Initial commit

internal/auth/manager.go

@@ -0,0 +1,101 @@
+package auth
+
+import (
+	"errors"
+	"fmt"
+	"os"
+	"time"
+
+	"github.com/golang-jwt/jwt/v5"
+)
+
+var (
+	ErrInvalidToken     = errors.New("invalid token")
+	ErrExpiredToken     = errors.New("token has expired")
+	ErrInvalidSignature = errors.New("invalid token signature")
+	ErrMissingClaims    = errors.New("missing required claims")
+)
+
+// Claims represents the JWT claims structure
+type Claims struct {
+	UserID int64  `json:"user_id"`
+	Email  string `json:"email"`
+	jwt.RegisteredClaims
+}
+
+type JWTManager struct {
+	secretKey     []byte
+	tokenDuration time.Duration
+}
+
+func NewJWTManager(secretKey string, tokenDuration time.Duration) *JWTManager {
+	return &JWTManager{
+		secretKey:     []byte(secretKey),
+		tokenDuration: tokenDuration,
+	}
+}
+
+// GenerateToken creates a new JWT token for a user
+func (m *JWTManager) GenerateToken(userID int64, email string) (string, error) {
+	claims := Claims{
+		UserID: userID,
+		Email:  email,
+		RegisteredClaims: jwt.RegisteredClaims{
+			ExpiresAt: jwt.NewNumericDate(time.Now().Add(m.tokenDuration)),
+			IssuedAt:  jwt.NewNumericDate(time.Now()),
+			NotBefore: jwt.NewNumericDate(time.Now()),
+			Issuer:    os.Getenv("JWT_ISSUER"),
+		},
+	}
+
+	token := jwt.NewWithClaims(jwt.SigningMethodHS256, claims)
+
+	tokenString, err := token.SignedString(m.secretKey)
+	if err != nil {
+		return "", fmt.Errorf("failed to sign token: %w", err)
+	}
+
+	return tokenString, nil
+}
+
+// ValidateToken validates the JWT token and returns the claims
+func (m *JWTManager) ValidateToken(tokenString string) (*Claims, error) {
+	token, err := jwt.ParseWithClaims(
+		tokenString,
+		&Claims{},
+		func(token *jwt.Token) (interface{}, error) {
+			// Verify signing method
+			if _, ok := token.Method.(*jwt.SigningMethodHMAC); !ok {
+				return nil, fmt.Errorf("unexpected signing method: %v", token.Header["alg"])
+			}
+			return m.secretKey, nil
+		},
+	)
+
+	if err != nil {
+		if errors.Is(err, jwt.ErrTokenExpired) {
+			return nil, ErrExpiredToken
+		}
+		if errors.Is(err, jwt.ErrSignatureInvalid) {
+			return nil, ErrInvalidSignature
+		}
+		return nil, ErrInvalidToken
+	}
+
+	claims, ok := token.Claims.(*Claims)
+	if !ok || !token.Valid {
+		return nil, ErrInvalidToken
+	}
+
+	return claims, nil
+}
+
+// RefreshToken generates a new token from an existing valid token
+func (m *JWTManager) RefreshToken(tokenString string) (string, error) {
+	claims, err := m.ValidateToken(tokenString)
+	if err != nil {
+		return "", err
+	}
+
+	return m.GenerateToken(claims.UserID, claims.Email)
+}