defmodule Manganese.CoreKit do
  @doc """

  Similar to `Macro.underscore` but with different handling of numbers in strings.

  For example, take the string `"asset3d"`.  `Macro.underscore` returns simply `"asset3d".  `underscore_key/1` returns `"asset_3d"` for consistency with the Foreverdaunt codebase when de/serializing JSON.

  """
  @spec underscore_key(binary | atom | integer) :: binary
  def underscore_key(integer) when is_integer(integer), do: underscore_key Integer.to_string integer
  def underscore_key(atom) when is_atom(atom), do: underscore_key Atom.to_string atom
  def underscore_key(string) when is_binary(string) do
    string = Macro.underscore(string)
    string = Regex.replace(~r/([a-z]\d)/, string, fn _, pair -> "#{String.at(pair, 0)}_#{String.at(pair, 1)}" end)
    string
  end
end