From 2d206708cd695bfaa54fd8d9b848967ccad10617 Mon Sep 17 00:00:00 2001
From: phosit <phosit@autistici.org>
Date: Wed, 12 Mar 2025 14:05:27 +0100
Subject: [PATCH] Start Atlas by closing the root page

Theere is now an  `Engine.startAtlas` property that will start Atlas
when it's returned from the root page. The `Engine.RestartInAtlas`
function is removed.
---
 .../data/mods/_test.gui/gui/Result/Result.js  |  4 ++
 .../data/mods/_test.gui/gui/Result/Result.xml |  4 ++
 .../mods/_test.gui/gui/Result/page_Result.xml |  4 ++
 .../mods/public/gui/pregame/MainMenuItems.js  |  4 +-
 source/gui/GUIManager.cpp                     | 37 ++++++++++++++++---
 source/gui/GUIManager.h                       |  6 ++-
 source/gui/tests/test_GuiManager.h            | 12 ++++++
 source/main.cpp                               | 11 ++----
 source/ps/scripting/JSInterface_Main.cpp      |  8 ----
 9 files changed, 64 insertions(+), 26 deletions(-)
 create mode 100644 binaries/data/mods/_test.gui/gui/Result/Result.js
 create mode 100644 binaries/data/mods/_test.gui/gui/Result/Result.xml
 create mode 100644 binaries/data/mods/_test.gui/gui/Result/page_Result.xml

diff --git a/binaries/data/mods/_test.gui/gui/Result/Result.js b/binaries/data/mods/_test.gui/gui/Result/Result.js
new file mode 100644
index 0000000000..6edd414e33
--- /dev/null
+++ b/binaries/data/mods/_test.gui/gui/Result/Result.js
@@ -0,0 +1,4 @@
+async function init(arg)
+{
+	return arg ? Engine.startAtlas : undefined;
+}
diff --git a/binaries/data/mods/_test.gui/gui/Result/Result.xml b/binaries/data/mods/_test.gui/gui/Result/Result.xml
new file mode 100644
index 0000000000..2a39d60b34
--- /dev/null
+++ b/binaries/data/mods/_test.gui/gui/Result/Result.xml
@@ -0,0 +1,4 @@
+<?xml version="1.0" encoding="utf-8"?>
+<objects>
+	<script file="gui/Result/Result.js"/>
+</objects>
diff --git a/binaries/data/mods/_test.gui/gui/Result/page_Result.xml b/binaries/data/mods/_test.gui/gui/Result/page_Result.xml
new file mode 100644
index 0000000000..f40f0fa1fd
--- /dev/null
+++ b/binaries/data/mods/_test.gui/gui/Result/page_Result.xml
@@ -0,0 +1,4 @@
+<?xml version="1.0" encoding="utf-8"?>
+<page>
+	<include>Result/Result.xml</include>
+</page>
diff --git a/binaries/data/mods/public/gui/pregame/MainMenuItems.js b/binaries/data/mods/public/gui/pregame/MainMenuItems.js
index d84217bdc0..943e216dde 100644
--- a/binaries/data/mods/public/gui/pregame/MainMenuItems.js
+++ b/binaries/data/mods/public/gui/pregame/MainMenuItems.js
@@ -275,7 +275,7 @@ var g_MainMenuItems = [
 	{
 		"caption": translate("Scenario Editor"),
 		"tooltip": translate('Open the Atlas Scenario Editor in a new window. You can run this more reliably by starting the game with the command-line argument "-editor".'),
-		"onPress": async() => {
+		"onPress": async(closePageCallback) => {
 			if (!Engine.AtlasIsAvailable())
 			{
 				messageBox(
@@ -292,7 +292,7 @@ var g_MainMenuItems = [
 				[translate("No"), translate("Yes")]);
 
 			if (buttonIndex === 1)
-				Engine.RestartInAtlas();
+				closePageCallback(Engine.startAtlas);
 		}
 	},
 	{
diff --git a/source/gui/GUIManager.cpp b/source/gui/GUIManager.cpp
index 3eb2a0fe39..d82c135919 100644
--- a/source/gui/GUIManager.cpp
+++ b/source/gui/GUIManager.cpp
@@ -35,11 +35,14 @@
 #include "scriptinterface/ScriptInterface.h"
 #include "scriptinterface/StructuredClone.h"
 
+#include "js/Equality.h"
+
 namespace
 {
 
 const CStr EVENT_NAME_GAME_LOAD_PROGRESS = "GameLoadProgress";
 const CStr EVENT_NAME_WINDOW_RESIZED = "WindowResized";
+constexpr const char* START_ATLAS{"startAtlas"};
 
 } // anonymous namespace
 
@@ -165,6 +168,12 @@ void CGUIManager::SGUIPage::LoadPage(ScriptContext& scriptContext)
 	sendingPromise = std::make_shared<JS::PersistentRootedObject>(rq.cx,
 		JS::NewPromiseObject(rq.cx, nullptr));
 
+	{
+		JS::RootedString jsName{rq.cx, JS_NewStringCopyZ(rq.cx, START_ATLAS)};
+		JS::RootedValue symbol{rq.cx, JS::SymbolValue(JS::NewSymbol(rq.cx, jsName))};
+		JS::RootedValue nativeScope{rq.cx, JS::ObjectValue(*rq.nativeScope)};
+		Script::SetProperty(rq, nativeScope, START_ATLAS, symbol, true);
+	}
 	gui->AddObjectTypes();
 
 	VfsPath path = VfsPath("gui") / m_Name;
@@ -257,7 +266,7 @@ JS::Value CGUIManager::SGUIPage::ReplacePromise(ScriptInterface& scriptInterface
 	return JS::ObjectValue(**receivingPromise);
 }
 
-std::optional<CGUIManager::SGUIPage::CloseResult> CGUIManager::SGUIPage::MaybeClose()
+std::optional<CGUIManager::SGUIPage::CloseResult> CGUIManager::SGUIPage::MaybeClose(const bool topmostPage)
 {
 	if (JS::GetPromiseState(*sendingPromise) == JS::PromiseState::Pending)
 		return std::nullopt;
@@ -267,8 +276,20 @@ std::optional<CGUIManager::SGUIPage::CloseResult> CGUIManager::SGUIPage::MaybeCl
 
 	const ScriptRequest rq{gui->GetScriptInterface()};
 	JS::RootedValue arg{rq.cx, JS::GetPromiseResult(*sendingPromise)};
-	return CGUIManager::SGUIPage::CloseResult{Script::WriteStructuredClone(rq, arg),
-		JS::GetPromiseState(*sendingPromise) == JS::PromiseState::Rejected};
+	const bool rejected{JS::GetPromiseState(*sendingPromise) == JS::PromiseState::Rejected};
+	if (topmostPage)
+	{
+		JS::RootedValue nativeScope{rq.cx, JS::ObjectValue(*rq.nativeScope)};
+		JS::RootedValue symbol{rq.cx};
+		Script::GetProperty(rq, nativeScope, START_ATLAS, &symbol);
+		bool equals;
+		if (!JS::StrictlyEqual(rq.cx, arg, symbol, &equals))
+			throw std::runtime_error{"Error while comparing return value to a symbol."};
+
+		if (equals)
+			return CGUIManager::SGUIPage::CloseResult{nullptr, rejected};
+	}
+	return CGUIManager::SGUIPage::CloseResult{Script::WriteStructuredClone(rq, arg), rejected};
 }
 
 void CGUIManager::SGUIPage::Refocus(const CloseResult& result)
@@ -375,7 +396,7 @@ void CGUIManager::SendEventToAll(const CStr& eventName, JS::HandleValueArray par
 		p.gui->SendEventToAll(eventName, paramData);
 }
 
-void CGUIManager::TickObjects()
+std::optional<bool> CGUIManager::TickObjects()
 {
 	PROFILE3("gui tick");
 
@@ -394,16 +415,20 @@ void CGUIManager::TickObjects()
 	while (!m_PageStack.empty())
 	{
 		const size_t stackSize{m_PageStack.size()};
-		const std::optional<SGUIPage::CloseResult> result{m_PageStack.back().MaybeClose()};
+		const std::optional<SGUIPage::CloseResult> result{
+			m_PageStack.back().MaybeClose(stackSize == 1)};
 		if (!result.has_value())
 			break;
 		ENSURE(m_PageStack.size() == stackSize);
 		m_PageStack.pop_back();
-		if (!m_PageStack.empty())
+		if (m_PageStack.empty())
+			return !result.value().arg;
+		else
 			m_PageStack.back().Refocus(result.value());
 
 		m_ScriptContext.RunJobs();
 	}
+	return std::nullopt;
 }
 
 void CGUIManager::Draw(CCanvas2D& canvas) const
diff --git a/source/gui/GUIManager.h b/source/gui/GUIManager.h
index 140b62a3c4..359a6239cb 100644
--- a/source/gui/GUIManager.h
+++ b/source/gui/GUIManager.h
@@ -96,8 +96,10 @@ public:
 
 	/**
 	 * See CGUI::TickObjects; applies to @em all loaded pages.
+	 * When the root page is closed it's returned wheter Atlas should be
+	 * started.
 	 */
-	void TickObjects();
+	std::optional<bool> TickObjects();
 
 	/**
 	 * See CGUI::Draw; applies to @em all loaded pages.
@@ -156,7 +158,7 @@ private:
 		 * returns the result of the @c init function.
 		 * If this page wasn't closed an empty optional is returned.
 		 */
-		std::optional<CloseResult> MaybeClose();
+		std::optional<CloseResult> MaybeClose(const bool topmostPage);
 
 		/**
 		 * This function should be called when a child page got closed. The
diff --git a/source/gui/tests/test_GuiManager.h b/source/gui/tests/test_GuiManager.h
index b46da35147..1f3fda722b 100644
--- a/source/gui/tests/test_GuiManager.h
+++ b/source/gui/tests/test_GuiManager.h
@@ -284,4 +284,16 @@ public:
 		CloseTopmostPage();
 		TS_ASSERT_EQUALS(g_GUI->GetPageCount(), 0);
 	}
+
+	void test_Result()
+	{
+		const ScriptRequest rq{g_GUI->GetScriptInterface()};
+		g_GUI->OpenChildPage(L"Result/page_Result.xml",
+			Script::WriteStructuredClone(rq, JS::FalseHandleValue));
+		TS_ASSERT(!g_GUI->TickObjects().value());
+
+		g_GUI->OpenChildPage(L"Result/page_Result.xml",
+			Script::WriteStructuredClone(rq, JS::TrueHandleValue));
+		TS_ASSERT(g_GUI->TickObjects().value());
+	}
 };
diff --git a/source/main.cpp b/source/main.cpp
index 0e242ebd1f..b10e51b606 100644
--- a/source/main.cpp
+++ b/source/main.cpp
@@ -172,11 +172,6 @@ void RestartEngine()
 	g_Shutdown = ShutdownType::Restart;
 }
 
-void StartAtlas()
-{
-	g_Shutdown = ShutdownType::RestartAsAtlas;
-}
-
 // main app message handler
 static InReaction MainInputHandler(const SDL_Event_* ev)
 {
@@ -430,9 +425,9 @@ static void Frame(RL::Interface* rlInterface)
 	if (g_NetClient)
 		g_NetClient->Poll();
 
-	g_GUI->TickObjects();
-	if (g_GUI->GetPageCount() == 0)
-		QuitEngine();
+	std::optional<bool> completionCommand{g_GUI->TickObjects()};
+	if (completionCommand.has_value())
+		g_Shutdown = completionCommand.value() ? ShutdownType::RestartAsAtlas : ShutdownType::Quit;
 
 	if (rlInterface)
 		rlInterface->TryApplyMessage();
diff --git a/source/ps/scripting/JSInterface_Main.cpp b/source/ps/scripting/JSInterface_Main.cpp
index 17e70748ac..13e6f85915 100644
--- a/source/ps/scripting/JSInterface_Main.cpp
+++ b/source/ps/scripting/JSInterface_Main.cpp
@@ -34,15 +34,8 @@
 #include "scriptinterface/FunctionWrapper.h"
 #include "tools/atlas/GameInterface/GameLoop.h"
 
-extern void StartAtlas();
-
 namespace JSI_Main
 {
-void StartAtlas()
-{
-	::StartAtlas();
-}
-
 bool AtlasIsAvailable()
 {
 	return ATLAS_IsAvailable();
@@ -120,7 +113,6 @@ std::string CalculateMD5(const std::string& input)
 
 void RegisterScriptFunctions(const ScriptRequest& rq)
 {
-	ScriptFunction::Register<&StartAtlas>(rq, "RestartInAtlas");
 	ScriptFunction::Register<&AtlasIsAvailable>(rq, "AtlasIsAvailable");
 	ScriptFunction::Register<&IsAtlasRunning>(rq, "IsAtlasRunning");
 	ScriptFunction::Register<&OpenURL>(rq, "OpenURL");