progress

progress/spinner.go

@@ -0,0 +1,102 @@
+package progress
+
+import (
+	"fmt"
+	"os"
+	"strings"
+	"time"
+
+	"golang.org/x/term"
+)
+
+type Spinner struct {
+	message      string
+	messageWidth int
+
+	parts []string
+
+	value int
+
+	ticker  *time.Ticker
+	started time.Time
+	stopped time.Time
+}
+
+func NewSpinner(message string) *Spinner {
+	s := &Spinner{
+		message: message,
+		parts: []string{
+			"⠋", "⠙", "⠹", "⠸", "⠼", "⠴", "⠦", "⠧", "⠇", "⠏",
+		},
+		started: time.Now(),
+	}
+	go s.start()
+	return s
+}
+
+func (s *Spinner) String() string {
+	termWidth, _, err := term.GetSize(int(os.Stderr.Fd()))
+	if err != nil {
+		panic(err)
+	}
+
+	var pre strings.Builder
+	if len(s.message) > 0 {
+		message := strings.TrimSpace(s.message)
+		if s.messageWidth > 0 && len(message) > s.messageWidth {
+			message = message[:s.messageWidth]
+		}
+
+		fmt.Fprintf(&pre, "%s", message)
+		if s.messageWidth-pre.Len() >= 0 {
+			pre.WriteString(strings.Repeat(" ", s.messageWidth-pre.Len()))
+		}
+
+		pre.WriteString(" ")
+	}
+
+	var pad int
+	if s.stopped.IsZero() {
+		// spinner has a string length of 3 but a rune length of 1
+		// in order to align correctly, we need to pad with (3 - 1) = 2 spaces
+		spinner := s.parts[s.value]
+		pre.WriteString(spinner)
+		pad = len(spinner) - len([]rune(spinner))
+	}
+
+	var suf strings.Builder
+	fmt.Fprintf(&suf, "(%s)", s.elapsed())
+
+	var mid strings.Builder
+	f := termWidth - pre.Len() - mid.Len() - suf.Len() + pad
+	if f > 0 {
+		mid.WriteString(strings.Repeat(" ", f))
+	}
+
+	return pre.String() + mid.String() + suf.String()
+}
+
+func (s *Spinner) start() {
+	s.ticker = time.NewTicker(100 * time.Millisecond)
+	for range s.ticker.C {
+		s.value = (s.value + 1) % len(s.parts)
+		if !s.stopped.IsZero() {
+			return
+		}
+	}
+}
+
+func (s *Spinner) Stop() {
+	if s.stopped.IsZero() {
+		s.stopped = time.Now()
+	}
+}
+
+func (s *Spinner) elapsed() time.Duration {
+	stopped := s.stopped
+	if stopped.IsZero() {
+		stopped = time.Now()
+	}
+
+	return stopped.Sub(s.started).Round(time.Second)
+}