GoMembership/go-backend/internal/middlewares/auth.go

package middlewares

import (
	"GoMembership/internal/config"
	"GoMembership/internal/models"
	"GoMembership/internal/utils"
	customerrors "GoMembership/pkg/errors"
	"GoMembership/pkg/logger"
	"errors"
	"fmt"
	"net/http"
	"time"

	"github.com/gin-gonic/gin"
	"github.com/golang-jwt/jwt/v5"
	"github.com/google/uuid"
)

type Session struct {
	UserID    uint
	ExpiresAt time.Time
}

var (
	sessionDuration  = 5 * 24 * time.Hour
	jwtSigningMethod = jwt.SigningMethodHS256
	jwtParser        = jwt.NewParser(jwt.WithValidMethods([]string{jwtSigningMethod.Alg()}))
	sessions         = make(map[string]*Session)
)

func verifyAndRenewToken(tokenString string) (string, uint, error) {
	if tokenString == "" {
		logger.Error.Printf("empty tokenstring")
		return "", 0, fmt.Errorf("Authorization token is required")
	}
	token, claims, err := ExtractContentFrom(tokenString)
	if err != nil {
		logger.Error.Printf("Couldn't parse JWT token String: %v", err)
		return "", 0, err
	}
	sessionID := (*claims)["session_id"].(string)
	userID := uint((*claims)["user_id"].(float64))
	roleID := int8((*claims)["role_id"].(float64))

	session, ok := sessions[sessionID]
	if !ok {
		logger.Error.Printf("session not found")
		return "", 0, fmt.Errorf("session not found")
	}
	if userID != session.UserID {
		return "", 0, fmt.Errorf("Cookie has been altered, aborting..")
	}
	if token.Valid {
		// token is valid, so we can return the old tokenString
		return tokenString, session.UserID, customerrors.ErrValidToken
	}

	if time.Now().After(sessions[sessionID].ExpiresAt) {
		delete(sessions, sessionID)
		logger.Error.Printf("session expired")
		return "", 0, fmt.Errorf("session expired")
	}
	session.ExpiresAt = time.Now().Add(sessionDuration)

	logger.Error.Printf("Session still valid generating new token")
	// Session is still valid, generate a new token
	user := models.User{ID: userID, RoleID: roleID}
	newTokenString, err := GenerateToken(config.Auth.JWTSecret, &user, sessionID)
	if err != nil {
		return "", 0, err
	}

	return newTokenString, session.UserID, nil
}

func AuthMiddleware() gin.HandlerFunc {
	return func(c *gin.Context) {
		tokenString, err := c.Cookie("jwt")
		if err != nil {
			logger.Error.Printf("No Auth token: %v\n", err)
			c.JSON(http.StatusUnauthorized,
				gin.H{"errors": []gin.H{{
					"field": "general",
					"key":   "server.error.no_auth_token",
				}}})
			c.Abort()
			return
		}

		newToken, userID, err := verifyAndRenewToken(tokenString)
		if err != nil {
			if err == customerrors.ErrValidToken {
				c.Set("user_id", uint(userID))
				c.Next()
				return
			}
			logger.Error.Printf("Token(%v) is invalid: %v\n", tokenString, err)
			c.JSON(http.StatusUnauthorized,
				gin.H{"errors": []gin.H{{
					"field": "general",
					"key":   "server.error.no_auth_token",
				}}})
			c.Abort()
			return
		}

		utils.SetCookie(c, newToken)
		c.Set("user_id", uint(userID))
		c.Next()
	}
}

func GenerateToken(jwtKey string, user *models.User, sessionID string) (string, error) {
	if sessionID == "" {
		sessionID = uuid.New().String()
	}
	token := jwt.NewWithClaims(jwtSigningMethod, jwt.MapClaims{
		"user_id":    user.ID,
		"role_id":    user.RoleID,
		"session_id": sessionID,
		"exp":        time.Now().Add(time.Minute * 1).Unix(), // Token expires in 10 Minutes
	})
	UpdateSession(sessionID, user.ID)
	return token.SignedString([]byte(jwtKey))
}

func ExtractContentFrom(tokenString string) (*jwt.Token, *jwt.MapClaims, error) {

	token, err := jwtParser.Parse(tokenString, func(_ *jwt.Token) (interface{}, error) {
		return []byte(config.Auth.JWTSecret), nil
	})

	if !errors.Is(err, jwt.ErrTokenExpired) && err != nil {
		logger.Error.Printf("Error during token(%v) parsing: %#v", tokenString, err)
		return nil, nil, err
	}

	// Token is expired, check if session is still valid
	claims, ok := token.Claims.(jwt.MapClaims)
	if !ok {
		logger.Error.Printf("Invalid Token Claims")
		return nil, nil, fmt.Errorf("invalid token claims")
	}

	if !ok {
		logger.Error.Printf("invalid session_id in token")
		return nil, nil, fmt.Errorf("invalid session_id in token")
	}
	return token, &claims, nil
}

func UpdateSession(sessionID string, userID uint) {
	sessions[sessionID] = &Session{
		UserID:    userID,
		ExpiresAt: time.Now().Add(sessionDuration),
	}
}

func InvalidateSession(token string) (bool, error) {
	claims := jwt.MapClaims{}
	_, err := jwt.ParseWithClaims(
		token,
		claims,
		func(token *jwt.Token) (interface{}, error) {
			return config.Auth.JWTSecret, nil
		},
	)
	if err != nil {
		return false, fmt.Errorf("Couldn't get JWT claims: %#v", err)
	}

	sessionID, ok := claims["session_id"].(string)
	if !ok {
		return false, fmt.Errorf("No SessionID found")
	}

	delete(sessions, sessionID)
	return true, nil
}