fix: correctly generates otp code from token with extra padding

helper/totp.go

@@ -33,6 +33,9 @@ func GenerateOTPCode(token string, when time.Time) (string, error) {
 	// It should be uppercase always
 	token = strings.ToUpper(token)
 
+	// Remove all the extra "=" padding at the end
+	token = strings.TrimRight(token, "=")
+
 	secretBytes, err := base32.StdEncoding.WithPadding(base32.NoPadding).DecodeString(token)
 	if err != nil {
 		return "", fmt.Errorf("Decoding token string: %w", err)

helper/totp_test.go

@@ -0,0 +1,36 @@
+package helper
+
+import (
+	"testing"
+	"time"
+)
+
+var testCases = []struct {
+	description string
+	token       string
+	expectErr   bool
+}{
+	{"generates otpcode from token with padding", "PGWXXL7B66MMSRBAWSKEKIYD3P675KRJ===", false},
+	{"generates otpcode from token without padding", "JBSWY3DPEHPK3PXPJBSWY3DPEHPK3PXP", false},
+	{"invalid token format", "INVALIDTOKEN123", true},
+}
+
+func TestGenerateOTPCode(t *testing.T) {
+	for _, tc := range testCases {
+		t.Run(tc.description, func(t *testing.T) {
+			code, err := GenerateOTPCode(tc.token, time.Now())
+
+			if tc.expectErr {
+				if err == nil {
+					t.Errorf("Expected error for input '%s', but got none", tc.token)
+				}
+			} else {
+				if err != nil {
+					t.Errorf("GenerateOTPCode returned an error: %s", err.Error())
+				} else if len(code) != 6 {
+					t.Errorf("Expected 6-digit OTP, got: %s", code)
+				}
+			}
+		})
+	}
+}