Add OnQuit hook for controllers

This allows the controller of the currently focused context to do some last
minute cleanup before quitting.

pkg/gui/context/base_context.go

@@ -21,6 +21,7 @@ type BaseContext struct {
 	onRenderToMainFn         func()
 	onFocusFns               []onFocusFn
 	onFocusLostFns           []onFocusLostFn
+	onQuitFns                []func()
 
 	focusable                   bool
 	transient                   bool
@@ -141,6 +142,7 @@ func (self *BaseContext) ClearAllAttachedControllerFunctions() {
 	self.mouseKeybindingsFns = nil
 	self.onFocusFns = nil
 	self.onFocusLostFns = nil
+	self.onQuitFns = nil
 	self.onDoubleClickFn = nil
 	self.onClickFn = nil
 	self.onClickFocusedMainViewFn = nil
@@ -207,6 +209,12 @@ func (self *BaseContext) AddOnFocusLostFn(fn onFocusLostFn) {
 	}
 }
 
+func (self *BaseContext) AddOnQuitFn(fn func()) {
+	if fn != nil {
+		self.onQuitFns = append(self.onQuitFns, fn)
+	}
+}
+
 func (self *BaseContext) GetMouseKeybindings(opts types.KeybindingsOpts) []*gocui.ViewMouseBinding {
 	bindings := []*gocui.ViewMouseBinding{}
 	for i := range self.mouseKeybindingsFns {

pkg/gui/context/simple_context.go

@@ -54,6 +54,12 @@ func (self *SimpleContext) HandleFocusLost(opts types.OnFocusLostOpts) {
 	}
 }
 
+func (self *SimpleContext) HandleQuit() {
+	for _, fn := range self.onQuitFns {
+		fn()
+	}
+}
+
 func (self *SimpleContext) FocusLine(scrollIntoView bool) {
 }
 

pkg/gui/controllers/attach.go

@@ -12,5 +12,6 @@ func AttachControllers(context types.Context, controllers ...types.IController)
 		context.AddOnRenderToMainFn(controller.GetOnRenderToMain())
 		context.AddOnFocusFn(controller.GetOnFocus())
 		context.AddOnFocusLostFn(controller.GetOnFocusLost())
+		context.AddOnQuitFn(controller.GetOnQuit())
 	}
 }

pkg/gui/controllers/base_controller.go

@@ -38,3 +38,7 @@ func (self *baseController) GetOnFocus() func(types.OnFocusOpts) {
 func (self *baseController) GetOnFocusLost() func(types.OnFocusLostOpts) {
 	return nil
 }
+
+func (self *baseController) GetOnQuit() func() {
+	return nil
+}

pkg/gui/gui.go

@@ -935,7 +935,12 @@ func (gui *Gui) Run(startArgs appTypes.StartArgs) error {
 	// setting here so we can use it in layout.go
 	gui.integrationTest = startArgs.IntegrationTest
 
-	return gui.g.MainLoop()
+	err = gui.g.MainLoop()
+	if errors.Is(err, gocui.ErrQuit) {
+		// Give the focused context a chance to clean up before we tear down the app.
+		gui.c.Context().Current().HandleQuit()
+	}
+	return err
 }
 
 func (gui *Gui) RunAndHandleError(startArgs appTypes.StartArgs) error {

pkg/gui/types/context.go

@@ -105,6 +105,7 @@ type IBaseContext interface {
 	AddOnRenderToMainFn(func())
 	AddOnFocusFn(func(OnFocusOpts))
 	AddOnFocusLostFn(func(OnFocusLostOpts))
+	AddOnQuitFn(func())
 }
 
 type Context interface {
@@ -112,6 +113,7 @@ type Context interface {
 
 	HandleFocus(opts OnFocusOpts)
 	HandleFocusLost(opts OnFocusLostOpts)
+	HandleQuit()
 	FocusLine(scrollIntoView bool)
 	HandleRender()
 	HandleRenderToMain()
@@ -273,6 +275,10 @@ type IController interface {
 	GetOnRenderToMain() func()
 	GetOnFocus() func(OnFocusOpts)
 	GetOnFocusLost() func(OnFocusLostOpts)
+
+	// Implement this to get called when the app quits, and the controller's context has the focus.
+	// Useful for saving state on quit.
+	GetOnQuit() func()
 }
 
 type IList interface {