defmodule DndCharacter do
  @type t :: %__MODULE__{
          strength: pos_integer(),
          dexterity: pos_integer(),
          constitution: pos_integer(),
          intelligence: pos_integer(),
          wisdom: pos_integer(),
          charisma: pos_integer(),
          hitpoints: pos_integer()
        }

  @abilities ~w(strength dexterity constitution intelligence wisdom charisma hitpoints)a

  defstruct @abilities

  @spec modifier(pos_integer()) :: integer()
  def modifier(score), do: floor((score - 10) / 2)

  @spec ability :: pos_integer()
  def ability do
    0..2
    |> Enum.map(fn _x -> Enum.random(1..6) end)
    |> Enum.sort(:desc)
    |> Enum.sum()
  end

  @spec character :: t()
  def character do
    for ability <- @abilities, reduce: %{} do acc -> Map.put(acc, ability, ability()) end
    |> then(&Map.put(&1, :hitpoints, 10 + modifier(Map.get(&1, :constitution))))
    |> then(&struct(__MODULE__, &1))
  end
end