defmodule StatefulAgents do
  @moduledoc """
  StatefulAgents is a repository of Agents that I use frequently. These are
  needed all the time when developing, so I just made a library of them.
  """

  defmodule MapAgent do
    use Agent

    @doc """
      iex> alias StatefulAgents.MapAgent
      ...> {:ok, pid} = MapAgent.start
      ...> assert is_pid(pid)
      true
    """
    def start, do: Agent.start(fn -> %{} end)

    @doc """
      iex> alias StatefulAgents.MapAgent
      ...> {:ok, pid} = MapAgent.start
      ...> assert is_pid(pid)
      true
      ...> MapAgent.stop(pid)
      :ok
    """
    def stop(pid), do: Agent.stop(pid)

    @doc """
      iex> alias StatefulAgents.MapAgent
      ...> {:ok, pid} = MapAgent.start
      ...> assert is_pid(pid)
      true
      ...> map = MapAgent.get(pid)
      ...> assert is_map(map)
      true
    """
    def get(pid), do: Agent.get(pid, fn state -> state end)

    @doc """
      iex> alias StatefulAgents.MapAgent
      ...> {:ok, pid} = MapAgent.start
      ...> assert is_pid(pid)
      true
      ...> MapAgent.set(pid, %{foo: "bar", baz: "bong"})
      :ok
    """
    def set(pid, state) when is_map(state) do
      Agent.update(pid, fn _ -> state end)
    end
    def set(_pid, state) do
      raise ArgumentError, message: "set/1 requires argument of type map. Got: '" <> IO.inspect(state) <> "'"
    end
  end

  defmodule BooleanAgent do
    use Agent

    @doc """
      Stores a boolean as the Agent's state. Provides helper functions to access
      and set state in the Agent.

      iex> alias StatefulAgents.BooleanAgent
      ...> {:ok, pid} = BooleanAgent.start_link
      ...> is_pid(pid)
      true
    """
    def start_link, do: Agent.start_link(fn -> false end, [name: __MODULE__])

    @doc """
      iex> alias StatefulAgents.BooleanAgent
      ...> {:ok, pid} = BooleanAgent.start_link
      ...> assert is_pid(pid)
      true
      ...> value = BooleanAgent.get
      ...> is_boolean(value)
      true
    """
    def get, do: Agent.get(__MODULE__, fn state -> state end)

    @doc """
      iex> alias StatefulAgents.BooleanAgent
      ...> {:ok, pid} = BooleanAgent.start_link
      ...> assert is_pid(pid)
      true
      ...> BooleanAgent.set(true)
      :ok
    """
    def set(state) when is_boolean(state) do
      Agent.update(__MODULE__, fn _ -> state end)
    end
    def set(state) do
      raise ArgumentError, message: "set/1 requires argument of type boolean. Got: '" <> IO.inspect(state) <> "'"
    end
  end
end