class_name SonarSampleBuffer
extends RefCounted

const SonarMaterial = preload("res://game/domain/sonar/sonar_material.gd")
const SonarSample = preload("res://game/domain/sonar/sonar_sample.gd")

var columns: int
var rows: int

var _positions := PackedVector3Array()
var _normals := PackedVector3Array()
var _intensities := PackedFloat32Array()
var _elevations_m := PackedFloat32Array()
var _materials := PackedInt32Array()
var _observed := PackedByteArray()
var _sealed := false


func _init(p_columns: int, p_rows: int) -> void:
	columns = p_columns
	rows = p_rows
	var sample_count := maxi(columns, 0) * maxi(rows, 0)
	_positions.resize(sample_count)
	_normals.resize(sample_count)
	_intensities.resize(sample_count)
	_elevations_m.resize(sample_count)
	_materials.resize(sample_count)
	_observed.resize(sample_count)
	for index in sample_count:
		_normals[index] = Vector3.UP
		_materials[index] = SonarMaterial.Value.UNKNOWN


func set_sample(row: int, column: int, sample: SonarSample) -> String:
	if _sealed:
		return "sonar sample buffer is sealed"
	var index := _index_of(row, column)
	if index < 0:
		return "sonar sample coordinates are outside the buffer"
	if sample == null:
		return "sonar sample is missing"
	var error := sample.validation_error()
	if not error.is_empty():
		return error
	if not sample.observed:
		return "cannot write an unobserved sonar sample"
	if _observed[index] == 1:
		return "sonar sample coordinates are duplicated"
	_positions[index] = sample.position_m
	_normals[index] = sample.normal.normalized()
	_intensities[index] = sample.intensity
	_elevations_m[index] = sample.elevation_m
	_materials[index] = sample.material
	_observed[index] = 1
	return ""


func seal() -> String:
	if columns < 2 or rows < 2:
		return "sonar sample buffer dimensions must be at least 2 by 2"
	_sealed = true
	return ""


func is_sealed() -> bool:
	return _sealed


func sample_count() -> int:
	return columns * rows


func observed_count() -> int:
	var count := 0
	for value: int in _observed:
		count += value
	return count


func sample_at(row: int, column: int) -> SonarSample:
	var index := _index_of(row, column)
	if index < 0 or _observed[index] == 0:
		return SonarSample.unknown()
	return SonarSample.new(
		_positions[index],
		_normals[index],
		_intensities[index],
		_elevations_m[index],
		_materials[index],
		true
	)


func validation_error() -> String:
	if columns < 2 or rows < 2:
		return "sonar sample buffer dimensions must be at least 2 by 2"
	if not _sealed:
		return "sonar sample buffer must be sealed before publication"
	var expected_size := columns * rows
	if (
		_positions.size() != expected_size
		or _normals.size() != expected_size
		or _intensities.size() != expected_size
		or _elevations_m.size() != expected_size
		or _materials.size() != expected_size
		or _observed.size() != expected_size
	):
		return "sonar sample buffer arrays are not aligned"
	return ""


func _index_of(row: int, column: int) -> int:
	if row < 0 or row >= rows or column < 0 or column >= columns:
		return -1
	return row * columns + column