
	if err != nil {
		return 0, "", err
	}

	if err := ValidateToken(userID, token); err != nil {
		return 0, "", err
	}

	for _, field := range requiredFields {
		if _, ok := reqMap[field]; !ok {
			return 0, "", fmt.Errorf("required field %s is missing", field)
		}
	}

	return userID, token, nil
}

func GetUserType(userID int) (string, error) {
	user, err := GetUserByID(userID)
	if err != nil {
		return "", err
	}
	return user.Type, nil
}

func CheckPermission(userID int, requiredTypes ...string) error {
	userType, err := GetUserType(userID)
	if err != nil {
		return err
	}

	for _, t := range requiredTypes {
		if userType == t {
			return nil
		}
	}

	return errors.New("permission denied")
}

func GetClientIP(r *http.Request) string {
	forwarded := r.Header.Get("X-Forwarded-For")
	if forwarded != "" {
		return forwarded
	}
	return r.RemoteAddr
}

func LogRequest(r *http.Request, userID int) {
	log.Printf("[%s] %s %s - UserID: %d - IP: %s",
		time.Now().Format("2006-01-02 15:04:05"),
		r.Method,
		r.URL.Path,
		userID,
		GetClientIP(r),
	)
}

func IntToString(i int) string {
	return strconv.Itoa(i)
}