extends SceneTree

## Deterministic third-person run-to-stop capture.
##
## Run:
##   godot --path . --resolution 1280x720 \
##     --script res://debug/locomotion_stop_capture.gd -- <out_dir> [skin_id]

const DT := 1.0 / 60.0
const RUN_FRAMES := 90

var _out_dir := "."
var _skin_id := "miku"
var _frames := 0
var _player: CharacterBody3D = null
var _model: SkinnedPlayerModel = null
var _camera: Camera3D = null
var _motion_frame := 0
var _stop_frame := -1
var _worst_run_stride_error := 0.0
var _worst_stop_stride := 0.0
var _failures: Array[String] = []


func _initialize() -> void:
	Engine.max_fps = 60
	var args := OS.get_cmdline_user_args()
	if args.size() > 0:
		_out_dir = args[0]
	if args.size() > 1:
		_skin_id = args[1]
	if not _out_dir.is_absolute_path():
		_out_dir = ProjectSettings.globalize_path(_out_dir)
	var mkdir_error := DirAccess.make_dir_recursive_absolute(_out_dir)
	if mkdir_error != OK:
		printerr("LOCO_STOP could not create '%s' (error %d)" % [
			_out_dir, mkdir_error])
		quit(mkdir_error)
		return
	change_scene_to_file("res://ui/main_menu/main_menu.tscn")


func _process(_delta: float) -> bool:
	_frames += 1
	if _frames == 40:
		var skin_manager = root.get_node_or_null("SkinManager")
		if skin_manager:
			skin_manager.set_active_skin(_skin_id)
		var network = root.get_node_or_null("NetworkManager")
		if network and network.has_method("start_singleplayer_match"):
			network.start_singleplayer_match(GameMode.DEATHMATCH)
		change_scene_to_file("res://scenes/maps/test_level/test_level.tscn")
		return false
	if _frames < 160:
		return false
	if _player == null:
		if not _setup():
			_finish()
			return true

	_motion_frame += 1
	if _motion_frame <= RUN_FRAMES:
		_model.set_locomotion(0.0, 1.0, 0.0)
		_model.update_state("ground", 9.0, false)
		_worst_run_stride_error = maxf(_worst_run_stride_error,
			absf(_model.locomotion_effective_speed_debug() - 9.0))
		if _motion_frame == RUN_FRAMES - 1:
			_snap("loco_stop_00_run")
	else:
		if _stop_frame < 0:
			_stop_frame = 0
		else:
			_stop_frame += 1
		_model.set_locomotion(0.0, 0.0, 0.0)
		_model.update_state("ground", 0.0, false)
		_worst_stop_stride = maxf(_worst_stop_stride,
			_model.locomotion_effective_speed_debug())
	_model._process(DT)

	if _stop_frame >= 0:
		match _stop_frame:
			3:
				_snap("loco_stop_01_idle_blend")
			9:
				_snap("loco_stop_02_idle_arrival")
			20:
				_snap("loco_stop_03_idle")
			50:
				_snap("loco_stop_04_settled")
				if _worst_run_stride_error > 0.02:
					_failures.append("run stride diverged from physical speed")
				if _worst_stop_stride > 0.02:
					_failures.append("authored stride did not stop immediately")
				if absf(_model.get_brake_debug()) > 0.001:
					_failures.append("procedural brake pose is still active")
				_finish()
				return true
	return false


func _setup() -> bool:
	for candidate in root.find_children("*", "CharacterBody3D", true, false):
		if candidate.has_method("get_visual_model") \
				and candidate.is_multiplayer_authority():
			_player = candidate
			break
	if _player == null:
		_failures.append("local player was not created")
		return false
	_model = _player.get_node_or_null("SkinnedModel")
	if _model == null or not _model.loaded:
		_failures.append("skinned model '%s' was not ready" % _skin_id)
		return false
	_player.set_physics_process(false)
	_player.set_process(false)
	_model.set_process(false)
	_player.global_position = Vector3(0.0, 1.2, 14.0)
	_player.rotation = Vector3.ZERO
	_model.set_owner_visible(true)
	if _model.has_method("set_weapon"):
		_model.set_weapon("res://weapons/ak47.gd")
	# The match HUD and the isolated first-person SubViewport are separate
	# CanvasLayers, so a cull mask alone cannot keep them out of this shot.
	for layer in root.find_children("*", "CanvasLayer", true, false):
		layer.visible = false

	_camera = Camera3D.new()
	_camera.cull_mask &= ~(1 << 19)
	current_scene.add_child(_camera)
	_camera.global_position = _player.global_position + Vector3(1.8, 0.85, -1.9)
	_camera.look_at(_player.global_position + Vector3(0.0, 0.45, 0.0), Vector3.UP)
	_camera.current = true
	return true


func _snap(tag: String) -> void:
	var image := root.get_viewport().get_texture().get_image()
	var path := _out_dir.path_join(tag + ".png")
	var error := image.save_png(path)
	if error == OK:
		print("LOCO_STOP saved ", path)
	else:
		_failures.append("could not save %s (error %d)" % [path, error])


func _finish() -> void:
	if _failures.is_empty() and _stop_frame >= 50:
		print("LOCO_STOP PASS: run error %.5f, stop stride %.5f, procedural brake %.5f" % [
			_worst_run_stride_error, _worst_stop_stride,
			_model.get_brake_debug()])
		quit(0)
	else:
		for failure in _failures:
			push_error("LOCO_STOP FAIL: " + failure)
		quit(1)