feat: stopwatch (#68)

* feat: stopwatch

Signed-off-by: Carlos Alexandro Becker <caarlos0@gmail.com>

stopwatch/stopwatch.go

@@ -0,0 +1,112 @@
+// Package stopwatch provides a simple stopwatch component.
+package stopwatch
+
+import (
+	"time"
+
+	tea "github.com/charmbracelet/bubbletea"
+)
+
+// TickMsg is a message that is sent on every timer tick.
+type TickMsg struct{}
+
+type startStopMsg struct {
+	running bool
+}
+
+type resetMsg struct{}
+
+// Model of the timer component.
+type Model struct {
+	d time.Duration
+
+	running bool
+
+	// How long to wait before every tick. Defaults to 1 second.
+	Interval time.Duration
+}
+
+// NewWithInterval creates a new stopwatch with the given timeout and tick interval.
+func NewWithInterval(interval time.Duration) Model {
+	return Model{
+		Interval: interval,
+	}
+}
+
+// New creates a new stopwatch with 1s interval.
+func New() Model {
+	return NewWithInterval(time.Second)
+}
+
+// Init starts the stopwatch..
+func (m Model) Init() tea.Cmd {
+	return m.Start()
+}
+
+// Start starts the stopwatch.
+func (m Model) Start() tea.Cmd {
+	return tea.Batch(func() tea.Msg {
+		return startStopMsg{true}
+	}, tick(m.Interval))
+}
+
+// Stop stops the stopwatch.
+func (m Model) Stop() tea.Cmd {
+	return func() tea.Msg {
+		return startStopMsg{false}
+	}
+}
+
+// Toggle stops the stopwatch if it is running and starts it if it is stopped.
+func (m Model) Toggle() tea.Cmd {
+	if m.Running() {
+		return m.Stop()
+	}
+	return m.Start()
+}
+
+// Reset restes the stopwatch to 0.
+func (m Model) Reset() tea.Cmd {
+	return func() tea.Msg {
+		return resetMsg{}
+	}
+}
+
+// Running returns true if the stopwatch is running or false if it is stopped.
+func (m Model) Running() bool {
+	return m.running
+}
+
+// Update handles the timer tick.
+func (m Model) Update(msg tea.Msg) (Model, tea.Cmd) {
+	switch msg := msg.(type) {
+	case startStopMsg:
+		m.running = msg.running
+	case resetMsg:
+		m.d = 0
+	case TickMsg:
+		if !m.running {
+			break
+		}
+		m.d += m.Interval
+		return m, tick(m.Interval)
+	}
+
+	return m, nil
+}
+
+// Elapsed returns the time elapsed.
+func (m Model) Elapsed() time.Duration {
+	return m.d
+}
+
+// View of the timer component.
+func (m Model) View() string {
+	return m.d.String()
+}
+
+func tick(d time.Duration) tea.Cmd {
+	return tea.Tick(d, func(_ time.Time) tea.Msg {
+		return TickMsg{}
+	})
+}