From fe39e0cd86bd4938172a1987f014224f9ce16bc5 Mon Sep 17 00:00:00 2001
From: Christian Kaiser <info@ckaiser.com.ar>
Date: Wed, 23 Jul 2025 10:11:57 -0300
Subject: [PATCH] [lua] Add sprite.undoHistory

---
 src/app/script/site_class.cpp   |  2 ++
 src/app/script/sprite_class.cpp | 38 +++++++++++++++++++++++++++
 tests/scripts/sprite.lua        | 46 +++++++++++++++++++++++++++++++++
 3 files changed, 86 insertions(+)

diff --git a/src/app/script/site_class.cpp b/src/app/script/site_class.cpp
index 301bc5285..73934e36e 100644
--- a/src/app/script/site_class.cpp
+++ b/src/app/script/site_class.cpp
@@ -13,6 +13,8 @@
 #include "app/console.h"
 #include "app/context.h"
 #include "app/context_observer.h"
+#include "app/doc.h"
+#include "app/doc_undo.h"
 #include "app/script/docobj.h"
 #include "app/script/engine.h"
 #include "app/script/luacpp.h"
diff --git a/src/app/script/sprite_class.cpp b/src/app/script/sprite_class.cpp
index 92fd395d5..892944acd 100644
--- a/src/app/script/sprite_class.cpp
+++ b/src/app/script/sprite_class.cpp
@@ -64,6 +64,7 @@
 #include "doc/tag.h"
 #include "doc/tileset.h"
 #include "doc/tilesets.h"
+#include "undo/undo_state.h"
 
 #include <algorithm>
 
@@ -1029,6 +1030,42 @@ int Sprite_set_useLayerUuids(lua_State* L)
   return 0;
 }
 
+int Sprite_get_undoHistory(lua_State* L)
+{
+  const auto* sprite = get_docobj<Sprite>(L, 1);
+  const auto* doc = static_cast<Doc*>(sprite->document());
+  const auto* history = doc->undoHistory();
+
+  if (!history) {
+    lua_pushnil(L);
+    return 1;
+  }
+
+  const undo::UndoState* currentState = history->currentState();
+  const undo::UndoState* s = history->firstState();
+  const bool canRedo = history->canRedo();
+  bool pastCurrent = !currentState && canRedo;
+
+  int undoSteps = 0;
+  int redoSteps = 0;
+  while (s) {
+    if (pastCurrent && canRedo)
+      redoSteps++;
+    else if (currentState || !canRedo)
+      undoSteps++;
+
+    if (s == currentState || !currentState)
+      pastCurrent = true;
+
+    s = s->next();
+  }
+
+  lua_newtable(L);
+  setfield_integer(L, "undoSteps", undoSteps);
+  setfield_integer(L, "redoSteps", redoSteps);
+  return 1;
+}
+
 const luaL_Reg Sprite_methods[] = {
   { "__eq",              Sprite_eq                },
   { "resize",            Sprite_resize            },
@@ -1094,6 +1131,7 @@ const Property Sprite_properties[] = {
   { "events",               Sprite_get_events,               nullptr                         },
   { "tileManagementPlugin", Sprite_get_tileManagementPlugin, Sprite_set_tileManagementPlugin },
   { "useLayerUuids",        Sprite_get_useLayerUuids,        Sprite_set_useLayerUuids        },
+  { "undoHistory",          Sprite_get_undoHistory,          nullptr                         },
   { nullptr,                nullptr,                         nullptr                         }
 };
 
diff --git a/tests/scripts/sprite.lua b/tests/scripts/sprite.lua
index ac964eada..3e288ec53 100644
--- a/tests/scripts/sprite.lua
+++ b/tests/scripts/sprite.lua
@@ -228,3 +228,49 @@ do
   c = app.open(fn)
   assert(c.tileManagementPlugin == nil)
 end
+
+-- Undo History
+do
+  local sprite = Sprite(1, 1)
+
+  assert(sprite.undoHistory.undoSteps == 0)
+  assert(sprite.undoHistory.redoSteps == 0)
+
+  sprite:resize(10, 10)
+
+  assert(sprite.undoHistory.undoSteps == 1)
+  assert(sprite.undoHistory.redoSteps == 0)
+
+  sprite:resize(10, 15)
+
+  assert(sprite.undoHistory.undoSteps == 2)
+  assert(sprite.undoHistory.redoSteps == 0)
+
+  sprite:resize(10, 30)
+
+  assert(sprite.undoHistory.undoSteps == 3)
+  assert(sprite.undoHistory.redoSteps == 0)
+
+  app.undo()
+  assert(sprite.undoHistory.undoSteps == 2)
+  assert(sprite.undoHistory.redoSteps == 1)
+
+  app.undo()
+  assert(sprite.undoHistory.undoSteps == 1)
+  assert(sprite.undoHistory.redoSteps == 2)
+
+  app.redo()
+  assert(sprite.undoHistory.undoSteps == 2)
+  assert(sprite.undoHistory.redoSteps == 1)
+
+  app.undo()
+  app.undo()
+
+  assert(sprite.undoHistory.undoSteps == 0)
+  assert(sprite.undoHistory.redoSteps == 3)
+
+  sprite:resize(10, 30)
+
+  assert(sprite.undoHistory.undoSteps == 1)
+  assert(sprite.undoHistory.redoSteps == 0)
+end