class IteratorWrap<Value> implements Iterator<Value> {
  index = -1
  array: Array<Value>

  constructor(array: Array<Value>) {
    this.array = array
  }
  hasNext() {
    return this.index + 1 < this.array.length
  }
  next(): IteratorResult<Value> {
    this.index += 1
    if (this.index > this.array.length) {
      return {
        done: true,
        value: undefined,
      }
    } else {
      return {
        value: this.array[this.index],
        done: false,
      }
    }
  }
  remove() {
    this.index -= 1
    this.array.splice(this.index, 1)
  }
}

function toIterator<Value>(
  x: Array<Value> | Value
): Iterator<Value> | IterableIterator<[string, Value]> {
  if (Array.isArray(x)) {
    return x[Symbol.iterator]()
  } else if (typeof x === 'object') {
    return Object.entries(x)[Symbol.iterator]()
  } else {
    return new IteratorWrap([x])
  }
}

export { IteratorWrap }
export { toIterator }