#pragma once

#include "Components.h"
#include <cstdint>
#include <unordered_map>
#include <vector>
#include <typeindex>
#include <memory>
#include <utility>

class ComponentManager {
public:
	static ComponentManager& GetInstance();	//Singleton

	ComponentManager(const ComponentManager&) = delete;	//Singleton
    ComponentManager(ComponentManager&&) = delete;	//Singleton
    ComponentManager& operator=(const ComponentManager&) = delete;	//Singleton
    ComponentManager& operator=(ComponentManager&&) = delete;	//Singleton

	template <typename T, typename... Args>
	void AddComponent(std::uint32_t id, Args&&... args);	//Add a component
	//TODO: void DeleteAllComponentsOfId(std::uint32_t id);	//Deletes all components of a specific id
	//TODO: void DeleteAllComponents();	//Deletes all components

	template <typename T>
    std::vector<std::reference_wrapper<T>> GetComponentsByID(std::uint32_t id) const;	//Get a vector<> of all components at specific id
	template <typename T>
	std::vector<std::pair<std::reference_wrapper<T>, std::uint32_t>> GetComponentsByType() const;	//Get a vector<> of all components of a specific type

private:
    static ComponentManager mInstance;	//Singleton

    ComponentManager();	//Singleton

	/*
	 * The std::unordered_map<std::type_index, std::vector<std::vector<std::unique_ptr<Component>>>> below might seem a bit strange, let me explain this structure:
	 * The std::unordered_map<> has a key and value. The key is a std::type_index and the value is a std::vector. So, a new std::vector will be created for each new std::type_index.
	 * The first std::vector<> stores another vector<>. This first vector<> is to bind the entity's id to a component.
	 * The second std::vector<> stores unique_ptrs. Each component can be gathered via an unique_ptr. This second vector<> allows multiple components of the same std::type_index for one entity (id).
	 */
	std::unordered_map<std::type_index, std::vector<std::vector<std::unique_ptr<Component>>>> mComponents;
};

#include "ComponentManager.hpp"