extends SceneTree

# Forgejo #228: the HUD must not be three times larger on a PC than on a
# phone.
#
# The layout is authored in CANVAS units. With stretch "canvas_items" and
# aspect "expand" over a 1920x1080 base, a 720x1280 phone scales by 0.375 and
# gets 1920x3413 canvas units, while ANY 16:9-or-wider screen lands on
# 1920x1080 units however many pixels it really has. The canvas is three
# times shorter, so an unscaled 148-unit button goes from 4.3% of the
# screen's height to 13.7% of it.
#
# Nothing collides - that was checked pair by pair on both canvases and the
# same six pairs overlap on each, all of them same-slot alternatives. The
# fault is purely that everything is enormous.
#
# Covers:
#   A. on a phone the HUD is left exactly as authored
#   B. on a desktop canvas a control takes a similar FRACTION of the screen
#      rather than three times more
#   C. the shrink is bounded, so a landscape phone keeps thumb-sized targets
#   D. it follows a resize rather than only applying once at startup

const PHONE: Vector2i = Vector2i(720, 1280)
const DESKTOP: Vector2i = Vector2i(1920, 1080)
const BIG_DESKTOP: Vector2i = Vector2i(2560, 1440)

var scene: Node
var hud: Node
var button: Control
var frames: int = 0
var stage: int = 0
var phone_fraction: float = 0.0


func _initialize() -> void:
	var gs: Node = root.get_node("GameState")
	gs.buildings.clear()
	gs.reset_new_game()
	gs.intro_active = false
	scene = load("res://world/Main.tscn").instantiate()
	root.add_child(scene)
	current_scene = scene
	hud = scene.get_node("UI/HudScale")
	button = scene.get_node("UI/MapButton")


func _fraction() -> float:
	# Height of a HUD control as a share of the screen's height - the number
	# that actually differs between the two, and the one a player sees.
	# Rendered height, not the layout rect: the rect keeps its authored size
	# and the node is scaled, so scale is where the shrink actually lives.
	return (button.size.y * button.scale.y) / button.get_viewport_rect().size.y


func _process(_delta: float) -> bool:
	frames += 1
	if frames < 10:
		return false
	frames = 0
	match stage:
		0:
			root.size = PHONE
			stage = 1
			return false
		1:
			# --- A. authored size on the shape it was authored for -------
			var k: float = hud.hud_scale()
			if not is_equal_approx(k, 1.0):
				return _fail("the phone HUD is being scaled by %.3f, but it is the authored shape" % k)
			phone_fraction = _fraction()
			print("phone %s: canvas %.0f tall, scale %.2f, control is %.1f%% of the screen" % [
				PHONE, button.get_viewport_rect().size.y, k, phone_fraction * 100.0])
			root.size = DESKTOP
			stage = 2
			return false
		2:
			# --- B. a similar share of a desktop screen ------------------
			var pc_fraction: float = _fraction()
			var ratio: float = pc_fraction / maxf(phone_fraction, 0.0001)
			print("desktop %s: canvas %.0f tall, scale %.2f, control is %.1f%% of the screen (%.2fx the phone)" % [
				DESKTOP, button.get_viewport_rect().size.y, hud.hud_scale(),
				pc_fraction * 100.0, ratio])
			if ratio > 1.75:
				return _fail("a HUD control is %.2fx its phone share on a desktop screen - that is the bug" % ratio)
			# --- C. and not shrunk into uselessness ----------------------
			if hud.hud_scale() < 0.4:
				return _fail("the HUD shrank to %.2f, past anything pressable" % hud.hud_scale())
			root.size = BIG_DESKTOP
			stage = 3
			return false
		3:
			# --- D. follows the resize -----------------------------------
			var big: float = _fraction()
			print("big desktop %s: control is %.1f%% of the screen" % [BIG_DESKTOP, big * 100.0])
			if absf(big - phone_fraction) / maxf(phone_fraction, 0.0001) > 0.75:
				return _fail("a bigger desktop screen did not keep the control proportional (%.1f%% vs %.1f%%)" \
					% [big * 100.0, phone_fraction * 100.0])
			# Back to the phone: the HUD must return, not stay shrunk.
			root.size = PHONE
			stage = 4
			return false
		4:
			if not is_equal_approx(hud.hud_scale(), 1.0):
				return _fail("returning to the phone shape left the HUD at %.3f" % hud.hud_scale())
			if absf(_fraction() - phone_fraction) > 0.001:
				return _fail("the HUD did not come back to its authored size on resize")
			print("resizing back to the phone restored the authored size")
			print("TEST_HUD_SCALES_TO_SCREEN: PASS")
			quit(0)
			return true
	return false


func _fail(message: String) -> bool:
	print("TEST_HUD_SCALES_TO_SCREEN: FAIL (%s)" % message)
	quit(1)
	return true