/**
 * @name deepClone - Node.js function for deep cloning objects
 * 
 * @author Kumar Abhirup · 🐦 Twitter: @kumar_abhirup
 * 
 * @param {object} objectToClone
 * 
 * @returns object | null | undefined | Error
 */
function deepClone(objectToClone) {
  if (!objectToClone) return objectToClone // Check for null, undefined, 0 and false

  // Throw an error if `objectToClone` is not an array or object
  if (typeof objectToClone !== 'object') throw new Error(`Expected argument of type 'object' but received a '${typeof objectToClone}'`)

  // To support older node versions which might not have support for Array.isArray
  if (typeof Array.isArray === 'undefined') {
    Array.isArray = function (obj) {
      return Object.prototype.toString.call(obj) === '[object Array]'
    }
  }

  let node

  // This is so that the function understands the difference between Arrays, Objects, and Regular Expressions.
  const clonedObject = (() => {
    if (Array.isArray(objectToClone)) return []
    else if (objectToClone instanceof RegExp) return objectToClone // If it is a RegExp, just return that instead of an empty object
    else return {}
  })()

  /**
   * Iterates through `objectToClone` and generates the `clonedObject`.
   * If while iterating, it finds another object, it deep clones it again.
   */
  for (const key in objectToClone) {
    node = objectToClone[key]

    clonedObject[key] = (() => {
      // Check for `node`
      if (!node) return node
      else if (typeof node === "object") return deepClone(node) // This is a recursion
      else return node
    })()
  }

  return clonedObject
}

// Export it so that you can unit test this function
module.exports = deepClone

// Use the function
const objectToClone = {
  name: "Paddy", 
  address: {
    town: "Lerum", 
    country: "Sweden"
  }
}

const clonedObject = deepClone(objectToClone)

console.log(clonedObject)