refactor(launch system): Make shared.Run cancellable

Not sure if it works yet

launcher/viewMain.go

@@ -0,0 +1,67 @@
+package launcher
+
+import (
+	"sync"
+
+	"gioui.org/app"
+	"gioui.org/io/event"
+	"git.mstar.dev/mstar/timer/shared"
+	"github.com/rs/zerolog/log"
+)
+
+type LauncherState struct {
+	possibleTargets     map[string]func() shared.WindowState
+	possibleTargetsLock sync.RWMutex
+	activeWindows       map[string]bool
+	activeWindowsLock   sync.RWMutex
+	initialSetupDone    bool
+	initialSetupLock    sync.RWMutex
+}
+
+func (s *LauncherState) Run(globalState *shared.GlobalState, event event.Event) shared.NewState {
+	if !s.initialSetupDone {
+		s.initialSetup(globalState)
+	}
+	switch event := event.(type) {
+	case app.FrameEvent:
+		return s.handleFrameEvent(globalState, &event)
+	case app.DestroyEvent:
+		return s.handleQuitEvent()
+	case app.WaylandViewEvent, app.X11ViewEvent:
+		return shared.EmptyEvent()
+	default:
+		log.Debug().Any("event", event).Type("type", event).Msg("Unknown event")
+		return shared.NewState{}
+	}
+}
+
+func (s *LauncherState) Exit(globalState *shared.GlobalState, wg *sync.WaitGroup) {
+	wg.Done()
+}
+
+func (s *LauncherState) AddTarget(name string, builder func() shared.WindowState) {
+	s.possibleTargets[name] = builder
+}
+
+func (s *LauncherState) initialSetup(globalState *shared.GlobalState) {
+	s.activeWindowsLock.Lock()
+	defer s.activeWindowsLock.Unlock()
+	s.possibleTargetsLock.Lock()
+	defer s.possibleTargetsLock.Unlock()
+	s.initialSetupLock.Lock()
+	defer s.initialSetupLock.Unlock()
+	s.initialSetupDone = true
+	s.possibleTargets = map[string]func() shared.WindowState{}
+	s.activeWindows = map[string]bool{}
+}
+
+func (s *LauncherState) handleQuitEvent() shared.NewState {
+	return shared.NewState{ExitCode: shared.ErrExitOk}
+}
+
+func (s *LauncherState) handleFrameEvent(
+	globalState *shared.GlobalState,
+	frameEvent *app.FrameEvent,
+) shared.NewState {
+	return shared.NewState{}
+}

shared/window.go

@@ -1,9 +1,11 @@
 package shared
 
 import (
+	"context"
 	"sync"
 
 	"gioui.org/app"
+	"gioui.org/io/event"
 	"gioui.org/widget/material"
 	"github.com/rs/zerolog/log"
 )
@@ -14,7 +16,7 @@ type GlobalState struct {
 	state  WindowState
 }
 
-func Run(window *app.Window, initialState WindowState) error {
+func Run(ctx context.Context, window *app.Window, initialState WindowState) error {
 	// Set up global data first
 	state := GlobalState{}
 	theme := material.NewTheme()
@@ -26,21 +28,38 @@ func Run(window *app.Window, initialState WindowState) error {
 	// Then start showing the window and polling for events
 	// Though technically, I don't think window.Event will cause the window to display yet
 	// since what should it display? It doesn't have anything to display. So first display happens at event.Frame
-	for {
-		e := window.Event()
-		// Let the current view handle the event, then update accordingly
-		newState := state.state.Run(&state, e)
-		if newState.NextState != nil {
-			state.state = newState.NextState
+	eventChan := make(chan event.Event)
+	go func() {
+		for {
+			eventChan <- window.Event()
+			if ctx.Err() != nil {
+				return
+			}
 		}
-		if newState.ExitCode != nil {
-			log.Info().Msg("Received shutdown request")
-			wg := sync.WaitGroup{}
-			wg.Add(1)
-			go state.state.Exit(&state, &wg)
-			wg.Wait()
-			log.Info().Msg("Shutdown of window complete")
-			return nil
+	}()
+	for {
+		select {
+		case <-ctx.Done():
+			log.Info().Msg("Context cancelled, preparing shutdown")
+			// Force one update for polling goroutine to exit
+			state.Window.Invalidate()
+			// Then keep awaiting more events. Since quit is just another event
+			// and the event channel is unbuffered, at least one more event has to be read for the poller to exit
+		case e := <-eventChan:
+			// Let the current view handle the event, then update accordingly
+			newState := state.state.Run(&state, e)
+			if newState.NextState != nil {
+				state.state = newState.NextState
+			}
+			if newState.ExitCode != nil {
+				log.Info().Msg("Received shutdown request from window")
+				wg := sync.WaitGroup{}
+				wg.Add(1)
+				go state.state.Exit(&state, &wg)
+				wg.Wait()
+				log.Info().Msg("Shutdown of window complete")
+				return nil
+			}
 		}
 	}
 }