defmodule BasicSignupAllowlist do
  import FunCore.BasicSignupAllowlist

  @signup_allowlist_emails "SIGNUP_ALLOWLIST_EMAILS"

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

  @doc """
  Returns the name of the environment variable used for the signup allowlist.
  """
  @spec signup_allowlist_emails() :: String.t()
  def signup_allowlist_emails, do: @signup_allowlist_emails


  @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 allowlist

  ## Examples

      iex> BasicSignupAllowlist.forbid_signup_with_any_email() 
      iex> BasicSignupAllowlist.signup_allowed?("joe@example.com")
      false
      iex> BasicSignupAllowlist.allow_signup_with_all_emails() 
      iex> BasicSignupAllowlist.signup_allowed?("joe@example.com")
      true

  """
  @spec signup_allowed?(String.t()) :: boolean()
  def signup_allowed?(email) do
    env_value = System.get_env(@signup_allowlist_emails)
    signup_allowed_fun(env_value, email)
  end

  def allow_signup_with_all_emails() do
      System.put_env(signup_allowlist_emails(), "*")
  end
  
  def forbid_signup_with_any_email() do
      System.delete_env(signup_allowlist_emails())
  end
end