feat: simple timer component

[caarlos0]

closes #22

A simple timer component:

• ticks every second
• on timeout, executes the given tea.Cmd

Simplest possible usage example:

package main

import (
	"fmt"
	"os"
	"time"

	"github.com/charmbracelet/bubbles/timer"
	tea "github.com/charmbracelet/bubbletea"
)

func main() {
	m := timer.Model{
		Timeout: 10 * time.Second,
		OnTimeout: func() tea.Cmd {
			return tea.Quit
		},
	}

	if err := tea.NewProgram(m).Start(); err != nil {
		fmt.Println("Oh no, it didn't work:", err)
		os.Exit(1)
	}
}

let me know what you think

[caarlos0]

one thing that comes to mind now is: should we have an "increasing timer" as well? if so, maybe this component should be called timeout or something like that

[meowgorithm]

This is cool!

• I'd expose tickMsg so users can respond to ticks if they want
• It should probably also send a TimeoutMsg on timeout so that users have the option of listening for timeouts without running a command
• It would be cool if View returned the time remaining (otherwise it won't ever change)

It would also be useful to allow for a custom decrement value, so you could do something like:

m := Timer{
	Timeout: time.Millisecond * 250,
	TickEvery: time.Millisecond, // or maybe it's called Decrement?
}

…and then maybe if the decrement value is 0 it defaults to time.Second?

Otherwise, Timer seems like a good name for this since it's similar to the functionality in time.Timer. I'd probably call an increasing one Stopwatch, which I think makes sense to include.

[caarlos0]

agreed, made the changes...

view actually returns the time remaining because on update we do timeout =- interval

an example usage now looks like:

package main

import (
	"fmt"
	"os"
	"time"

	"github.com/charmbracelet/bubbles/timer"
	tea "github.com/charmbracelet/bubbletea"
)

type model struct {
	timer timer.Model
}

func (m model) Init() tea.Cmd {
	return m.timer.Init()
}

func (m model) View() string {
	return "Will exit in " + m.timer.View()
}

func (m model) Update(msg tea.Msg) (tea.Model, tea.Cmd) {
	switch msg.(type) {
	case timer.TimeoutMsg:
		return m, tea.Quit
	}
	var cmd tea.Cmd
	m.timer, cmd = m.timer.Update(msg)
	return m, cmd
}

func main() {
	m := model{
		timer: timer.New(3*time.Second),
	}

	if err := tea.NewProgram(m).Start(); err != nil {
		fmt.Println("Oh no, it didn't work:", err)
		os.Exit(1)
	}
}

[meowgorithm]

LGTM!