pam: use dynamic padding for URL/Code labels alignment

examplebroker/broker.go

@@ -536,6 +536,10 @@ func qrcodeData(sessionInfo *sessionInfo) (content string, code string) {
 		"https://www.ubuntu-it.org/",
 	}
 
+	if strings.HasPrefix(sessionInfo.username, UserIntegrationQRcodeWithoutCodePrefix) {
+		return qrcodeURIs[0], ""
+	}
+
 	if strings.HasPrefix(sessionInfo.username, UserIntegrationQRcodeStaticPrefix) {
 		return qrcodeURIs[0], fmt.Sprint(baseCode)
 	}

examplebroker/users.go

@@ -41,6 +41,8 @@ const (
 	UserIntegrationCanResetPrefix = "user-can-reset-integration-"
 	// UserIntegrationLocalGroupsPrefix is the prefix for a local-groups user for integration tests.
 	UserIntegrationLocalGroupsPrefix = "user-local-groups-integration-"
+	// UserIntegrationQRcodeWithoutCodePrefix is the prefix for a qrcode user returning an URI without a code for integration tests.
+	UserIntegrationQRcodeWithoutCodePrefix = "user-integration-qrcode-without-code-"
 	// UserIntegrationQRcodeStaticPrefix is the prefix for a static qrcode user for integration tests.
 	UserIntegrationQRcodeStaticPrefix = "user-integration-qrcode-static-"
 	// UserIntegrationPreCheckValue is the value for a pre-check user for integration tests.

pam/integration-tests/native_test.go

@@ -134,6 +134,17 @@ func TestNativeAuthenticate(t *testing.T) {
 				"AUTHD_QRCODE_TAPE_ITEM_NAME": "QR code",
 			},
 		},
+		"Authenticate_user_with_qr_code_without_code": {
+			tape:         "qr_code",
+			tapeSettings: []tapeSetting{{vhsHeight, 3000}},
+			tapeVariables: map[string]string{
+				"AUTHD_QRCODE_TAPE_ITEM":      "7",
+				"AUTHD_QRCODE_TAPE_ITEM_NAME": "QR code",
+			},
+			clientOptions: clientOptions{
+				PamUser: examplebroker.UserIntegrationQRcodeWithoutCodePrefix + "native@example.com",
+			},
+		},
 		"Authenticate_user_with_qr_code_in_a_TTY": {
 			tape:         "qr_code",
 			tapeSettings: []tapeSetting{{vhsHeight, 4000}},

pam/internal/adapter/nativemodel.go

@@ -729,11 +729,11 @@ func (m nativeModel) handleQrCode() tea.Cmd {
 		qrcodeView = append(qrcodeView, qrcode)
 	}
 
-	qrcodeView = append(qrcodeView, fmt.Sprintf("URL:  %s", m.uiLayout.GetContent()))
-
+	labeledFields := []labeledField{{"URL", m.uiLayout.GetContent()}}
 	if code := m.uiLayout.GetCode(); code != "" {
-		qrcodeView = append(qrcodeView, fmt.Sprintf("Code: %s", code))
+		labeledFields = append(labeledFields, labeledField{"Code", code})
 	}
+	qrcodeView = append(qrcodeView, formatAlignedFields(labeledFields)...)
 
 	// Add some extra vertical space to improve readability
 	qrcodeView = append(qrcodeView, " ")

pam/internal/adapter/qrcodemodel.go

@@ -106,11 +106,11 @@ func (m qrcodeModel) View() string {
 	// Add some extra vertical space to improve readability
 	fields = append(fields, "")
 
-	fields = append(fields, fmt.Sprintf("URL:  %s", m.content))
-
+	labeledFields := []labeledField{{"URL", m.content}}
 	if m.code != "" {
-		fields = append(fields, fmt.Sprintf("Code: %s", m.code))
+		labeledFields = append(labeledFields, labeledField{"Code", m.code})
 	}
+	fields = append(fields, formatAlignedFields(labeledFields)...)
 
 	if m.buttonModel != nil {
 		fields = append(fields, style.Render(m.buttonModel.View()))

pam/internal/adapter/utils.go

@@ -8,6 +8,7 @@ import (
 	"os"
 	"strings"
 	"sync"
+	"unicode/utf8"
 
 	"github.com/canonical/authd/internal/proto/authd"
 	"github.com/canonical/authd/log"
@@ -252,3 +253,26 @@ func goBackLabel(previousStage proto.Stage) string {
 		return ""
 	}
 }
+
+// labeledField is a label-value pair used by [formatAlignedFields].
+type labeledField struct{ label, value string }
+
+// formatAlignedFields pads labels so that all values start at the same column.
+//
+// NOTE: This is not RTL-friendly and should be adjusted when adding RTL
+// language support.
+func formatAlignedFields(fields []labeledField) []string {
+	maxLen := 0
+	for _, f := range fields {
+		if n := utf8.RuneCountInString(f.label); n > maxLen {
+			maxLen = n
+		}
+	}
+
+	out := make([]string, 0, len(fields))
+	for _, f := range fields {
+		padding := strings.Repeat(" ", maxLen-utf8.RuneCountInString(f.label)+1)
+		out = append(out, f.label+":"+padding+f.value)
+	}
+	return out
+}

pam/internal/adapter/utils_test.go

@@ -313,3 +313,42 @@ func TestSafeMessageDebug(t *testing.T) {
 		})
 	}
 }
+
+func TestFormatAlignedFields(t *testing.T) {
+	t.Parallel()
+
+	tests := map[string]struct {
+		fields []labeledField
+		want   []string
+	}{
+		"Single field has no extra padding": {
+			fields: []labeledField{{"URL", "https://example.com"}},
+			want:   []string{"URL: https://example.com"},
+		},
+		"Two fields are padded to equal width": {
+			fields: []labeledField{{"URL", "https://example.com"}, {"Code", "1337"}},
+			want:   []string{"URL:  https://example.com", "Code: 1337"},
+		},
+		"Longer first label pads the second": {
+			fields: []labeledField{{"Verification URL", "https://example.com"}, {"Code", "1337"}},
+			want:   []string{"Verification URL: https://example.com", "Code:             1337"},
+		},
+		"Equal length labels": {
+			fields: []labeledField{{"Name", "Alice"}, {"Role", "Admin"}},
+			want:   []string{"Name: Alice", "Role: Admin"},
+		},
+		"Multibyte label is measured by rune count": {
+			// "URLé" is 5 bytes but 4 runes — padding must use rune count.
+			fields: []labeledField{{"URLé", "https://example.com"}, {"Code", "1337"}},
+			want:   []string{"URLé: https://example.com", "Code: 1337"},
+		},
+	}
+
+	for name, tc := range tests {
+		t.Run(name, func(t *testing.T) {
+			t.Parallel()
+			got := formatAlignedFields(tc.fields)
+			require.Equal(t, tc.want, got)
+		})
+	}
+}