defmodule LSG.IRC.CalcPlugin do
  @moduledoc """
  # calc

  * **!calc `<expression>`**: évalue l'expression mathématique `<expression>`.
  """

  def irc_doc, do: @moduledoc

  def start_link() do
    GenServer.start_link(__MODULE__, [], name: __MODULE__)
  end

  def init(_) do
    {:ok, _} = Registry.register(IRC.PubSub, "trigger:calc", [plugin: __MODULE__])
    {:ok, nil}
  end

  def handle_info({:irc, :trigger, "calc", message = %IRC.Message{trigger: %IRC.Trigger{type: :bang, args: expr_list}}}, state) do
    expr = Enum.join(expr_list, " ")
    result = try do
      case Abacus.eval(expr) do
        {:ok, result} -> result
        error -> inspect(error)
      end
    rescue
      error -> if(error[:message], do: "#{error.message}", else: "erreur")
    end
    message.replyfun.("#{message.sender.nick}: #{expr} = #{result}")
    {:noreply, state}
  end

  def handle_info(msg, state) do
    {:noreply, state}
  end

end