From 6fa78218d251e83a6f69ea5106eaeec7bb68559e Mon Sep 17 00:00:00 2001
From: mbalfour <mbalfour@amazon.com>
Date: Fri, 21 May 2021 17:32:55 -0500
Subject: [PATCH] [LYN-3548] Change IMGUI to use list of levels with prefab
 LoadLevel instead of text box

There was an intermittent crash related to garbage in the level name box with prefabs, possibly due to levelName being uninitialized.  This change improves the UX by listing out all the possible choices, instead of making people type it in.
---
 .../Source/LYCommonMenu/ImGuiLYCommonMenu.cpp | 42 ++++++++++++++-----
 1 file changed, 32 insertions(+), 10 deletions(-)

diff --git a/Gems/ImGui/Code/Source/LYCommonMenu/ImGuiLYCommonMenu.cpp b/Gems/ImGui/Code/Source/LYCommonMenu/ImGuiLYCommonMenu.cpp
index 8e3e2663d5..5107a02835 100644
--- a/Gems/ImGui/Code/Source/LYCommonMenu/ImGuiLYCommonMenu.cpp
+++ b/Gems/ImGui/Code/Source/LYCommonMenu/ImGuiLYCommonMenu.cpp
@@ -15,6 +15,7 @@
 
 #ifdef IMGUI_ENABLED
 #include <AzCore/std/string/conversions.h>
+#include <AzCore/std/sort.h>
 #include <AzFramework/Input/Buses/Requests/InputSystemCursorRequestBus.h>
 #include <AzFramework/Input/Devices/Mouse/InputDeviceMouse.h>
 #include <ILevelSystem.h>
@@ -251,15 +252,37 @@ namespace ImGui
 
                     if (usePrefabSystemForLevels)
                     {
-                        char levelName[256];
+                        // Run through all the assets in the asset catalog and gather up the list of level assets
+
+                        AZ::Data::AssetType levelAssetType = lvlSystem->GetLevelAssetType();
+                        AZStd::vector<AZStd::string> levelNames;
+                        auto enumerateCB =
+                            [levelAssetType, &levelNames]([[maybe_unused]] const AZ::Data::AssetId id, const AZ::Data::AssetInfo& assetInfo)
+                        {
+                            if (assetInfo.m_assetType == levelAssetType)
+                            {
+                                levelNames.emplace_back(assetInfo.m_relativePath);
+                            }
+                        };
+
+                        AZ::Data::AssetCatalogRequestBus::Broadcast(
+                            &AZ::Data::AssetCatalogRequestBus::Events::EnumerateAssets, nullptr, enumerateCB, nullptr);
+
+                        AZStd::sort(levelNames.begin(), levelNames.end());
+
+                        // Create a menu item for each level asset, with an action to load it if selected.
+
                         ImGui::TextColored(ImGui::Colors::s_PlainLabelColor, "Load Level: ");
-                        bool result = ImGui::InputText("", levelName, sizeof(levelName), ImGuiInputTextFlags_EnterReturnsTrue);
-                        if (result)
+                        for (int i = 0; i < levelNames.size(); i++)
                         {
-                            AZ_TracePrintf("Imgui", "Attempting to load level '%s'\n", levelName);
-                            AZ::TickBus::QueueFunction([lvlSystem, levelName]() {
-                                lvlSystem->LoadLevel(levelName);
-                            });
+                            if (ImGui::MenuItem(AZStd::string::format("%d- %s", i, levelNames[i].c_str()).c_str()))
+                            {
+                                AZ::TickBus::QueueFunction(
+                                    [lvlSystem, levelNames, i]()
+                                    {
+                                        lvlSystem->LoadLevel(levelNames[i].c_str());
+                                    });
+                            }
                         }
                     }
                     else
@@ -269,9 +292,8 @@ namespace ImGui
                         {
                             if (ImGui::MenuItem(AZStd::string::format("%d- %s", i, lvlSystem->GetLevelInfo(i)->GetName()).c_str()))
                             {
-                                AZStd::string mapCommandString = AZStd::string::format("map %s", lvlSystem->GetLevelInfo(i)->GetName());
-                                AZ::TickBus::QueueFunction([mapCommandString]() {
-                                    gEnv->pConsole->ExecuteString(mapCommandString.c_str());
+                                AZ::TickBus::QueueFunction([lvlSystem, i]() {
+                                    lvlSystem->LoadLevel(lvlSystem->GetLevelInfo(i)->GetName());
                                 });
                             }
                         }