1 files changed, 89 insertions, 0 deletions
diff --git a/cli/internal/spinner/spinner.go b/cli/internal/spinner/spinner.go
new file mode 100644
index 0000000..8ce6b4a
--- /dev/null
+++ b/cli/internal/spinner/spinner.go
@@ -0,0 +1,89 @@
+package spinner
+
+import (
+	"context"
+	"fmt"
+	"io"
+	"time"
+
+	"github.com/mitchellh/cli"
+	progressbar "github.com/schollz/progressbar/v3"
+	"github.com/vercel/turbo/cli/internal/ui"
+)
+
+// getWriterAndColor unwraps cli.Ui instances until it gets to a BasicUi.
+// If it happens to spot a ColoredUi along the way, it marks that color is
+// enabled.
+func getWriterAndColor(terminal cli.Ui, useColor bool) (io.Writer, bool) {
+	switch terminal := terminal.(type) {
+	case *cli.BasicUi:
+		return terminal.Writer, useColor
+	case *cli.ColoredUi:
+		return getWriterAndColor(terminal.Ui, true)
+	case *cli.ConcurrentUi:
+		return getWriterAndColor(terminal.Ui, useColor)
+	case *cli.PrefixedUi:
+		return getWriterAndColor(terminal.Ui, useColor)
+	case *cli.MockUi:
+		return terminal.OutputWriter, false
+	default:
+		panic(fmt.Sprintf("unknown Ui: %v", terminal))
+	}
+}
+
+// WaitFor runs fn, and prints msg to the terminal if it takes longer
+// than initialDelay to complete. Depending on the terminal configuration, it may
+// display a single instance of msg, or an infinite spinner, updated every 250ms.
+func WaitFor(ctx context.Context, fn func(), terminal cli.Ui, msg string, initialDelay time.Duration) error {
+	doneCh := make(chan struct{})
+	go func() {
+		fn()
+		close(doneCh)
+	}()
+	if ui.IsTTY {
+		select {
+		case <-ctx.Done():
+			return nil
+		case <-time.After(initialDelay):
+			writer, useColor := getWriterAndColor(terminal, false)
+			bar := progressbar.NewOptions(
+				-1,
+				progressbar.OptionEnableColorCodes(useColor),
+				progressbar.OptionSetDescription(fmt.Sprintf("[yellow]%v[reset]", msg)),
+				progressbar.OptionSpinnerType(14),
+				progressbar.OptionSetWriter(writer),
+			)
+			for {
+				select {
+				case <-doneCh:
+					err := bar.Finish()
+					terminal.Output("")
+					return err
+				case <-time.After(250 * time.Millisecond):
+					if err := bar.Add(1); err != nil {
+						return err
+					}
+				case <-ctx.Done():
+					return nil
+				}
+			}
+		case <-doneCh:
+			return nil
+		}
+	} else {
+		// wait for the timeout before displaying a message, even with no tty
+		select {
+		case <-ctx.Done():
+			return nil
+		case <-doneCh:
+			return nil
+		case <-time.After(initialDelay):
+			terminal.Output(msg)
+		}
+		select {
+		case <-ctx.Done():
+		case <-doneCh:
+		}
+		return nil
+	}
+}