defmodule ExCrap.Score do
  @moduledoc false

  use Boundary

  # CRAP = complexity^2 * (1 - coverage_percent / 100)^3 + complexity.

  @doc false
  def score(complexity, coverage_percent) do
    with :ok <- validate_complexity(complexity),
         :ok <- validate_coverage(coverage_percent) do
      uncovered = 1 - coverage_percent / 100
      {:ok, complexity * complexity * uncovered * uncovered * uncovered + complexity * 1.0}
    end
  end

  defp validate_complexity(complexity) when is_number(complexity) and complexity >= 0, do: :ok
  defp validate_complexity(_complexity), do: {:error, :invalid_complexity}

  defp validate_coverage(coverage_percent)
       when is_number(coverage_percent) and coverage_percent >= 0 and coverage_percent <= 100,
       do: :ok

  defp validate_coverage(_coverage_percent), do: {:error, :invalid_coverage}
end