#pragma once

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

#include "Component.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 add_component(uint32_t id, Args &&... args);
	//! Deletes all components of a specific type and id
	template <typename T>
	void delete_components_by_id(uint32_t id);
	//! Deletes all components of a specific type
	template <typename T>
	void delete_components();
	//! Deletes all components of a specific id
	void delete_all_components_of_id(uint32_t id);
	//! Deletes all components
	void delete_all_components();

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

private:
	ComponentManager();
	virtual ~ComponentManager();

	/*
	 * 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;
};

} // namespace crepe

#include "ComponentManager.hpp"