feat: support time_zone for user registration context

authsession/internal/service/shared/normalize.go

@@ -91,6 +91,20 @@ func ParseClientPublicKey(value string) (common.ClientPublicKey, error) {
 	return key, nil
 }
 
+// ParseTimeZone trims value and validates it as an IANA time zone name.
+func ParseTimeZone(value string) (string, error) {
+	timeZone := NormalizeString(value)
+	if timeZone == "" {
+		return "", InvalidRequest("time_zone must not be empty")
+	}
+
+	if _, err := time.LoadLocation(timeZone); err != nil {
+		return "", InvalidRequest("time_zone must be a valid IANA time zone name")
+	}
+
+	return timeZone, nil
+}
+
 // ParseRevokeReasonCode trims value and validates it as one machine-readable
 // revoke reason code.
 func ParseRevokeReasonCode(value string) (common.RevokeReasonCode, error) {

authsession/internal/service/shared/shared_test.go

@@ -34,6 +34,19 @@ func TestParseClientPublicKey(t *testing.T) {
 	assert.Equal(t, ErrorCodeInvalidClientPublicKey, CodeOf(err))
 }
 
+func TestParseTimeZone(t *testing.T) {
+	t.Parallel()
+
+	timeZone, err := ParseTimeZone("  Europe/Kaliningrad  ")
+	require.NoError(t, err)
+	assert.Equal(t, "Europe/Kaliningrad", timeZone)
+
+	_, err = ParseTimeZone("Mars/Olympus")
+	require.Error(t, err)
+	assert.Equal(t, ErrorCodeInvalidRequest, CodeOf(err))
+	assert.Equal(t, "time_zone must be a valid IANA time zone name", err.Error())
+}
+
 func TestToSession(t *testing.T) {
 	t.Parallel()