#pragma once

#include <cstdint>
#include <memory>
#include <typeindex>
#include <unordered_map>
#include <utility>
#include <vector>

#include "Components.h"

namespace crepe {

class ComponentManager {
public:
	// Singleton
	static ComponentManager & get_instance();
	ComponentManager(const ComponentManager &) = delete;
	ComponentManager(ComponentManager &&) = delete;
	ComponentManager & operator=(const ComponentManager &) = delete;
	ComponentManager & operator=(ComponentManager &&) = delete;

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

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

private:
	ComponentManager() = default;

	/*
	 * 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>>>> components;
};

}

// #include "ComponentManager.hpp"