// Mesh category utilities
// TODO - move to mesh category module, or to math.gl/geometry module
import {TypedArray} from '../../types/types';
import {MeshAttributes} from '../../types/category-mesh';

type TypedArrays = {[key: string]: TypedArray};

/**
 * Holds an axis aligned bounding box
 * TODO - make sure AxisAlignedBoundingBox in math.gl/culling understands this format (or change this format)
 */
type BoundingBox = [[number, number, number], [number, number, number]];

/**
 * Get number of vertices in mesh
 * @param attributes
 */
export function getMeshSize(attributes: TypedArrays): number {
  let size = 0;
  for (const attributeName in attributes) {
    const attribute = attributes[attributeName];
    if (ArrayBuffer.isView(attribute)) {
      // @ts-ignore DataView doesn't have BYTES_PER_ELEMENT
      size += attribute.byteLength * attribute.BYTES_PER_ELEMENT;
    }
  }
  return size;
}

/**
 * Get the (axis aligned) bounding box of a mesh
 * @param attributes
 * @returns array of two vectors representing the axis aligned bounding box
 */
// eslint-disable-next-line complexity
export function getMeshBoundingBox(attributes: MeshAttributes): BoundingBox {
  let minX = Infinity;
  let minY = Infinity;
  let minZ = Infinity;
  let maxX = -Infinity;
  let maxY = -Infinity;
  let maxZ = -Infinity;

  const positions = attributes.POSITION ? attributes.POSITION.value : [];
  const len = positions && positions.length;

  for (let i = 0; i < len; i += 3) {
    const x = positions[i];
    const y = positions[i + 1];
    const z = positions[i + 2];

    minX = x < minX ? x : minX;
    minY = y < minY ? y : minY;
    minZ = z < minZ ? z : minZ;

    maxX = x > maxX ? x : maxX;
    maxY = y > maxY ? y : maxY;
    maxZ = z > maxZ ? z : maxZ;
  }
  return [
    [minX, minY, minZ],
    [maxX, maxY, maxZ]
  ];
}