Given a 2D array, write a function that flips it vertically or horizontally.

2d-array-reversed.ts

/*
  Given a 2D array, write a function that flips it vertically or horizontally.
*/

export function flip(matrix: number[][], direction: "horizontal" | "vertical") {
  if (direction === "horizontal") {
    return matrix.map((row) => row.toReversed());
  }

  if (direction === "vertical") {
    return matrix.toReversed();
  }

  throw new Error("Direction not supported");
}

// tests

import { expect, test } from "bun:test";

import { flip } from ".";

test("that horizontal direction returns sorted matrix", () => {
  const array = [
    [1, 2, 3],
    [4, 5, 6],
    [7, 8, 9],
  ];
  expect(flip(array, "horizontal")).toEqual([
    [3, 2, 1],
    [6, 5, 4],
    [9, 8, 7],
  ]);
});

test("that vertical direction returns sorted matrix", () => {
  const array = [
    [1, 2, 3],
    [4, 5, 6],
    [7, 8, 9],
  ];

  expect(flip(array, "vertical")).toEqual([
    [7, 8, 9],
    [4, 5, 6],
    [1, 2, 3],
  ]);
});

test("that unrecognized direction throws an error", () => {
  const array = [[0]];

  expect(() => flip(array, "diagonal")).toThrow("Direction not supported");
});