extends Control

const VELOCITY_DECAYING_FACTOR: float = 5.5
const BINNING_THRESHOLD: float = 0.75
const BINNING_ADJUST_P: float = 5.0

export var min_value: int setget set_min_value
export var max_value: int setget set_max_value
var num_of_values: int

func set_min_value(value: int):
	min_value = value
	num_of_values = max_value - min_value + 1

func set_max_value(value: int):
	max_value = value
	num_of_values = max_value - min_value + 1

var pointer: Dictionary
var value: float = 0.0
var anchor: float = 0.0

var current_value_base_position: float
var next_value_base_position: float
var previous_value_base_position: float


func _ready():
	pointer = {
			index = -1,
			initial_position = Vector2.ZERO,
			current_position = Vector2.ZERO,
			velocity = Vector2.ZERO,
			is_active = false,
		}
	current_value_base_position = ($value as Label).rect_position.y
	next_value_base_position = ($value_next as Label).rect_position.y
	previous_value_base_position = ($value_previous as Label).rect_position.y


func _process(delta: float):
	
	# @DAM TODO It's weird that we use '-value'... check maths.
	var scroll_unit_height := ($value as Label).rect_size.y
	var normalized_value := - value / scroll_unit_height
	var normalized_int_value := round(normalized_value) as int
	#	$debug.text = "%s | %s" % [normalized_value, normalized_int_value]
	
	pointer.velocity *= clamp((1.0 - VELOCITY_DECAYING_FACTOR * delta), 0.0, 1.0)
	if pointer.is_active:
		value = anchor + (pointer.current_position.y - pointer.initial_position.y)
	elif is_zero_approx(pointer.velocity.y) == false:
		value += pointer.velocity.y * delta
		if abs(pointer.velocity.y) < BINNING_THRESHOLD * scroll_unit_height:
			var fix := ((normalized_int_value as float) - normalized_value) * scroll_unit_height
			value -= fix * BINNING_ADJUST_P * delta
	
	var logic_value := min_value + fposmod(normalized_int_value, num_of_values)
	var logic_next_value := min_value + fposmod(normalized_int_value + 1, num_of_values)
	var logic_previous_value := min_value + fposmod(normalized_int_value - 1, num_of_values)
	
	$value.text = "%d" % logic_value
	$value_next.text = "%d" % logic_next_value
	$value_previous.text = "%d" % logic_previous_value
	
	var normalized_displacement := normalized_value - normalized_int_value
	var displacement := normalized_displacement * scroll_unit_height
	
	($value as Label).rect_position.y = current_value_base_position - displacement
	($value_previous as Label).rect_position.y = previous_value_base_position - displacement
	($value_next as Label).rect_position.y = next_value_base_position - displacement
	
	($value_next as Label).modulate.a = normalized_displacement + 0.5
	($value_previous as Label).modulate.a = 0.5 - normalized_displacement
	
	var current_pos := value
	var turn_over := num_of_values * scroll_unit_height
	if current_pos >= turn_over || current_pos < 0.0:
		value = fposmod(current_pos, turn_over)


func _gui_input(event: InputEvent):
	
	# @DAM TODO When we release the pointer, we will receive an event that will se the 'current_position' as the last 'touch.position'.
	if event is InputEventScreenTouch:
#	if (event is InputEventScreenTouch && pointer.is_active && pointer.index == event.index
#	|| event is InputEventScreenTouch && pointer.is_active == false):
		var touch := event as InputEventScreenTouch
		pointer.is_active = event.pressed
		pointer.current_position = touch.position
		if pointer.is_active:
			pointer.index = touch.index
			pointer.initial_position = touch.position
			anchor = value
		else:
			pointer.index = -1
	
	if event is InputEventScreenDrag && event.index == pointer.index:
		var drag := event as InputEventScreenDrag
		pointer.current_position = drag.position
		pointer.velocity = drag.speed


func set_value(value: int):
	breakpoint # @DAM TODO


func get_value() -> int:
	breakpoint # @DAM TODO
	return 0