split UI from event handling

Signed-off-by: Alex Goodman <wagoodman@gmail.com>

cmd/event_loop.go

@@ -0,0 +1,77 @@
+package cmd
+
+import (
+	"errors"
+	"os"
+
+	"github.com/anchore/syft/internal/log"
+	"github.com/anchore/syft/internal/ui"
+	"github.com/hashicorp/go-multierror"
+	"github.com/wagoodman/go-partybus"
+)
+
+// eventLoop listens to worker errors (from execution path), worker events (from a partybus subscription), and
+// signal interrupts. Is responsible for handling each event relative to a given UI an to coordinate eventing until
+// an eventual graceful exit.
+func eventLoop(workerErrs <-chan error, signals <-chan os.Signal, subscription *partybus.Subscription, ux ui.UI) error {
+	events := subscription.Events()
+	if err := setupUI(subscription.Unsubscribe, ux); err != nil {
+		return err
+	}
+
+	var retErr error
+
+	for {
+		if workerErrs == nil && events == nil {
+			break
+		}
+		select {
+		case err, isOpen := <-workerErrs:
+			if !isOpen {
+				workerErrs = nil
+				continue
+			}
+			if err != nil {
+				retErr = err
+			}
+		case e, isOpen := <-events:
+			if !isOpen {
+				events = nil
+				continue
+			}
+
+			if err := ux.Handle(e); err != nil {
+				if errors.Is(err, partybus.ErrUnsubscribe) {
+					log.Warnf("unable to unsubscribe from the event bus")
+					events = nil
+				} else {
+					retErr = multierror.Append(retErr, err)
+					// TODO: should we unsubscribe? should we try to halt execution? or continue?
+				}
+			}
+		case <-signals:
+			if err := subscription.Unsubscribe(); err != nil {
+				log.Warnf("unable to unsubscribe from the event bus: %+v", err)
+				events = nil
+			}
+		}
+	}
+
+	if err := ux.Teardown(); err != nil {
+		retErr = multierror.Append(retErr, err)
+	}
+
+	return retErr
+}
+
+func setupUI(unsubscribe func() error, ux ui.UI) error {
+	if err := ux.Setup(unsubscribe); err != nil {
+		ux = ui.NewLoggerUI()
+		if err := ux.Setup(unsubscribe); err != nil {
+			// something is very wrong, bail.
+			return err
+		}
+		log.Errorf("unable to setup given UI, falling back to logger: %+v", err)
+	}
+	return nil
+}

cmd/packages.go

@@ -186,9 +186,12 @@ func bindPackagesConfigOptions(flags *pflag.FlagSet) error {
 }
 
 func packagesExec(_ *cobra.Command, args []string) error {
-	errs := packagesExecWorker(args[0])
-	ux := ui.Select(appConfig.CliOptions.Verbosity > 0, appConfig.Quiet)
-	return ux(errs, eventSubscription)
+	return eventLoop(
+		packagesExecWorker(args[0]),
+		setupSignals(),
+		eventSubscription,
+		ui.Select(appConfig.CliOptions.Verbosity > 0, appConfig.Quiet),
+	)
 }
 
 func packagesExecWorker(userInput string) <-chan error {

cmd/power_user.go

@@ -63,9 +63,12 @@ func init() {
 }
 
 func powerUserExec(_ *cobra.Command, args []string) error {
-	errs := powerUserExecWorker(args[0])
-	ux := ui.Select(appConfig.CliOptions.Verbosity > 0, appConfig.Quiet)
-	return ux(errs, eventSubscription)
+	return eventLoop(
+		powerUserExecWorker(args[0]),
+		setupSignals(),
+		eventSubscription,
+		ui.Select(appConfig.CliOptions.Verbosity > 0, appConfig.Quiet),
+	)
 }
 
 func powerUserExecWorker(userInput string) <-chan error {

cmd/signals.go

@@ -0,0 +1,20 @@
+package cmd
+
+import (
+	"os"
+	"os/signal"
+	"syscall"
+)
+
+func setupSignals() <-chan os.Signal {
+	c := make(chan os.Signal, 1) // Note: A buffered channel is recommended for this; see https://golang.org/pkg/os/signal/#Notify
+
+	interruptions := []os.Signal{
+		syscall.SIGINT,
+		syscall.SIGTERM,
+	}
+
+	signal.Notify(c, interruptions...)
+
+	return c
+}

go.mod

@@ -21,6 +21,7 @@ require (
 	github.com/gookit/color v1.2.7
 	github.com/hashicorp/go-multierror v1.1.0
 	github.com/hashicorp/go-version v1.2.0
+	github.com/k0kubun/go-ansi v0.0.0-20180517002512-3bf9e2903213
 	github.com/mitchellh/go-homedir v1.1.0
 	github.com/mitchellh/mapstructure v1.3.1
 	github.com/olekukonko/tablewriter v0.0.4
@@ -36,7 +37,7 @@ require (
 	github.com/spf13/pflag v1.0.5
 	github.com/spf13/viper v1.7.0
 	github.com/stretchr/testify v1.6.0
-	github.com/wagoodman/go-partybus v0.0.0-20200526224238-eb215533f07d
+	github.com/wagoodman/go-partybus v0.0.0-20210627031916-db1f5573bbc5
 	github.com/wagoodman/go-progress v0.0.0-20200731105512-1020f39e6240
 	github.com/wagoodman/jotframe v0.0.0-20200730190914-3517092dd163
 	github.com/x-cray/logrus-prefixed-formatter v0.5.2

go.sum

@@ -466,6 +466,7 @@ github.com/jstemmer/go-junit-report v0.9.1/go.mod h1:Brl9GWCQeLvo8nXZwPNNblvFj/X
 github.com/jtolds/gls v4.20.0+incompatible h1:xdiiI2gbIgH/gLH7ADydsJ1uDOEzR8yvV7C0MuV77Wo=
 github.com/jtolds/gls v4.20.0+incompatible/go.mod h1:QJZ7F/aHp+rZTRtaJ1ow/lLfFfVYBRgL+9YlvaHOwJU=
 github.com/julienschmidt/httprouter v1.2.0/go.mod h1:SYymIcj16QtmaHHD7aYtjjsJG7VTCxuUUipMqKk8s4w=
+github.com/k0kubun/go-ansi v0.0.0-20180517002512-3bf9e2903213 h1:qGQQKEcAR99REcMpsXCp3lJ03zYT1PkRd3kQGPn9GVg=
 github.com/k0kubun/go-ansi v0.0.0-20180517002512-3bf9e2903213/go.mod h1:vNUNkEQ1e29fT/6vq2aBdFsgNPmy8qMdSay1npru+Sw=
 github.com/kisielk/errcheck v1.1.0/go.mod h1:EZBBE59ingxPouuu3KfxchcWSUPOHkagtvWXihfKN4Q=
 github.com/kisielk/errcheck v1.2.0/go.mod h1:/BMXB+zMLi60iA8Vv6Ksmxu/1UDYcXs4uQLJ+jE2L00=
@@ -744,8 +745,9 @@ github.com/valyala/quicktemplate v1.2.0/go.mod h1:EH+4AkTd43SvgIbQHYu59/cJyxDoOV
 github.com/valyala/tcplisten v0.0.0-20161114210144-ceec8f93295a/go.mod h1:v3UYOV9WzVtRmSR+PDvWpU/qWl4Wa5LApYYX4ZtKbio=
 github.com/vdemeester/k8s-pkg-credentialprovider v1.17.4/go.mod h1:inCTmtUdr5KJbreVojo06krnTgaeAz/Z7lynpPk/Q2c=
 github.com/vmware/govmomi v0.20.3/go.mod h1:URlwyTFZX72RmxtxuaFL2Uj3fD1JTvZdx59bHWk6aFU=
-github.com/wagoodman/go-partybus v0.0.0-20200526224238-eb215533f07d h1:KOxOL6qpmqwoPloNwi+CEgc1ayjHNOFNrvoOmeDOjDg=
 github.com/wagoodman/go-partybus v0.0.0-20200526224238-eb215533f07d/go.mod h1:JPirS5jde/CF5qIjcK4WX+eQmKXdPc6vcZkJ/P0hfPw=
+github.com/wagoodman/go-partybus v0.0.0-20210627031916-db1f5573bbc5 h1:phTLPgMRDYTizrBSKsNSOa2zthoC2KsJsaY/8sg3rD8=
+github.com/wagoodman/go-partybus v0.0.0-20210627031916-db1f5573bbc5/go.mod h1:JPirS5jde/CF5qIjcK4WX+eQmKXdPc6vcZkJ/P0hfPw=
 github.com/wagoodman/go-progress v0.0.0-20200621122631-1a2120f0695a/go.mod h1:jLXFoL31zFaHKAAyZUh+sxiTDFe1L1ZHrcK2T1itVKA=
 github.com/wagoodman/go-progress v0.0.0-20200731105512-1020f39e6240 h1:r6BlIP7CVZtMlxUQhT40h1IE1TzEgKVqwmsVGuscvdk=
 github.com/wagoodman/go-progress v0.0.0-20200731105512-1020f39e6240/go.mod h1:jLXFoL31zFaHKAAyZUh+sxiTDFe1L1ZHrcK2T1itVKA=

internal/ui/common/event_handlers.go

@@ -1,8 +1,15 @@
 package common
 
 import (
+	"context"
 	"fmt"
+	"io"
 	"os"
+	"sync"
+
+	"github.com/anchore/syft/internal"
+	"github.com/gookit/color"
+	"github.com/wagoodman/jotframe/pkg/frame"
 
 	syftEventParsers "github.com/anchore/syft/syft/event/parsers"
 	"github.com/wagoodman/go-partybus"
@@ -22,3 +29,21 @@ func CatalogerPresenterReady(event partybus.Event) error {
 	}
 	return nil
 }
+
+// appUpdateAvailableHandler is a UI handler function to display a new application version to the top of the screen.
+func AppUpdateAvailableHandler(_ context.Context, fr *frame.Frame, event partybus.Event, _ *sync.WaitGroup) error {
+	newVersion, err := syftEventParsers.ParseAppUpdateAvailable(event)
+	if err != nil {
+		return fmt.Errorf("bad AppUpdateAvailable event: %w", err)
+	}
+
+	line, err := fr.Prepend()
+	if err != nil {
+		return err
+	}
+
+	message := color.Magenta.Sprintf("New version of %s is available: %s", internal.ApplicationName, newVersion)
+	_, _ = io.WriteString(line, message)
+
+	return nil
+}

internal/ui/common/spinner.go

@@ -8,33 +8,9 @@ import (
 // TODO: move me to a common module (used in multiple repos)
 
 const (
-	SpinnerCircleOutlineSet = "◜◠◯◎◉●◉◎◯◡◞"
-	SpinnerCircleSet        = "◌◯◎◉●◉◎◯"
 	SpinnerDotSet = "⠋⠙⠹⠸⠼⠴⠦⠧⠇⠏"
-	SpinnerHorizontalBarSet = "▉▊▋▌▍▎▏▎▍▌▋▊▉"
-	SpinnerVerticalBarSet   = "▁▃▄▅▆▇█▇▆▅▄▃▁"
-	SpinnerDoubleBarSet     = "▁▂▃▄▅▆▇█▉▊▋▌▍▎▏▏▎▍▌▋▊▉█▇▆▅▄▃▂▁"
-	SpinnerArrowSet         = "←↖↑↗→↘↓↙"
 )
 
-var SpinnerCircleDotSet = []string{
-	"⠈⠁",
-	"⠈⠑",
-	"⠈⠱",
-	"⠈⡱",
-	"⢀⡱",
-	"⢄⡱",
-	"⢄⡱",
-	"⢆⡱",
-	"⢎⡱",
-	"⢎⡰",
-	"⢎⡠",
-	"⢎⡀",
-	"⢎⠁",
-	"⠎⠁",
-	"⠊⠁",
-}
-
 type Spinner struct {
 	index   int
 	charset []string
@@ -47,12 +23,6 @@ func NewSpinner(charset string) Spinner {
 	}
 }
 
-func NewSpinnerFromSlice(charset []string) Spinner {
-	return Spinner{
-		charset: charset,
-	}
-}
-
 func (s *Spinner) Current() string {
 	s.lock.Lock()
 	defer s.lock.Unlock()

internal/ui/ephemeral_terminal_ui.go

@@ -0,0 +1,138 @@
+package ui
+
+import (
+	"bytes"
+	"context"
+	"fmt"
+	"os"
+	"sync"
+
+	"github.com/anchore/syft/internal/log"
+	"github.com/anchore/syft/internal/logger"
+	"github.com/anchore/syft/internal/ui/common"
+	syftEvent "github.com/anchore/syft/syft/event"
+	"github.com/anchore/syft/ui"
+	"github.com/k0kubun/go-ansi"
+	"github.com/wagoodman/go-partybus"
+	"github.com/wagoodman/jotframe/pkg/frame"
+)
+
+// ephemeralTerminalUI provides an "ephemeral" terminal user interface to display the application state dynamically.
+// The terminal is placed into raw mode and the cursor is manipulated to allow for a dynamic, multi-line
+// UI (provided by the jotframe lib), for this reason all other application mechanisms that write to the screen
+// must be suppressed before starting (such as logs); since bytes in the device and in application memory combine to make
+// a shared state, bytes coming from elsewhere to the screen will disrupt this state.
+//
+// This UI is primarily driven off of events from the event bus, creating single-line terminal widgets to represent a
+// published element on the event bus, typically polling the element for the latest state. This allows for the UI to
+// control update frequency to the screen, provide "liveness" indications that are interpolated between bus events,
+// and overall loosely couple the bus events from screen interactions.
+//
+// By convention, all elements published on the bus should be treated as read-only, and publishers on the bus should
+// attempt to enforce this when possible by wrapping complex objects with interfaces to prescribe interactions. Also by
+// convention, each new event that the UI should respond to should be added either in this package as a handler function,
+// or in the shared ui package as a function on the main handler object. All handler functions should be completed
+// processing an event before the ETUI exits (coordinated with a sync.WaitGroup)
+type ephemeralTerminalUI struct {
+	unsubscribe func() error
+	handler     *ui.Handler
+	waitGroup   *sync.WaitGroup
+	frame       *frame.Frame
+	logBuffer   *bytes.Buffer
+}
+
+func NewEphemeralTerminalUI() UI {
+	return &ephemeralTerminalUI{
+		handler:   ui.NewHandler(),
+		waitGroup: &sync.WaitGroup{},
+	}
+}
+
+func (h *ephemeralTerminalUI) Setup(unsubscribe func() error) error {
+	h.unsubscribe = unsubscribe
+	ansi.CursorHide()
+
+	// prep the logger to not clobber the screen from now on (logrus only)
+	h.logBuffer = bytes.NewBufferString("")
+	logWrapper, ok := log.Log.(*logger.LogrusLogger)
+	if ok {
+		logWrapper.Logger.SetOutput(h.logBuffer)
+	}
+
+	return h.openScreen()
+}
+
+func (h *ephemeralTerminalUI) Handle(event partybus.Event) error {
+	ctx := context.Background()
+	switch {
+	case h.handler.RespondsTo(event):
+		if err := h.handler.Handle(ctx, h.frame, event, h.waitGroup); err != nil {
+			log.Errorf("unable to show %s event: %+v", event.Type, err)
+		}
+
+	case event.Type == syftEvent.AppUpdateAvailable:
+		if err := common.AppUpdateAvailableHandler(ctx, h.frame, event, h.waitGroup); err != nil {
+			log.Errorf("unable to show %s event: %+v", event.Type, err)
+		}
+
+	case event.Type == syftEvent.PresenterReady:
+		// we need to close the screen now since signaling the the presenter is ready means that we
+		// are about to write bytes to stdout, so we should reset the terminal state first
+		h.closeScreen()
+
+		if err := common.CatalogerPresenterReady(event); err != nil {
+			log.Errorf("unable to show %s event: %+v", event.Type, err)
+		}
+
+		// this is the last expected event, stop listening to events
+		return h.unsubscribe()
+	}
+	return nil
+}
+
+func (h *ephemeralTerminalUI) openScreen() error {
+	config := frame.Config{
+		PositionPolicy: frame.PolicyFloatForward,
+		// only report output to stderr, reserve report output for stdout
+		Output: os.Stderr,
+	}
+
+	fr, err := frame.New(config)
+	if err != nil {
+		return fmt.Errorf("failed to create the screen object: %w", err)
+	}
+	h.frame = fr
+
+	return nil
+}
+
+func (h *ephemeralTerminalUI) closeScreen() {
+	// we may have other background processes still displaying progress, wait for them to
+	// finish before discontinuing dynamic content and showing the final report
+	if !h.frame.IsClosed() {
+		h.waitGroup.Wait()
+		h.frame.Close()
+		// TODO: there is a race condition within frame.Close() that sometimes leads to an extra blank line being output
+		frame.Close()
+
+		// only flush the log on close
+		h.flushLog()
+	}
+}
+
+func (h *ephemeralTerminalUI) flushLog() {
+	// flush any errors to the screen before the report
+	logWrapper, ok := log.Log.(*logger.LogrusLogger)
+	if ok {
+		fmt.Fprint(logWrapper.Output, h.logBuffer.String())
+		logWrapper.Logger.SetOutput(os.Stderr)
+	} else {
+		fmt.Fprint(os.Stderr, h.logBuffer.String())
+	}
+}
+
+func (h *ephemeralTerminalUI) Teardown() error {
+	h.closeScreen()
+	ansi.CursorShow()
+	return nil
+}

internal/ui/etui/ephemeral_tui.go

@@ -1,180 +0,0 @@
-/*
-Package etui provides an "ephemeral" terminal user interface to display the application state dynamically.
-The terminal is placed into raw mode and the cursor is manipulated to allow for a dynamic, multi-line
-UI (provided by the jotframe lib), for this reason all other application mechanisms that write to the screen
-must be suppressed before starting (such as logs); since bytes in the device and in application memory combine to make
-a shared state, bytes coming from elsewhere to the screen will disrupt this state.
-
-This UI is primarily driven off of events from the event bus, creating single-line terminal widgets to represent a
-published element on the event bus, typically polling the element for the latest state. This allows for the UI to
-control update frequency to the screen, provide "liveness" indications that are interpolated between bus events,
-and overall loosely couple the bus events from screen interactions.
-
-By convention, all elements published on the bus should be treated as read-only, and publishers on the bus should
-attempt to enforce this when possible by wrapping complex objects with interfaces to prescribe interactions. Also by
-convention, each new event that the UI should respond to should be added either in this package as a handler function,
-or in the shared ui package as a function on the main handler object. All handler functions should be completed
-processing an event before the ETUI exits (coordinated with a sync.WaitGroup)
-*/
-package etui
-
-import (
-	"bytes"
-	"context"
-	"fmt"
-	"os"
-	"os/signal"
-	"sync"
-	"syscall"
-
-	"github.com/anchore/syft/internal/logger"
-
-	"github.com/anchore/syft/internal/ui/common"
-	"github.com/anchore/syft/ui"
-
-	"github.com/anchore/syft/internal/log"
-	syftEvent "github.com/anchore/syft/syft/event"
-	"github.com/wagoodman/go-partybus"
-	"github.com/wagoodman/jotframe/pkg/frame"
-)
-
-// TODO: specify per-platform implementations with build tags (needed when windows is supported by syft)
-
-// setupScreen creates a new jotframe object to manage specific screen lines dynamically, preparing the screen device
-// as needed (i.e. setting the terminal to raw mode).
-func setupScreen(output *os.File) *frame.Frame {
-	config := frame.Config{
-		PositionPolicy: frame.PolicyFloatForward,
-		// only report output to stderr, reserve report output for stdout
-		Output: output,
-	}
-
-	fr, err := frame.New(config)
-	if err != nil {
-		log.Errorf("failed to create screen object: %+v", err)
-		return nil
-	}
-	return fr
-}
-
-// nolint:funlen,gocognit
-// OutputToEphemeralTUI is a UI function that provides a terminal UI experience without a separate, in-application
-// screen buffer. All logging is suppressed, buffered to a string, and output after the ETUI has been torn down.
-func OutputToEphemeralTUI(workerErrs <-chan error, subscription *partybus.Subscription) error {
-	output := os.Stderr
-
-	// prep the logger to not clobber the screen from now on (logrus only)
-	logBuffer := bytes.NewBufferString("")
-	logWrapper, ok := log.Log.(*logger.LogrusLogger)
-	if ok {
-		logWrapper.Logger.SetOutput(logBuffer)
-	}
-
-	// hide cursor
-	_, _ = fmt.Fprint(output, "\x1b[?25l")
-	// show cursor
-	defer fmt.Fprint(output, "\x1b[?25h")
-
-	fr := setupScreen(output)
-	if fr == nil {
-		return fmt.Errorf("unable to setup screen")
-	}
-	var isClosed bool
-	defer func() {
-		if !isClosed {
-			fr.Close()
-			frame.Close()
-			// flush any errors to the screen before the report
-			logWrapper, ok := log.Log.(*logger.LogrusLogger)
-			if ok {
-				fmt.Fprint(logWrapper.Output, logBuffer.String())
-			} else {
-				fmt.Fprint(output, logBuffer.String())
-			}
-		}
-		logWrapper, ok := log.Log.(*logger.LogrusLogger)
-		if ok {
-			logWrapper.Logger.SetOutput(output)
-		}
-	}()
-
-	var err error
-	var wg = &sync.WaitGroup{}
-	events := subscription.Events()
-	ctx := context.Background()
-	syftUIHandler := ui.NewHandler()
-
-	signals := interruptingSignals()
-
-eventLoop:
-	for {
-		select {
-		case err := <-workerErrs:
-			// TODO: we should show errors more explicitly in the ETUI
-			if err != nil {
-				return err
-			}
-		case e, ok := <-events:
-			if !ok {
-				break eventLoop
-			}
-			switch {
-			case syftUIHandler.RespondsTo(e):
-				if err = syftUIHandler.Handle(ctx, fr, e, wg); err != nil {
-					log.Errorf("unable to show %s event: %+v", e.Type, err)
-				}
-
-			case e.Type == syftEvent.AppUpdateAvailable:
-				if err = appUpdateAvailableHandler(ctx, fr, e, wg); err != nil {
-					log.Errorf("unable to show %s event: %+v", e.Type, err)
-				}
-
-			case e.Type == syftEvent.PresenterReady:
-				// we may have other background processes still displaying progress, wait for them to
-				// finish before discontinuing dynamic content and showing the final report
-				wg.Wait()
-				fr.Close()
-				// TODO: there is a race condition within frame.Close() that sometimes leads to an extra blank line being output
-				frame.Close()
-				isClosed = true
-
-				// flush any errors to the screen before the report
-				logWrapper, ok := log.Log.(*logger.LogrusLogger)
-				if ok {
-					fmt.Fprint(logWrapper.Output, logBuffer.String())
-				} else {
-					fmt.Fprint(output, logBuffer.String())
-				}
-
-				if err := common.CatalogerPresenterReady(e); err != nil {
-					log.Errorf("unable to show %s event: %+v", e.Type, err)
-				}
-
-				// this is the last expected event
-				break eventLoop
-			}
-		case <-ctx.Done():
-			if ctx.Err() != nil {
-				log.Errorf("cancelled (%+v)", err)
-			}
-			break eventLoop
-		case <-signals:
-			break eventLoop
-		}
-	}
-
-	return nil
-}
-
-func interruptingSignals() chan os.Signal {
-	c := make(chan os.Signal, 1) // Note: A buffered channel is recommended for this; see https://golang.org/pkg/os/signal/#Notify
-
-	interruptions := []os.Signal{
-		syscall.SIGINT,
-		syscall.SIGTERM,
-	}
-
-	signal.Notify(c, interruptions...)
-
-	return c
-}

internal/ui/etui/internal_event_handlers.go

@@ -1,32 +0,0 @@
-package etui
-
-import (
-	"context"
-	"fmt"
-	"io"
-	"sync"
-
-	"github.com/anchore/syft/internal"
-	syftEventParsers "github.com/anchore/syft/syft/event/parsers"
-	"github.com/gookit/color"
-	"github.com/wagoodman/go-partybus"
-	"github.com/wagoodman/jotframe/pkg/frame"
-)
-
-// appUpdateAvailableHandler is a UI handler function to display a new application version to the top of the screen.
-func appUpdateAvailableHandler(_ context.Context, fr *frame.Frame, event partybus.Event, _ *sync.WaitGroup) error {
-	newVersion, err := syftEventParsers.ParseAppUpdateAvailable(event)
-	if err != nil {
-		return fmt.Errorf("bad AppUpdateAvailable event: %w", err)
-	}
-
-	line, err := fr.Prepend()
-	if err != nil {
-		return err
-	}
-
-	message := color.Magenta.Sprintf("New version of %s is available: %s", internal.ApplicationName, newVersion)
-	_, _ = io.WriteString(line, message)
-
-	return nil
-}

internal/ui/logger_output.go

@@ -1,40 +0,0 @@
-package ui
-
-import (
-	"github.com/anchore/syft/internal/log"
-	"github.com/anchore/syft/internal/ui/common"
-	syftEvent "github.com/anchore/syft/syft/event"
-	"github.com/wagoodman/go-partybus"
-)
-
-// LoggerUI is a UI function that leverages the displays all application logs to the screen.
-func LoggerUI(workerErrs <-chan error, subscription *partybus.Subscription) error {
-	events := subscription.Events()
-eventLoop:
-	for {
-		select {
-		case err := <-workerErrs:
-			if err != nil {
-				return err
-			}
-		case e, ok := <-events:
-			if !ok {
-				// event bus closed...
-				break eventLoop
-			}
-
-			// ignore all events except for the final event
-			if e.Type == syftEvent.PresenterReady {
-				err := common.CatalogerPresenterReady(e)
-				if err != nil {
-					log.Errorf("unable to show catalog image finished event: %+v", err)
-				}
-
-				// this is the last expected event
-				break eventLoop
-			}
-		}
-	}
-
-	return nil
-}

internal/ui/logger_ui.go

@@ -0,0 +1,40 @@
+package ui
+
+import (
+	"github.com/anchore/syft/internal/log"
+	"github.com/anchore/syft/internal/ui/common"
+	syftEvent "github.com/anchore/syft/syft/event"
+	"github.com/wagoodman/go-partybus"
+)
+
+type loggerUI struct {
+	unsubscribe func() error
+}
+
+func NewLoggerUI() UI {
+	return &loggerUI{}
+}
+
+func (l *loggerUI) Setup(unsubscribe func() error) error {
+	l.unsubscribe = unsubscribe
+	return nil
+}
+
+func (l loggerUI) Handle(event partybus.Event) error {
+	// ignore all events except for the final event
+	if event.Type != syftEvent.PresenterReady {
+		return nil
+	}
+
+	err := common.CatalogerPresenterReady(event)
+	if err != nil {
+		log.Errorf("unable to show catalog image finished event: %+v", err)
+	}
+
+	// this is the last expected event, stop listening to events
+	return l.unsubscribe()
+}
+
+func (l loggerUI) Teardown() error {
+	return nil
+}

internal/ui/select.go

@@ -4,7 +4,6 @@ import (
 	"os"
 	"runtime"
 
-	"github.com/anchore/syft/internal/ui/etui"
 	"golang.org/x/crypto/ssh/terminal"
 )
 
@@ -21,9 +20,9 @@ func Select(verbose, quiet bool) UI {
 
 	switch {
 	case runtime.GOOS == "windows" || verbose || quiet || notATerminal || !isStderrATty:
-		ui = LoggerUI
+		ui = NewLoggerUI()
 	default:
-		ui = etui.OutputToEphemeralTUI
+		ui = NewEphemeralTerminalUI()
 	}
 
 	return ui

internal/ui/ui.go

@@ -4,6 +4,8 @@ import (
 	"github.com/wagoodman/go-partybus"
 )
 
-// UI is a function that takes a channel of errors from the main() worker and a event bus subscription and is
-// responsible for displaying pertinent events to the user, on the screen or otherwise.
-type UI func(<-chan error, *partybus.Subscription) error
+type UI interface {
+	Setup(unsubscribe func() error) error
+	partybus.Handler
+	Teardown() error
+}

syft/source/source.go

@@ -49,9 +49,7 @@ func New(userInput string, registryOptions *image.RegistryOptions) (Source, func
 
 	case ImageScheme:
 		img, err := stereoscope.GetImageFromSource(location, imageSource, registryOptions)
-		cleanup := func() {
-			stereoscope.Cleanup()
-		}
+		cleanup := stereoscope.Cleanup
 
 		if err != nil || img == nil {
 			return Source{}, cleanup, fmt.Errorf("could not fetch image '%s': %w", location, err)

ui/event_handlers.go

@@ -8,11 +8,12 @@ import (
 	"sync"
 	"time"
 
+	"github.com/anchore/syft/internal/ui/common"
+
 	"github.com/anchore/stereoscope/pkg/image/docker"
 	"github.com/dustin/go-humanize"
 
 	stereoEventParsers "github.com/anchore/stereoscope/pkg/event/parsers"
-	"github.com/anchore/syft/internal/ui/common"
 	syftEventParsers "github.com/anchore/syft/syft/event/parsers"
 	"github.com/gookit/color"
 	"github.com/wagoodman/go-partybus"