defmodule BasicSignupWhitelist do
  import FunCore.BasicSignupWhitelist

  @moduledoc """
  Checks if an email address is allowed based on the SIGNUP_ALLOWLIST_EMAILS env variable.
  """

  @doc """
  Checks if an email address is allowed based on the SIGNUP_ALLOWLIST_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> System.delete_env("SIGNUP_ALLOWLIST_EMAILS")
      iex> BasicSignupWhitelist.mail_whitelisted("joe@example.com")
      false
      iex> System.put_env("SIGNUP_ALLOWLIST_EMAILS","*")
      iex> BasicSignupWhitelist.mail_whitelisted("joe@example.com")
      true

  """
  def mail_whitelisted(email) do
    env_value = System.get_env("SIGNUP_ALLOWLIST_EMAILS")
    mail_whitelisted_fun(env_value, email)
  end
end