feat: impl cookie-based auth tokens exchange

implement access/refresh token exchange via cookies as well as automatic
access token refresh

apps/backend/internal/auth/cookies.go

@@ -0,0 +1,56 @@
+package auth
+
+import (
+	"time"
+
+	"github.com/gofiber/fiber/v2"
+)
+
+// CookieConfig controls auth cookie behavior.
+type CookieConfig struct {
+	// Domain for cross-subdomain cookies (e.g., "app.com" for web.app.com + api.app.com).
+	// Leave empty for same-host cookies (localhost, single domain).
+	Domain string
+}
+
+// authCookies returns auth cookies from the given fiber context.
+// Returns a map with the cookie names as keys and the cookie values as values.
+func authCookies(c *fiber.Ctx) map[string]string {
+	m := make(map[string]string)
+	at := c.Cookies(cookieKeyAccessToken)
+	if at != "" {
+		m[cookieKeyAccessToken] = at
+	}
+	rt := c.Cookies(cookieKeyRefreshToken)
+	if rt != "" {
+		m[cookieKeyRefreshToken] = rt
+	}
+	return m
+}
+
+// setAuthCookies sets HTTP-only auth cookies with security settings derived from the request.
+// Secure flag is based on actual protocol (works automatically with proxies/tunnels).
+func setAuthCookies(c *fiber.Ctx, accessToken, refreshToken string, cfg CookieConfig) {
+	secure := c.Protocol() == "https"
+
+	c.Cookie(&fiber.Cookie{
+		Name:     cookieKeyAccessToken,
+		Value:    accessToken,
+		Path:     "/",
+		Domain:   cfg.Domain,
+		Expires:  time.Now().Add(accessTokenValidFor),
+		SameSite: fiber.CookieSameSiteLaxMode,
+		HTTPOnly: true,
+		Secure:   secure,
+	})
+	c.Cookie(&fiber.Cookie{
+		Name:     cookieKeyRefreshToken,
+		Value:    refreshToken,
+		Path:     "/",
+		Domain:   cfg.Domain,
+		Expires:  time.Now().Add(refreshTokenValidFor),
+		SameSite: fiber.CookieSameSiteLaxMode,
+		HTTPOnly: true,
+		Secure:   secure,
+	})
+}

apps/backend/internal/auth/http.go

@@ -10,15 +10,26 @@ import (
 	"github.com/uptrace/bun"
 )
 
+const (
+	tokenDeliveryCookie = "cookie"
+	tokenDeliveryBody   = "body"
+)
+
+const (
+	cookieKeyAccessToken  = "access_token"
+	cookieKeyRefreshToken = "refresh_token"
+)
+
 type loginRequest struct {
-	Email    string `json:"email"`
-	Password string `json:"password"`
+	Email         string `json:"email"`
+	Password      string `json:"password"`
+	TokenDelivery string `json:"tokenDelivery"`
 }
 
 type loginResponse struct {
 	User         user.User `json:"user"`
-	AccessToken  string    `json:"accessToken"`
-	RefreshToken string    `json:"refreshToken"`
+	AccessToken  string    `json:"accessToken,omitempty"`
+	RefreshToken string    `json:"refreshToken,omitempty"`
 }
 
 type refreshAccessTokenRequest struct {
@@ -31,12 +42,13 @@ type tokenResponse struct {
 }
 
 type HTTPHandler struct {
-	service *Service
-	db      *bun.DB
+	service      *Service
+	db           *bun.DB
+	cookieConfig CookieConfig
 }
 
-func NewHTTPHandler(s *Service, db *bun.DB) *HTTPHandler {
-	return &HTTPHandler{service: s, db: db}
+func NewHTTPHandler(s *Service, db *bun.DB, cookieConfig CookieConfig) *HTTPHandler {
+	return &HTTPHandler{service: s, db: db, cookieConfig: cookieConfig}
 }
 
 func (h *HTTPHandler) RegisterRoutes(api fiber.Router) {
@@ -69,11 +81,23 @@ func (h *HTTPHandler) Login(c *fiber.Ctx) error {
 		return httperr.Internal(err)
 	}
 
-	return c.JSON(loginResponse{
-		User:         *result.User,
-		AccessToken:  result.AccessToken,
-		RefreshToken: result.RefreshToken,
-	})
+	switch req.TokenDelivery {
+	default:
+		return c.Status(fiber.StatusBadRequest).JSON(fiber.Map{"error": "invalid token delivery method"})
+
+	case tokenDeliveryCookie:
+		setAuthCookies(c, result.AccessToken, result.RefreshToken, h.cookieConfig)
+		return c.JSON(loginResponse{
+			User: *result.User,
+		})
+
+	case tokenDeliveryBody:
+		return c.JSON(loginResponse{
+			User:         *result.User,
+			AccessToken:  result.AccessToken,
+			RefreshToken: result.RefreshToken,
+		})
+	}
 }
 
 func (h *HTTPHandler) refreshAccessToken(c *fiber.Ctx) error {

apps/backend/internal/auth/middleware.go

@@ -4,6 +4,7 @@ import (
 	"errors"
 	"log/slog"
 	"strings"
+	"time"
 
 	"github.com/get-drexa/drexa/internal/httperr"
 	"github.com/get-drexa/drexa/internal/user"
@@ -13,24 +14,35 @@ import (
 
 const authenticatedUserKey = "authenticatedUser"
 
-// NewBearerAuthMiddleware is a middleware that authenticates a request using a bearer token.
+// NewAuthMiddleware creates a middleware that authenticates requests via Bearer token or cookies.
 // To obtain the authenticated user in subsequent handlers, see AuthenticatedUser.
-func NewBearerAuthMiddleware(s *Service, db *bun.DB) fiber.Handler {
+func NewAuthMiddleware(s *Service, db *bun.DB, cookieConfig CookieConfig) fiber.Handler {
 	return func(c *fiber.Ctx) error {
+		var at string
+		var rt string
+		var setCookies bool
 		authHeader := c.Get("Authorization")
-		if authHeader == "" {
-			slog.Info("no auth header")
+		if authHeader != "" {
+			parts := strings.Split(authHeader, " ")
+			if len(parts) != 2 || parts[0] != "Bearer" {
+				slog.Info("invalid auth header")
+				return c.SendStatus(fiber.StatusUnauthorized)
+			}
+			at = parts[1]
+			setCookies = false
+		} else {
+			cookies := authCookies(c)
+			at = cookies[cookieKeyAccessToken]
+			rt = cookies[cookieKeyRefreshToken]
+			setCookies = true
+		}
+
+		if at == "" {
+			slog.Info("no access token")
 			return c.SendStatus(fiber.StatusUnauthorized)
 		}
 
-		parts := strings.Split(authHeader, " ")
-		if len(parts) != 2 || parts[0] != "Bearer" {
-			slog.Info("invalid auth header")
-			return c.SendStatus(fiber.StatusUnauthorized)
-		}
-
-		token := parts[1]
-		u, err := s.AuthenticateWithAccessToken(c.Context(), db, token)
+		authResult, err := s.AuthenticateWithAccessToken(c.Context(), db, at)
 		if err != nil {
 			var e *InvalidAccessTokenError
 			if errors.As(err, &e) {
@@ -47,7 +59,24 @@ func NewBearerAuthMiddleware(s *Service, db *bun.DB) fiber.Handler {
 			return httperr.Internal(err)
 		}
 
-		c.Locals(authenticatedUserKey, u)
+		c.Locals(authenticatedUserKey, authResult.User)
+
+		// if cookie based auth and access token is about to expire (within 5 minutes),
+		// attempt to refresh the access token. if there is any error, ignore it and let the request continue.
+		if setCookies && time.Until(authResult.Claims.ExpiresAt.Time) < 5*time.Minute && rt != "" {
+			tx, txErr := db.BeginTx(c.Context(), nil)
+			if txErr == nil {
+				newTokens, err := s.RefreshAccessToken(c.Context(), tx, rt)
+				if err == nil {
+					if commitErr := tx.Commit(); commitErr == nil {
+						setAuthCookies(c, newTokens.AccessToken, newTokens.RefreshToken, cookieConfig)
+					}
+				} else {
+					_ = tx.Rollback()
+					slog.Debug("auto-refresh failed", "error", err)
+				}
+			}
+		}
 
 		return c.Next()
 	}

apps/backend/internal/auth/service.go

@@ -10,6 +10,7 @@ import (
 
 	"github.com/get-drexa/drexa/internal/password"
 	"github.com/get-drexa/drexa/internal/user"
+	"github.com/golang-jwt/jwt/v5"
 	"github.com/google/uuid"
 	"github.com/uptrace/bun"
 )
@@ -20,6 +21,11 @@ type AuthenticationTokens struct {
 	RefreshToken string
 }
 
+type AccessTokenAuthentication struct {
+	Claims *jwt.RegisteredClaims
+	User   *user.User
+}
+
 var ErrInvalidCredentials = errors.New("invalid credentials")
 
 type Service struct {
@@ -65,7 +71,7 @@ func (s *Service) GrantForUser(ctx context.Context, db bun.IDB, user *user.User)
 	return result, nil
 }
 
-func (s *Service) AuthenticateWithAccessToken(ctx context.Context, db bun.IDB, token string) (*user.User, error) {
+func (s *Service) AuthenticateWithAccessToken(ctx context.Context, db bun.IDB, token string) (*AccessTokenAuthentication, error) {
 	claims, err := ParseAccessToken(token, &s.tokenConfig)
 	if err != nil {
 		slog.Info("failed to parse access token", "error", err)
@@ -78,7 +84,19 @@ func (s *Service) AuthenticateWithAccessToken(ctx context.Context, db bun.IDB, t
 		return nil, newInvalidAccessTokenError(err)
 	}
 
-	return s.userService.UserByID(ctx, db, id)
+	u, err := s.userService.UserByID(ctx, db, id)
+	if err != nil {
+		var nf *user.NotFoundError
+		if errors.As(err, &nf) {
+			return nil, newInvalidAccessTokenError(err)
+		}
+		return nil, err
+	}
+
+	return &AccessTokenAuthentication{
+		Claims: claims,
+		User:   u,
+	}, nil
 }
 
 func (s *Service) RefreshAccessToken(ctx context.Context, db bun.IDB, refreshToken string) (*AuthenticationTokens, error) {