class_name PropThumbnail
extends Node

const PROP_BLOCK := preload("res://scripts/prop_block.gd")

const SIZE := Vector2i(200, 200)

var _viewport: SubViewport
var _world: Node2D
var _camera: Camera2D


func _ready() -> void:
	_viewport = SubViewport.new()
	_viewport.size = SIZE
	_viewport.transparent_bg = true
	_viewport.render_target_update_mode = SubViewport.UPDATE_ALWAYS
	add_child(_viewport)
	_world = Node2D.new()
	_viewport.add_child(_world)
	_camera = Camera2D.new()
	_camera.enabled = true
	_viewport.add_child(_camera)
	_camera.make_current()


func render(payload: Dictionary, material_preset: int) -> Texture2D:
	_clear_world()
	var points := _compute_points(payload)
	var fill := Color(payload.get("fill_color", Color.WHITE))
	var outline := Color(payload.get("outline_color", Color.BLACK))
	if material_preset != PROP_BLOCK.MaterialPreset.NONE:
		var tint := PROP_BLOCK.tint_for(material_preset)
		fill = tint
		outline = tint.darkened(0.55)
	var outline_width := float(payload.get("outline_width", 2.0))
	var visual := Node2D.new()
	var poly := Polygon2D.new()
	poly.polygon = points
	poly.color = fill
	var line := Line2D.new()
	var loop := points.duplicate()
	if not loop.is_empty():
		loop.append(points[0])
	line.points = loop
	line.default_color = outline
	line.width = outline_width
	line.joint_mode = Line2D.LINE_JOINT_ROUND
	line.begin_cap_mode = Line2D.LINE_CAP_ROUND
	line.end_cap_mode = Line2D.LINE_CAP_ROUND
	visual.add_child(poly)
	visual.add_child(line)
	_world.add_child(visual)
	_frame_camera(_points_bbox(points))
	await RenderingServer.frame_post_draw
	await RenderingServer.frame_post_draw
	var tex := _viewport.get_texture()
	visual.queue_free()
	if tex == null:
		return null
	var img := tex.get_image()
	if _is_blank(img):
		return null
	return ImageTexture.create_from_image(img)


func _compute_points(payload: Dictionary) -> PackedVector2Array:
	var shape_type: int = int(payload.get("type", PROP_BLOCK.ShapeType.POLYGON))
	if shape_type == PROP_BLOCK.ShapeType.CIRCLE:
		var radius := float(payload.get("radius", 24.0))
		var loop := PackedVector2Array()
		for i: int in PROP_BLOCK.CIRCLE_SEGMENTS:
			var angle: float = TAU * float(i) / float(PROP_BLOCK.CIRCLE_SEGMENTS)
			loop.append(Vector2(cos(angle), sin(angle)) * radius)
		return loop
	return payload.get("points", PackedVector2Array())


func _points_bbox(points: PackedVector2Array) -> Rect2:
	if points.is_empty():
		return Rect2(Vector2(-24, -24), Vector2(48, 48))
	var rect := Rect2(points[0], Vector2.ZERO)
	for p: Vector2 in points:
		rect = rect.expand(p)
	if rect.size.x < 1.0 or rect.size.y < 1.0:
		return Rect2(Vector2(-24, -24), Vector2(48, 48))
	return rect


func _clear_world() -> void:
	for child: Node in _world.get_children():
		child.queue_free()


func _frame_camera(bbox: Rect2) -> void:
	var margin := 12.0
	var fit := minf((SIZE.x - margin * 2.0) / bbox.size.x, (SIZE.y - margin * 2.0) / bbox.size.y)
	_camera.position = bbox.get_center()
	_camera.zoom = Vector2(maxf(fit, 0.05), maxf(fit, 0.05))


func _is_blank(img: Image) -> bool:
	if img == null or img.is_empty():
		return true
	var used := img.get_used_rect()
	if used.size.x <= 0 or used.size.y <= 0:
		return true
	for y: int in range(used.position.y, used.end.y):
		for x: int in range(used.position.x, used.end.x):
			if img.get_pixel(x, y).a > 0.0:
				return false
	return true