Advent of PBT 2021 - Day 14

/**
 * Re-order multiple tabs at the same time and relatively to others
 * (as browsers do).
 * 
 * In modern browsers including Mozilla Firefox or Google Chrome,
 * users can easily select N non-contiguous tabs at the same time
 * and reorder them in a single move.
 * 
 * For instance if you have the tabs, A, B, C, D and E
 * you can select A and C and move them after D
 * to get B, D, A, C and E.
 *
 * @param tabs - The original set of tabs of the browser
 * @param selectedTabs - The tab currently being moved, a subarray
 *                       of tabs
 * @param moveBeforeTab - One of the tabs oftabs but not of
 *                        selectedTabs taken as a reference
 *                        for the dropping place
 *
 * @returns
 * New tabs configuration after the drop.
 */
export function reorderTabs(
  tabs: number[],
  selectedTabs: number[],
  moveBeforeTab: number
): number[]

it("should be able to re-order one tab alone", () => {
  // Arrange
  const originalTabs = [0, 1, 2, 3, 4];
  const selectedTabs = [2];
  const moveTabsBefore = 4;

  // Act
  const reordered = reorderTabs(originalTabs, selectedTabs, moveTabsBefore);

  // Assert
  expect(reordered).toEqual([0, 1, 3, 2, 4]);
});

it("should be able to re-order many contiguous tabs", () => {
  // Arrange
  const originalTabs = [0, 1, 2, 3, 4];
  const selectedTabs = [0, 1];
  const moveTabsBefore = 4;

  // Act
  const reordered = reorderTabs(originalTabs, selectedTabs, moveTabsBefore);

  // Assert
  expect(reordered).toEqual([2, 3, 0, 1, 4]);
});

it("should be able to re-order many non-contiguous tabs", () => {
  // Arrange
  const originalTabs = [0, 1, 2, 3, 4];
  const selectedTabs = [0, 2];
  const moveTabsBefore = 4;

  // Act
  const reordered = reorderTabs(originalTabs, selectedTabs, moveTabsBefore);

  // Assert
  expect(reordered).toEqual([1, 3, 0, 2, 4]);
});