extends SceneTree

const JajceWatercourse := preload("res://world/jajce/JajceWatercourse.gd")

var failures: Array[String] = []


func _initialize() -> void:
	call_deferred("_run")


func _run() -> void:
	var camera := Camera3D.new()
	camera.current = true
	root.add_child(camera)
	var world: Node3D = load("res://world/jajce/JajceWorld.tscn").instantiate()
	root.add_child(world)
	await process_frame
	for _frame in 4:
		await physics_frame

	var terrain := world.get_node("TerrainRoot/Terrain3D") as Terrain3D
	_check(terrain != null, "Jajce watercourse validation requires Terrain3D")
	if terrain == null:
		_finish()
		return

	var shelf_z := -36.0
	var shelf_center_x := JajceWatercourse.upper_stream_center_x(shelf_z)
	var shelf_half_width := JajceWatercourse.upper_stream_half_width(shelf_z)
	var shelf_stream_height := _terrain_height(terrain, shelf_center_x, shelf_z)
	var shelf_bank_height := _terrain_height(
		terrain, shelf_center_x + shelf_half_width + 4.0, shelf_z
	)
	var plunge_height := _terrain_height(
		terrain, JajceWatercourse.PLUNGE_POOL_CENTER.x, JajceWatercourse.PLUNGE_POOL_CENTER.y
	)
	_check(shelf_stream_height >= 10.8, "Upper stream should remain on the raised waterfall shelf")
	_check(
		shelf_bank_height - shelf_stream_height >= 0.45,
		"Upper stream should be visibly carved below its shelf bank"
	)
	_check(
		shelf_stream_height - plunge_height >= 10.0,
		"Waterfall shelf should create a readable drop into the plunge basin"
	)

	var downstream_samples := PackedFloat32Array([-10.0, 12.0, 34.0])
	for world_z in downstream_samples:
		var center_x := JajceWatercourse.downstream_center_x(world_z)
		var half_width := JajceWatercourse.downstream_half_width(world_z)
		var channel_height := _terrain_height(terrain, center_x, world_z)
		var left_bank_height := _terrain_height(terrain, center_x - half_width - 5.0, world_z)
		var right_bank_height := _terrain_height(terrain, center_x + half_width + 5.0, world_z)
		_check(
			channel_height <= JajceWatercourse.downstream_bed_height(world_z) + 0.08,
			"Downstream bed should follow its authored profile at z=%.1f" % world_z
		)
		_check(
			maxf(left_bank_height, right_bank_height) - channel_height >= 0.45,
			"Downstream channel should read below a natural bank at z=%.1f" % world_z
		)

	var river_surface := world.get_node("WaterRoot/RiverSurface") as Node3D
	_check_ribbon_tracks_terrain(
		terrain, river_surface.get_node("RiverRibbon") as MeshInstance3D, "Downstream water"
	)
	_check_ribbon_tracks_terrain(
		terrain, river_surface.get_node("UpperRiverRibbon") as MeshInstance3D, "Upper-stream water"
	)

	print(
		(
			"[TEST] Jajce watercourse samples | shelf=%.2f bank=%.2f pool=%.2f"
			% [shelf_stream_height, shelf_bank_height, plunge_height]
		)
	)
	_finish()


func _terrain_height(terrain: Terrain3D, world_x: float, world_z: float) -> float:
	return terrain.data.get_height(Vector3(world_x, 0.0, world_z))


func _check_ribbon_tracks_terrain(
	terrain: Terrain3D, ribbon: MeshInstance3D, label: String
) -> void:
	_check(ribbon != null and ribbon.mesh is ArrayMesh, "%s ribbon should be generated" % label)
	if ribbon == null or not ribbon.mesh is ArrayMesh:
		return
	var arrays := ribbon.mesh.surface_get_arrays(0)
	var vertices: PackedVector3Array = arrays[Mesh.ARRAY_VERTEX]
	_check(not vertices.is_empty(), "%s ribbon should contain vertices" % label)
	for vertex_index in range(0, vertices.size(), maxi(1, vertices.size() / 12)):
		var world_vertex := ribbon.to_global(vertices[vertex_index])
		var terrain_height := terrain.data.get_height(world_vertex)
		if is_nan(terrain_height):
			failures.append("%s ribbon sampled outside Terrain3D" % label)
			return
		if absf(world_vertex.y - terrain_height - JajceWatercourse.WATER_SURFACE_OFFSET) > 0.03:
			failures.append("%s ribbon should hug the carved terrain" % label)
			return


func _check(condition: bool, message: String) -> void:
	if not condition:
		failures.append(message)


func _finish() -> void:
	if failures.is_empty():
		print("[TEST] Jajce watercourse terrain passed")
		quit(0)
		return
	for failure in failures:
		push_error("[TEST] " + failure)
	quit(1)