From 7ee43f199af97bfad7a80b579201b9c189dc74bc Mon Sep 17 00:00:00 2001
From: "5684185+vsariola@users.noreply.github.com"
 <5684185+vsariola@users.noreply.github.com>
Date: Mon, 2 Oct 2023 15:43:52 +0300
Subject: [PATCH] fix(tracker): make sure undo & redo stack never grow beyond
 limit

---
 tracker/model.go | 21 ++++++++++++---------
 1 file changed, 12 insertions(+), 9 deletions(-)

diff --git a/tracker/model.go b/tracker/model.go
index b30343a..1d037bc 100644
--- a/tracker/model.go
+++ b/tracker/model.go
@@ -981,12 +981,10 @@ func (m *Model) Undo() {
 	if !m.CanUndo() {
 		return
 	}
-	if len(m.d.RedoStack) >= maxUndo {
-		m.d.RedoStack = m.d.RedoStack[1:]
-	}
 	m.d.RedoStack = append(m.d.RedoStack, m.d.Song.Copy())
 	m.setSongNoUndo(m.d.UndoStack[len(m.d.UndoStack)-1])
 	m.d.UndoStack = m.d.UndoStack[:len(m.d.UndoStack)-1]
+	m.limitUndoRedoLengths()
 }
 
 func (m *Model) CanUndo() bool {
@@ -1006,12 +1004,10 @@ func (m *Model) Redo() {
 	if !m.CanRedo() {
 		return
 	}
-	if len(m.d.UndoStack) >= maxUndo {
-		m.d.UndoStack = m.d.UndoStack[1:]
-	}
 	m.d.UndoStack = append(m.d.UndoStack, m.d.Song.Copy())
 	m.setSongNoUndo(m.d.RedoStack[len(m.d.RedoStack)-1])
 	m.d.RedoStack = m.d.RedoStack[:len(m.d.RedoStack)-1]
+	m.limitUndoRedoLengths()
 }
 
 func (m *Model) CanRedo() bool {
@@ -1084,6 +1080,15 @@ func (m *Model) ParamIndex() int {
 	return m.d.ParamIndex
 }
 
+func (m *Model) limitUndoRedoLengths() {
+	if len(m.d.UndoStack) >= maxUndo {
+		m.d.UndoStack = m.d.UndoStack[len(m.d.UndoStack)-maxUndo:]
+	}
+	if len(m.d.RedoStack) >= maxUndo {
+		m.d.RedoStack = m.d.RedoStack[len(m.d.RedoStack)-maxUndo:]
+	}
+}
+
 func (m *Model) clampPositions() {
 	m.d.Cursor = m.d.Cursor.Wrap(m.d.Song.Score)
 	m.d.SelectionCorner = m.d.SelectionCorner.Wrap(m.d.Song.Score)
@@ -1377,11 +1382,9 @@ func (m *Model) saveUndo(undoType string, undoSkipping int) {
 	m.d.ChangedSinceSave = true
 	m.d.PrevUndoType = undoType
 	m.d.UndoSkipCounter = 0
-	if len(m.d.UndoStack) >= maxUndo {
-		m.d.UndoStack = m.d.UndoStack[1:]
-	}
 	m.d.UndoStack = append(m.d.UndoStack, m.d.Song.Copy())
 	m.d.RedoStack = m.d.RedoStack[:0]
+	m.limitUndoRedoLengths()
 }
 
 func (m *Model) freeUnitIDs(units []sointu.Unit) {