export const MIN_VIEW_DISTANCE = 2;
export const DEFAULT_VIEW_DISTANCE = 3;
export const MAX_VIEW_DISTANCE = 64;
export const WORLD_MIN_Y = -64;
export const WORLD_MAX_Y = 319;
export const VIEW_HEIGHT = WORLD_MAX_Y - WORLD_MIN_Y + 1;
export const VIEW_BUFFER = 1;
export const MAX_VIEW_WIDTH = ((MAX_VIEW_DISTANCE + VIEW_BUFFER) * 2 + 1) * 16;
export const MAX_VIEW_CELLS = MAX_VIEW_WIDTH ** 2 * VIEW_HEIGHT;
// Lighting uses local windows; raising render distance must not allocate a
// multi-gigabyte dense light volume.
export const MAX_LIGHT_CELLS = 304 ** 2 * 80;
export const MAX_VIEW_COORDINATE = 30_000_000 + (MAX_VIEW_DISTANCE + VIEW_BUFFER) * 16;

export function normalizeViewDistance(value) {
  const distance = Number(value);
  return Number.isInteger(distance) && distance >= MIN_VIEW_DISTANCE && distance <= MAX_VIEW_DISTANCE
    ? distance : DEFAULT_VIEW_DISTANCE;
}

export function viewDistanceProfile(value) {
  const chunks = normalizeViewDistance(value), width = (chunks * 2 + 1) * 16;
  const drawRadius = Math.SQRT2 * chunks * 16 + 24;
  const verticalSections = VIEW_HEIGHT / 16;
  return { chunks, radius: chunks * 16, width, sections: (chunks * 2 + 1) ** 2 * verticalSections,
    voxelBytes: width * width * VIEW_HEIGHT * 4,
    streamWidth: width + VIEW_BUFFER * 32, streamSections: (chunks * 2 + 1 + VIEW_BUFFER * 2) ** 2 * verticalSections,
    streamVoxelBytes: (width + VIEW_BUFFER * 32) ** 2 * VIEW_HEIGHT * 4, drawRadius,
    farClip: Math.max(190, drawRadius + 60), fogDistance: 78 * chunks / DEFAULT_VIEW_DISTANCE };
}