From 28e8b7966825d057d9b8c3e3d297cedb47945321 Mon Sep 17 00:00:00 2001
From: Romuald R <dafunix@gmail.com>
Date: Sat, 30 Nov 2019 18:34:23 +0100
Subject: [PATCH] [feat] Windows support for submenus

---
 systray.go         | 37 ++++++++++++++++++++++++++++++++++---
 systray_windows.go | 46 +++++++++++++++++++++++++++++++++++++++++-----
 2 files changed, 75 insertions(+), 8 deletions(-)

diff --git a/systray.go b/systray.go
index 750e5f3..7b4aea6 100644
--- a/systray.go
+++ b/systray.go
@@ -8,6 +8,7 @@ at the very beginning of main() to lock at main thread.
 package systray
 
 import (
+	"fmt"
 	"runtime"
 	"sync"
 	"sync/atomic"
@@ -36,6 +37,28 @@ type MenuItem struct {
 	disabled bool
 	// checked menu item has a tick before the title
 	checked bool
+	// parent item, for sub menus
+	parent *MenuItem
+}
+
+func (item *MenuItem) String() string {
+	if item.parent == nil {
+		return fmt.Sprintf("MenuItem[%d, %q]", item.id, item.title)
+	}
+	return fmt.Sprintf("MenuItem[%d, parent %d, %q]", item.id, item.parent.id, item.title)
+}
+
+// newMenuItem returns a populated MenuItem object
+func newMenuItem(title string, tooltip string, parent *MenuItem) *MenuItem {
+	return &MenuItem{
+		ClickedCh: 		make(chan struct{}),
+		id:        		atomic.AddInt32(&currentID, 1),
+		title:     		title,
+		tooltip:   		tooltip,
+		disabled:  		false,
+		checked:   		false,
+		parent:    		parent,
+	}
 }
 
 var (
@@ -97,9 +120,7 @@ func Quit() {
 //
 // It can be safely invoked from different goroutines.
 func AddMenuItem(title string, tooltip string) *MenuItem {
-	id := atomic.AddInt32(&currentID, 1)
-	item := &MenuItem{nil, id, title, tooltip, false, false}
-	item.ClickedCh = make(chan struct{})
+	item := newMenuItem(title, tooltip, nil)
 	item.update()
 	return item
 }
@@ -109,6 +130,16 @@ func AddSeparator() {
 	addSeparator(atomic.AddInt32(&currentID, 1))
 }
 
+// AddSubMenuItem adds nested sub-menu item with designated title and tooltip, returning a channel
+// that notifies whenever that menu item is clicked.
+//
+// It can be safely invoked from different goroutines.
+func (item *MenuItem) AddSubMenuItem(title string, tooltip string) *MenuItem {
+	child := newMenuItem(title, tooltip, item)
+	child.update()
+	return child
+}
+
 // SetTitle set the text to display on a menu item
 func (item *MenuItem) SetTitle(title string) {
 	item.title = title
diff --git a/systray_windows.go b/systray_windows.go
index 11893b1..04be6f1 100644
--- a/systray_windows.go
+++ b/systray_windows.go
@@ -18,6 +18,7 @@ var (
 	notifyIcon *walk.NotifyIcon
 
 	actions      = make(map[int32]*walk.Action)
+	menus        = make(map[int32]*walk.Menu)
 	nextActionId int32
 
 	okayToClose int32
@@ -119,11 +120,39 @@ func ShowAppWindow(url string) {
 	mainWindow.SetVisible(true)
 }
 
-func addOrUpdateMenuItem(item *MenuItem) {
+func getOrCreateMenu(item *MenuItem) *walk.Menu {
+	if item == nil {
+		return notifyIcon.ContextMenu()
+	}
+	menu := menus[item.id]
+	if menu != nil {
+		return menu
+	}
+	menu, err := walk.NewMenu()
+	if err != nil {
+		fail("Unable to create new menu", err)
+	}
+	menus[item.id] = menu
+	action := actions[item.id]
+	// If we already have an action in array, it means an action is already created (as a simple action)
+	// Get parent menu to remove it and create a menu entry instead
+	if action != nil {
+		parent := getOrCreateMenu(item.parent)
+		parent.Actions().Remove(action)
+		actions[item.id] = nil
+		updateAction(item, getOrCreateAction(item, menu))
+	}
+	return menu
+}
+
+func getOrCreateAction(item *MenuItem, menu *walk.Menu) *walk.Action {
 	action := actions[item.id]
 	if action == nil {
-		item.id = nextActionId
-		action = walk.NewAction()
+		if menu != nil {
+			action = walk.NewMenuAction(menu)
+		} else {
+			action = walk.NewAction()
+		}
 		action.Triggered().Attach(func() {
 			select {
 			case item.ClickedCh <- struct{}{}:
@@ -132,12 +161,15 @@ func addOrUpdateMenuItem(item *MenuItem) {
 				// no listener, ignore
 			}
 		})
-		if err := notifyIcon.ContextMenu().Actions().Add(action); err != nil {
+		if err := getOrCreateMenu(item.parent).Actions().Add(action); err != nil {
 			fail("Unable to add menu item to systray", err)
 		}
 		actions[item.id] = action
-		atomic.AddInt32(&nextActionId, 1)
 	}
+	return action
+}
+
+func updateAction(item *MenuItem, action *walk.Action) {
 	err := action.SetText(item.title)
 	if err != nil {
 		fail("Unable to set menu item text", err)
@@ -152,6 +184,10 @@ func addOrUpdateMenuItem(item *MenuItem) {
 	}
 }
 
+func addOrUpdateMenuItem(item *MenuItem) {
+	updateAction(item, getOrCreateAction(item, nil))
+}
+
 func (item *MenuItem) SetIcon(iconBytes []byte) {
 	filename := fmt.Sprintf("systray.%d.ico", item.id)
 	err := ioutil.WriteFile(filename, iconBytes, 0644)