extends SceneTree

## Dev tool: how abruptly does the model change posture when you start running?
##
##   godot --headless --path . -s res://debug/transition_check.gd -- [skin_glb]
##
## Accelerates from a standstill the way the movement code does, then stops, and
## logs the clip in play plus the body's forward lean each frame. Reports the
## worst single-frame change in lean and how long the lean took to arrive.
##
## Written for "idle to running snaps the character leaning forward". The lean
## is procedural (ShooterPoseModifier), so it does NOT come from the clip
## crossfade and is not visible in an animation-blend graph — it was driven by a
## normalised input direction that steps 0 -> 1 the instant a key goes down,
## planting a full run posture in ~0.1 s while the Idle->Run crossfade still had
## 0.4 s to run.

const ACCEL := 18.0     # m/s^2, roughly the controller's ground acceleration
const TOP := 9.0        # m/s
const DT := 1.0 / 60.0

var _t := 0.0
var _frames := 0
var _model: SkinnedPlayerModel = null
var _speed := 0.0
var _prev_lean := 0.0
var _worst_step := 0.0
var _clip_changes: Array = []
var _last_clip := ""
var _t_10 := -1.0
var _t_90 := -1.0
var _peak := 0.0


func _initialize() -> void:
	var args := OS.get_cmdline_user_args()
	var path: String = args[0] if args.size() > 0 \
		else "res://assets/characters/skins/taila.glb"
	var scene := Node3D.new()
	root.add_child(scene)
	current_scene = scene
	_model = SkinnedPlayerModel.new()
	_model.model_path = path
	scene.add_child(_model)


func _process(_delta: float) -> bool:
	_frames += 1
	if _frames < 8:
		return false
	if not _model.loaded:
		return false

	# Accelerate for 1.5 s, then coast at top speed to 2.5 s.
	_t += DT
	_speed = minf(TOP, _speed + ACCEL * DT) if _t < 2.5 else 0.0
	_model.update_state("ground", _speed, false)
	_model.set_locomotion(0.0, 1.0 if _speed > 0.01 else 0.0, 0.0)

	var lean: float = _model.get_lean_debug()
	if _last_clip != _model.current_clip_debug():
		_last_clip = _model.current_clip_debug()
		_clip_changes.append("%.2fs %s @ %.1f m/s" % [_t, _last_clip, _speed])
	if _t < 2.5:
		_peak = maxf(_peak, lean)
		if _t_10 < 0.0 and lean > 0.1:
			_t_10 = _t
		if _t_90 < 0.0 and lean > 0.9:
			_t_90 = _t
		_worst_step = maxf(_worst_step, absf(lean - _prev_lean))
	_prev_lean = lean

	if _t > 3.5:
		print("\n=== idle -> run transition ===")
		print("  clip changes: " + ", ".join(_clip_changes))
		print("  lean reached 10%% at %.2fs, 90%% at %.2fs (peak %.2f)" % [_t_10, _t_90, _peak])
		print("  worst single-frame lean change: %.4f  (%.2f per second at 60fps)"
			% [_worst_step, _worst_step * 60.0])
		print("  a snap looks like ~0.10s to 90%%; a blended move is ~0.6s or more\n")
		return true
	return false