defmodule BasicSignupWhitelist do
  @moduledoc """
  Checks if an email address is allowed based on the SIGNUP_ALLOWED_EMAILS env variable.
  """

  @doc """
  Checks if an email address is allowed based on the SIGNUP_ALLOWED_EMAILS env variable.

  Rules:
    - Returns true if ALLOWED_EMAILS == "*" (all emails allowed)
    - Returns true if email matches any entry in the comma-separated list
    - Returns false if:
        * Environment variable doesn't exist
        * Environment variable is empty string
        * Email not found in whitelist

  ## Examples

      iex> BasicSignupWhitelist.mail_whitelisted("joe@example.com")
      false

  """
  def mail_whitelisted(_email) do
    false
  end
end