Add basic authentication

backend/internal/security/jwt.go

@@ -0,0 +1,66 @@
+package security
+
+import (
+	"errors"
+	"os"
+	"time"
+
+	"github.com/golang-jwt/jwt/v5"
+)
+
+var ErrMissingSecret = errors.New("JWT secret not set")
+
+type Claims struct {
+    UserID string `json:"sub"`
+    Role   string `json:"role"`
+    jwt.RegisteredClaims
+}
+
+func getSecret() (string, error) {
+    s := os.Getenv("JWT_SECRET")
+    if s == "" {
+        return "", ErrMissingSecret
+    }
+    return s, nil
+}
+
+func GenerateToken(userID, role string, ttl time.Duration) (string, error) {
+    secret, err := getSecret()
+    if err != nil {
+        return "", err
+    }
+
+    claims := Claims{
+        UserID: userID,
+        Role:   role,
+        RegisteredClaims: jwt.RegisteredClaims{
+            ExpiresAt: jwt.NewNumericDate(time.Now().Add(ttl)),
+            IssuedAt:  jwt.NewNumericDate(time.Now()),
+        },
+    }
+
+    token := jwt.NewWithClaims(jwt.SigningMethodHS256, claims)
+    return token.SignedString([]byte(secret))
+}
+
+func ValidateToken(tokenString string) (*Claims, error) {
+    secret, err := getSecret()
+    if err != nil {
+        return nil, err
+    }
+
+    token, err := jwt.ParseWithClaims(tokenString, &Claims{}, func(t *jwt.Token) (interface{}, error) {
+        if _, ok := t.Method.(*jwt.SigningMethodHMAC); !ok {
+            return nil, errors.New("unexpected signing method")
+        }
+        return []byte(secret), nil
+    })
+    if err != nil {
+        return nil, err
+    }
+
+    if claims, ok := token.Claims.(*Claims); ok && token.Valid {
+        return claims, nil
+    }
+    return nil, errors.New("invalid token")
+}