feat: fully implemented Refresh method;

fix: Improve error handling in Refresh method for token validation;
fix: Update Refresh route to use correct request model;
fix: Correct request model for password reset complete route;
fix: Redis pipeline error handling in AuthService constructor;
fix: Refresh method wanted access token;
refactor: Enhance error handling for unexpected token validation errors;
refactor: Simplify claims extraction in ValidateToken method;
fix: Ensure session termination state is correctly dereferenced;
refactor: Return structured session info in ValidateToken method;
feat: New util method to check if an error is one of multiple given ones;

backend/internal/controllers/auth.go

@@ -155,8 +155,16 @@ func (a *authControllerImpl) Refresh(c *gin.Context) {
 
 	response, err := a.auth.Refresh(request.Body)
 	if err != nil {
-		if errors.Is(err, errs.ErrUnauthorized) {
+		if errors.Is(err, errs.ErrTokenExpired) {
-			c.Status(http.StatusUnauthorized)
+			c.JSON(http.StatusUnauthorized, gin.H{"error": "Token is expired"})
+		} else if errors.Is(err, errs.ErrTokenInvalid) {
+			c.JSON(http.StatusUnauthorized, gin.H{"error": "Token is invalid"})
+		} else if errors.Is(err, errs.ErrWrongTokenType) {
+			c.JSON(http.StatusUnauthorized, gin.H{"error": "Invalid token type"})
+		} else if errors.Is(err, errs.ErrSessionNotFound) {
+			c.JSON(http.StatusUnauthorized, gin.H{"error": "Could not find session in database"})
+		} else if errors.Is(err, errs.ErrSessionTerminated) {
+			c.JSON(http.StatusUnauthorized, gin.H{"error": "Session is terminated"})
 		} else {
 			c.Status(http.StatusInternalServerError)
 		}
@@ -233,7 +241,7 @@ func (a *authControllerImpl) RegisterRoutes(group *gin.RouterGroup) {
 	group.POST("/registrationBegin", middleware.RequestMiddleware[models.RegistrationBeginRequest](enums.GuestRole), a.RegistrationBegin)
 	group.POST("/registrationComplete", middleware.RequestMiddleware[models.RegistrationCompleteRequest](enums.GuestRole), a.RegistrationComplete)
 	group.POST("/login", middleware.RequestMiddleware[models.LoginRequest](enums.GuestRole), a.Login)
-	group.POST("/refresh", middleware.RequestMiddleware[models.RegistrationBeginRequest](enums.UserRole), a.Refresh)
+	group.POST("/refresh", middleware.RequestMiddleware[models.RefreshRequest](enums.GuestRole), a.Refresh)
 	group.POST("/passwordResetBegin", middleware.RequestMiddleware[models.PasswordResetBeginRequest](enums.GuestRole), a.PasswordResetBegin)
-	group.POST("/passwordResetComplete", middleware.RequestMiddleware[models.RegistrationBeginRequest](enums.GuestRole), a.PasswordResetComplete)
+	group.POST("/passwordResetComplete", middleware.RequestMiddleware[models.PasswordResetCompleteRequest](enums.GuestRole), a.PasswordResetComplete)
 }

backend/internal/services/auth.go

@@ -71,8 +71,8 @@ func NewAuthService(_log *zap.Logger, _dbctx database.DbContext, _redis *redis.C
 	// FIXME: review possible problems due to a large pipeline request
 	pipe := _redis.Pipeline()
 	for _, guid := range guids {
-		if err := pipe.Set(ctx, fmt.Sprintf("session::%s::is_terminated", guid), true, 0); err != nil {
+		if err := pipe.Set(ctx, fmt.Sprintf("session::%s::is_terminated", guid), true, 0).Err(); err != nil {
-			panic("Failed to cache terminated session: " + err.Err().Error()) 
+			panic("Failed to cache terminated session: " + err.Error())
 		}
 	}
 	_log.Info("Cached terminated sessions' GUIDs in Redis", zap.Int("amount", len(guids)))
@@ -509,8 +509,23 @@ func (a *authServiceImpl) Login(request models.LoginRequest) (*models.LoginRespo
 
 func (a *authServiceImpl) Refresh(request models.RefreshRequest) (*models.RefreshResponse, error) {
 
-	sessionInfo, err := a.ValidateToken(request.RefreshToken, enums.JwtAccessTokenType); if err != nil {
+	sessionInfo, err := a.ValidateToken(request.RefreshToken, enums.JwtRefreshTokenType); if err != nil {
-		return nil, err
+	
+		if utils.ErrorIsOneOf(
+			err, 
+			errs.ErrInvalidToken,
+			errs.ErrTokenExpired, 
+			errs.ErrWrongTokenType,
+			errs.ErrSessionNotFound,
+			errs.ErrSessionTerminated,
+		) {
+			return nil, err
+		} else {
+			a.log.Error(
+				"Encountered an unexpected error while validating token",	
+				zap.Error(err))
+			return nil, errs.ErrServerError
+		}
 	} 
 
 	accessToken, refreshToken, err := utils.GenerateTokens(
@@ -558,7 +573,7 @@ func (a *authServiceImpl)	ValidateToken(jwtToken string, tokenType enums.JwtToke
 		return nil, errs.ErrInvalidToken
 	}
 
-	if claims, ok := token.Claims.(*dto.UserClaims); ok && token.Valid {
+	claims, ok := token.Claims.(*dto.UserClaims); if ok && token.Valid {
 
 		if claims.Type != tokenType {
 			return nil, errs.ErrWrongTokenType
@@ -597,7 +612,7 @@ func (a *authServiceImpl)	ValidateToken(jwtToken string, tokenType enums.JwtToke
 			if err := a.redis.Set(
 				ctx, 
 				fmt.Sprintf("session::%s::is_terminated", claims.Session), 
-				session.Terminated, 
+				*session.Terminated, 
 				time.Duration(8 * time.Hour), // XXX: magic number
 			).Err(); err != nil {
 				a.log.Error(
@@ -615,7 +630,14 @@ func (a *authServiceImpl)	ValidateToken(jwtToken string, tokenType enums.JwtToke
 			return nil, errs.ErrSessionTerminated
 		}
 	}
-	return nil, errs.ErrNotImplemented
+
+	sessionInfo := dto.SessionInfo{
+		Username: claims.Username,
+		Session: claims.Session,
+		Role: claims.Role,
+	}
+
+	return &sessionInfo, nil
 }
 
 func (a *authServiceImpl) PasswordResetBegin(request models.PasswordResetBeginRequest) (bool, error) {

backend/internal/utils/errors.go

@@ -0,0 +1,29 @@
+// Copyright (c) 2025 Nikolai Papin
+//
+// This file is part of Easywish
+//
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See
+// the GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with this program.  If not, see <https://www.gnu.org/licenses/>.
+
+package utils
+
+import "errors"
+
+func ErrorIsOneOf(err error, ignoreErrors ...error) bool {
+	for _, ignore := range ignoreErrors {
+		if errors.Is(err, ignore) {
+			return false
+		}
+	}
+	return true
+}