text: /*************************************************************************/
  /*  undo_redo.cpp                                                        */
  /*************************************************************************/
  /*                       This file is part of:                           */
  /*                           GODOT ENGINE                                */
  /*                      https://godotengine.org                          */
  /*************************************************************************/
  /* Copyright (c) 2007-2020 Juan Linietsky, Ariel Manzur.                 */
  /* Copyright (c) 2014-2020 Godot Engine contributors (cf. AUTHORS.md).   */
  /*                                                                       */
  /* Permission is hereby granted, free of charge, to any person obtaining */
  /* a copy of this software and associated documentation files (the       */
  /* "Software"), to deal in the Software without restriction, including   */
  /* without limitation the rights to use, copy, modify, merge, publish,   */
  /* distribute, sublicense, and/or sell copies of the Software, and to    */
  /* permit persons to whom the Software is furnished to do so, subject to */
  /* the following conditions:                                             */
  /*                                                                       */
  /* The above copyright notice and this permission notice shall be        */
  /* included in all copies or substantial portions of the Software.       */
  /*                                                                       */
  /* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,       */
  /* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF    */
  /* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.*/
  /* IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY  */
  /* CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,  */
  /* TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE     */
  /* SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.                */
  /*************************************************************************/
  
  #include "undo_redo.h"
  
  #include "core/os/os.h"
  
  void UndoRedo::_discard_redo() {
  
  	if (current_action == actions.size() - 1)
  		return;
  
  	for (int i = current_action + 1; i < actions.size(); i++) {
  
  		for (List<Operation>::Element *E = actions.write[i].do_ops.front(); E; E = E->next()) {
  
  			if (E->get().type == Operation::TYPE_REFERENCE) {
  
  				Object *obj = ObjectDB::get_instance(E->get().object);
  				if (obj)
  					memdelete(obj);
  			}
  		}
  		//ERASE do data
  	}
  
  	actions.resize(current_action + 1);
  }
  
  void UndoRedo::create_action(const String &p_name, MergeMode p_mode) {
  
  	uint32_t ticks = OS::get_singleton()->get_ticks_msec();
  
  	if (action_level == 0) {
  
  		_discard_redo();
  
  		// Check if the merge operation is valid
  		if (p_mode != MERGE_DISABLE && actions.size() && actions[actions.size() - 1].name == p_name && actions[actions.size() - 1].last_tick + 800 > ticks) {
  
  			current_action = actions.size() - 2;
  
  			if (p_mode == MERGE_ENDS) {
  
  				// Clear all do ops from last action, and delete all object references
  				List<Operation>::Element *E = actions.write[current_action + 1].do_ops.front();
  
  				while (E) {
  
  					if (E->get().type == Operation::TYPE_REFERENCE) {
  
  						Object *obj = ObjectDB::get_instance(E->get().object);
  
  						if (obj)
  							memdelete(obj);
  					}
  
  					E = E->next();
  					actions.write[current_action + 1].do_ops.pop_front();
  				}
  			}
  
  			actions.write[actions.size() - 1].last_tick = ticks;
  
  			merge_mode = p_mode;
  			merging = true;
  		} else {
  
  			Action new_action;
  			new_action.name = p_name;
  			new_action.last_tick = ticks;
  			actions.push_back(new_action);
  
  			merge_mode = MERGE_DISABLE;
  		}
  	}
  
  	action_level++;
  }
  
  void UndoRedo::add_do_method(Object *p_object, const StringName &p_method, VARIANT_ARG_DECLARE) {
  
  	VARIANT_ARGPTRS
  	ERR_FAIL_COND(p_object == nullptr);
  	ERR_FAIL_COND(action_level <= 0);
  	ERR_FAIL_COND((current_action + 1) >= actions.size());
  	Operation do_op;
  	do_op.object = p_object->get_instance_id();
  	if (Object::cast_to<Resource>(p_object))
  		do_op.resref = Ref<Resource>(Object::cast_to<Resource>(p_object));
  
  	do_op.type = Operation::TYPE_METHOD;
  	do_op.name = p_method;
  
  	for (int i = 0; i < VARIANT_ARG_MAX; i++) {
  		do_op.args[i] = *argptr[i];
  	}
  	actions.write[current_action + 1].do_ops.push_back(do_op);
  }
  
  void UndoRedo::add_undo_method(Object *p_object, const StringName &p_method, VARIANT_ARG_DECLARE) {
  
  	VARIANT_ARGPTRS
  	ERR_FAIL_COND(p_object == nullptr);
  	ERR_FAIL_COND(action_level <= 0);
  	ERR_FAIL_COND((current_action + 1) >= actions.size());
  
  	// No undo if the merge mode is MERGE_ENDS
  	if (merge_mode == MERGE_ENDS)
  		return;
  
  	Operation undo_op;
  	undo_op.object = p_object->get_instance_id();
  	if (Object::cast_to<Resource>(p_object))
  		undo_op.resref = Ref<Resource>(Object::cast_to<Resource>(p_object));
  
  	undo_op.type = Operation::TYPE_METHOD;
  	undo_op.name = p_method;
  
  	for (int i = 0; i < VARIANT_ARG_MAX; i++) {
  		undo_op.args[i] = *argptr[i];
  	}
  	actions.write[current_action + 1].undo_ops.push_back(undo_op);
  }
  void UndoRedo::add_do_property(Object *p_object, const StringName &p_property, const Variant &p_value) {
  
  	ERR_FAIL_COND(p_object == nullptr);
  	ERR_FAIL_COND(action_level <= 0);
  	ERR_FAIL_COND((current_action + 1) >= actions.size());
  	Operation do_op;
  	do_op.object = p_object->get_instance_id();
  	if (Object::cast_to<Resource>(p_object))
  		do_op.resref = Ref<Resource>(Object::cast_to<Resource>(p_object));
  
  	do_op.type = Operation::TYPE_PROPERTY;
  	do_op.name = p_property;
  	do_op.args[0] = p_value;
  	actions.write[current_action + 1].do_ops.push_back(do_op);
  }
  void UndoRedo::add_undo_property(Object *p_object, const StringName &p_property, const Variant &p_value) {
  
  	ERR_FAIL_COND(p_object == nullptr);
  	ERR_FAIL_COND(action_level <= 0);
  	ERR_FAIL_COND((current_action + 1) >= actions.size());
  
  	// No undo if the merge mode is MERGE_ENDS
  	if (merge_mode == MERGE_ENDS)
  		return;
  
  	Operation undo_op;
  	undo_op.object = p_object->get_instance_id();
  	if (Object::cast_to<Resource>(p_object))
  		undo_op.resref = Ref<Resource>(Object::cast_to<Resource>(p_object));
  
  	undo_op.type = Operation::TYPE_PROPERTY;
  	undo_op.name = p_property;
  	undo_op.args[0] = p_value;
  	actions.write[current_action + 1].undo_ops.push_back(undo_op);
  }
  void UndoRedo::add_do_reference(Object *p_object) {
  
  	ERR_FAIL_COND(p_object == nullptr);
  	ERR_FAIL_COND(action_level <= 0);
  	ERR_FAIL_COND((current_action + 1) >= actions.size());
  	Operation do_op;
  	do_op.object = p_object->get_instance_id();
  	if (Object::cast_to<Resource>(p_object))
  		do_op.resref = Ref<Resource>(Object::cast_to<Resource>(p_object));
  
  	do_op.type = Operation::TYPE_REFERENCE;
  	actions.write[current_action + 1].do_ops.push_back(do_op);
  }
  void UndoRedo::add_undo_reference(Object *p_object) {
  
  	ERR_FAIL_COND(p_object == nullptr);
  	ERR_FAIL_COND(action_level <= 0);
  	ERR_FAIL_COND((current_action + 1) >= actions.size());
  
  	// No undo if the merge mode is MERGE_ENDS
  	if (merge_mode == MERGE_ENDS)
  		return;
  
  	Operation undo_op;
  	undo_op.object = p_object->get_instance_id();
  	if (Object::cast_to<Resource>(p_object))
  		undo_op.resref = Ref<Resource>(Object::cast_to<Resource>(p_object));
  
  	undo_op.type = Operation::TYPE_REFERENCE;
  	actions.write[current_action + 1].undo_ops.push_back(undo_op);
  }
  
  void UndoRedo::_pop_history_tail() {
  
  	_discard_redo();
  
  	if (!actions.size())
  		return;
  
  	for (List<Operation>::Element *E = actions.write[0].undo_ops.front(); E; E = E->next()) {
  
  		if (E->get().type == Operation::TYPE_REFERENCE) {
  
  			Object *obj = ObjectDB::get_instance(E->get().object);
  			if (obj)
  				memdelete(obj);
  		}
  	}
  
  	actions.remove(0);
  	if (current_action >= 0) {
  		current_action--;
  	}
  }
  
  bool UndoRedo::is_committing_action() const {
  	return committing > 0;
  }
  
  void UndoRedo::commit_action() {
  
  	ERR_FAIL_COND(action_level <= 0);
  	action_level--;
  	if (action_level > 0)
  		return; //still nested
  
  	if (merging) {
  		version--;
  		merging = false;
  	}
  
  	committing++;
  	redo(); // perform action
  	committing--;
  	if (callback && actions.size() > 0) {
  		callback(callback_ud, actions[actions.size() - 1].name);
  	}
  }
  
  void UndoRedo::_process_operation_list(List<Operation>::Element *E) {
  
  	for (; E; E = E->next()) {
  
  		Operation &op = E->get();
  
  		Object *obj = ObjectDB::get_instance(op.object);
  		if (!obj) //may have been deleted and this is fine
  			continue;
  
  		switch (op.type) {
  
  			case Operation::TYPE_METHOD: {
  
  				Vector<const Variant *> argptrs;
  				argptrs.resize(VARIANT_ARG_MAX);
  				int argc = 0;
  
  				for (int i = 0; i < VARIANT_ARG_MAX; i++) {
  					if (op.args[i].get_type() == Variant::NIL) {
  						break;
  					}
  					argptrs.write[i] = &op.args[i];
  					argc++;
  				}
  				argptrs.resize(argc);
  
  				Callable::CallError ce;
  				obj->call(op.name, (const Variant **)argptrs.ptr(), argc, ce);
  				if (ce.error != Callable::CallError::CALL_OK) {
  					ERR_PRINT("Error calling method from signal '" + String(op.name) + "': " + Variant::get_call_error_text(obj, op.name, (const Variant **)argptrs.ptr(), argc, ce));
  				}
  #ifdef TOOLS_ENABLED
  				Resource *res = Object::cast_to<Resource>(obj);
  				if (res)
  					res->set_edited(true);
  
  #endif
  
  				if (method_callback) {
  					method_callback(method_callbck_ud, obj, op.name, VARIANT_ARGS_FROM_ARRAY(op.args));
  				}
  			} break;
  			case Operation::TYPE_PROPERTY: {
  
  				obj->set(op.name, op.args[0]);
  #ifdef TOOLS_ENABLED
  				Resource *res = Object::cast_to<Resource>(obj);
  				if (res)
  					res->set_edited(true);
  #endif
  				if (property_callback) {
  					property_callback(prop_callback_ud, obj, op.name, op.args[0]);
  				}
  			} break;
  			case Operation::TYPE_REFERENCE: {
  				//do nothing
  			} break;
  		}
  	}
  }
  
  bool UndoRedo::redo() {
  
  	ERR_FAIL_COND_V(action_level > 0, false);
  
  	if ((current_action + 1) >= actions.size())
  		return false; //nothing to redo
  
  	current_action++;
  
  	_process_operation_list(actions.write[current_action].do_ops.front());
  	version++;
  	emit_signal("version_changed");
  
  	return true;
  }
  
  bool UndoRedo::undo() {
  
  	ERR_FAIL_COND_V(action_level > 0, false);
  	if (current_action < 0)
  		return false; //nothing to redo
  	_process_operation_list(actions.write[current_action].undo_ops.front());
  	current_action--;
  	version--;
  	emit_signal("version_changed");
  
  	return true;
  }
  
  void UndoRedo::clear_history(bool p_increase_version) {
  
  	ERR_FAIL_COND(action_level > 0);
  	_discard_redo();
  
  	while (actions.size())
  		_pop_history_tail();
  
  	if (p_increase_version) {
  		version++;
  		emit_signal("version_changed");
  	}
  }
  
  String UndoRedo::get_current_action_name() const {
  
  	ERR_FAIL_COND_V(action_level > 0, "");
  	if (current_action < 0)
  		return "";
  	return actions[current_action].name;
  }
  
  bool UndoRedo::has_undo() {
  
  	return current_action >= 0;
  }
  
  bool UndoRedo::has_redo() {
  
  	return (current_action + 1) < actions.size();
  }
  
  uint64_t UndoRedo::get_version() const {
  
  	return version;
  }
  
  void UndoRedo::set_commit_notify_callback(CommitNotifyCallback p_callback, void *p_ud) {
  
  	callback = p_callback;
  	callback_ud = p_ud;
  }
  
  void UndoRedo::set_method_notify_callback(MethodNotifyCallback p_method_callback, void *p_ud) {
  
  	method_callback = p_method_callback;
  	method_callbck_ud = p_ud;
  }
  
  void UndoRedo::set_property_notify_callback(PropertyNotifyCallback p_property_callback, void *p_ud) {
  
  	property_callback = p_property_callback;
  	prop_callback_ud = p_ud;
  }
  
  UndoRedo::~UndoRedo() {
  
  	clear_history();
  }
  
  Variant UndoRedo::_add_do_method(const Variant **p_args, int p_argcount, Callable::CallError &r_error) {
  
  	if (p_argcount < 2) {
  		r_error.error = Callable::CallError::CALL_ERROR_TOO_FEW_ARGUMENTS;
  		r_error.argument = 0;
  		return Variant();
  	}
  
  	if (p_args[0]->get_type() != Variant::OBJECT) {
  		r_error.error = Callable::CallError::CALL_ERROR_INVALID_ARGUMENT;
  		r_error.argument = 0;
  		r_error.expected = Variant::OBJECT;
  		return Variant();
  	}
  
  	if (p_args[1]->get_type() != Variant::STRING_NAME && p_args[1]->get_type() != Variant::STRING) {
  		r_error.error = Callable::CallError::CALL_ERROR_INVALID_ARGUMENT;
  		r_error.argument = 1;
  		r_error.expected = Variant::STRING_NAME;
  		return Variant();
  	}
  
  	r_error.error = Callable::CallError::CALL_OK;
  
  	Object *object = *p_args[0];
  	StringName method = *p_args[1];
  
  	Variant v[VARIANT_ARG_MAX];
  
  	for (int i = 0; i < MIN(VARIANT_ARG_MAX, p_argcount - 2); ++i) {
  
  		v[i] = *p_args[i + 2];
  	}
  
  	add_do_method(object, method, v[0], v[1], v[2], v[3], v[4]);
  	return Variant();
  }
  
  Variant UndoRedo::_add_undo_method(const Variant **p_args, int p_argcount, Callable::CallError &r_error) {
  
  	if (p_argcount < 2) {
  		r_error.error = Callable::CallError::CALL_ERROR_TOO_FEW_ARGUMENTS;
  		r_error.argument = 0;
  		return Variant();
  	}
  
  	if (p_args[0]->get_type() != Variant::OBJECT) {
  		r_error.error = Callable::CallError::CALL_ERROR_INVALID_ARGUMENT;
  		r_error.argument = 0;
  		r_error.expected = Variant::OBJECT;
  		return Variant();
  	}
  
  	if (p_args[1]->get_type() != Variant::STRING_NAME && p_args[1]->get_type() != Variant::STRING) {
  		r_error.error = Callable::CallError::CALL_ERROR_INVALID_ARGUMENT;
  		r_error.argument = 1;
  		r_error.expected = Variant::STRING_NAME;
  		return Variant();
  	}
  
  	r_error.error = Callable::CallError::CALL_OK;
  
  	Object *object = *p_args[0];
  	StringName method = *p_args[1];
  
  	Variant v[VARIANT_ARG_MAX];
  
  	for (int i = 0; i < MIN(VARIANT_ARG_MAX, p_argcount - 2); ++i) {
  
  		v[i] = *p_args[i + 2];
  	}
  
  	add_undo_method(object, method, v[0], v[1], v[2], v[3], v[4]);
  	return Variant();
  }
  
  void UndoRedo::_bind_methods() {
  
  	ClassDB::bind_method(D_METHOD("create_action", "name", "merge_mode"), &UndoRedo::create_action, DEFVAL(MERGE_DISABLE));
  	ClassDB::bind_method(D_METHOD("commit_action"), &UndoRedo::commit_action);
  	ClassDB::bind_method(D_METHOD("is_committing_action"), &UndoRedo::is_committing_action);
  
  	{
  		MethodInfo mi;
  		mi.name = "add_do_method";
  		mi.arguments.push_back(PropertyInfo(Variant::OBJECT, "object"));
  		mi.arguments.push_back(PropertyInfo(Variant::STRING_NAME, "method"));
  
  		ClassDB::bind_vararg_method(METHOD_FLAGS_DEFAULT, "add_do_method", &UndoRedo::_add_do_method, mi, varray(), false);
  	}
  
  	{
  		MethodInfo mi;
  		mi.name = "add_undo_method";
  		mi.arguments.push_back(PropertyInfo(Variant::OBJECT, "object"));
  		mi.arguments.push_back(PropertyInfo(Variant::STRING_NAME, "method"));
  
  		ClassDB::bind_vararg_method(METHOD_FLAGS_DEFAULT, "add_undo_method", &UndoRedo::_add_undo_method, mi, varray(), false);
  	}
  
  	ClassDB::bind_method(D_METHOD("add_do_property", "object", "property", "value"), &UndoRedo::add_do_property);
  	ClassDB::bind_method(D_METHOD("add_undo_property", "object", "property", "value"), &UndoRedo::add_undo_property);
  	ClassDB::bind_method(D_METHOD("add_do_reference", "object"), &UndoRedo::add_do_reference);
  	ClassDB::bind_method(D_METHOD("add_undo_reference", "object"), &UndoRedo::add_undo_reference);
  	ClassDB::bind_method(D_METHOD("clear_history", "increase_version"), &UndoRedo::clear_history, DEFVAL(true));
  	ClassDB::bind_method(D_METHOD("get_current_action_name"), &UndoRedo::get_current_action_name);
  	ClassDB::bind_method(D_METHOD("has_undo"), &UndoRedo::has_undo);
  	ClassDB::bind_method(D_METHOD("has_redo"), &UndoRedo::has_redo);
  	ClassDB::bind_method(D_METHOD("get_version"), &UndoRedo::get_version);
  	ClassDB::bind_method(D_METHOD("redo"), &UndoRedo::redo);
  	ClassDB::bind_method(D_METHOD("undo"), &UndoRedo::undo);
  
  	ADD_SIGNAL(MethodInfo("version_changed"));
  
  	BIND_ENUM_CONSTANT(MERGE_DISABLE);
  	BIND_ENUM_CONSTANT(MERGE_ENDS);
  	BIND_ENUM_CONSTANT(MERGE_ALL);
  }
  