defmodule ALF.Components.Basic do
  def build_component(component_module, atom, name, opts, current_module) do
    name = if name, do: name, else: atom

    if module_exist?(atom) do
      struct(component_module, %{
        pipe_module: current_module,
        pipeline_module: current_module,
        name: name,
        module: atom,
        function: :call,
        opts: opts || []
      })
    else
      struct(component_module, %{
        pipe_module: current_module,
        pipeline_module: current_module,
        name: name,
        module: current_module,
        function: atom,
        opts: opts || []
      })
    end
  end

  defp module_exist?(module), do: function_exported?(module, :__info__, 1)

  defmacro __using__(_opts) do
    quote do
      use GenStage

      alias ALF.{IP, ErrorIP, Manager}

      def __state__(pid) when is_pid(pid) do
        GenStage.call(pid, :__state__)
      end

      def subscribers(pid) do
        GenStage.call(pid, :subscribers)
      end

      def init_opts(module, opts) do
        if function_exported?(module, :init, 1) do
          apply(module, :init, [opts])
        else
          opts
        end
      end

      def send_error_result(ip, error, stacktrace, state) do
        error_ip = build_error_ip(ip, error, stacktrace, state)
        Manager.result_ready(error_ip.manager_name, error_ip)
      end

      def handle_call(:subscribers, _form, state) do
        {:reply, state.subscribers, [], state}
      end

      def handle_call(:__state__, _from, state) do
        {:reply, state, [], state}
      end

      def handle_subscribe(:consumer, subscription_options, from, state) do
        subscribers = [from | state.subscribers]
        {:automatic, %{state | subscribers: subscribers}}
      end

      def handle_subscribe(:producer, subscription_options, from, state) do
        {:automatic, state}
      end

      defp build_error_ip(ip, error, stacktrace, state) do
        %ErrorIP{
          ip: ip,
          manager_name: ip.manager_name,
          ref: ip.ref,
          stream_ref: ip.stream_ref,
          error: error,
          stacktrace: stacktrace,
          component: state,
          decomposed: ip.decomposed,
          recomposed: ip.recomposed,
          in_progress: ip.in_progress,
          plugs: ip.plugs
        }
      end
    end
  end
end