export const DEFAULT_LOCALIZATION_ALGORITHM = "das";
export const DEFAULT_PHAT_RELATIVE_FLOOR = 1e-6;

function definition(id, label, rawScale, spectralWeighting, backends) {
  return Object.freeze({
    id,
    label,
    rawScale,
    spectralWeighting,
    backends: Object.freeze([...backends]),
  });
}

const ALGORITHM_DEFINITIONS = Object.freeze([
  definition("das", "DAS", "power", "none", ["cpu", "webgpu"]),
  definition("das-phat", "DAS-PHAT", "score", "phat", ["cpu", "webgpu"]),
  definition("gcc-phat", "GCC-PHAT", "score", "phat", ["cpu"]),
]);

const ALGORITHM_BY_ID = new Map(
  ALGORITHM_DEFINITIONS.map((algorithm) => [algorithm.id, algorithm]),
);

export const LOCALIZATION_ALGORITHM_IDS = Object.freeze(
  ALGORITHM_DEFINITIONS.map((algorithm) => algorithm.id),
);

export function localizationAlgorithmDefinition(id = DEFAULT_LOCALIZATION_ALGORITHM) {
  return ALGORITHM_BY_ID.get(id);
}

export function requireLocalizationAlgorithmDefinition(
  id = DEFAULT_LOCALIZATION_ALGORITHM,
) {
  const algorithm = localizationAlgorithmDefinition(id);
  if (!algorithm) {
    throw new RangeError(`unsupported localization algorithm: ${id}`);
  }
  return algorithm;
}

export function isDasAlgorithm(id = DEFAULT_LOCALIZATION_ALGORITHM) {
  return id === "das" || id === "das-phat";
}

export function localizationAlgorithmLabel(id = DEFAULT_LOCALIZATION_ALGORITHM) {
  return localizationAlgorithmDefinition(id)?.label ?? String(id);
}

export function localizationAlgorithmSupportsBackend(id, backend) {
  return localizationAlgorithmDefinition(id)?.backends.includes(backend) ?? false;
}