fix: make LAN preparation status transient

Author: roie

internal/app/lan_qr.go

@@ -43,13 +43,17 @@ func renderLANSetupQR(setupURL string) (string, int, error) {
 	return output.String(), width, nil
 }
 
-func maybePrintLANSetupQR(output io.Writer, setupURL string) bool {
+func isTerminalOutput(output io.Writer) bool {
 	file, ok := output.(*os.File)
 	if !ok {
 		return false
 	}
 	info, err := file.Stat()
-	if err != nil || info.Mode()&os.ModeCharDevice == 0 {
+	return err == nil && info.Mode()&os.ModeCharDevice != 0
+}
+
+func maybePrintLANSetupQR(output io.Writer, setupURL string) bool {
+	if !isTerminalOutput(output) {
 		return false
 	}
 	rendered, width, err := renderLANSetupQR(setupURL)

internal/app/lan_share.go

@@ -27,9 +27,8 @@ func createLANShare(ctx context.Context, client adminClient, cmd cli.Command, re
 	if !ok {
 		return nil, errors.New("router control does not support LAN sharing; update gohere")
 	}
-	if progress != nil {
-		fmt.Fprintln(progress, "Preparing LAN access…")
-	}
+	finishProgress := startLANProgress(progress, isTerminalOutput(progress))
+	defer finishProgress()
 	result, err := lanClient.CreateLANShare(ctx, ref)
 	if err != nil {
 		if errors.Is(err, context.DeadlineExceeded) || strings.Contains(err.Error(), "Client.Timeout exceeded") {
@@ -40,6 +39,15 @@ func createLANShare(ctx context.Context, client adminClient, cmd cli.Command, re
 	return &result, nil
 }
 
+func startLANProgress(output io.Writer, terminal bool) func() {
+	if output == nil || !terminal {
+		return func() {}
+	}
+	const message = "Preparing LAN access…"
+	_, _ = fmt.Fprint(output, message)
+	return func() { _, _ = fmt.Fprintf(output, "\r%s\r", strings.Repeat(" ", len([]rune(message)))) }
+}
+
 func deleteLANShare(ctx context.Context, client adminClient, ref router.RouteRef) error {
 	lanClient, ok := client.(lanShareClient)
 	if !ok {

internal/app/share_test.go

@@ -31,8 +31,8 @@ func TestCreateAndPrintLANShare(t *testing.T) {
 	if err != nil {
 		t.Fatal(err)
 	}
-	if progress.String() != "Preparing LAN access…\n" {
-		t.Fatalf("progress = %q", progress.String())
+	if progress.String() != "" {
+		t.Fatalf("non-terminal progress = %q", progress.String())
 	}
 	if client.created != ref || result.URL != "https://shop.local" {
 		t.Fatalf("created = %#v, result = %#v", client.created, result)
@@ -51,6 +51,18 @@ func TestCreateAndPrintLANShare(t *testing.T) {
 	}
 }
 
+func TestLANProgressIsTransientOnTerminal(t *testing.T) {
+	var output bytes.Buffer
+	finish := startLANProgress(&output, true)
+	if output.String() != "Preparing LAN access…" {
+		t.Fatalf("progress start = %q", output.String())
+	}
+	finish()
+	if output.String() != "Preparing LAN access…\r                     \r" {
+		t.Fatalf("progress finish = %q", output.String())
+	}
+}
+
 func TestCreateLANShareExplainsWindowsFirewallTimeout(t *testing.T) {
 	client := &fakeLANShareClient{createErr: errors.New(`companion authority_error: Post "http://127.0.0.1:39399/v2/lan-shares": context deadline exceeded (Client.Timeout exceeded while awaiting headers)`)}
 	_, err := createLANShare(t.Context(), client, cli.Command{ShareMode: "lan"}, router.RouteRef{ID: "route-1", Generation: 1}, nil)