/* ScummVM - Graphic Adventure Engine
 *
 * ScummVM is the legal property of its developers, whose names
 * are too numerous to list here. Please refer to the COPYRIGHT
 * file distributed with this source distribution.
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 *
 */

#ifndef COMMON_EVENTS_H
#define COMMON_EVENTS_H

#include "common/keyboard.h"
#include "common/path.h"
#include "common/queue.h"
#include "common/rect.h"
#include "common/noncopyable.h"

#include "common/list.h"
#include "common/singleton.h"

namespace Common {

/**
 * @defgroup common_events Events
 * @ingroup common
 *
 * @brief  The types of events backends may generate.
 *
 * @todo Merge EVENT_LBUTTONDOWN, EVENT_RBUTTONDOWN and EVENT_WHEELDOWN;
 *       likewise EVENT_LBUTTONUP, EVENT_RBUTTONUP, EVENT_WHEELUP.
 *       To do that, we just have to add a field to the Event which
 *       indicates which button was pressed.
 * @{
 */

enum EventType {
	EVENT_INVALID = 0,
	/** A key was pressed, details in Event::kbd. */
	EVENT_KEYDOWN = 1,
	/** A key was released, details in Event::kbd. */
	EVENT_KEYUP = 2,
	/** The mouse moved, details in Event::mouse. */
	EVENT_MOUSEMOVE = 3,
	EVENT_LBUTTONDOWN = 4,
	EVENT_LBUTTONUP = 5,
	EVENT_RBUTTONDOWN = 6,
	EVENT_RBUTTONUP = 7,
	EVENT_WHEELUP = 8,
	EVENT_WHEELDOWN = 9,
	EVENT_MBUTTONDOWN = 13,
	EVENT_MBUTTONUP = 14,

	EVENT_MAINMENU = 15,
	EVENT_RETURN_TO_LAUNCHER = 16,
	EVENT_MUTE = 17,

	EVENT_QUIT = 10,
	EVENT_SCREEN_CHANGED = 11,

	/** The input devices have changed, input-related configuration must be reapplied. */
	EVENT_INPUT_CHANGED  = 35,

	/**
	 * The backend requests the AGI engine's predictive dialog to be shown.
	 *
	 * @todo Fingolfin suggests that it would be of better value to expand
	 * on this notion by generalizing its use. For example the backend could
	 * use events to ask for the save game dialog or to pause the engine.
	 * An associated enumerated type can accomplish this.
	 **/
	EVENT_PREDICTIVE_DIALOG = 12,

	EVENT_CUSTOM_BACKEND_ACTION_START = 18,
	EVENT_CUSTOM_BACKEND_ACTION_END   = 19,
	EVENT_CUSTOM_BACKEND_ACTION_AXIS  = 34,
	EVENT_CUSTOM_ENGINE_ACTION_START  = 20,
	EVENT_CUSTOM_ENGINE_ACTION_END    = 21,

	EVENT_VIRTUAL_KEYBOARD = 22,

	EVENT_DROP_FILE = 23,

	EVENT_JOYAXIS_MOTION = 24,
	EVENT_JOYBUTTON_DOWN = 25,
	EVENT_JOYBUTTON_UP = 26,

	EVENT_CLIPBOARD_UPDATE = 27,

	EVENT_CUSTOM_BACKEND_HARDWARE = 28,
	EVENT_DEBUGGER = 29,

	/**
	 * Additional mouse events, details in Event::mouse.
	 *
	 * Note that X1 and X2 are usually back and forward, however
	 * this cannot be guaranteed on all platforms.
	 */
	EVENT_X1BUTTONDOWN = 30,
	EVENT_X1BUTTONUP = 31,
	EVENT_X2BUTTONDOWN = 32,
	EVENT_X2BUTTONUP = 33,

	/** ScummVM has gained or lost focus. */
	EVENT_FOCUS_GAINED = 36,
	EVENT_FOCUS_LOST = 37
};

const int16 JOYAXIS_MIN = -32768;
const int16 JOYAXIS_MAX = 32767;

/**
 * Data structure for joystick events.
 */
struct JoystickState {
	/** The axis for EVENT_JOYAXIS_MOTION events. */
	byte axis;
	/** The new axis position for EVENT_JOYAXIS_MOTION events. */
	int16 position;
	/**
	 * The button index for EVENT_JOYBUTTON_DOWN/UP events.
	 *
	 * Some of the button indices match well-known game controller
	 * buttons. See JoystickButton.
	 */
	uint8 button;

	JoystickState() : axis(0), position(0), button(0) {}
};

/**
 *  The list of named buttons available from a joystick.
 */
enum JoystickButton {
	JOYSTICK_BUTTON_INVALID,
	JOYSTICK_BUTTON_A,
	JOYSTICK_BUTTON_B,
	JOYSTICK_BUTTON_X,
	JOYSTICK_BUTTON_Y,
	JOYSTICK_BUTTON_BACK,
	JOYSTICK_BUTTON_GUIDE,
	JOYSTICK_BUTTON_START,
	JOYSTICK_BUTTON_LEFT_STICK,
	JOYSTICK_BUTTON_RIGHT_STICK,
	JOYSTICK_BUTTON_LEFT_SHOULDER,
	JOYSTICK_BUTTON_RIGHT_SHOULDER,
	JOYSTICK_BUTTON_DPAD_UP,
	JOYSTICK_BUTTON_DPAD_DOWN,
	JOYSTICK_BUTTON_DPAD_LEFT,
	JOYSTICK_BUTTON_DPAD_RIGHT,
	JOYSTICK_BUTTON_DPAD_CENTER
};

/**
 *  The list of named axes available from a joystick.
 */
enum JoystickAxis {
	JOYSTICK_AXIS_LEFT_STICK_X,
	JOYSTICK_AXIS_LEFT_STICK_Y,
	JOYSTICK_AXIS_RIGHT_STICK_X,
	JOYSTICK_AXIS_RIGHT_STICK_Y,
	JOYSTICK_AXIS_LEFT_TRIGGER,
	JOYSTICK_AXIS_RIGHT_TRIGGER,
	JOYSTICK_AXIS_HAT_X,
	JOYSTICK_AXIS_HAT_Y
};

/**
 *  The list named buttons available from a mouse.
 */
enum MouseButton {
	MOUSE_BUTTON_LEFT   = 0,
	MOUSE_BUTTON_RIGHT  = 1,
	MOUSE_BUTTON_MIDDLE = 2,
	MOUSE_WHEEL_UP      = 3,
	MOUSE_WHEEL_DOWN    = 4,
	MOUSE_BUTTON_X1     = 5,
	MOUSE_BUTTON_X2     = 6
};
/** Used by @ref ArtificialEventSource. */
typedef uint32 CustomEventType;

/**
 * Data structure for an event. A pointer to an instance of Event
 * can be passed to pollEvent.
 */
struct Event {

	/** The type of the event. */
	EventType type;

	/**
	 * True if this is a key-down repeat event.
	 *
	 * Only valid for EVENT_KEYDOWN events.
	 */
	bool kbdRepeat;

	/**
	  * Keyboard data; only valid for keyboard events (EVENT_KEYDOWN and
	  * EVENT_KEYUP). For all other event types, content is undefined.
	  */
	KeyState kbd;

	/**
	 * The mouse coordinates, in virtual screen coordinates. Only valid
	 * for mouse events.
	 * 'Virtual screen coordinates' refers to the coordinate system of the
	 * screen area as defined by the most recent call to initSize().
	 */
	Point mouse;

	/** Refers to an event generated by @ref ArtificialEventSource. */
	CustomEventType customType;

	/** The path of the file or directory dragged to the ScummVM window. */
	Common::Path path;

	/**
	 * Mouse movement since the last mouse movement event.
	 */
	Common::Point relMouse;

	/**
	 * Joystick data; only valid for joystick events (EVENT_JOYAXIS_MOTION,
	 * EVENT_JOYBUTTON_DOWN and EVENT_JOYBUTTON_UP).
	 */
	JoystickState joystick;

	Event() : type(EVENT_INVALID), kbdRepeat(false), customType(0) {
	}
};

/**
 * Determine whether an event is a mouse event.
 *
 * Mouse events have valid mouse coordinates.
 */
bool isMouseEvent(const Event &event);

/**
 * A source of Events.
 *
 * An example for this is OSystem, which provides events created by the system
 * and/or user.
 */
class EventSource {
public:
	virtual ~EventSource();

	/**
	 * Query an event from the source.
	 *
	 * @param	event 	Reference to the event struct where the event should be stored.
	 * @retval	true If an event was polled, false otherwise.
	 */
	virtual bool pollEvent(Event &event) = 0;

	/**
	 * Check whether events from this source are allowed to be mapped.
	 *
	 * Possible event sources not allowing mapping are: the event recorder/player and/or
	 * the EventManager, which allows user events to be pushed.
	 *
	 * By default, mapping is allowed for every event source.
	 */
	virtual bool allowMapping() const { return true; }
};

/**
 * An artificial event source. This class is used as an event source, which is
 * made up by client-specific events.
 *
 * Example use cases for this are the Keymapper or the DefaultEventManager.
 */
class ArtificialEventSource : public EventSource {
protected:
	Queue<Event> _artificialEventQueue;
public:
	/** Put the specified event into the queue. */
	void addEvent(const Event &ev) {
		_artificialEventQueue.push(ev);
	}

	bool pollEvent(Event &ev) {
		if (!_artificialEventQueue.empty()) {
			ev = _artificialEventQueue.pop();
			return true;
		} else {
			return false;
		}
	}

	/**
	 * By default, an artificial event source prevents its events
	 * from being mapped.
	 */
	virtual bool allowMapping() const { return false; }
};

/**
 * Object that catches and processes Events.
 *
 * An example for this is the Engine object - it catches events and processes them.
 */
class EventObserver {
public:
	virtual ~EventObserver();

	/**
	 * Notify the observer of an incoming event.
	 *
	 * An observer is supposed to 'eat' the event, with returning true, when
	 * it wants to prevent other observers from receiving the event.
	 * A usage example here is the keymapper:
	 * If it processes an Event, it should 'eat' it and create a new
	 * event, which the EventDispatcher will then catch.
	 *
	 * @param   event   The event that is incoming.
	 * @retval  true If the event should not be passed to other observers,
	 *          false otherwise.
	 */
	virtual bool notifyEvent(const Event &event) = 0;

	/**
	 * Notify the observer of pollEvent() query.
	 */
	virtual void notifyPoll() { }
};

/**
 * A event mapper that maps events to others.
 *
 * An example for this is the Keymapper.
 */
class EventMapper {
public:
	virtual ~EventMapper();

	/**
	 * Map an incoming event to one or more action events.
	 */
	virtual bool mapEvent(const Event &ev, List<Event> &mappedEvents) = 0;
};

/**
 * Dispatch events from various sources to various observers.
 *
 * EventDispatcher uses a priority-based approach. Observers
 * with higher priority are notified before observers with
 * lower priority. Note that observers might 'eat' events,
 * and thus not all observers might be notified.
 *
 * Another speciality is the support for an event mapper that
 * will catch events and create new events out of them. This
 * mapper will be processed before an event is sent to the
 * observers.
 */
class EventDispatcher {
public:
	EventDispatcher();
	~EventDispatcher();

	/**
	 * Attempt to catch events from the registered event
	 * sources and dispatch them to the observers.
	 *
	 * This dispatches *all* events the sources offer.
	 */
	void dispatch();

	/**
	 * Clear all events currently in the event queue.
	 * The cleared events are not dispatched and are simply discarded.
	 */
	void clearEvents();

	/**
	 * Register a new EventMapper with the dispatcher.
	 */
	void registerMapper(EventMapper *mapper, bool autoFree);

	/**
	 * Unregister an EventMapper.
	 *
	 * This takes the "autoFree" flag passed to registerSource into account.
	 */
	void unregisterMapper(EventMapper *mapper);

	/**
	 * Register a new EventSource with the Dispatcher.
	 */
	void registerSource(EventSource *source, bool autoFree);

	/**
	 * Unregister an EventSource.
	 *
	 * This takes the "autoFree" flag passed to registerSource into account.
	 */
	void unregisterSource(EventSource *source);

	/**
	 * Ignore some event sources and don't poll them. This is useful for e.g. the EventRecorder
	 * where you don't want the other EventSource instances to interfer with the serialized events.
	 */
	void ignoreSources(bool ignore);

	/**
	 * Register a new EventObserver with the Dispatcher.
	 *
	 * @param listenPolls If set, then all pollEvent() calls are passed to the observer.
	 *                    Currently, it is used by keyMapper.
	 */
	void registerObserver(EventObserver *obs, uint priority, bool autoFree, bool listenPolls = false);

	/**
	 * Unregister an EventObserver.
	 *
	 * This takes the "autoFree" flag passed to registerObserver into account.
	 */
	void unregisterObserver(EventObserver *obs);
private:
	struct Entry {
		bool autoFree;
		bool ignore;
	};

	struct MapperEntry : public Entry {
		EventMapper *mapper;
	};

	List<MapperEntry> _mappers;

	struct SourceEntry : public Entry {
		EventSource *source;
	};

	List<SourceEntry> _sources;

	struct ObserverEntry : public Entry {
		uint priority;
		EventObserver *observer;
		bool poll;
	};

	List<ObserverEntry> _observers;

	void dispatchEvent(const Event &event);
	void dispatchPoll();
};

class Keymap;
class Keymapper;

/**
 * The EventManager provides user input events to the client code.
 * In addition, it keeps track of the state of various input devices,
 * like keys, mouse position, and buttons.
 */
class EventManager : NonCopyable {
public:
	virtual ~EventManager();

	enum {
		LBUTTON = 1 << MOUSE_BUTTON_LEFT,
		RBUTTON = 1 << MOUSE_BUTTON_RIGHT
	};


	/**
	 * Initialize the event manager.
	 * @note	Called after graphics system has been set up.
	 */
	virtual void init() {}

	/**
	 * Get the next event in the event queue.
	 * @param event	Point to an Event struct, which will be filled with the event data.
	 * @retval true If an event was retrieved.
	 */
	virtual bool pollEvent(Event &event) = 0;

	/**
	 * Push a "fake" event into the event queue.
	 */
	virtual void pushEvent(const Event &event) = 0;

	/**
	 * Purge all unprocessed mouse events already in the event queue.
	 */
	virtual void purgeMouseEvents() = 0;

	/**
	 * Purge all unprocessed keyboard events already in the event queue.
	 */
	virtual void purgeKeyboardEvents() = 0;

	/** Return the current mouse position. */
	virtual Point getMousePos() const = 0;

	/**
	 * Return a bitmask with the button states:
	 * - bit 0: left button up=0, down=1
	 * - bit 1: right button up=0, down=1
	 */
	virtual int getButtonState() const = 0;

	/** Get a bitmask with the current modifier state. */
	virtual int getModifierState() const = 0;

	/**
	 * Whether the application should terminate. Set to true if EVENT_QUIT was received.
	 */
	virtual int shouldQuit() const = 0;

	/**
	 * Whether to return to the launcher.
	 */
	virtual int shouldReturnToLauncher() const = 0;

	/**
	 * Reset the "return to launcher" flag (as returned shouldReturnToLauncher()) to false.
	 * Used when we have returned to the launcher.
	 */
	virtual void resetReturnToLauncher() = 0;
	virtual void resetQuit() = 0;
	// Optional: check whether a given key is currently pressed ????
	//virtual bool isKeyPressed(int keycode) = 0;

	// TODO: Keyboard repeat support?

	// TODO: Consider removing OSystem::getScreenChangeID and
	// replacing it by a generic getScreenChangeID method here
	/** Return the @ref Keymapper object. */
	virtual Keymapper *getKeymapper() = 0;
	/** Return the global @ref Keymap object. */
	virtual Keymap *getGlobalKeymap() = 0;

	enum {
		/**
		 * Priority of the event manager. For now, it is lowest since it eats
		 * *all* events. This might be changed in the future though.
		 */
		kEventManPriority = 0,
		/**
		 * Priority of the event recorder. It must go after the event manager
		 * in order to record events generated by it.
		 */
		kEventRecorderPriority = 1,
		/**
		 * Priority of the remap dialog. It must go first to capture all
		 * the events before they are consumed by other observers.
		 */
		kEventRemapperPriority = 999
	};

	/**
	 * Return the underlying EventDispatcher.
	 */
	EventDispatcher *getEventDispatcher() { return &_dispatcher; }

protected:
	EventDispatcher _dispatcher;
};

/**
 * Wrap an event source so the key-down events are repeated while
 * keys are held down.
 *
 * Does not take ownership of the wrapped EventSource.
 */
EventSource *makeKeyboardRepeatingEventSource(EventSource *eventSource);

/** @} */

} // End of namespace Common

#endif