feat: Add UI port for guard

internal/ui/spinner.go

@@ -0,0 +1,45 @@
+package ui
+
+import (
+	"fmt"
+	"time"
+)
+
+var spinnerChan chan bool
+
+func StartSpinner(msg string) {
+	style := `⠋⠙⠹⠸⠼⠴⠦⠧⠇⠏`
+	frames := []rune(style)
+	length := len(frames)
+
+	spinnerChan = make(chan bool)
+
+	ticker := time.NewTicker(100 * time.Millisecond)
+	go func() {
+		pos := 0
+
+		for {
+			select {
+			case <-spinnerChan:
+				ticker.Stop()
+				return
+			case <-ticker.C:
+				fmt.Printf("\r%s ... %s", msg, string(frames[pos%length]))
+				pos += 1
+			}
+		}
+	}()
+}
+
+func StopSpinner() {
+	// Gracefully handle the case where the spinner is already stopped
+	// and the channel is closed, yet client code calls StopSpinner() again.
+	defer func() {
+		_ = recover()
+	}()
+
+	close(spinnerChan)
+
+	fmt.Printf("\r")
+	fmt.Println()
+}