fix: /login now has better error handling/reporting

internal/api/handler/auth.go

@@ -1,6 +1,7 @@
 package handler
 
 import (
+	"errors"
 	"log/slog"
 	"net/http"
 
@@ -41,8 +42,15 @@ func (h *AuthHandler) Login(w http.ResponseWriter, r *http.Request) {
 
 	tokens, err := h.AuthService.Login(ctx, payload.Email, payload.Password)
 	if err != nil {
+		if errors.Is(err, domain.ErrEmailNotFound) {
+			response.Error(ctx, w, http.StatusUnauthorized, "email not found")
+		} else if errors.Is(err, domain.ErrPasswordWrong) {
+			response.Error(ctx, w, http.StatusUnauthorized, "password is wrong")
+		} else {
+			response.Error(ctx, w, http.StatusInternalServerError, "failed to login")
+		}
+
 		slog.ErrorContext(ctx, "failed to login", slog.Any("error", err))
-		response.Error(ctx, w, http.StatusInternalServerError, "failed to login")
 		return
 	}
 

internal/domain/auth.go

@@ -14,6 +14,11 @@ import (
 	"golang.org/x/crypto/bcrypt"
 )
 
+var (
+	ErrEmailNotFound = errors.New("email not found")
+	ErrPasswordWrong = errors.New("password is wrong")
+)
+
 type AuthRepository interface {
 	GetUserById(ctx context.Context, id string) (*AuthUser, error)
 	GetUserByEmail(ctx context.Context, email string) (*AuthUser, error)
@@ -71,7 +76,7 @@ func (s *AuthService) Authenticate(ctx context.Context, email string, password s
 	err = bcrypt.CompareHashAndPassword([]byte(user.PasswordHash), []byte(password))
 	if err != nil {
 		if errors.Is(err, bcrypt.ErrMismatchedHashAndPassword) {
-			return user, errors.New("invalid email or password")
+			return user, ErrPasswordWrong
 		}
 		return user, err
 	}

internal/repository/auth.go

@@ -36,6 +36,9 @@ func (r *AuthRepo) GetUserByEmail(ctx context.Context, email string) (*domain.Au
 		email,
 	).Scan(&user.ID, &user.Email, &user.Name, &user.PasswordHash)
 	if err != nil {
+		if errors.Is(err, sql.ErrNoRows) {
+			return nil, domain.ErrEmailNotFound
+		}
 		return nil, fmt.Errorf("failed to get user: %w", err)
 	}