/*************************************************************************/
/*  gd_mono_method.cpp                                                   */
/*************************************************************************/
/*                       This file is part of:                           */
/*                           GODOT ENGINE                                */
/*                      https://godotengine.org                          */
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/* Copyright (c) 2007-2022 Juan Linietsky, Ariel Manzur.                 */
/* Copyright (c) 2014-2022 Godot Engine contributors (cf. AUTHORS.md).   */
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/*************************************************************************/

#include "gd_mono_method.h"

#include <mono/metadata/attrdefs.h>
#include <mono/metadata/debug-helpers.h>

#include "gd_mono_cache.h"
#include "gd_mono_class.h"
#include "gd_mono_marshal.h"
#include "gd_mono_utils.h"

void GDMonoMethod::_update_signature() {
	// Apparently MonoMethodSignature needs not to be freed.
	// mono_method_signature caches the result, we don't need to cache it ourselves.

	MonoMethodSignature *method_sig = mono_method_signature(mono_method);
	_update_signature(method_sig);
}

void GDMonoMethod::_update_signature(MonoMethodSignature *p_method_sig) {
	params_count = mono_signature_get_param_count(p_method_sig);

	MonoType *ret_type = mono_signature_get_return_type(p_method_sig);
	if (ret_type) {
		return_type.type_encoding = mono_type_get_type(ret_type);

		if (return_type.type_encoding != MONO_TYPE_VOID) {
			MonoClass *ret_type_class = mono_class_from_mono_type(ret_type);
			return_type.type_class = GDMono::get_singleton()->get_class(ret_type_class);
		}
	}

	void *iter = nullptr;
	MonoType *param_raw_type;
	while ((param_raw_type = mono_signature_get_params(p_method_sig, &iter)) != nullptr) {
		ManagedType param_type;

		param_type.type_encoding = mono_type_get_type(param_raw_type);

		MonoClass *param_type_class = mono_class_from_mono_type(param_raw_type);
		param_type.type_class = GDMono::get_singleton()->get_class(param_type_class);

		param_types.push_back(param_type);
	}

	// clear the cache
	method_info_fetched = false;
	method_info = MethodInfo();

	for (int i = 0; i < params_count; i++) {
		params_buffer_size += GDMonoMarshal::variant_get_managed_unboxed_size(param_types[i]);
	}
}

GDMonoClass *GDMonoMethod::get_enclosing_class() const {
	return GDMono::get_singleton()->get_class(mono_method_get_class(mono_method));
}

bool GDMonoMethod::is_static() {
	return mono_method_get_flags(mono_method, nullptr) & MONO_METHOD_ATTR_STATIC;
}

IMonoClassMember::Visibility GDMonoMethod::get_visibility() {
	switch (mono_method_get_flags(mono_method, nullptr) & MONO_METHOD_ATTR_ACCESS_MASK) {
		case MONO_METHOD_ATTR_PRIVATE:
			return IMonoClassMember::PRIVATE;
		case MONO_METHOD_ATTR_FAM_AND_ASSEM:
			return IMonoClassMember::PROTECTED_AND_INTERNAL;
		case MONO_METHOD_ATTR_ASSEM:
			return IMonoClassMember::INTERNAL;
		case MONO_METHOD_ATTR_FAMILY:
			return IMonoClassMember::PROTECTED;
		case MONO_METHOD_ATTR_PUBLIC:
			return IMonoClassMember::PUBLIC;
		default:
			ERR_FAIL_V(IMonoClassMember::PRIVATE);
	}
}

MonoObject *GDMonoMethod::invoke(MonoObject *p_object, const Variant **p_params, MonoException **r_exc) const {
	MonoException *exc = nullptr;
	MonoObject *ret;

	if (params_count > 0) {
		void **params = (void **)alloca(params_count * sizeof(void *));
		uint8_t *buffer = (uint8_t *)alloca(params_buffer_size);
		unsigned int offset = 0;

		for (int i = 0; i < params_count; i++) {
			params[i] = GDMonoMarshal::variant_to_managed_unboxed(p_params[i], param_types[i], buffer + offset, offset);
		}

		ret = GDMonoUtils::runtime_invoke(mono_method, p_object, params, &exc);
	} else {
		ret = GDMonoUtils::runtime_invoke(mono_method, p_object, nullptr, &exc);
	}

	if (exc) {
		ret = nullptr;
		if (r_exc) {
			*r_exc = exc;
		} else {
			GDMonoUtils::set_pending_exception(exc);
		}
	}

	return ret;
}

MonoObject *GDMonoMethod::invoke(MonoObject *p_object, MonoException **r_exc) const {
	ERR_FAIL_COND_V(get_parameters_count() > 0, nullptr);
	return invoke_raw(p_object, nullptr, r_exc);
}

MonoObject *GDMonoMethod::invoke_raw(MonoObject *p_object, void **p_params, MonoException **r_exc) const {
	MonoException *exc = nullptr;
	MonoObject *ret = GDMonoUtils::runtime_invoke(mono_method, p_object, p_params, &exc);

	if (exc) {
		ret = nullptr;
		if (r_exc) {
			*r_exc = exc;
		} else {
			GDMonoUtils::set_pending_exception(exc);
		}
	}

	return ret;
}

bool GDMonoMethod::has_attribute(GDMonoClass *p_attr_class) {
	ERR_FAIL_NULL_V(p_attr_class, false);

	if (!attrs_fetched) {
		fetch_attributes();
	}

	if (!attributes) {
		return false;
	}

	return mono_custom_attrs_has_attr(attributes, p_attr_class->get_mono_ptr());
}

MonoObject *GDMonoMethod::get_attribute(GDMonoClass *p_attr_class) {
	ERR_FAIL_NULL_V(p_attr_class, nullptr);

	if (!attrs_fetched) {
		fetch_attributes();
	}

	if (!attributes) {
		return nullptr;
	}

	return mono_custom_attrs_get_attr(attributes, p_attr_class->get_mono_ptr());
}

void GDMonoMethod::fetch_attributes() {
	ERR_FAIL_COND(attributes != nullptr);
	attributes = mono_custom_attrs_from_method(mono_method);
	attrs_fetched = true;
}

String GDMonoMethod::get_full_name(bool p_signature) const {
	char *res = mono_method_full_name(mono_method, p_signature);
	String full_name(res);
	mono_free(res);
	return full_name;
}

String GDMonoMethod::get_full_name_no_class() const {
	String res;

	MonoMethodSignature *method_sig = mono_method_signature(mono_method);

	char *ret_str = mono_type_full_name(mono_signature_get_return_type(method_sig));
	res += ret_str;
	mono_free(ret_str);

	res += " ";
	res += name;
	res += "(";

	char *sig_desc = mono_signature_get_desc(method_sig, true);
	res += sig_desc;
	mono_free(sig_desc);

	res += ")";

	return res;
}

String GDMonoMethod::get_ret_type_full_name() const {
	MonoMethodSignature *method_sig = mono_method_signature(mono_method);
	char *ret_str = mono_type_full_name(mono_signature_get_return_type(method_sig));
	String res = ret_str;
	mono_free(ret_str);
	return res;
}

String GDMonoMethod::get_signature_desc(bool p_namespaces) const {
	MonoMethodSignature *method_sig = mono_method_signature(mono_method);
	char *sig_desc = mono_signature_get_desc(method_sig, p_namespaces);
	String res = sig_desc;
	mono_free(sig_desc);
	return res;
}

void GDMonoMethod::get_parameter_names(Vector<StringName> &names) const {
	if (params_count > 0) {
		const char **_names = memnew_arr(const char *, params_count);
		mono_method_get_param_names(mono_method, _names);
		for (int i = 0; i < params_count; ++i) {
			names.push_back(StringName(_names[i]));
		}
		memdelete_arr(_names);
	}
}

void GDMonoMethod::get_parameter_types(Vector<ManagedType> &types) const {
	for (int i = 0; i < params_count; ++i) {
		types.push_back(param_types[i]);
	}
}

const MethodInfo &GDMonoMethod::get_method_info() {
	if (!method_info_fetched) {
		method_info.name = name;

		bool nil_is_variant = false;
		method_info.return_val = PropertyInfo(GDMonoMarshal::managed_to_variant_type(return_type, &nil_is_variant), "");
		if (method_info.return_val.type == Variant::NIL && nil_is_variant) {
			method_info.return_val.usage |= PROPERTY_USAGE_NIL_IS_VARIANT;
		}

		Vector<StringName> names;
		get_parameter_names(names);

		for (int i = 0; i < params_count; ++i) {
			nil_is_variant = false;
			PropertyInfo arg_info = PropertyInfo(GDMonoMarshal::managed_to_variant_type(param_types[i], &nil_is_variant), names[i]);
			if (arg_info.type == Variant::NIL && nil_is_variant) {
				arg_info.usage |= PROPERTY_USAGE_NIL_IS_VARIANT;
			}

			method_info.arguments.push_back(arg_info);
		}

		// TODO: default arguments

		method_info_fetched = true;
	}

	return method_info;
}

GDMonoMethod::GDMonoMethod(StringName p_name, MonoMethod *p_method) :
		name(p_name), mono_method(p_method) {
	_update_signature();
}

GDMonoMethod::~GDMonoMethod() {
	if (attributes) {
		mono_custom_attrs_free(attributes);
	}
}