From 115a10ed6639740485f26ece73aecb8816790a80 Mon Sep 17 00:00:00 2001
From: nutcas3 <mauricee423@gmail.com>
Date: Thu, 23 Apr 2026 01:55:21 +0300
Subject: [PATCH] feat: Add authentication service with JWT token management,
 session handling, and user operations

- Add JWTService struct with db/secretKey fields and NewJWTService constructor
- Add Claims struct with UserID/Username/Role fields and jwt.RegisteredClaims embedding
- Add GenerateToken method with 15-minute access token, 7-day refresh token, session storage, and inactive session cleanup
- Add ValidateToken method with JWT parsing, HMAC signature verification, and active session validation
- Add validateTokenWithoutSessionCheck for token parsing
---
 apps/api-server/internal/services/auth.go | 327 ++++++++++++++++++++++
 1 file changed, 327 insertions(+)
 create mode 100644 apps/api-server/internal/services/auth.go

diff --git a/apps/api-server/internal/services/auth.go b/apps/api-server/internal/services/auth.go
new file mode 100644
index 0000000..c2ba53c
--- /dev/null
+++ b/apps/api-server/internal/services/auth.go
@@ -0,0 +1,327 @@
+package services
+
+import (
+	"crypto/rand"
+	"encoding/hex"
+	"errors"
+	"fmt"
+	"time"
+
+	"github.com/golang-jwt/jwt/v5"
+	"golang.org/x/crypto/bcrypt"
+	"gorm.io/gorm"
+
+	"github.com/nutcas3/telecom-platform/apps/api-server/internal/models"
+)
+
+// JWTService handles JWT token generation and validation
+type JWTService struct {
+	db        *gorm.DB
+	secretKey string
+}
+
+// NewJWTService creates a new JWT service
+func NewJWTService(db *gorm.DB, secretKey string) *JWTService {
+	return &JWTService{
+		db:        db,
+		secretKey: secretKey,
+	}
+}
+
+// Claims represents JWT claims
+type Claims struct {
+	UserID   uint   `json:"user_id"`
+	Username string `json:"username"`
+	Role     string `json:"role"`
+	jwt.RegisteredClaims
+}
+
+// GenerateToken generates a new JWT token for a user
+func (s *JWTService) GenerateToken(user *models.User) (string, string, error) {
+	// Generate access token (short-lived)
+	accessTokenExpiry := time.Now().Add(15 * time.Minute)
+	accessClaims := &Claims{
+		UserID:   user.ID,
+		Username: user.Username,
+		Role:     user.Role,
+		RegisteredClaims: jwt.RegisteredClaims{
+			ExpiresAt: jwt.NewNumericDate(accessTokenExpiry),
+			IssuedAt:  jwt.NewNumericDate(time.Now()),
+			NotBefore: jwt.NewNumericDate(time.Now()),
+			Issuer:    "telecom-platform",
+			Subject:   fmt.Sprintf("%d", user.ID),
+		},
+	}
+
+	accessToken := jwt.NewWithClaims(jwt.SigningMethodHS256, accessClaims)
+	accessTokenString, err := accessToken.SignedString([]byte(s.secretKey))
+	if err != nil {
+		return "", "", fmt.Errorf("failed to sign access token: %w", err)
+	}
+
+	// Generate refresh token (long-lived)
+	refreshTokenExpiry := time.Now().Add(7 * 24 * time.Hour) // 7 days
+	refreshClaims := &Claims{
+		UserID:   user.ID,
+		Username: user.Username,
+		Role:     user.Role,
+		RegisteredClaims: jwt.RegisteredClaims{
+			ExpiresAt: jwt.NewNumericDate(refreshTokenExpiry),
+			IssuedAt:  jwt.NewNumericDate(time.Now()),
+			NotBefore: jwt.NewNumericDate(time.Now()),
+			Issuer:    "telecom-platform",
+			Subject:   fmt.Sprintf("%d", user.ID),
+		},
+	}
+
+	refreshToken := jwt.NewWithClaims(jwt.SigningMethodHS256, refreshClaims)
+	refreshTokenString, err := refreshToken.SignedString([]byte(s.secretKey))
+	if err != nil {
+		return "", "", fmt.Errorf("failed to sign refresh token: %w", err)
+	}
+
+	// Store session in database
+	sessionID := generateSessionID()
+	session := &models.AuthSession{
+		ID:           sessionID,
+		UserID:       user.ID,
+		Token:        accessTokenString,
+		RefreshToken: refreshTokenString,
+		ExpiresAt:    accessTokenExpiry,
+		IsActive:     true,
+	}
+
+	// Delete any existing inactive sessions for this user to clean up
+	s.db.Where("user_id = ? AND is_active = ?", user.ID, false).Delete(&models.AuthSession{})
+
+	if err := s.db.Create(session).Error; err != nil {
+		return "", "", fmt.Errorf("failed to create session: %w", err)
+	}
+
+	return accessTokenString, refreshTokenString, nil
+}
+
+// ValidateToken validates a JWT token and returns the claims
+func (s *JWTService) ValidateToken(tokenString string) (*Claims, error) {
+	token, err := jwt.ParseWithClaims(tokenString, &Claims{}, func(token *jwt.Token) (any, error) {
+		if _, ok := token.Method.(*jwt.SigningMethodHMAC); !ok {
+			return nil, fmt.Errorf("unexpected signing method: %v", token.Header["alg"])
+		}
+		return []byte(s.secretKey), nil
+	})
+
+	if err != nil {
+		return nil, fmt.Errorf("failed to parse token: %w", err)
+	}
+
+	if claims, ok := token.Claims.(*Claims); ok && token.Valid {
+		// Check if session is still active
+		var session models.AuthSession
+		if err := s.db.Where("token = ? AND is_active = ?", tokenString, true).First(&session).Error; err != nil {
+			return nil, fmt.Errorf("session not found or inactive")
+		}
+
+		if time.Now().After(session.ExpiresAt) {
+			return nil, fmt.Errorf("session expired")
+		}
+
+		return claims, nil
+	}
+
+	return nil, fmt.Errorf("invalid token")
+}
+
+// validateTokenWithoutSessionCheck validates a JWT token without checking the database session
+func (s *JWTService) validateTokenWithoutSessionCheck(tokenString string) (*Claims, error) {
+	token, err := jwt.ParseWithClaims(tokenString, &Claims{}, func(token *jwt.Token) (any, error) {
+		if _, ok := token.Method.(*jwt.SigningMethodHMAC); !ok {
+			return nil, fmt.Errorf("unexpected signing method: %v", token.Header["alg"])
+		}
+		return []byte(s.secretKey), nil
+	})
+
+	if err != nil {
+		return nil, fmt.Errorf("failed to parse token: %w", err)
+	}
+
+	if claims, ok := token.Claims.(*Claims); ok && token.Valid {
+		return claims, nil
+	}
+
+	return nil, fmt.Errorf("invalid token")
+}
+
+// RefreshToken generates new tokens using a refresh token
+func (s *JWTService) RefreshToken(refreshTokenString string) (string, string, error) {
+	// First validate the refresh token by checking it in the database
+	var session models.AuthSession
+	if err := s.db.Where("refresh_token = ? AND is_active = ?", refreshTokenString, true).First(&session).Error; err != nil {
+		return "", "", fmt.Errorf("invalid refresh token: %w", err)
+	}
+
+	// Check if session has expired
+	if time.Now().After(session.ExpiresAt) {
+		return "", "", fmt.Errorf("refresh token expired")
+	}
+
+	// Parse the refresh token to get claims
+	claims, err := s.validateTokenWithoutSessionCheck(refreshTokenString)
+	if err != nil {
+		return "", "", fmt.Errorf("invalid refresh token: %w", err)
+	}
+
+	// Get user from database
+	var user models.User
+	if err := s.db.First(&user, claims.UserID).Error; err != nil {
+		return "", "", fmt.Errorf("user not found: %w", err)
+	}
+
+	// Deactivate old session
+	s.db.Model(&models.AuthSession{}).Where("refresh_token = ?", refreshTokenString).Update("is_active", false)
+
+	// Generate new tokens
+	return s.GenerateToken(&user)
+}
+
+// InvalidateSession invalidates a user session
+func (s *JWTService) InvalidateSession(tokenString string) error {
+	return s.db.Model(&models.AuthSession{}).Where("token = ?", tokenString).Update("is_active", false).Error
+}
+
+// InvalidateAllUserSessions invalidates all sessions for a user
+func (s *JWTService) InvalidateAllUserSessions(userID uint) error {
+	return s.db.Model(&models.AuthSession{}).Where("user_id = ?", userID).Update("is_active", false).Error
+}
+
+// HashPassword hashes a password using bcrypt
+func HashPassword(password string) (string, error) {
+	bytes, err := bcrypt.GenerateFromPassword([]byte(password), bcrypt.DefaultCost)
+	if err != nil {
+		return "", fmt.Errorf("failed to hash password: %w", err)
+	}
+	return string(bytes), nil
+}
+
+// CheckPassword verifies a password against its hash
+func CheckPassword(password, hash string) error {
+	return bcrypt.CompareHashAndPassword([]byte(hash), []byte(password))
+}
+
+// generateSessionID generates a random session ID
+func generateSessionID() string {
+	bytes := make([]byte, 32)
+	rand.Read(bytes)
+	return hex.EncodeToString(bytes)
+}
+
+// AuthService handles authentication operations
+type AuthService struct {
+	db         *gorm.DB
+	jwtService *JWTService
+}
+
+// NewAuthService creates a new authentication service
+func NewAuthService(db *gorm.DB, secretKey string) *AuthService {
+	return &AuthService{
+		db:         db,
+		jwtService: NewJWTService(db, secretKey),
+	}
+}
+
+// Login authenticates a user and returns tokens
+func (s *AuthService) Login(username, password string) (string, string, *models.User, error) {
+	var user models.User
+	if err := s.db.Where("username = ? AND is_active = ?", username, true).First(&user).Error; err != nil {
+		if errors.Is(err, gorm.ErrRecordNotFound) {
+			return "", "", nil, fmt.Errorf("invalid credentials")
+		}
+		return "", "", nil, fmt.Errorf("database error: %w", err)
+	}
+
+	if err := CheckPassword(password, user.Password); err != nil {
+		return "", "", nil, fmt.Errorf("invalid credentials")
+	}
+
+	// Update last login
+	now := time.Now()
+	s.db.Model(&user).Update("last_login", &now)
+
+	// Generate tokens
+	accessToken, refreshToken, err := s.jwtService.GenerateToken(&user)
+	if err != nil {
+		return "", "", nil, fmt.Errorf("failed to generate tokens: %w", err)
+	}
+
+	return accessToken, refreshToken, &user, nil
+}
+
+// Register creates a new user
+func (s *AuthService) Register(username, email, password, firstName, lastName, role string) (*models.User, error) {
+	// Hash password
+	hashedPassword, err := HashPassword(password)
+	if err != nil {
+		return nil, fmt.Errorf("failed to hash password: %w", err)
+	}
+
+	// Create user
+	user := &models.User{
+		Username:  username,
+		Email:     email,
+		Password:  hashedPassword,
+		FirstName: firstName,
+		LastName:  lastName,
+		Role:      role,
+		IsActive:  true,
+	}
+
+	if err := s.db.Create(user).Error; err != nil {
+		return nil, fmt.Errorf("failed to create user: %w", err)
+	}
+
+	return user, nil
+}
+
+// GetUserByID retrieves a user by ID
+func (s *AuthService) GetUserByID(userID uint) (*models.User, error) {
+	var user models.User
+	if err := s.db.First(&user, userID).Error; err != nil {
+		return nil, fmt.Errorf("user not found: %w", err)
+	}
+	return &user, nil
+}
+
+// ChangePassword changes a user's password
+func (s *AuthService) ChangePassword(userID uint, oldPassword, newPassword string) error {
+	var user models.User
+	if err := s.db.First(&user, userID).Error; err != nil {
+		return fmt.Errorf("user not found: %w", err)
+	}
+
+	if err := CheckPassword(oldPassword, user.Password); err != nil {
+		return fmt.Errorf("invalid old password")
+	}
+
+	hashedPassword, err := HashPassword(newPassword)
+	if err != nil {
+		return fmt.Errorf("failed to hash new password: %w", err)
+	}
+
+	if err := s.db.Model(&user).Update("password", hashedPassword).Error; err != nil {
+		return fmt.Errorf("failed to update password: %w", err)
+	}
+
+	// Invalidate all sessions for this user
+	s.jwtService.InvalidateAllUserSessions(userID)
+
+	return nil
+}
+
+// GetJWTService returns the JWT service
+func (s *AuthService) GetJWTService() *JWTService {
+	return s.jwtService
+}
+
+// GetDB returns the database instance
+func (s *AuthService) GetDB() *gorm.DB {
+	return s.db
+}