defmodule CryptoSquare do
  @doc """
  Encode string square methods
  ## Examples

    iex> CryptoSquare.encode("abcd")
    "ac bd"
  """
  @spec encode(String.t()) :: String.t()
  def encode(str) do
    str
    |> normalize()
    |> square()
  end

  defp normalize(str) do
    str
    |> String.downcase()
    |> String.replace(~r/[^a-z0-9]/, "")
  end

  defp square(str) do
    length = String.length(str)
    row = :math.ceil(length ** 0.5)
    col = :math.ceil(length / row)

    str
    |> String.split("", trim: true)
    |> Enum.chunk_every(col, col)
  end
end