extends ItemList
class_name TouchItemList

const POINTER_VELOCITY_DECAYING_FACTOR: float = 2.5

var is_pointer_dragging		:= false
var pointer_drag_velocity	:= 0.0

onready var drag_sensor		:= get_node("drag_sensor") as PointerInputSensor
onready var v_scroll_bar	:= get_v_scroll() as ScrollBar


func _ready():
	drag_sensor.connect("on_press", self, "pointer_input_handler")
	drag_sensor.connect("on_drag", self, "pointer_input_handler")
	drag_sensor.connect("on_end_drag", self, "pointer_input_handler")
	drag_sensor.connect("on_click", self, "pointer_input_handler")
	drag_sensor.connect("on_scroll", self, "pointer_input_handler")


func _process(delta: float):
	# Apply drag movement inertia.
	if is_pointer_dragging == false && abs(pointer_drag_velocity) > 0.5:
		pointer_drag_velocity *= clamp((1.0 - POINTER_VELOCITY_DECAYING_FACTOR * delta), 0.0, 1.0)
		v_scroll_bar.value -= pointer_drag_velocity * delta


func pointer_input_handler(pointer: PointerInputSensor.PointerInputData):
	match pointer.action:
		PointerInputSensor.PointerInputAction.ON_PRESS:
			is_pointer_dragging = true
		
		PointerInputSensor.PointerInputAction.ON_DRAG:
			is_pointer_dragging = true
			pointer_drag_velocity = pointer.velocity.y
			v_scroll_bar.value -= pointer.relative_position.y
		
		PointerInputSensor.PointerInputAction.ON_END_DRAG:
			is_pointer_dragging = false
		
		PointerInputSensor.PointerInputAction.ON_SCROLL:
			var target := self
			target._gui_input(pointer.event)
		
		PointerInputSensor.PointerInputAction.ON_CLICK:
			var target := self
			var position := target.get_global_mouse_position() - target.rect_global_position
			
			var event_touch := InputEventScreenTouch.new()
			event_touch.index = 0
			event_touch.position = position
			
			var event_mouse := InputEventMouseButton.new()
			event_mouse.button_index = BUTTON_LEFT
			event_mouse.button_mask = BUTTON_MASK_LEFT
			event_mouse.position = position
			
			event_mouse.pressed = true
			event_touch.pressed = true
			target._gui_input(event_mouse)
			target._gui_input(event_touch)
			
			target.grab_focus()
			
			event_mouse.pressed = false
			event_touch.pressed = false
			target._gui_input(event_mouse)
			target._gui_input(event_touch)