syft/cmd/syft/internal/ui/ui.go

package ui

import (
	"os"
	"sync"

	tea "github.com/charmbracelet/bubbletea"
	"github.com/wagoodman/go-partybus"

	"github.com/anchore/bubbly/bubbles/frame"
	"github.com/anchore/clio"
	"github.com/anchore/go-logger"
	handler "github.com/anchore/syft/cmd/syft/cli/ui"
	"github.com/anchore/syft/internal/bus"
	"github.com/anchore/syft/internal/log"
	"github.com/anchore/syft/syft/event"
)

var _ interface {
	tea.Model
	partybus.Responder
	clio.UI
} = (*UI)(nil)

type UI struct {
	program        *tea.Program
	running        *sync.WaitGroup
	quiet          bool
	subscription   partybus.Unsubscribable
	finalizeEvents []partybus.Event

	handler *handler.Handler
	frame   tea.Model
}

func New(h *handler.Handler, _, quiet bool) *UI {
	return &UI{
		handler: h,
		frame:   frame.New(),
		running: &sync.WaitGroup{},
		quiet:   quiet,
	}
}

func (m *UI) Setup(subscription partybus.Unsubscribable) error {
	// we still want to collect log messages, however, we also the logger shouldn't write to the screen directly
	if logWrapper, ok := log.Get().(logger.Controller); ok {
		logWrapper.SetOutput(m.frame.(*frame.Frame).Footer())
	}

	m.subscription = subscription
	m.program = tea.NewProgram(m, tea.WithOutput(os.Stderr), tea.WithInput(os.Stdin))
	m.running.Add(1)

	go func() {
		defer m.running.Done()
		if _, err := m.program.Run(); err != nil {
			log.Errorf("unable to start UI: %+v", err)
			m.exit()
		}
	}()

	return nil
}

func (m *UI) exit() {
	// stop the event loop
	bus.Exit()
}

func (m *UI) Handle(e partybus.Event) error {
	if m.program != nil {
		m.program.Send(e)
		if e.Type == event.CLIExit {
			return m.subscription.Unsubscribe()
		}
	}
	return nil
}

func (m *UI) Teardown(force bool) error {
	if !force {
		m.handler.Running.Wait()
		m.program.Quit()
		// typically in all cases we would want to wait for the UI to finish. However there are still error cases
		// that are not accounted for, resulting in hangs. For now, we'll just wait for the UI to finish in the
		// happy path only. There will always be an indication of the problem to the user via reporting the error
		// string from the worker (outside of the UI after teardown).
		m.running.Wait()
	} else {
		m.program.Kill()
	}

	// TODO: allow for writing out the full log output to the screen (only a partial log is shown currently)
	// this needs coordination to know what the last frame event is to change the state accordingly (which isn't possible now)

	return newPostUIEventWriter(os.Stdout, os.Stderr).write(m.quiet, m.finalizeEvents...)
}

// bubbletea.Model functions

func (m UI) Init() tea.Cmd {
	return m.frame.Init()
}

func (m UI) RespondsTo() []partybus.EventType {
	return append([]partybus.EventType{
		event.CLIReport,
		event.CLINotification,
		event.CLIExit,
		event.CLIAppUpdateAvailable,
	}, m.handler.RespondsTo()...)
}

func (m *UI) Update(msg tea.Msg) (tea.Model, tea.Cmd) {
	// note: we need a pointer receiver such that the same instance of UI used in Teardown is referenced (to keep finalize events)

	var cmds []tea.Cmd

	// allow for non-partybus UI updates (such as window size events). Note: these must not affect existing models,
	// that is the responsibility of the frame object on this UI object. The handler is a factory of models
	// which the frame is responsible for the lifecycle of. This update allows for injecting the initial state
	// of the world when creating those models.
	m.handler.OnMessage(msg)

	switch msg := msg.(type) {
	case tea.KeyMsg:
		switch msg.String() {
		case "esc", "ctrl+c":
			m.exit()
			return m, tea.Quit
		}

	case partybus.Event:
		log.WithFields("component", "ui").Tracef("event: %q", msg.Type)

		switch msg.Type {
		case event.CLIReport, event.CLINotification, event.CLIExit, event.CLIAppUpdateAvailable:
			// keep these for when the UI is terminated to show to the screen (or perform other events)
			m.finalizeEvents = append(m.finalizeEvents, msg)

			// why not return tea.Quit here for exit events? because there may be UI components that still need the update-render loop.
			// for this reason we'll let the syft event loop call Teardown() which will explicitly wait for these components
			return m, nil
		}

		for _, newModel := range m.handler.Handle(msg) {
			if newModel == nil {
				continue
			}
			cmds = append(cmds, newModel.Init())
			m.frame.(*frame.Frame).AppendModel(newModel)
		}
		// intentionally fallthrough to update the frame model
	}

	frameModel, cmd := m.frame.Update(msg)
	m.frame = frameModel
	cmds = append(cmds, cmd)

	return m, tea.Batch(cmds...)
}

func (m UI) View() string {
	return m.frame.View()
}