diff --git a/timer/timer.go b/timer/timer.go index 5de4eee..26720e7 100644 --- a/timer/timer.go +++ b/timer/timer.go @@ -2,16 +2,80 @@ package timer import ( + "sync" "time" tea "github.com/charmbracelet/bubbletea" ) +var ( + lastID int + idMtx sync.Mutex +) + +func nextID() int { + idMtx.Lock() + defer idMtx.Unlock() + lastID++ + return lastID +} + +// Authors note with regard to start and stop commands: +// +// Technically speaking, sending commands to start and stop the timer in this +// case is extraneous. To stop the timer we'd just need to set the 'running' +// property on the model to false which cause logic in the update function to +// stop responding to TickMsgs. To start the model we'd set 'running' to true +// and fire off a TickMsg. Helper functions would look like: +// +// func (m *model) Start() tea.Cmd +// func (m *model) Stop() +// +// The danger with this approach, however, is that order of operations becomes +// important with helper functions like the above. Consider the following: +// +// // Would not work +// return m, m.timer.Start() +// +// // Would work +// cmd := m.timer.start() +// return m, cmd +// +// Thus, because of potential pitfalls like the ones above, we've introduced +// the extraneous StartStopMsg to simplify the mental model when using this +// package. Bear in mind that the practice of sending commands to simply +// communicate with other parts of your application, such as in this package, +// is still not recommended. + +// StartStopMsg is used to start and stop the timer. +type StartStopMsg struct { + ID int + running bool +} + // TickMsg is a message that is sent on every timer tick. -type TickMsg struct{} +type TickMsg struct { + // ID is the identifier of the stopwatch that send the message. This makes + // it possible to determine which timer a tick belongs to when there + // are multiple timers running. + // + // Note, however, that a timer will reject ticks from other stopwatches, so + // it's safe to flow all TickMsgs through all timers and have them still + // behave appropriately. + ID int + + // Timeout returns whether or not this tick is a timeout tick. You can + // alternatively listen for TimeoutMsg. + Timeout bool +} // TimeoutMsg is a message that is sent once when the timer times out. -type TimeoutMsg struct{} +// +// It's a convenience message sent alongside a TickMsg with the Timeout value +// set to true. +type TimeoutMsg struct { + ID int +} // Model of the timer component. type Model struct { @@ -20,6 +84,9 @@ type Model struct { // How long to wait before every tick. Defaults to 1 second. Interval time.Duration + + id int + running bool } // NewWithInterval creates a new timer with the given timeout and tick interval. @@ -27,6 +94,8 @@ func NewWithInterval(timeout, interval time.Duration) Model { return Model{ Timeout: timeout, Interval: interval, + running: true, + id: nextID(), } } @@ -35,22 +104,47 @@ func New(timeout time.Duration) Model { return NewWithInterval(timeout, time.Second) } +// ID returns the model's identifier. This can be used to determine if messages +// belong to this timer instance when there are multiple timers. +func (m Model) ID() int { + return m.id +} + +// Running returns whether or not the timer is running. If the timer has timed +// out this will always return false. +func (m Model) Running() bool { + if m.Timedout() || !m.running { + return false + } + return true +} + +// Timedout returns whether or not the timer has timed out. +func (m Model) Timedout() bool { + return m.Timeout <= 0 +} + // Init starts the timer. func (m Model) Init() tea.Cmd { - return tick(m.Interval) + return m.tick() } // Update handles the timer tick. func (m Model) Update(msg tea.Msg) (Model, tea.Cmd) { - switch msg.(type) { - case TickMsg: - m.Timeout -= m.Interval - if m.Timeout <= 0 { - return m, func() tea.Msg { - return TimeoutMsg{} - } + switch msg := msg.(type) { + case StartStopMsg: + if msg.ID != 0 && msg.ID != m.id { + return m, nil } - return m, tick(m.Interval) + m.running = msg.running + return m, m.tick() + case TickMsg: + if !m.Running() || (msg.ID != 0 && msg.ID != m.id) { + break + } + + m.Timeout -= m.Interval + return m, tea.Batch(m.tick(), m.timedout()) } return m, nil @@ -61,8 +155,40 @@ func (m Model) View() string { return m.Timeout.String() } -func tick(d time.Duration) tea.Cmd { - return tea.Tick(d, func(_ time.Time) tea.Msg { - return TickMsg{} +// Start resumes the timer. Has no effect if the timer has timed out. +func (m *Model) Start() tea.Cmd { + return m.startStop(true) +} + +// Stop pauses the timer. Has no effect if the timer has timed out. +func (m *Model) Stop() tea.Cmd { + return func() tea.Msg { + return m.startStop(false) + } +} + +// Toggle stops the timer if it's running and starts it if it's stopped. +func (m *Model) Toggle() tea.Cmd { + return m.startStop(!m.Running()) +} + +func (m Model) tick() tea.Cmd { + return tea.Tick(m.Interval, func(_ time.Time) tea.Msg { + return TickMsg{ID: m.id, Timeout: m.Timedout()} }) } + +func (m Model) timedout() tea.Cmd { + if !m.Timedout() { + return nil + } + return func() tea.Msg { + return TimeoutMsg{ID: m.id} + } +} + +func (m Model) startStop(v bool) tea.Cmd { + return func() tea.Msg { + return StartStopMsg{ID: m.id, running: v} + } +}