/*************************************************************************/
/*  property_utils.cpp                                                   */
/*************************************************************************/
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/*                           GODOT ENGINE                                */
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/* Copyright (c) 2007-2021 Juan Linietsky, Ariel Manzur.                 */
/* Copyright (c) 2014-2021 Godot Engine contributors (cf. AUTHORS.md).   */
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#include "property_utils.h"

#include "core/config/engine.h"
#include "core/templates/local_vector.h"
#include "editor/editor_node.h"
#include "scene/resources/packed_scene.h"

bool PropertyUtils::is_property_value_different(const Variant &p_a, const Variant &p_b) {
	if (p_a.get_type() == Variant::FLOAT && p_b.get_type() == Variant::FLOAT) {
		//this must be done because, as some scenes save as text, there might be a tiny difference in floats due to numerical error
		return !Math::is_equal_approx((float)p_a, (float)p_b);
	} else {
		// For our purposes, treating null object as NIL is the right thing to do
		const Variant &a = p_a.get_type() == Variant::OBJECT && (Object *)p_a == nullptr ? Variant() : p_a;
		const Variant &b = p_b.get_type() == Variant::OBJECT && (Object *)p_b == nullptr ? Variant() : p_b;
		return a != b;
	}
}

Variant PropertyUtils::get_property_default_value(const Object *p_object, const StringName &p_property, const Vector<SceneState::PackState> *p_states_stack_cache, bool p_update_exports, const Node *p_owner, bool *r_is_class_default) {
	// This function obeys the way property values are set when an object is instantiated,
	// which is the following (the latter wins):
	// 1. Default value from builtin class
	// 2. Default value from script exported variable (from the topmost script)
	// 3. Value overrides from the instantiation/inheritance stack

	if (r_is_class_default) {
		*r_is_class_default = false;
	}

	Ref<Script> topmost_script;

	if (const Node *node = Object::cast_to<Node>(p_object)) {
		// Check inheritance/instantiation ancestors
		const Vector<SceneState::PackState> &states_stack = p_states_stack_cache ? *p_states_stack_cache : PropertyUtils::get_node_states_stack(node, p_owner);
		for (int i = 0; i < states_stack.size(); ++i) {
			const SceneState::PackState &ia = states_stack[i];
			bool found = false;
			Variant value_in_ancestor = ia.state->get_property_value(ia.node, p_property, found);
			if (found) {
				return value_in_ancestor;
			}
			// Save script for later
			bool has_script = false;
			Variant script = ia.state->get_property_value(ia.node, SNAME("script"), has_script);
			if (has_script) {
				Ref<Script> scr = script;
				if (scr.is_valid()) {
					topmost_script = scr;
				}
			}
		}
	}

	// Let's see what default is set by the topmost script having a default, if any
	if (topmost_script.is_null()) {
		topmost_script = p_object->get_script();
	}
	if (topmost_script.is_valid()) {
		// Should be called in the editor only and not at runtime,
		// otherwise it can cause problems because of missing instance state support
		if (p_update_exports && Engine::get_singleton()->is_editor_hint()) {
			topmost_script->update_exports();
		}
		Variant default_value;
		if (topmost_script->get_property_default_value(p_property, default_value)) {
			return default_value;
		}
	}

	// Fall back to the default from the native class
	if (r_is_class_default) {
		*r_is_class_default = true;
	}
	return ClassDB::class_get_default_property_value(p_object->get_class_name(), p_property);
}

// Like SceneState::PackState, but using a raw pointer to avoid the cost of
// updating the reference count during the internal work of the functions below
namespace {
struct _FastPackState {
	SceneState *state = nullptr;
	int node = -1;
};
} // namespace

static bool _collect_inheritance_chain(const Ref<SceneState> &p_state, const NodePath &p_path, LocalVector<_FastPackState> &r_states_stack) {
	bool found = false;

	LocalVector<_FastPackState> inheritance_states;

	Ref<SceneState> state = p_state;
	while (state.is_valid()) {
		int node = state->find_node_by_path(p_path);
		if (node >= 0) {
			// This one has state for this node
			inheritance_states.push_back({ state.ptr(), node });
			found = true;
		}
		state = state->get_base_scene_state();
	}

	for (int i = inheritance_states.size() - 1; i >= 0; --i) {
		r_states_stack.push_back(inheritance_states[i]);
	}

	return found;
}

Vector<SceneState::PackState> PropertyUtils::get_node_states_stack(const Node *p_node, const Node *p_owner, bool *r_instantiated_by_owner) {
	if (r_instantiated_by_owner) {
		*r_instantiated_by_owner = true;
	}

	LocalVector<_FastPackState> states_stack;
	{
		const Node *owner = p_owner;
#ifdef TOOLS_ENABLED
		if (!p_owner && Engine::get_singleton()->is_editor_hint()) {
			owner = EditorNode::get_singleton()->get_edited_scene();
		}
#endif

		const Node *n = p_node;
		while (n) {
			if (n == owner) {
				const Ref<SceneState> &state = n->get_scene_inherited_state();
				if (_collect_inheritance_chain(state, n->get_path_to(p_node), states_stack)) {
					if (r_instantiated_by_owner) {
						*r_instantiated_by_owner = false;
					}
				}
				break;
			} else if (n->get_scene_file_path() != String()) {
				const Ref<SceneState> &state = n->get_scene_instance_state();
				_collect_inheritance_chain(state, n->get_path_to(p_node), states_stack);
			}
			n = n->get_owner();
		}
	}

	// Convert to the proper type for returning, inverting the vector on the go
	// (it was more convenient to fill the vector in reverse order)
	Vector<SceneState::PackState> states_stack_ret;
	{
		states_stack_ret.resize(states_stack.size());
		_FastPackState *ps = states_stack.ptr();
		for (int i = states_stack.size() - 1; i >= 0; --i) {
			states_stack_ret.write[i].state.reference_ptr(ps->state);
			states_stack_ret.write[i].node = ps->node;
			++ps;
		}
	}
	return states_stack_ret;
}