constellation/cli/internal/cmd/spinner.go
2023-01-18 13:10:24 +01:00

133 lines
2.8 KiB
Go

/*
Copyright (c) Edgeless Systems GmbH
SPDX-License-Identifier: AGPL-3.0-only
*/
package cmd
import (
"fmt"
"io"
"os"
"sync"
"sync/atomic"
"time"
tty "github.com/mattn/go-isatty"
"github.com/spf13/cobra"
)
const (
// hideCursor and showCursor are ANSI escape sequences to hide and show the cursor.
hideCursor = "\033[?25l"
showCursor = "\033[?25h"
)
var (
spinnerStates = []string{"⣷", "⣯", "⣟", "⡿", "⢿", "⣻", "⣽", "⣾"}
dotsStates = []string{". ", ".. ", "..."}
)
type spinnerInterf interface {
Start(text string, showDots bool)
Stop()
io.Writer
}
type spinner struct {
out io.Writer
delay time.Duration
wg *sync.WaitGroup
stop *atomic.Bool
spinFunc func(out io.Writer, wg *sync.WaitGroup, stop *atomic.Bool, delay time.Duration, text string, showDots bool)
}
func newSpinnerOrStderr(cmd *cobra.Command) (spinnerInterf, error) {
debug, err := cmd.Flags().GetBool("debug")
if err != nil {
return nil, err
}
if debug {
return &nopSpinner{cmd.ErrOrStderr()}, nil
}
return newSpinner(cmd.ErrOrStderr()), nil
}
func newSpinner(writer io.Writer) *spinner {
s := &spinner{
out: writer,
wg: &sync.WaitGroup{},
delay: time.Millisecond * 100,
stop: &atomic.Bool{},
}
s.spinFunc = spinTTY
if !(writer == os.Stderr && tty.IsTerminal(os.Stderr.Fd())) {
s.spinFunc = spinNoTTY
}
return s
}
// Start starts the spinner using the given text.
func (s *spinner) Start(text string, showDots bool) {
s.wg.Add(1)
go s.spinFunc(s.out, s.wg, s.stop, s.delay, text, showDots)
}
// Stop stops the spinner.
func (s *spinner) Stop() {
s.stop.Store(true)
s.wg.Wait()
}
// Write stops the spinner and writes the given bytes to the underlying writer.
func (s *spinner) Write(p []byte) (n int, err error) {
s.Stop()
return s.out.Write(p)
}
func spinTTY(out io.Writer, wg *sync.WaitGroup, stop *atomic.Bool, delay time.Duration, text string, showDots bool) {
defer wg.Done()
fmt.Fprint(out, hideCursor)
for i := 0; ; i = (i + 1) % len(spinnerStates) {
if stop.Load() {
break
}
dotsState := ""
if showDots {
dotsState = dotsStates[i%len(dotsStates)]
}
state := fmt.Sprintf("\r%s %s%s", spinnerStates[i], text, dotsState)
fmt.Fprint(out, state)
time.Sleep(delay)
}
dotsState := ""
if showDots {
dotsState = dotsStates[len(dotsStates)-1]
}
finalState := fmt.Sprintf("\r%s%s ", text, dotsState)
fmt.Fprintln(out, finalState)
fmt.Fprint(out, showCursor)
}
func spinNoTTY(out io.Writer, wg *sync.WaitGroup, _ *atomic.Bool, _ time.Duration, text string, _ bool) {
defer wg.Done()
fmt.Fprintln(out, text+"...")
}
type nopSpinner struct {
io.Writer
}
func (s *nopSpinner) Start(string, bool) {}
func (s *nopSpinner) Stop() {}
func (s *nopSpinner) Write(p []byte) (n int, err error) {
return s.Writer.Write(p)
}