/*************************************************************************/
/*  managed_callable.cpp                                                 */
/*************************************************************************/
/*                       This file is part of:                           */
/*                           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 "managed_callable.h"

#include "csharp_script.h"
#include "mono_gd/gd_mono_marshal.h"
#include "mono_gd/gd_mono_utils.h"

#ifdef GD_MONO_HOT_RELOAD
SelfList<ManagedCallable>::List ManagedCallable::instances;
Map<ManagedCallable *, Array> ManagedCallable::instances_pending_reload;
Mutex ManagedCallable::instances_mutex;
#endif

bool ManagedCallable::compare_equal(const CallableCustom *p_a, const CallableCustom *p_b) {
	const ManagedCallable *a = static_cast<const ManagedCallable *>(p_a);
	const ManagedCallable *b = static_cast<const ManagedCallable *>(p_b);

	MonoDelegate *delegate_a = (MonoDelegate *)a->delegate_handle.get_target();
	MonoDelegate *delegate_b = (MonoDelegate *)b->delegate_handle.get_target();

	if (!delegate_a || !delegate_b) {
		if (!delegate_a && !delegate_b) {
			return true;
		}
		return false;
	}

	// Call Delegate's 'Equals'
	return GDMonoUtils::mono_delegate_equal(delegate_a, delegate_b);
}

bool ManagedCallable::compare_less(const CallableCustom *p_a, const CallableCustom *p_b) {
	if (compare_equal(p_a, p_b)) {
		return false;
	}
	return p_a < p_b;
}

uint32_t ManagedCallable::hash() const {
	// hmm
	uint32_t hash = delegate_invoke->get_name().hash();
	return hash_djb2_one_64(delegate_handle.handle, hash);
}

String ManagedCallable::get_as_text() const {
	return "Delegate::Invoke";
}

CallableCustom::CompareEqualFunc ManagedCallable::get_compare_equal_func() const {
	return compare_equal_func_ptr;
}

CallableCustom::CompareLessFunc ManagedCallable::get_compare_less_func() const {
	return compare_less_func_ptr;
}

ObjectID ManagedCallable::get_object() const {
	// TODO: If the delegate target extends Godot.Object, use that instead!
	return CSharpLanguage::get_singleton()->get_managed_callable_middleman()->get_instance_id();
}

void ManagedCallable::call(const Variant **p_arguments, int p_argcount, Variant &r_return_value, Callable::CallError &r_call_error) const {
	r_call_error.error = Callable::CallError::CALL_ERROR_INVALID_METHOD; // Can't find anything better
	r_return_value = Variant();

#ifdef GD_MONO_HOT_RELOAD
	// Lost during hot-reload
	ERR_FAIL_NULL(delegate_invoke);
	ERR_FAIL_COND(delegate_handle.is_released());
#endif

	ERR_FAIL_COND(delegate_invoke->get_parameters_count() < p_argcount);

	MonoObject *delegate = delegate_handle.get_target();

	MonoException *exc = nullptr;
	MonoObject *ret = delegate_invoke->invoke(delegate, p_arguments, &exc);

	if (exc) {
		GDMonoUtils::set_pending_exception(exc);
	} else {
		r_return_value = GDMonoMarshal::mono_object_to_variant(ret);
		r_call_error.error = Callable::CallError::CALL_OK;
	}
}

void ManagedCallable::set_delegate(MonoDelegate *p_delegate) {
	delegate_handle = MonoGCHandleData::new_strong_handle((MonoObject *)p_delegate);
	MonoMethod *delegate_invoke_raw = mono_get_delegate_invoke(mono_object_get_class((MonoObject *)p_delegate));
	const StringName &delegate_invoke_name = CSharpLanguage::get_singleton()->get_string_names().delegate_invoke_method_name;
	delegate_invoke = memnew(GDMonoMethod(delegate_invoke_name, delegate_invoke_raw)); // TODO: Use pooling for this GDMonoMethod instances
}

ManagedCallable::ManagedCallable(MonoDelegate *p_delegate) {
#ifdef DEBUG_ENABLED
	CRASH_COND(p_delegate == nullptr);
#endif

	set_delegate(p_delegate);

#ifdef GD_MONO_HOT_RELOAD
	{
		MutexLock lock(instances_mutex);
		instances.add(&self_instance);
	}
#endif
}

ManagedCallable::~ManagedCallable() {
#ifdef GD_MONO_HOT_RELOAD
	{
		MutexLock lock(instances_mutex);
		instances.remove(&self_instance);
		instances_pending_reload.erase(this);
	}
#endif

	delegate_handle.release();
}