/**
 * Finds duplicate sub-arrays in a multidimensional array.
 *
 * @param {Array<Array>} arr - The multidimensional array to check
 * @returns {Array<Array>|false} - Array of duplicates or false if none
 *
 * @example
 * findDuplicatesInMultidimensionalArray([[1,2],[3,4],[1,2]])
 * // returns [[1,2]]
 */
export function findDuplicatesInMultidimensionalArray(arr) {
  const seen = new Set()
  const duplicates = []

  for (const subArr of arr) {
    const key = JSON.stringify(subArr)
    if (seen.has(key)) {
      duplicates.push(subArr)
    } else {
      seen.add(key)
    }
  }

  return duplicates.length ? duplicates : false
}


/**
 * Joins array elements with a hyphen.
 *
 * @param {Array<string|number>} arr
 * @returns {string}
 *
 * @example
 * implodeArrayWithHyphen([1,2,3]) // "1-2-3"
 */
export function implodeArrayWithHyphen(arr) {
  if (!Array.isArray(arr)) return ''
  return arr.join('-')
}


/**
 * Shuffles an array in-place using the Fisher–Yates algorithm.
 *
 * @param {Array} array - The array to shuffle
 * @returns {Array} The shuffled array
 *
 * @example
 * shuffleArray([1,2,3,4])
 * // might return [3,1,4,2]
 */
export function shuffleArray(array) {
  if (!Array.isArray(array)) return []

  let currentIndex = array.length
  let randomIndex

  while (currentIndex !== 0) {
    randomIndex = Math.floor(Math.random() * currentIndex)
    currentIndex--
    ;[array[currentIndex], array[randomIndex]] = [array[randomIndex], array[currentIndex]]
  }

  return array
}