package allegro5

// #include <allegro5/allegro.h>
import "C"

import (
	"fmt"
	"unsafe"
)

type EventQueue struct {
	queue *C.ALLEGRO_EVENT_QUEUE
}

type Event interface {
	Stamp() float64
}

type EventBase struct {
	stamp float64
}

func (eb EventBase) Stamp() float64 {
	return eb.stamp
}

type DisplayCloseEvent struct {
	EventBase
}

type KeyEvent struct {
	EventBase
	KeyCode int
	Display *Display
}

type KeyCharEvent struct {
	KeyEvent
	UnicodeCharacter rune
	Modifiers        uint
	Repeat           bool
}

type KeyDownEvent struct {
	KeyEvent
}

type KeyUpEvent struct {
	KeyEvent
}

type MouseButtonDownEvent struct {
	MouseEvent
	Button   uint
	Pressure float32
}

type MouseButtonUpEvent struct {
	MouseEvent
	Button   uint
	Pressure float32
}

type MouseEvent struct {
	EventBase
	X, Y    int
	Z, W    int
	Display *Display
}

type MouseMoveEvent struct {
	MouseEvent
	DeltaX, DeltaY int
	DeltaZ, DeltaW int
	Pressure       float32
}

func NewEventQueue() (*EventQueue, error) {
	q := C.al_create_event_queue()
	if nil == q {
		return nil, fmt.Errorf("Unable to create event queue")
	}
	return &EventQueue{q}, nil
}

func (eq *EventQueue) register(source *C.ALLEGRO_EVENT_SOURCE) {
	C.al_register_event_source(eq.queue, source)
}

func (eq *EventQueue) RegisterDisplay(d *Display) {
	eq.register(C.al_get_display_event_source(d.display))
}

func (eq *EventQueue) RegisterMouse() {
	eq.register(C.al_get_mouse_event_source())
}

func (eq *EventQueue) RegisterKeyboard() {
	eq.register(C.al_get_keyboard_event_source())
}

func (eq *EventQueue) mapEvent(e *C.ALLEGRO_EVENT) Event {
	any := (*C.ALLEGRO_ANY_EVENT)(unsafe.Pointer(e))
	eb := EventBase{float64(any.timestamp)}
	switch any._type {
	case C.ALLEGRO_EVENT_DISPLAY_CLOSE:
		return &DisplayCloseEvent{EventBase{float64(any.timestamp)}}
	case C.ALLEGRO_EVENT_MOUSE_AXES:
		mouse := (*C.ALLEGRO_MOUSE_EVENT)(unsafe.Pointer(e))
		return &MouseMoveEvent{MouseEvent{eb, int(mouse.x), int(mouse.y), int(mouse.z), int(mouse.w), nil}, int(mouse.dx), int(mouse.dy), int(mouse.dz), int(mouse.dw), float32(mouse.pressure)}
	case C.ALLEGRO_EVENT_MOUSE_BUTTON_DOWN:
		mouse := (*C.ALLEGRO_MOUSE_EVENT)(unsafe.Pointer(e))
		return &MouseButtonDownEvent{MouseEvent{eb, int(mouse.x), int(mouse.y), int(mouse.z), int(mouse.w), nil}, uint(mouse.button), float32(mouse.pressure)}
	case C.ALLEGRO_EVENT_MOUSE_BUTTON_UP:
		mouse := (*C.ALLEGRO_MOUSE_EVENT)(unsafe.Pointer(e))
		return &MouseButtonUpEvent{MouseEvent{eb, int(mouse.x), int(mouse.y), int(mouse.z), int(mouse.w), nil}, uint(mouse.button), float32(mouse.pressure)}
	case C.ALLEGRO_EVENT_KEY_DOWN:
		key := (*C.ALLEGRO_KEYBOARD_EVENT)(unsafe.Pointer(e))
		return &KeyDownEvent{KeyEvent{eb, int(key.keycode), nil}}
	case C.ALLEGRO_EVENT_KEY_UP:
		key := (*C.ALLEGRO_KEYBOARD_EVENT)(unsafe.Pointer(e))
		return &KeyUpEvent{KeyEvent{eb, int(key.keycode), nil}}
	case C.ALLEGRO_EVENT_KEY_CHAR:
		key := (*C.ALLEGRO_KEYBOARD_EVENT)(unsafe.Pointer(e))
		return &KeyCharEvent{KeyEvent{eb, int(key.keycode), nil}, rune(key.unichar), uint(key.modifiers), bool(key.repeat)}
	}
	return nil
}

func (eq *EventQueue) Get() Event {
	var event C.ALLEGRO_EVENT
	if !bool(C.al_get_next_event(eq.queue, &event)) {
		return nil
	}
	return eq.mapEvent(&event)
}

func (eq *EventQueue) GetWait() Event {
	var event C.ALLEGRO_EVENT
	C.al_wait_for_event(eq.queue, &event)
	return eq.mapEvent(&event)
}

func (eq *EventQueue) Destroy() {
	C.al_destroy_event_queue(eq.queue)
}