// SPDX-FileCopyrightText: 2012 Icinga GmbH <https://icinga.com>
// SPDX-License-Identifier: GPL-2.0-or-later

#include "base/type.hpp"
#include "base/atomic.hpp"
#include "base/configobject.hpp"
#include "base/debug.hpp"
#include "base/scriptglobal.hpp"
#include "base/namespace.hpp"
#include "base/objectlock.hpp"
#include <functional>

using namespace icinga;

Type::Ptr Type::TypeInstance;

static Namespace::Ptr l_TypesNS = new Namespace(true);

INITIALIZE_ONCE_WITH_PRIORITY([]() {
	ScriptGlobal::GetGlobals()->Set("Types", l_TypesNS, true);
}, InitializePriority::CreateNamespaces);

INITIALIZE_ONCE_WITH_PRIORITY([]() {
	l_TypesNS->Freeze();

	ObjectLock olock (l_TypesNS);
	for (const auto& t : l_TypesNS) {
		VERIFY(t.second.Val.IsObjectType<Type>());
	}
}, InitializePriority::FreezeNamespaces);

/* Ensure that the priority is lower than the basic namespace initialization in scriptframe.cpp. */
INITIALIZE_ONCE_WITH_PRIORITY([]() {
	Type::Ptr type = new TypeType();
	type->SetPrototype(TypeType::GetPrototype());
	Type::TypeInstance = type;
	Type::Register(type);
}, InitializePriority::RegisterTypeType);

static std::vector<Type::Ptr> l_SortedByLoadDependencies;
static Atomic l_SortingByLoadDependenciesDone (false);

INITIALIZE_ONCE_WITH_PRIORITY([] {
	std::unordered_set<Type*> visited;

	std::function<void(Type*)> visit;
	// Please note that this callback does not detect any cyclic load dependencies,
	// instead, it relies on the "sort_by_load_after" unit test to fail.
	visit = ([&visit, &visited](Type* type) {
		if (visited.find(type) != visited.end()) {
			return;
		}
		visited.emplace(type);

		for (auto dependency : type->GetLoadDependencies()) {
			visit(dependency);
		}

		// We have managed to reach the final/top node in this dependency graph,
		// so let's place them in reverse order to their final place.
		l_SortedByLoadDependencies.emplace_back(type);
	});

	// Sort the types by their load_after dependencies in a Depth-First search manner.
	for (const Type::Ptr& type : Type::GetAllTypes()) {
		// Note that only those types that are assignable to the dynamic ConfigObject type can have "load_after"
		// dependencies, otherwise they are just some Icinga 2 primitive types such as Number, String, etc. and
		// we need to ignore them.
		if (ConfigObject::TypeInstance->IsAssignableFrom(type)) {
			visit(type.get());
		}
	}

	l_SortingByLoadDependenciesDone.store(true);
}, InitializePriority::SortTypes);

String Type::ToString() const
{
	return "type '" + GetName() + "'";
}

void Type::Register(const Type::Ptr& type)
{
	ScriptGlobal::Set("Types." + type->GetName(), type);
}

Type::Ptr Type::GetByName(const String& name)
{
	Value ptype;

	if (!l_TypesNS->Get(name, &ptype))
		return nullptr;

	return ptype;
}

std::vector<Type::Ptr> Type::GetAllTypes()
{
	std::vector<Type::Ptr> types;

	Namespace::Ptr typesNS = ScriptGlobal::Get("Types", &Empty);

	if (typesNS) {
		ObjectLock olock(typesNS);

		for (const Namespace::Pair& kv : typesNS) {
			Value value = kv.second.Val;

			if (value.IsObjectType<Type>())
				types.push_back(value);
		}
	}

	return types;
}

const std::vector<Type::Ptr>& Type::GetConfigTypesSortedByLoadDependencies()
{
	VERIFY(l_SortingByLoadDependenciesDone.load());
	return l_SortedByLoadDependencies;
}

String Type::GetPluralName() const
{
	String name = GetName();

	if (name.GetLength() >= 2 && name[name.GetLength() - 1] == 'y' &&
		name.SubStr(name.GetLength() - 2, 1).FindFirstOf("aeiou") == String::NPos)
		return name.SubStr(0, name.GetLength() - 1) + "ies";
	else
		return name + "s";
}

Object::Ptr Type::Instantiate(const std::vector<Value>& args) const
{
	ObjectFactory factory = GetFactory();

	if (!factory)
		BOOST_THROW_EXCEPTION(std::runtime_error("Type does not have a factory function."));

	return factory(args);
}

bool Type::IsAbstract() const
{
	return ((GetAttributes() & TAAbstract) != 0);
}

bool Type::IsAssignableFrom(const Type::Ptr& other) const
{
	for (Type::Ptr t = other; t; t = t->GetBaseType()) {
		if (t.get() == this)
			return true;
	}

	return false;
}

Object::Ptr Type::GetPrototype() const
{
	return m_Prototype;
}

void Type::SetPrototype(const Object::Ptr& object)
{
	m_Prototype = object;
}

void Type::SetField(int id, const Value& value, bool suppress_events, const Value& cookie)
{
	if (id == 1) {
		SetPrototype(value);
		return;
	}

	Object::SetField(id, value, suppress_events, cookie);
}

Value Type::GetField(int id) const
{
	int real_id = id - Object::TypeInstance->GetFieldCount();
	if (real_id < 0)
		return Object::GetField(id);

	if (real_id == 0)
		return GetName();
	else if (real_id == 1)
		return GetPrototype();
	else if (real_id == 2)
		return GetBaseType();

	BOOST_THROW_EXCEPTION(std::runtime_error("Invalid field ID."));
}

const std::unordered_set<Type*>& Type::GetLoadDependencies() const
{
	static const std::unordered_set<Type*> noDeps;
	return noDeps;
}

int Type::GetActivationPriority() const
{
	return 0;
}

void Type::RegisterAttributeHandler([[maybe_unused]] int fieldId, const AttributeHandler&)
{
	throw std::runtime_error("Invalid field ID.");
}

String TypeType::GetName() const
{
	return "Type";
}

Type::Ptr TypeType::GetBaseType() const
{
	return Object::TypeInstance;
}

int TypeType::GetAttributes() const
{
	return 0;
}

int TypeType::GetFieldId(const String& name) const
{
	int base_field_count = GetBaseType()->GetFieldCount();

	if (name == "name")
		return base_field_count + 0;
	else if (name == "prototype")
		return base_field_count + 1;
	else if (name == "base")
		return base_field_count + 2;

	return GetBaseType()->GetFieldId(name);
}

Field TypeType::GetFieldInfo(int id) const
{
	int real_id = id - GetBaseType()->GetFieldCount();
	if (real_id < 0)
		return GetBaseType()->GetFieldInfo(id);

	if (real_id == 0)
		return {0, "String", "name", "", nullptr, 0, 0};
	else if (real_id == 1)
		return Field(1, "Object", "prototype", "", nullptr, 0, 0);
	else if (real_id == 2)
		return Field(2, "Type", "base", "", nullptr, 0, 0);

	throw std::runtime_error("Invalid field ID.");
}

int TypeType::GetFieldCount() const
{
	return GetBaseType()->GetFieldCount() + 3;
}

ObjectFactory TypeType::GetFactory() const
{
	return nullptr;
}
