extends Control
class_name PointerInputSensor

# All on_ACTION signals have a single argument of type PointerInputData.
signal on_press
signal on_release
#signal on_release_outside
signal on_click
signal on_enter
signal on_exit
#signal on_exit_app_window
signal on_begin_drag
signal on_drag
signal on_end_drag
signal on_scroll

enum PointerInputAction {
	UNDEFINED,
	ON_PRESS,
	ON_RELEASE,
#	ON_RELEASE_OUTSIDE,
	ON_CLICK,
	ON_ENTER,
	ON_EXIT,
#	ON_EXIT_APP_WINDOW,
	ON_BEGIN_DRAG,
	ON_DRAG,
	ON_END_DRAG,
	ON_SCROLL,
}

class PointerInputData:
	var target: PointerInputSensor
	var event: InputEvent
	var index := -1
	var initial_position := Vector2.ZERO
	var current_position := Vector2.ZERO
	var relative_position := Vector2.ZERO
	var velocity := Vector2.ZERO
	var was_dragged := false
	var is_pressed := false
	var scroll := 0.0
	var action: int = PointerInputAction.UNDEFINED


export var drag_threshold_cm: float = 0.250

var pointer: PointerInputData
var screen_dpcm: float


func _ready():
	screen_dpcm = float(OS.get_screen_dpi()) / 2.54
	pointer = PointerInputData.new()
	pointer.target = self
	connect("mouse_entered", self, "_on_enter_exit", [true])
	connect("mouse_exited", self, "_on_enter_exit", [false])


func _on_enter_exit(is_inside: bool):
	pointer.action = PointerInputAction.ON_ENTER if is_inside else PointerInputAction.ON_EXIT
	emit_signal("on_enter" if is_inside else "on_exit", pointer)


func _gui_input(event: InputEvent):
	
	# @DAM A bug on GODOT-3.X makes events from non-mouse-emulated pointers (index > 0) unreliable.
	if event is InputEventScreenTouch || event is InputEventScreenDrag:
		if event.index != 0:
			return
	
	pointer.event = event
	pointer.action = PointerInputAction.UNDEFINED
	pointer.velocity = Vector2.ZERO
	pointer.relative_position = Vector2.ZERO
	pointer.scroll = 0.0
	pointer.current_position = get_global_mouse_position()
	
	if event is InputEventScreenTouch && (pointer.is_pressed == false || pointer.index == event.index):
		var touch := event as InputEventScreenTouch
		pointer.is_pressed = event.pressed
		
		if pointer.is_pressed:
			pointer.index = touch.index
			pointer.initial_position = pointer.current_position
			pointer.action = PointerInputAction.ON_PRESS
			emit_signal("on_press", pointer)
		else:
			pointer.action = PointerInputAction.ON_RELEASE
			emit_signal("on_release", pointer)
			if pointer.was_dragged == false:
				pointer.action = PointerInputAction.ON_CLICK
				emit_signal("on_click", pointer)
			else:
				pointer.action = PointerInputAction.ON_END_DRAG
				emit_signal("on_end_drag", pointer)
			pointer.index = -1
			pointer.was_dragged = false
	
	if event is InputEventScreenDrag && event.index == pointer.index:
		var drag := event as InputEventScreenDrag
		pointer.velocity = drag.speed
		pointer.relative_position = drag.relative
		if pointer.was_dragged == false && pointer.current_position.distance_to(pointer.initial_position) > drag_threshold_cm * screen_dpcm:
			pointer.was_dragged = true
			pointer.action = PointerInputAction.ON_BEGIN_DRAG
			emit_signal("on_begin_drag", pointer)
		pointer.action = PointerInputAction.ON_DRAG
		emit_signal("on_drag", pointer)
	
	if event is InputEventMouseButton && event.is_pressed():
		if event.button_index == BUTTON_WHEEL_UP || event.button_index == BUTTON_WHEEL_DOWN:
			pointer.scroll = -1.0 if event.button_index == BUTTON_WHEEL_UP else 1.0
			pointer.action = PointerInputAction.ON_SCROLL
			emit_signal("on_scroll", pointer)