/**************************************************************************/
/*  ref.hpp                                                               */
/**************************************************************************/
/*                         This file is part of:                          */
/*                             GODOT ENGINE                               */
/*                        https://godotengine.org                         */
/**************************************************************************/
/* Copyright (c) 2014-present Godot Engine contributors (see AUTHORS.md). */
/* Copyright (c) 2007-2014 Juan Linietsky, Ariel Manzur.                  */
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/* 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:                                              */
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/* 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,        */
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/**************************************************************************/

#pragma once

#include <godot_cpp/core/defs.hpp>

#include <godot_cpp/classes/object.hpp>
#include <godot_cpp/classes/ref_counted.hpp>
#include <godot_cpp/core/binder_common.hpp>
#include <godot_cpp/core/memory.hpp>
#include <godot_cpp/variant/variant.hpp>

namespace godot {

// Helper class for RefCounted objects, same as Godot one.

template <typename T>
class Ref {
	T *reference = nullptr;

	_FORCE_INLINE_ void ref(const Ref &p_from) {
		ref_pointer<false>(p_from.reference);
	}

	template <bool Init>
	_FORCE_INLINE_ void ref_pointer(T *p_refcounted) {
		if (p_refcounted == reference) {
			return;
		}

		// This will go out of scope and get unref'd.
		Ref cleanup_ref;
		cleanup_ref.reference = reference;
		reference = p_refcounted;
		if (reference) {
			if constexpr (Init) {
				if (!reference->init_ref()) {
					reference = nullptr;
				}
			} else {
				if (!reference->reference()) {
					reference = nullptr;
				}
			}
		}
	}

public:
	static _FORCE_INLINE_ String get_class_static() {
		return T::get_class_static();
	}

	_FORCE_INLINE_ bool operator==(const T *p_ptr) const {
		return reference == p_ptr;
	}
	_FORCE_INLINE_ bool operator!=(const T *p_ptr) const {
		return reference != p_ptr;
	}

	_FORCE_INLINE_ bool operator<(const Ref<T> &p_r) const {
		return reference < p_r.reference;
	}
	_FORCE_INLINE_ bool operator==(const Ref<T> &p_r) const {
		return reference == p_r.reference;
	}
	_FORCE_INLINE_ bool operator!=(const Ref<T> &p_r) const {
		return reference != p_r.reference;
	}

	_FORCE_INLINE_ T *operator*() const {
		return reference;
	}

	_FORCE_INLINE_ T *operator->() const {
		return reference;
	}

	_FORCE_INLINE_ T *ptr() const {
		return reference;
	}

	operator Variant() const {
		return Variant(reference);
	}

	void operator=(const Ref &p_from) {
		ref(p_from);
	}

	void operator=(Ref &&p_from) {
		if (reference == p_from.reference) {
			return;
		}
		unref();
		reference = p_from.reference;
		p_from.reference = nullptr;
	}

	template <typename T_Other>
	void operator=(const Ref<T_Other> &p_from) {
		ref_pointer<false>(Object::cast_to<T>(p_from.ptr()));
	}

	void operator=(T *p_from) {
		ref_pointer<true>(p_from);
	}

	void operator=(const Variant &p_variant) {
		Object *object = p_variant.get_validated_object();

		if (object == reference) {
			return;
		}

		ref_pointer<false>(Object::cast_to<T>(object));
	}

	template <typename T_Other>
	void reference_ptr(T_Other *p_ptr) {
		if (reference == p_ptr) {
			return;
		}

		ref_pointer<true>(Object::cast_to<T>(p_ptr));
	}

	Ref(const Ref &p_from) {
		this->operator=(p_from);
	}

	Ref(Ref &&p_from) {
		reference = p_from.reference;
		p_from.reference = nullptr;
	}

	template <typename T_Other>
	Ref(const Ref<T_Other> &p_from) {
		this->operator=(p_from);
	}

	Ref(T *p_from) {
		this->operator=(p_from);
	}

	Ref(const Variant &p_from) {
		this->operator=(p_from);
	}

	inline bool is_valid() const { return reference != nullptr; }
	inline bool is_null() const { return reference == nullptr; }

	void unref() {
		if (reference) {
			// NOTE: `reinterpret_cast` is "safe" here because we know `T` has simple linear
			// inheritance to `RefCounted`. This guarantees that `T * == `RefCounted *`, which
			// allows us to declare `Ref<T>` with forward declared `T` types.
			if (reinterpret_cast<RefCounted *>(reference)->unreference()) {
				memdelete(reinterpret_cast<RefCounted *>(reference));
			}
			reference = nullptr;
		}
	}

	template <typename... VarArgs>
	void instantiate(VarArgs... p_params) {
		ref(memnew(T(p_params...)));
	}

	uint32_t hash() const { return HashMapHasherDefault::hash(reference); }

	Ref() = default;

	~Ref() {
		unref();
	}

	// Used exclusively in the bindings to recreate the Ref Godot encapsulates in return values,
	// without adding to the refcount.
	inline static Ref<T> _gde_internal_constructor(Object *obj) {
		Ref<T> r;
		r.reference = reinterpret_cast<T *>(obj);
		return r;
	}
};

template <typename T>
struct PtrToArg<Ref<T>> {
	_FORCE_INLINE_ static Ref<T> convert(const void *p_ptr) {
		GDExtensionRefPtr ref = (GDExtensionRefPtr)p_ptr;
		if (unlikely(!p_ptr)) {
			return Ref<T>();
		}
		return Ref<T>(reinterpret_cast<T *>(::godot::internal::get_object_instance_binding(::godot::gdextension_interface::ref_get_object(ref))));
	}

	typedef Ref<T> EncodeT;

	_FORCE_INLINE_ static void encode(Ref<T> p_val, void *p_ptr) {
		GDExtensionRefPtr ref = (GDExtensionRefPtr)p_ptr;
		ERR_FAIL_NULL(ref);

		// This code assumes that p_ptr points to an unset Ref<T> variable on the Godot side
		// so we only set it if we have an object to set.
		if (p_val.is_valid()) {
			::godot::gdextension_interface::ref_set_object(ref, p_val->_owner);
		}
	}
};

template <typename T>
struct PtrToArg<const Ref<T> &> {
	typedef Ref<T> EncodeT;

	_FORCE_INLINE_ static Ref<T> convert(const void *p_ptr) {
		GDExtensionRefPtr ref = const_cast<GDExtensionRefPtr>(p_ptr);
		if (unlikely(!p_ptr)) {
			return Ref<T>();
		}
		return Ref<T>(reinterpret_cast<T *>(::godot::internal::get_object_instance_binding(::godot::gdextension_interface::ref_get_object(ref))));
	}
};

template <typename T>
struct GetTypeInfo<Ref<T>, typename EnableIf<TypeInherits<RefCounted, T>::value>::type> {
	static constexpr GDExtensionVariantType VARIANT_TYPE = GDEXTENSION_VARIANT_TYPE_OBJECT;
	static constexpr GDExtensionClassMethodArgumentMetadata METADATA = GDEXTENSION_METHOD_ARGUMENT_METADATA_NONE;

	static inline PropertyInfo get_class_info() {
		return make_property_info(Variant::Type::OBJECT, "", PROPERTY_HINT_RESOURCE_TYPE, T::get_class_static());
	}
};

template <typename T>
struct GetTypeInfo<const Ref<T> &, typename EnableIf<TypeInherits<RefCounted, T>::value>::type> {
	static constexpr GDExtensionVariantType VARIANT_TYPE = GDEXTENSION_VARIANT_TYPE_OBJECT;
	static constexpr GDExtensionClassMethodArgumentMetadata METADATA = GDEXTENSION_METHOD_ARGUMENT_METADATA_NONE;

	static inline PropertyInfo get_class_info() {
		return make_property_info(Variant::Type::OBJECT, "", PROPERTY_HINT_RESOURCE_TYPE, T::get_class_static());
	}
};

} // namespace godot