rotate-sequence-numbers.js

const _ = require('lodash');
const assert = require('assert');

const rotate = (value, max, min) => {
  const distance = max - min + 1;

  if (value > max) {
    return min + ((value - max - 1) % distance);
  } else if (value < min) {
    return max - ((min - value - 1) % distance);
  } else {
    return value;
  }
}

const test = (expect, value, max, min) => {
  assert.equal(expect, rotate(value, max, min), `${value} should be ${expect} for range ${min}-${max}`);
}

test(20, 20, 21, 19);
test(21, 18, 21, 19);
test(19, 22, 21, 19);
test(21, 24, 21, 19);
test(19, 16, 21, 19)

test(19, 25, 21, 19);
test(21, 15, 21, 19);

test(24, 19, 25, 21);
test(25, 20, 25, 21);
test(23, 18, 25, 21);
test(23, 28, 25, 21);
test(24, 29, 25, 21);
test(21, 31, 25, 21);

test(4, -1, 4, 0);
test(3, -2, 4, 0);
test(2, -3, 4, 0);
test(1, -4, 4, 0);
test(0, -5, 4, 0);
test(4, -6, 4, 0);