class_name EditorUndoRedoStack
extends RefCounted
## Command pattern over ChunkEditorModel mutations
## (docs/architecture/editor.md §7.1 `UndoRedoStack`).
##
## Thin wrapper around Godot's built-in `UndoRedo` -- the general-purpose
## class meant for use in game code (unlike the editor-only
## `EditorUndoRedoManager`, which only exists inside `EditorPlugin`s and
## isn't available at runtime). Every EditorCore tool (scripts/editor/tools/
## *.gd) opens exactly one action per user operation and adds a do/undo
## Callable pair that calls the *same* ChunkEditorModel raw setter in both
## directions (e.g. `set_tile_raw` with the new id, then again with the old
## one) -- so undo genuinely reverts the mutation instead of re-deriving it.
##
## `UndoRedo` extends `Object`, not `RefCounted`, so it is not automatically
## freed; `_notification(NOTIFICATION_PREDELETE)` frees it when this wrapper
## (a RefCounted) goes out of scope.

var _ur := UndoRedo.new()


func _notification(what: int) -> void:
	if what == NOTIFICATION_PREDELETE and _ur != null:
		_ur.free()
		_ur = null


## Begin a new undoable action. Must be paired with `commit()`.
func begin(action_name: String) -> void:
	_ur.create_action(action_name)


## Register the forward step of the current action. Called immediately by
## `commit()`, and again on every future `redo()`.
func add_do(callable: Callable) -> void:
	_ur.add_do_method(callable)


## Register the reverse step of the current action. Called on every
## `undo()`.
func add_undo(callable: Callable) -> void:
	_ur.add_undo_method(callable)


## Close the current action and execute its do-step once.
func commit() -> void:
	_ur.commit_action()


## Close the current action without executing anything (used when a tool
## decides mid-way that there is nothing worth recording).
func cancel() -> void:
	_ur.commit_action(false)


func undo() -> bool:
	return _ur.undo()


func redo() -> bool:
	return _ur.redo()


func can_undo() -> bool:
	return _ur.has_undo()


func can_redo() -> bool:
	return _ur.has_redo()


func clear_history() -> void:
	_ur.clear_history()