extends SceneTree
## Gameplay regression test — runs the full scene, captures a motion frame strip,
## and asserts that physics/IK stays within sane bounds.
##
## Run (headless, assertions only — screenshots will be blank):
##   godot --headless --script tests/gameplay_test.gd
##
## Run (with display for real screenshots):
##   godot --script tests/gameplay_test.gd
##
## Outputs: tests/output/gameplay/*.png + tests/output/gameplay/report.txt
## Exit code 0 = all assertions passed, 1 = any failure.

const OUTPUT_DIR := "res://tests/output/gameplay"

# Tail bone names mirrored from bull_legs.gd — update both if rig changes.
const TAIL_BONES: Array[StringName] = [
	&"tail_1", &"tail_2", &"tail_3", &"tail_4",
	&"tail_5", &"tail_6", &"tail_tip_1", &"tail_tip_2",
]

var _passed: int = 0
var _failed: int = 0
var _report: PackedStringArray = []


func _init() -> void:
	_run.call_deferred()


func _run() -> void:
	DirAccess.make_dir_recursive_absolute(OUTPUT_DIR)

	var scene_res := load("res://scene.tscn")
	if not scene_res:
		push_error("gameplay_test: failed to load scene.tscn")
		quit(1)
		return

	var scene: Node = scene_res.instantiate()
	root.add_child(scene)

	# Let physics, AI, and IK warm up.
	await create_timer(0.5).timeout

	# Capture 5 frames ~0.4 s apart (covers roughly one wander step and walk cycle).
	for i in range(5):
		_capture_frame("motion_%02d.png" % i)
		await create_timer(0.4).timeout

	# After ~2.5 s the tail Verlet chain and IK should be stable.
	_check_tail_integrity()

	# Trigger ragdoll on the first matador and check that bones don't explode.
	var matadors := get_nodes_in_group(&"matador")
	if matadors.size() > 0:
		var mat: Node3D = matadors[0] as Node3D
		var start_pos: Vector3 = mat.global_position
		mat._enter_ragdoll(Vector3(0.0, 0.0, 1.0), 10.0)
		_capture_frame("ragdoll_trigger.png")
		await create_timer(0.8).timeout
		_capture_frame("ragdoll_result.png")
		_check_ragdoll_sanity(mat, start_pos)
	else:
		_note("ragdoll check skipped — no matadors found in scene")

	_finish()


# ── Tail integrity ────────────────────────────────────────────────────────────

func _check_tail_integrity() -> void:
	print("\n-- check_tail_integrity --")
	var players := get_nodes_in_group(&"player")
	if players.is_empty():
		_note("tail check: no player in scene")
		return

	# Prefer reading from the live Verlet chain in the legs node.
	var legs: Node = _find_legs_node(players[0])
	if legs:
		_check_tail_verlet(legs)
		return

	# Fallback: sample bone global poses from Skeleton3D.
	var skel: Skeleton3D = _find_skeleton(players[0]) as Skeleton3D
	if not skel:
		_note("tail check: no Skeleton3D found under player")
		return
	_check_tail_skeleton(skel)


func _check_tail_verlet(legs: Node) -> void:
	var chain: Array = legs._tail_world
	if chain.size() < 2:
		_note("tail Verlet: chain has fewer than 2 nodes — skipping")
		return

	for i in range(chain.size()):
		var p: Vector3 = chain[i]
		_assert_true(p.is_finite(), "tail Verlet node %d is finite" % i)

	for i in range(1, chain.size()):
		var dist: float = (chain[i] as Vector3).distance_to(chain[i - 1])
		_assert_true(dist > 0.005,
			"tail Verlet segment %d–%d not collapsed (%.4f m)" % [i - 1, i, dist])

	var span: float = (chain[0] as Vector3).distance_to(chain[-1])
	_assert_true(span > 0.05,
		"tail chain root-to-tip span non-zero (%.3f m)" % span)

	# Verify no two nodes are at exactly the same position (bunching symptom).
	for i in range(1, chain.size()):
		for j in range(i + 1, chain.size()):
			var d: float = (chain[i] as Vector3).distance_to(chain[j])
			_assert_true(d > 0.001,
				"tail nodes %d and %d are distinct (%.4f m apart)" % [i, j, d])

	_note("tail Verlet: %d nodes, span %.3f m" % [chain.size(), span])


func _check_tail_skeleton(skel: Skeleton3D) -> void:
	var positions: Array[Vector3] = []
	for bone_name: StringName in TAIL_BONES:
		var idx: int = skel.find_bone(bone_name)
		if idx == -1:
			continue
		positions.append(skel.to_global(skel.get_bone_global_pose(idx).origin))

	if positions.size() < 2:
		_note("tail skeleton: fewer than 2 bones found")
		return

	for i in range(positions.size()):
		_assert_true(positions[i].is_finite(), "tail bone %d finite" % i)

	for i in range(1, positions.size()):
		var dist: float = positions[i].distance_to(positions[i - 1])
		_assert_true(dist > 0.005,
			"tail bone segment %d–%d not collapsed (%.4f m)" % [i - 1, i, dist])

	_note("tail skeleton: %d bones checked" % positions.size())


# ── Ragdoll sanity ────────────────────────────────────────────────────────────

func _check_ragdoll_sanity(matador: Node3D, start_pos: Vector3) -> void:
	print("\n-- check_ragdoll_sanity --")
	var sim: Node = _find_class_recursive(matador, "PhysicalBoneSimulator3D")
	if not sim:
		_note("ragdoll: no PhysicalBoneSimulator3D — check skipped")
		return

	var checked := 0
	var all_at_origin := true
	for child in sim.get_children():
		if not (child is PhysicalBone3D):
			continue
		var bone := child as PhysicalBone3D
		var bp: Vector3 = bone.global_position
		checked += 1

		if bp.distance_to(Vector3.ZERO) > 0.1:
			all_at_origin = false

		_assert_true(bp.is_finite(),
			"ragdoll '%s' position finite" % bone.bone_name)

		if bp.is_finite():
			var dist: float = bp.distance_to(start_pos)
			# 6 m: impulse + 0.8 s of movement should stay inside this.
			# Regression guard: bodies stuck at world origin fail (spawn is 10-20 m away).
			_assert_true(dist < 6.0,
				"ragdoll '%s' near spawn (%.1f m)" % [bone.bone_name, dist])
			_assert_true(bp.y > -1.0,
				"ragdoll '%s' above floor (y = %.2f)" % [bone.bone_name, bp.y])
			_assert_true(bp.y < 3.0,
				"ragdoll '%s' settled below 3 m (y = %.2f)" % [bone.bone_name, bp.y])

	if checked == 0:
		_note("ragdoll: simulator has no PhysicalBone3D children")
	elif all_at_origin:
		_note("ragdoll: all bones at world origin — physics may not have simulated (headless?)")
	else:
		_note("ragdoll: %d bones checked" % checked)


# ── Frame capture ─────────────────────────────────────────────────────────────

func _capture_frame(filename: String) -> void:
	var img: Image = root.get_viewport().get_texture().get_image()
	if img == null:
		_note("frame capture failed: %s" % filename)
		return
	var path := OUTPUT_DIR + "/" + filename
	img.save_png(path)
	_note("captured %s (%d×%d)" % [filename, img.get_width(), img.get_height()])


# ── Scene helpers ─────────────────────────────────────────────────────────────

func _find_legs_node(player: Node) -> Node:
	for child in player.get_children():
		var s: Script = child.get_script() as Script
		if s and s.resource_path.ends_with("bull_legs.gd"):
			return child
	return null


func _find_skeleton(node: Node) -> Node:
	if node is Skeleton3D:
		return node
	for child in node.get_children():
		var r := _find_skeleton(child)
		if r:
			return r
	return null


func _find_class_recursive(node: Node, class_name_str: String) -> Node:
	if node.get_class() == class_name_str:
		return node
	for child in node.get_children():
		var r := _find_class_recursive(child, class_name_str)
		if r:
			return r
	return null


# ── Assertions & report ───────────────────────────────────────────────────────

func _assert_true(condition: bool, desc: String) -> void:
	if condition:
		_passed += 1
		print("  PASS: %s" % desc)
		_report.append("PASS: " + desc)
	else:
		_failed += 1
		print("  FAIL: %s" % desc)
		_report.append("FAIL: " + desc)


func _note(msg: String) -> void:
	print("  NOTE: %s" % msg)
	_report.append("NOTE: " + msg)


func _finish() -> void:
	var f := FileAccess.open(OUTPUT_DIR + "/report.txt", FileAccess.WRITE)
	if f:
		f.store_string("\n".join(Array(_report)))
		f.close()

	print("")
	print("=".repeat(60))
	print("GAMEPLAY TESTS: %d passed, %d failed" % [_passed, _failed])
	print("Frame strip: %s" % OUTPUT_DIR)
	print("=".repeat(60))
	quit(1 if _failed > 0 else 0)