From 1930eb7cc2b82dbd88e4195fb3602b48fbd16a4d Mon Sep 17 00:00:00 2001
From: Nat Quayle Nelson <natquaylenelson@gmail.com>
Date: Tue, 3 Jun 2025 13:37:56 -0500
Subject: [PATCH] undo/redo for creating/deleting terrain types

---
 src/scenedit/scen.actions.cpp | 38 +++++++++++++++++++++++++++--------
 src/scenedit/scen.undo.cpp    | 16 +++++++++++++++
 src/scenedit/scen.undo.hpp    | 18 +++++++++++++++++
 3 files changed, 64 insertions(+), 8 deletions(-)

diff --git a/src/scenedit/scen.actions.cpp b/src/scenedit/scen.actions.cpp
index d716f005..c3bf1050 100644
--- a/src/scenedit/scen.actions.cpp
+++ b/src/scenedit/scen.actions.cpp
@@ -1301,23 +1301,45 @@ static bool handle_terpal_action(location cur_point, bool option_hit) {
 					return true;
 				}
 				if(option_hit) {
-					if(i == size_before - 1 && !scenario.is_ter_used(i))
-						scenario.ter_types.pop_back();
-					else if(i == size_before) {
+					// option-click the plus button: create a new row of terrains
+					if(i == size_before){
+						terrain_type_changes_t terrains;
 						scenario.ter_types.resize(size_before + 16);
-						for(; i < scenario.ter_types.size(); i++)
+						for(; i < scenario.ter_types.size(); i++){
 							scenario.ter_types[i].name = "New Terrain";
-					} else {
-						scenario.ter_types[i] = cTerrain();
-						scenario.ter_types[i].name = "Unused Terrain";
+							terrains.push_back(scenario.ter_types[i]);
+						}
+
+						undo_list.add(action_ptr(new aCreateDeleteTerrain(terrains)));
+						update_edit_menu();
+					}
+					else{
+						// option-click the last one and it's safe to delete: delete it
+						if(i == size_before - 1 && !scenario.is_ter_used(i)){
+							undo_list.add(action_ptr(new aCreateDeleteTerrain(false, scenario.ter_types.back())));
+							update_edit_menu();
+							scenario.ter_types.pop_back();
+						}
+						// option-click terrain that can't be deleted (because it would break other terrains' numbers, or is in use somewhere):
+						// reset type info
+						else{
+							scenario.ter_types[i] = cTerrain();
+							scenario.ter_types[i].name = "Unused Terrain";
+						}
 					}
 				} else {
+					// Click the plus button: create a new terrain and edit it immediately
 					if(i == size_before) {
 						scenario.ter_types.emplace_back();
 						scenario.ter_types.back().name = "New Terrain";
 					}
-					if(!edit_ter_type(i) && i == size_before && scenario.ter_types.back().name == "New Terrain")
+					if(!edit_ter_type(i) && i == size_before && scenario.ter_types.back().name == "New Terrain"){
+						// Canceled:
 						scenario.ter_types.pop_back();
+					}else{
+						undo_list.add(action_ptr(new aCreateDeleteTerrain(true, scenario.ter_types.back())));
+						update_edit_menu();
+					}
 				}
 				if(size_before / 16 > scenario.ter_types.size() / 16)
 					pos_before--;
diff --git a/src/scenedit/scen.undo.cpp b/src/scenedit/scen.undo.cpp
index 61d18c01..b8a4869b 100644
--- a/src/scenedit/scen.undo.cpp
+++ b/src/scenedit/scen.undo.cpp
@@ -94,6 +94,22 @@ aCreateDeleteTown::~aCreateDeleteTown() {
 	if(isDone() == reversed) delete theTown;
 }
 
+bool aCreateDeleteTerrain::undo_me() {
+	// TODO if not in MODE_EDIT_TYPES, show it
+	for(cTerrain ter : terrains){
+		scenario.ter_types.pop_back();
+	}
+	return true;
+}
+
+bool aCreateDeleteTerrain::redo_me() {
+	// TODO if not in MODE_EDIT_TYPES, show it
+	for(cTerrain ter : terrains){
+		scenario.ter_types.push_back(ter);
+	}
+	return true;
+}
+
 bool aDrawTerrain::undo_me() {
 	cArea* cur_area = get_current_area();
 	for(auto change : changes){
diff --git a/src/scenedit/scen.undo.hpp b/src/scenedit/scen.undo.hpp
index 40f7e4cd..90433b41 100644
--- a/src/scenedit/scen.undo.hpp
+++ b/src/scenedit/scen.undo.hpp
@@ -4,6 +4,9 @@
 #include "location.hpp"
 #include "tools/undo.hpp"
 #include "scenario/town.hpp"
+#include "scenario/scenario.hpp"
+
+extern cScenario scenario;
 
 struct area_ref_t {
 	bool is_town;
@@ -21,6 +24,7 @@ struct ter_change_t {
 typedef std::map<location,ter_change_t,loc_compare> stroke_ter_changes_t;
 typedef std::map<size_t, cTown::cItem> item_changes_t;
 typedef std::map<size_t, cTownperson> creature_changes_t;
+typedef std::vector<cTerrain> terrain_type_changes_t;
 
 // Action that modified something in town or outdoor terrain, so we should show the modified area when undoing or redoing
 class cTerrainAction : public cAction {
@@ -94,5 +98,19 @@ public:
 	~aCreateDeleteTown();
 };
 
+/// Action which adds new terrain type(s) to the end of the list, or deletes from the end of the list
+class aCreateDeleteTerrain : public cAction {
+	terrain_type_changes_t terrains;
+	bool undo_me() override;
+	bool redo_me() override;
+public:
+	aCreateDeleteTerrain(bool create, cTerrain terrain) :
+		cAction(create ? "Create Terrain Type" : "Delete Terrain Type", !create),
+		terrains({terrain}) {}
+	aCreateDeleteTerrain(terrain_type_changes_t terrains) :
+		cAction("Create Terrain Types", false),
+		terrains(terrains) {}
+};
+
 
 #endif
\ No newline at end of file