extends Tree


const TEXT_COLUMN := 0


# section ==  0 if dropping on item
# section == -1 if dropping above item
# section == +1 if dropping below item
signal item_moved(item, to_item, section)


var invite_text = "+"


func _ready():
	setup()
	setup_dummy_items()
	append_item_invitation()


func setup():
	var root := create_item()
	root.set_text(TEXT_COLUMN, "Candidates")
	
	var _c
	_c = connect("item_edited", self, "__on_item_edited")
	_c = connect("item_moved", self, "__on_item_moved")


func setup_dummy_items():
	create_candidate_item("Candidate A")
	create_candidate_item("Candidate B")


func create_candidate_item(__name:String):
	var candidate_item := create_item()
	candidate_item.set_editable(TEXT_COLUMN, true)
	candidate_item.set_text(TEXT_COLUMN, __name)


func append_item_invitation():
	var root = get_root()
	var items = __get_children_items(root)
	
	if items and items.back().get_text(TEXT_COLUMN) == invite_text:
		return
	
	var invite = create_item(root)
	invite.set_editable(TEXT_COLUMN, true)
	invite.set_text(TEXT_COLUMN, invite_text)
	invite.move_to_bottom()  # superfluous


func prune_empty_items():
#	var items_to_prune = Array()
	for item in __get_children_items(get_root()):
		if item.get_text(TEXT_COLUMN) == '':
			if item.get_next():
				item.get_next().select(TEXT_COLUMN)
				ensure_cursor_is_visible()
			item.free()


func __on_item_edited():
	append_item_invitation()
	
	var selected = get_next_selected(null)
	if selected and selected.get_next():
		selected.get_next().select(TEXT_COLUMN)
		ensure_cursor_is_visible()
	
	prune_empty_items()  # after, since it may change item selection


func __on_item_moved(item, to_item, section):
	if not to_item:
		printerr("No item unto which to drop.  Weird.")
	var offset = 0 if section <= 0 else 1
	var new_item = create_item(get_root(), __get_item_index(to_item)+offset)
	new_item.set_text(TEXT_COLUMN, item.get_text(TEXT_COLUMN))
	new_item.set_editable(TEXT_COLUMN, true)
	new_item.select(TEXT_COLUMN)
	item.free()
	ensure_cursor_is_visible()


func __get_children_items(parent:TreeItem) -> Array:
	var items := Array()
	var item = parent.get_children()
	while (item):
		items.append(item)
		item = item.get_next()
	return items


func __get_item_index(of_item:TreeItem):
	var parent = of_item.get_parent()
	assert(parent)  # or return … what, zero?
	var index := 0
	var item : TreeItem = parent.get_children()
	while (item):
		if item == of_item:
			return index
		item = item.get_next()
		index += 1
	assert(false, "Item not found")
	return -1


func get_drag_data(_position) -> TreeItem:
	set_drop_mode_flags(DROP_MODE_INBETWEEN)

	var item_preview = Label.new()
	item_preview.text = get_selected().get_text(TEXT_COLUMN)
	set_drag_preview(item_preview)

	return get_selected()


func can_drop_data(_position, data):
	return data is TreeItem


func drop_data(position, item):
	var to_item = get_item_at_position(position)
	var section = get_drop_section_at_position(position)
	if not to_item or section == -100:
		#printerr("Dropping in the void")
		to_item = get_root().get_children()
		section = 0
	
	emit_signal('item_moved', item, to_item, section)