extends Control

var vscrollbar:			VScrollBar
var labels:				Array
var labels_positions:	Array
var labels_sizes:		Array
var sizes:		Array
var items: Array = [
	"item 1",
	"item 22",
	"item 333",
	"item 4444",
	"item 55555",
	"item 666666",
	"item 7777777",
	"item 88888888",
	"item 999999999",
	"This is the longest item of all, but eventually stops.",
	"item 1",
	"item 22",
	"item 333",
	"item 4444",
	"item 55555",
	"item 666666",
	"item 7777777",
	"item 88888888",
	"item 999999999",
	"This is the longest item of all, but eventually stops.",
	"item 1",
	"item 22",
	"item 333",
	"item 4444",
	"item 55555",
	"item 666666",
	"item 7777777",
	"item 88888888",
	"item 999999999",
	"This is the longest item of all, but eventually stops.",
]

var limit := 60
var labels_pool: Array

onready var font: Font = get_font("font")

func _init():
	vscrollbar = VScrollBar.new()
	vscrollbar.anchor_left		= 1.0
	vscrollbar.anchor_bottom	= 1.0
	vscrollbar.grow_horizontal = Control.GROW_DIRECTION_BEGIN
	vscrollbar.name = "vscrollbar"
	add_child(vscrollbar)


func _ready():
	var num_labels := max_required_labels()
	var labels_pool_size = int(ceil(num_labels * 1.10))
	for idx in range(labels_pool_size):
		var label := Label.new()
		label.autowrap = true
		label.anchor_left = 0.0
		label.anchor_right = 1.0
		label.valign = Label.VALIGN_TOP
		labels_pool.push_back(label)
	
	for idx in range(min(num_labels, items.size())):
		var label = labels_pool.pop_back()
		label.text = items[idx]
		labels.append(label)
		add_child(label)
	
#	for it in items:
#		var label := Label.new()
#		label.text = it
#		label.autowrap = true
#		label.anchor_left = 0.0
#		label.anchor_right = 1.0
#		label.valign = Label.VALIGN_CENTER
#		labels.push_back(label)
#		add_child(label)
	
	process_labels()


func process_labels():
	labels_positions.clear()
	labels_sizes.clear()
	var position := 0.0
	var limit := rect_size.x
#	labels_positions.append(0)
	for it in items:
		var size := font.get_wordwrap_string_size(it, limit).y
		var lines = size / font.get_height()
		var height = size + font.get_descent() * lines
		position += height
		labels_positions.append(position)
		labels_sizes.append(height)


func _process(delta):
	
	var num_labels = max_required_labels()
	var difference = num_labels - labels.size()
	if difference > 0:
		for idx in range(difference):
			var label = labels_pool.pop_back()
			labels.append(label)
			add_child(label)
	elif difference < 0:
		for idx in range(abs(difference)):
			var label = labels.pop_back()
			labels_pool.append(label)
			remove_child(label)
	
	# @DAM Since the items may have different heights, we must look at the edge items
	# in order to update the offsets.
	process_labels()
	
	vscrollbar.min_value = 0
	vscrollbar.max_value = rect_size.y
	var ratio := rect_size.y / float(labels_positions[labels_positions.size()-1])
	vscrollbar.visible = ratio < 1.0
	vscrollbar.page = ratio * (vscrollbar.max_value - vscrollbar.min_value)
	
	var offset := vscrollbar.value
	var bs_value := offset / ratio
	var offset_idx := labels_positions.bsearch(bs_value)

#	offset_idx = 0
	for idx in range(min(num_labels, items.size())):
		var label = labels[idx]
		if idx + offset_idx >= items.size():
			label.text = ""
			break # @DAM Or should we use continue?
		label.text = items[idx + offset_idx]
		label.rect_position.y = labels_positions[idx + offset_idx] - labels_sizes[idx + offset_idx] - bs_value
		# This was initially used to bring back down the height of the labels that grow due to text
		# wrap because they were vertically aligned to CENTER without a good reason to do so.
		# Since the labels are now aligned to TOP, we may just forget about their height.
#		label.rect_size.y = 0.0
	
	
#	if difference != 0:
#		for idx in range(min(num_labels, items.size())):
#			labels[idx].text = items[idx]
	
#	if Engine.get_idle_frames() % 30 == 1:
#		print_debug("> %s | %5.3f > %s > %d | lastPos: %s" % [labels.size(), offset, bs_value, offset_idx, labels_positions[-1]])
	
	
	# Adapt scrollbar according to options and drawable size.
	# @DAM This does not take into consideration the items that are wrapped.

	
	



func max_required_labels() -> int:
	var max_labels := ceil(rect_size.y / font.get_height()) + 1
	return int(min(items.size(), max_labels))
	
#func _draw():
#	var position := Vector2(0.0, font.get_height())
#	for it in items:
#		var p = font.get_wordwrap_string_size(it, limit)
#		print_debug("> %s : %s" % [p, it])
#		draw_string(font, position, it, Color.white, limit)
#		font.get_string_size(it)
#		position.y += p.y