/* eslint-disable prefer-const */
import { DEG2RAD } from '~/modules/constants';
import { parseInput, restrictValues } from '~/modules/utils';

import { ConverterParameters, LAB, LCH } from '~/types';

const { sin, cos } = Math;

/** Convert oklch to oklab */
export default function oklch2oklab(input: ConverterParameters<LCH>, precision?: number): LAB {
  /*
  Convert from a qualitative parameter h and a quantitative parameter l to a 24-bit pixel.
  These formulas were invented by David Dalrymple to obtain maximum contrast without going
  out of gamut if the parameters are in the range 0-1.

  A saturation multiplier was added by Gregor Aisch
  */
  let { l, c, h } = parseInput(input, 'oklch');

  /* c8 ignore next 3 */
  if (Number.isNaN(h) || h < 0) {
    h = 0;
  }

  return restrictValues({ l, a: c * cos(h * DEG2RAD), b: c * sin(h * DEG2RAD) }, precision);
}