#pragma once

#include <vector>

#include "../api/KeyCodes.h"
#include "../manager/EventManager.h"
#include "../manager/LoopTimerManager.h"
#include "../manager/Mediator.h"
#include "../manager/ReplayManager.h"
#include "../system/CollisionSystem.h"
#include "../system/InputSystem.h"
#include "../types.h"
#include "../util/Log.h"
#include "../util/OptionalRef.h"

namespace crepe {

class ScriptSystem;
class BehaviorScript;
class ComponentManager;

/**
 * \brief Script interface
 *
 * This class is used as a base class for user-defined scripts that can be added to game
 * objects using the \c BehaviorScript component.
 *
 * \note Additional *events* (like Unity's OnDisable and OnEnable) should be implemented as
 * member or lambda methods in derivative user script classes and registered in \c init().
 *
 * \warning Concrete scripts are allowed do create a custom constructor, but the utility
 * functions should not be called inside the constructor as they rely on late references that
 * are only available after the constructor returns.
 *
 * \see feature_script
 */
class Script {
protected:
	/**
	 * \name Interface functions
	 * \{
	 */
	/**
	 * \brief Script initialization function (empty by default)
	 *
	 * This function is called during the ScriptSystem::update() routine *before*
	 * Script::update() if it (a) has not yet been called and (b) the \c BehaviorScript component
	 * holding this script instance is active.
	 */
	virtual void init() {}
	/**
	 * \brief Script fixed update function (empty by default)
	 *
	 * \param delta_time Time since last fixed update
	 *
	 * \note This function is called during the ScriptSystem::update() routine if the \c
	 * BehaviorScript component holding this script instance is active.
	 */
	virtual void fixed_update(duration_t delta_time) {}
	/**
	 * \brief Script frame update function (empty by default)
	 *
	 * \param delta_time Time since last frame update
	 *
	 * \note This function is called during the ScriptSystem::update() routine if the \c
	 * BehaviorScript component holding this script instance is active.
	 */
	virtual void frame_update(duration_t delta_time) {}
	//! \}

	//! ScriptSystem calls \c init() and \c update()
	friend class crepe::ScriptSystem;

protected:
	/**
	 * \name Component query functions
	 * \see ComponentManager
	 * \{
	 */
	/**
	 * \brief Get single component of type \c T on this game object
	 * \tparam T Type of component
	 * \returns Reference to component
	 * \throws std::runtime_error if this game object does not have a component with type \c T
	 */
	template <typename T>
	T & get_component() const;
	/**
	 * \brief Get all components of type \c T on this game object
	 * \tparam T Type of component
	 * \returns List of component references
	 */
	template <typename T>
	RefVector<T> get_components() const;
	//! \copydoc ComponentManager::get_components_by_id
	template <typename T>
	RefVector<T> get_components_by_id(game_object_id_t id) const;
	//! \copydoc ComponentManager::get_components_by_name
	template <typename T>
	RefVector<T> get_components_by_name(const std::string & name) const;
	//! \copydoc ComponentManager::get_components_by_tag
	template <typename T>
	RefVector<T> get_components_by_tag(const std::string & tag) const;
	//! \}

	/**
	 * \name Logging functions
	 * \see Log
	 * \{
	 */
	//! \copydoc Log::logf
	template <class... Args>
	void logf(const Log::Level & level, std::format_string<Args...> fmt, Args &&... args);
	//! \copydoc Log::logf
	template <class... Args>
	void logf(std::format_string<Args...> fmt, Args &&... args);
	// \}

	/**
	 * \name Event manager functions
	 * \see EventManager
	 * \{
	 */
	//! \copydoc EventManager::subscribe
	template <typename EventType>
	void subscribe(const EventHandler<EventType> & callback, event_channel_t channel);
	//! \copydoc EventManager::subscribe
	template <typename EventType>
	void subscribe(const EventHandler<EventType> & callback);
	//! \copydoc EventManager::trigger_event
	template <typename EventType>
	void trigger_event(
		const EventType & event = {}, event_channel_t channel = EventManager::CHANNEL_ALL
	);
	//! \copydoc EventManager::queue_event
	template <typename EventType>
	void queue_event(
		const EventType & event = {}, event_channel_t channel = EventManager::CHANNEL_ALL
	);
	//! \}

	/**
	 * \name Scene-related functions
	 * \see SceneManager
	 * \{
	 */
	//! \copydoc SceneManager::set_next_scene
	void set_next_scene(const std::string & name);
	//! \}

	/**
	 * \name Save data management functions
	 * \see SaveManager
	 * \{
	 */
	//! Retrieve SaveManager reference
	SaveManager & get_save_manager() const;
	//! \}

	/**
	 * \name Timing functions
	 * \see LoopTimerManager
	 * \{
	 */
	//! Retrieve LoopTimerManager reference
	LoopTimerManager & get_loop_timer() const;
	//! \}

	//! Replay management functions
	struct replay { // NOLINT
		//! \copydoc ReplayManager::record_start
		void record_start();
		//! \copydoc ReplayManager::record_end
		recording_t record_end();
		//! \copydoc ReplayManager::play
		void play(recording_t);
		//! \copydoc ReplayManager::release
		void release(recording_t);

	private:
		OptionalRef<Mediator> & mediator;
		replay(OptionalRef<Mediator> & mediator) : mediator(mediator) {}
		friend class Script;
	} replay {mediator};

	/**
	 * \brief Utility function to retrieve the keyboard state
	 * \see SDLContext::get_keyboard_state
	 * 
	 * \return current keyboard state map with Keycode as key and bool as value(true = pressed, false = not pressed)
	 */
	const keyboard_state_t & get_keyboard_state() const;
	/**
	 * \brief Utility function to retrieve a single key state.
	 * \see SDLContext::get_keyboard_state
	 * 
	 * \return Keycode state (true if pressed, false if not pressed).
	 */
	bool get_key_state(Keycode key) const noexcept;

private:
	/**
	 * \brief Internal subscribe function
	 *
	 * This function exists so certain template specializations of Script::subscribe can be
	 * explicitly deleted, and does the following:
	 * - Wrap the user-provided callback in a check that tests if the parent BehaviorScript
	 *   component is still active
	 * - Store the subscriber handle returned by the event manager so this listener is
	 *   automatically unsubscribed at the end of this Script instance's life
	 *
	 * \tparam EventType concrete Event class
	 * \param callback User-provided callback function
	 * \param channel Event channel (may have been overridden by template specializations)
	 */
	template <typename EventType>
	void subscribe_internal(const EventHandler<EventType> & callback, event_channel_t channel);

protected:
	// NOTE: This must be the only constructor on Script, see "Late references" below
	Script() = default;
	//! Only \c BehaviorScript instantiates Script
	friend class BehaviorScript;

public:
	// std::unique_ptr destroys script
	virtual ~Script();

private:
	Script(const Script &) = delete;
	Script(Script &&) = delete;
	Script & operator=(const Script &) = delete;
	Script & operator=(Script &&) = delete;

private:
	/**
	 * \name Late references
	 *
	 * These references are set by BehaviorScript immediately after calling the constructor of
	 * Script.
	 *
	 * \note Script must have a constructor without arguments so the game programmer doesn't need
	 * to manually add `using Script::Script` to their concrete script class if they want to
	 * implement a non-default constructor (e.g. for passing references to their own concrete
	 * Script classes).
	 *
	 * \{
	 */
	//! Game object ID of game object parent BehaviorScript is attached to
	game_object_id_t game_object_id;
	//! Reference to parent component
	OptionalRef<bool> active;
	//! Mediator reference
	OptionalRef<Mediator> mediator;
	//! \}

private:
	//! Flag to indicate if \c init() has been called already
	bool initialized = false;
	//! List of subscribed events
	std::vector<subscription_t> listeners;
};

/**
 * \brief Subscribe to CollisionEvent for the current GameObject
 *
 * This is a template specialization for Script::subscribe which automatically sets the event
 * channel so the callback handler is only called for CollisionEvent events that apply to the
 * current GameObject the parent BehaviorScript is attached to.
 */
template <>
void Script::subscribe(const EventHandler<CollisionEvent> & callback);
template <>
void Script::subscribe(const EventHandler<CollisionEvent> & callback, event_channel_t)
	= delete;
/**
 * \brief Subscribe to ButtonPressEvent for the current GameObject
 *
 * This is a template specialization for Script::subscribe which automatically sets the event
 * channel so the callback handler is only called for ButtonPressEvent events that apply to the
 * current GameObject the parent BehaviorScript is attached to.
 */
template <>
void Script::subscribe(const EventHandler<ButtonPressEvent> & callback);
template <>
void Script::subscribe(const EventHandler<ButtonPressEvent> & callback, event_channel_t)
	= delete;
/**
 * \brief Subscribe to ButtonExitEvent for the current GameObject
 *
 * This is a template specialization for Script::subscribe which automatically sets the event
 * channel so the callback handler is only called for ButtonExitEvent events that apply to the
 * current GameObject the parent BehaviorScript is attached to.
 */
template <>
void Script::subscribe(const EventHandler<ButtonExitEvent> & callback);
template <>
void Script::subscribe(const EventHandler<ButtonExitEvent> & callback, event_channel_t)
	= delete;
/**
 * \brief Subscribe to ButtonEnterEvent for the current GameObject
 *
 * This is a template specialization for Script::subscribe which automatically sets the event
 * channel so the callback handler is only called for ButtonEnterEvent events that apply to the
 * current GameObject the parent BehaviorScript is attached to.
 */
template <>
void Script::subscribe(const EventHandler<ButtonEnterEvent> & callback);
template <>
void Script::subscribe(const EventHandler<ButtonEnterEvent> & callback, event_channel_t)
	= delete;
} // namespace crepe

#include "Script.hpp"