extends SceneTree

const SonarMaterial = preload("res://game/domain/sonar/sonar_material.gd")
const SiteTerrainData = preload("res://game/domain/sites/site_terrain_data.gd")
const TerrainHeightField = preload("res://game/domain/sites/terrain_height_field.gd")

const TEST_COUNT := 20

var _failures: Array[String] = []


func _init() -> void:
	_test_terrain_data_validation()
	_test_height_field_sampling()

	if _failures.is_empty():
		print("Site domain unit tests: %d passed, 0 failed." % TEST_COUNT)
		quit(0)
	else:
		for failure: String in _failures:
			push_error(failure)
		print("Site domain unit tests: %d failed." % _failures.size())
		quit(1)


func _make_terrain(columns: int, rows: int) -> SiteTerrainData:
	var data := SiteTerrainData.new()
	data.columns = columns
	data.rows = rows
	data.cell_size_m = 2.0
	data.origin_x_m = -10.0
	data.origin_z_m = 100.0
	# Packed arrays are passed by value in GDScript: build locally, then assign.
	var elevations := PackedFloat32Array()
	var materials := PackedByteArray()
	elevations.resize(columns * rows)
	materials.resize(columns * rows)
	for row in rows:
		for column in columns:
			var index := row * columns + column
			# Plane sloping down toward +Z (south): -20 at row 0, -2 m per row.
			elevations[index] = -20.0 - 2.0 * float(row)
			materials[index] = (
				SonarMaterial.Value.ROCK if column == 0 else SonarMaterial.Value.SAND
			)
	data.elevations_m = elevations
	data.materials = materials
	return data


func _test_terrain_data_validation() -> void:
	var data := _make_terrain(3, 4)
	_expect(data.validation_error().is_empty(), "regular terrain data is valid")
	_expect(data.index_of(2, 3) == 11, "index is row-major with columns along X")

	var tiny := _make_terrain(1, 4)
	_expect(not tiny.validation_error().is_empty(), "terrain needs at least two columns")

	var mismatched := _make_terrain(3, 4)
	mismatched.elevations_m.resize(5)
	_expect(not mismatched.validation_error().is_empty(), "elevation array must match the grid")

	var non_finite := _make_terrain(3, 4)
	non_finite.elevations_m[0] = INF
	_expect(not non_finite.validation_error().is_empty(), "elevations must be finite")

	var metal_terrain := _make_terrain(3, 4)
	metal_terrain.materials[1] = SonarMaterial.Value.METAL
	_expect(not metal_terrain.validation_error().is_empty(), "terrain cells are rock or sand only")

	var bad_cell := _make_terrain(3, 4)
	bad_cell.cell_size_m = 0.0
	_expect(not bad_cell.validation_error().is_empty(), "cell size must be positive")

	var bad_reflectivity := _make_terrain(3, 4)
	bad_reflectivity.sand_reflectivity = 1.5
	_expect(not bad_reflectivity.validation_error().is_empty(), "reflectivity stays within 0..1")
	_expect(TerrainHeightField.from_data(bad_reflectivity) == null, "invalid data yields no field")


func _test_height_field_sampling() -> void:
	var field := TerrainHeightField.from_data(_make_terrain(3, 4))
	_expect(field != null, "valid data yields a field")
	if field == null:
		return
	_expect(field.bounds_m().is_equal_approx(Rect2(-10.0, 100.0, 4.0, 6.0)), "bounds cover (columns-1) by (rows-1) cells")
	_expect(field.cell_world_position(2, 3).is_equal_approx(Vector3(-6.0, -26.0, 106.0)), "cell position follows origin and cell size")
	_expect(is_equal_approx(field.elevation_at(-10.0, 100.0), -20.0), "elevation at a vertex is exact")
	_expect(is_equal_approx(field.elevation_at(-9.0, 101.0), -21.0), "elevation is bilinear between vertices")
	_expect(is_equal_approx(field.elevation_at(-50.0, 1000.0), -26.0), "sampling outside clamps to the nearest edge")
	_expect(field.material_at(-10.4, 100.0) == SonarMaterial.Value.ROCK, "material is the nearest cell")
	_expect(field.material_at(-6.0, 103.0) == SonarMaterial.Value.SAND, "material of an interior cell")
	_expect(field.normal_at_cell(1, 1).is_equal_approx(Vector3(0.0, 1.0, 1.0).normalized()), "normal leans against the downhill direction")
	_expect(not field.contains(-11.0, 100.0) and field.contains(-8.0, 103.0), "contains follows the bounds")
	_expect(is_equal_approx(field.reflectivity_for(SonarMaterial.Value.SAND), 0.45), "sand reflectivity comes from the data")


func _expect(condition: bool, label: String) -> void:
	if not condition:
		_failures.append(label)