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", false
	)
	_check_ribbon_tracks_terrain(
		terrain,
		river_surface.get_node("UpperRiverRibbon") as MeshInstance3D,
		"Upper-stream water",
		true
	)

	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, is_upper: bool
) -> 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]
	var uvs: PackedVector2Array = arrays[Mesh.ARRAY_TEX_UV]
	_check(not vertices.is_empty(), "%s ribbon should contain vertices" % label)
	if vertices.is_empty() or uvs.size() != vertices.size():
		failures.append("%s ribbon requires a complete coordinate profile" % label)
		return
	var start_z := (
		JajceWatercourse.UPPER_STREAM_START_Z if is_upper else JajceWatercourse.DOWNSTREAM_START_Z
	)
	var end_z := (
		JajceWatercourse.UPPER_STREAM_END_Z if is_upper else JajceWatercourse.DOWNSTREAM_END_Z
	)
	_check(
		(
			absf(ribbon.to_global(vertices[0]).z - start_z) < 0.03
			and absf(ribbon.to_global(vertices[-1]).z - end_z) < 0.03
		),
		"%s ribbon should span its entire authored stream length" % label
	)
	var pool := ribbon.get_parent().get_node("PlungePool") as MeshInstance3D
	var pool_mesh := pool.mesh as PlaneMesh
	var pool_radii := pool_mesh.size * Vector2(pool.scale.x, pool.scale.z) * 0.5
	var min_depth := INF
	var max_depth := -INF
	for vertex_index in vertices.size():
		var world_vertex := ribbon.to_global(vertices[vertex_index])
		var world_z := lerpf(start_z, end_z, uvs[vertex_index].y)
		var center_x := (
			JajceWatercourse.upper_stream_center_x(world_z)
			if is_upper
			else JajceWatercourse.downstream_center_x(world_z)
		)
		var half_width := (
			JajceWatercourse.upper_stream_half_width(world_z)
			if is_upper
			else JajceWatercourse.downstream_half_width(world_z)
		)
		if not is_upper:
			var pool_progress := (world_z - pool.global_position.z) / pool_radii.y
			if absf(pool_progress) < 1.0:
				half_width = maxf(
					half_width, pool_radii.x * sqrt(1.0 - pool_progress * pool_progress)
				)
		var center_height := _terrain_height(terrain, center_x, world_z)
		var terrain_height := terrain.data.get_height(world_vertex)
		if (
			not world_vertex.is_finite()
			or not is_finite(terrain_height)
			or not is_finite(center_height)
		):
			failures.append("%s ribbon sampled outside Terrain3D" % label)
			return
		if absf(world_vertex.y - center_height - JajceWatercourse.WATER_SURFACE_OFFSET) > 0.03:
			failures.append("%s cross-section should follow its actual carved centerline" % label)
			return
		if (
			absf(world_vertex.z - world_z) > 0.03
			or absf(world_vertex.x - center_x) > half_width + 0.03
		):
			failures.append(
				"%s ribbon should stay inside the authored stream/pool footprint" % label
			)
			return
		var depth := world_vertex.y - terrain_height
		min_depth = minf(min_depth, depth)
		max_depth = maxf(max_depth, depth)
		if depth < -0.03 or depth > JajceWatercourse.WATER_SURFACE_OFFSET + 0.03:
			failures.append("%s surface should remain shallow and above the channel bed" % label)
			return
		var across := uvs[vertex_index].x
		if is_zero_approx(across) or is_equal_approx(across, 1.0):
			var edge_distance := absf(world_vertex.x - center_x)
			if absf(edge_distance - half_width) > 0.03 and absf(depth) > 0.03:
				failures.append(
					"%s edges must reach the authored extent or the actual shoreline" % label
				)
				return
			if (
				(is_zero_approx(across) and world_vertex.x >= center_x)
				or (is_equal_approx(across, 1.0) and world_vertex.x <= center_x)
			):
				failures.append(
					"%s water must retain its authored centerline inside both banks" % label
				)
				return
	print("[TEST] %s depth bounds | min=%.3f max=%.3f" % [label, min_depth, max_depth])


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)