rollex

defmodule Rollex do
  # NOTE: Order Matters! If an item matches in Rollex.Lexer._do_tokenize/0, the lexer will skip the rest of the tokens
  # This is why number is after dice tokens, since number will very frequently match on what should be dice input
  @default_operations [%Rollex.Tokens.Subtraction{},
                    %Rollex.Tokens.Addition{},
                    %Rollex.Tokens.Number{},
                    %Rollex.Tokens.LeftParenthesis{},
                    %Rollex.Tokens.RightParenthesis{}]

  @default_dice [%Rollex.Tokens.ParanoiaDice{},
                  %Rollex.Tokens.FudgeDice{},
                  %Rollex.Tokens.RegularDice{}]

  # Use built-in defaults
  def roll(roll_expr, dice \\ @default_dice)
  def roll(roll_expr, dice) do

    roll_expr
    |> Rollex.Lexer.tokenize(dice ++ @default_operations)
    |> Rollex.Validator.validate
    |> Rollex.Evaluator.evaluate
    |> _build_final_output
  end

  defp _build_final_output({:ok, %{} = result, full_tokenized_input}) do
    %{status: :ok, totals: result, tokenized_input: full_tokenized_input}
  end
  defp _build_final_output({:error, msg}) when is_binary(msg) do
    %{status: :error, error_msg: msg}
  end
end