extends Container
class_name TopicDraggable


onready var topic_feed: VBoxContainer = get_node("..")
onready var scroll_container: ScrollContainer = get_node("../..")
onready var v_scroll: VScrollBar = get_node("../../_v_scroll")
onready var editable = get_node("TopicEditable")
onready var tween = get_node("Tween")

var global_position setget _set_global_position
var _in_fit_in_animation = false
var _previous_position
var _offset


func _ready():
	pass


func _input(event):
	if event is InputEventMouseButton and event.button_index == BUTTON_LEFT:
		if event.is_pressed():
			if _is_mouse_on_control():
				if event.shift:
					topic_feed._toggle_selection_result = _set_selection(null)
					topic_feed._shift_hold = true
				else:
					_deselect_all()
					if  not editable.edit_mode:
						if event.doubleclick:
							editable._enable_edit_mode()
							editable.text_edit.grab_focus()
							editable.text_edit.select_all()
						elif !_in_fit_in_animation:
								_set_as_grabbed()
			elif editable.edit_mode:
				editable.text_edit._confirm()
		else:
			_fit_in_animation()
			topic_feed._shift_hold = false
	
	if event is InputEventMouseMotion:
		if topic_feed.currently_grabbed_topic == self:
			_move_block(event)
			topic_feed.check_all_passings()
		if topic_feed._shift_hold and _is_mouse_on_control():
# warning-ignore:return_value_discarded
			_set_selection(topic_feed._toggle_selection_result)


func _set_selection(to) -> bool:
	# If 'to' is null, selection is toggled.
	if topic_feed.selected_topics.has(self) and to != true:
		topic_feed.selected_topics.erase(self)
		editable._update_color()
		return false
	elif !topic_feed.selected_topics.has(self) and to != false:
		topic_feed.selected_topics.append(self)
		editable._update_color()
		return true
	else:
		return topic_feed.selected_topics.has(self)


func _deselect_all():
	topic_feed.selected_topics.clear()
	topic_feed.update_all_colors()


func _set_as_grabbed():
	var rect = editable.get_global_rect()
	rect_min_size.y = editable.rect_size.y
	editable.set_as_toplevel(true)
	editable.rect_position = rect.position
	topic_feed.currently_grabbed_topic = self
	_previous_position = editable.rect_global_position
	_offset = 0


func _fit_in_animation():
	_in_fit_in_animation = true
	topic_feed.currently_grabbed_topic = null
	tween.stop_all()
	tween.interpolate_property(self, "global_position",
		editable.rect_global_position, rect_global_position,
		0.12, Tween.TRANS_LINEAR, Tween.EASE_IN_OUT
	)
	tween.start()
	yield(tween, "tween_completed")
	editable.set_as_toplevel(false)
	rect_min_size.y = 0
	editable.rect_position = Vector2.ZERO
	_in_fit_in_animation = false


func _move_block(event):
	_offset += event.relative.y
	editable.set_global_position(_previous_position + Vector2(0.0, _offset))


func _is_mouse_on_control() -> bool:
	return get_global_rect().has_point(get_viewport().get_mouse_position())


func set_previous_position():
	_previous_position = editable.rect_global_position


func check_for_passing() -> bool:
	var dragged: TopicDraggable = topic_feed.currently_grabbed_topic
	if dragged == self or dragged == null:
		return false
	
	var dir = sign(dragged.get_index() - get_index())
	
	var self_rect = get_global_rect()
	var self_half_size = self_rect.size.y * 0.5
	# Center line.
	var self_coll_line = self_rect.position.y + self_half_size
	
	var dragged_rect = dragged.editable.get_global_rect()
	var dragged_half_size = dragged_rect.size.y * 0.5
	var dragged_half_pos = dragged_rect.position.y + dragged_half_size
	# Top or bottom line, depending on if moved up or down.
	var dragged_coll_line = dragged_half_pos + dragged_half_size * -dir
	
	# +1 if dragged_coll_line is below; -1 if above.
	var coll_dir = sign(self_coll_line - dragged_coll_line)
	
	if coll_dir == dir:
		topic_feed.set_all_previous_positions()
		topic_feed.move_child(
			topic_feed.currently_grabbed_topic,
			get_index()
			)
		return true
	return false


func setup_tween():
	if _previous_position != editable.rect_global_position:
		tween.stop_all()
		tween.interpolate_property(self, "global_position",
				_previous_position, rect_global_position, 0.15,
				Tween.TRANS_LINEAR, Tween.EASE_IN_OUT
			)
		tween.start()


func _set_global_position(value):
	editable.set_global_position(value)