/**
 * This creates a collection of points relative to the center line of each supplied length. For example; a length of
 * 100 centered to 0 would result in the left position of -50 and a right position of +50.
 *
 * Length values should be unique, as duplicates will be trimmed from the result.
 *
 * @example
 * createGuidelinesFromLengths([100, 200, 200, -200, 201]) => [
 *  {left: -50, right: 50, length: 100},
 *  {left: -100, right: 100, length: 200},
 *  {left: 100, right: -100, length: -200},
 *  {left: -100.5, right: 100.5, length: 201},
 * ]
 * When length is 0, return  {left: 0, right: 0, length: 0}
 *
 * @param lengths A colection of length values which will be split into a left & right guides.
 * @returns A collection of LengthGuide objects which can be used to draw left & right guides
 */
export const createGuidesFromLengths = (lengths, hasFullWidthGuide = false) => {
  return Array.from(new Set(lengths)).reduce((acc, length, index) => {
    const h = length * 0.5;
    if (length === 0) {
      return [...acc, {
        left: 0,
        right: 0,
        length
      }];
    }
    if (!h || !Number.isFinite(length)) {
      // Filter out nonsensical values, null, undefined, NaN, empty string
      return acc;
    }
    return [...acc, {
      left: -h,
      right: h,
      length,
      // Assumes the full width guide is always the last length in the array
      ...(hasFullWidthGuide && index === lengths.length - 1 ? {
        isFullWidth: true
      } : {})
    }];
  }, []);
};