InsidersByte/honeymoon-gift-list

/* eslint-disable import/prefer-default-export */

import random from '../../lib/random';
import { MAXIMUM_NUMBER } from '../constants';

export function move({ sourceId, targetId, data }) {
  const items = [...data];
  const sourceIndex = items.findIndex(o => o.id === sourceId);
  const targetIndex = items.findIndex(o => o.id === targetId);
  const movingUp = sourceIndex > targetIndex;
  let nextTargetPosition;

  const item = { ...items[sourceIndex] };
  const { position: targetMemberPosition } = items[targetIndex];

  if (targetIndex === 0) {
    nextTargetPosition = 0;
  } else if (targetIndex === items.length - 1) {
    nextTargetPosition = targetMemberPosition + MAXIMUM_NUMBER;
  } else {
    const nextTargetMemberIndex = movingUp ? targetIndex - 1 : targetIndex + 1;
    nextTargetPosition = items[nextTargetMemberIndex].position;
  }

  let newPosition;

  if (movingUp) {
    newPosition = random.integer(nextTargetPosition + 1, targetMemberPosition - 1);
  } else {
    newPosition = random.integer(targetMemberPosition + 1, nextTargetPosition - 1);
  }

  item.position = newPosition;

  items.splice(sourceIndex, 1);
  items.splice(targetIndex, 0, item);

  return items;
}