bubbles/spinner/spinner.go

package spinner

import (
	"time"

	tea "github.com/charmbracelet/bubbletea"
	"github.com/muesli/termenv"
)

const (
	defaultFPS = time.Second / 10
)

// Spinner is a set of frames used in animating the spinner.
type Spinner = []string

var (
	// Some spinners to choose from. You could also make your own.
	Line = Spinner([]string{"|", "/", "-", "\\"})
	Dot  = Spinner([]string{"⣾ ", "⣽ ", "⣻ ", "⢿ ", "⡿ ", "⣟ ", "⣯ ", "⣷ "})

	color = termenv.ColorProfile().Color
)

// Model contains the state for the spinner. Use NewModel to create new models
// rather than using Model as a struct literal.
type Model struct {

	// Type is the set of frames to use. See Spinner.
	Frames Spinner

	// FPS is the speed at which the ticker should tick.
	FPS time.Duration

	// ForegroundColor sets the background color of the spinner. It can be a
	// hex code or one of the 256 ANSI colors. If the terminal emulator can't
	// doesn't support the color specified it will automatically degrade
	// (per github.com/muesli/termenv).
	ForegroundColor string

	// BackgroundColor sets the background color of the spinner. It can be a
	// hex code or one of the 256 ANSI colors. If the terminal emulator can't
	// doesn't support the color specified it will automatically degrade
	// (per github.com/muesli/termenv).
	BackgroundColor string

	// MinimumLifetime is the minimum amount of time the spinner can run. Any
	// logic around this can be implemented in view that implements this
	// spinner. If HideFor is set MinimumLifetime will be added on top of
	// HideFor. In other words, if HideFor is 100ms and MinimumLifetime is
	// 200ms then MinimumLifetime will expire after 300ms.
	//
	// MinimumLifetime is optional.
	//
	// This is considered experimental and may not appear in future versions of
	// this library.
	MinimumLifetime time.Duration

	// HideFor can be used to wait to show the spinner until a certain amount
	// of time has passed. This can be useful for preventing flicking when load
	// times are very fast. The hidden state can be set with HiddenState.
	// Optional.
	//
	// This is considered experimental and may not appear in future versions of
	// this library.
	HideFor time.Duration

	frame     int
	startTime time.Time
}

// Start resets resets the spinner start time. For use with MinimumLifetime and
// MinimumStartTime. Optional.
//
// This is considered experimental and may not appear in future versions of
// this library.
func (m *Model) Start() {
	m.startTime = time.Now()
}

// hidden returns whether or not Model.HideFor is in effect.
func (m Model) hidden() bool {
	if m.startTime.IsZero() {
		return false
	}
	if m.HideFor == 0 {
		return false
	}
	return m.startTime.Add(m.HideFor).After(time.Now())
}

// finished returns whether Model.MinimumLifetimeReached has been met.
func (m Model) finished() bool {
	if m.startTime.IsZero() {
		return true
	}
	if m.MinimumLifetime == 0 {
		return true
	}
	return m.startTime.Add(m.HideFor).Add(m.MinimumLifetime).Before(time.Now())
}

// Visible returns whether or not the view should be rendered. Works in
// conjunction with Model.HideFor and Model.MinimumLifetimeReached. You should
// use this message directly to determine whether or not to render this view in
// the parent view and whether to continue sending spin messaging in the
// parent update function.
//
// Also note that using this function is optional and generally considered for
// advanced use only. Most of the time your application logic will determine
// whether or not this view should be used.
//
// This is considered experimental and may not appear in future versions of
// this library.
func (m Model) Visible() bool {
	return !m.hidden() && !m.finished()
}

// NewModel returns a model with default values.
func NewModel() Model {
	return Model{
		Frames: Line,
		FPS:    defaultFPS,
	}
}

// TickMsg indicates that the timer has ticked and we should render a frame.
type TickMsg struct {
	Time time.Time
}

// Update is the Tea update function. This will advance the spinner one frame
// every time it's called, regardless the message passed, so be sure the logic
// is setup so as not to call this Update needlessly.
func Update(msg tea.Msg, m Model) (Model, tea.Cmd) {
	if _, ok := msg.(TickMsg); ok {
		m.frame++
		if m.frame >= len(m.Frames) {
			m.frame = 0
		}
		return m, Tick(m)
	}
	return m, nil
}

// View renders the model's view.
func View(model Model) string {
	if model.frame >= len(model.Frames) {
		return "error"
	}

	frame := model.Frames[model.frame]

	if model.ForegroundColor != "" || model.BackgroundColor != "" {
		return termenv.
			String(frame).
			Foreground(color(model.ForegroundColor)).
			Background(color(model.BackgroundColor)).
			String()
	}

	return frame
}

// Tick is the command used to advance the spinner one frame.
func Tick(m Model) tea.Cmd {
	return tea.Tick(m.FPS, func(t time.Time) tea.Msg {
		return TickMsg{
			Time: t,
		}
	})
}