defmodule Grapix.GraphqlWS.V1.JSONSerializer do
  @moduledoc false
  @behaviour Phoenix.Socket.Serializer

  alias Phoenix.Socket.{Broadcast, Message, Reply}

  @impl true
  def fastlane!(%Broadcast{} = msg) do
    data = phoenix2gql(nil, "1", msg.topic, msg.event, msg.payload.result)
    {:socket_push, :text, Phoenix.json_library().encode_to_iodata!(data)}
  end

  @impl true
  def encode!(%Reply{payload: %{ subscriptionId: _subscription_id }} = reply) do
    data = phoenix2gql(reply.join_ref, reply.ref, reply.topic, "subs_ack", reply.payload)

    # client doesn't like empty or unexpectedly-shapen data, but fine with nought
    #{:socket_push, :text, Phoenix.json_library().encode_to_iodata!(data)}
    {nil, :text, Phoenix.json_library().encode_to_iodata!(data)}
  end

  def encode!(%Reply{payload: %{}} = reply) do
    data =
      case reply.status do
        :error -> phoenix2gql(reply.join_ref, reply.ref, reply.topic, "phx_error", reply.payload)
        :ok -> phoenix2gql(reply.join_ref, reply.ref, reply.topic, "phx_reply", nil)
      end
    {:socket_push, :text, Phoenix.json_library().encode_to_iodata!(data)}
  end

  def encode!(%Message{} = msg) do
    data =
      phoenix2gql(msg.join_ref, msg.ref, msg.topic, "phx_message", msg.payload)
    {:socket_push, :text, Phoenix.json_library().encode_to_iodata!(data)}
  end

  defmodule(RandomId, do: use(Puid, bits: 64, charset: :alphanum_lower))
  @impl true
  def decode!(raw_message, _opts) do

    incoming = raw_message
     |> Phoenix.json_library().decode!

     Map.merge(%{ "payload" => %{}, "id" => RandomId.generate()}, incoming)
     |> gql2Phoenix
  end

  defp gql2Phoenix(%{ "type" => "connection_init", "payload" => payload, "id" => id }) do
    %Phoenix.Socket.Message{
      topic: "__absinthe__:control",
      event: "phx_join",
      payload: payload,
      ref: id,
      join_ref: nil
    }
  end

  defp gql2Phoenix(%{ "type" => "start", "payload" => payload, "id" => id }) do
    variables = Map.put(Map.get(payload, "variables", %{}), :__graphql_client_ref__, id)
    %Phoenix.Socket.Message{
      topic: "__absinthe__:control",
      event: "doc",
      payload: Map.put(payload, "variables", variables),
      ref: id,
      join_ref: nil
    }
  end

  defp gql2Phoenix(%{ "type" => "stop", "payload" => payload, "id" => id }) do
    %Phoenix.Socket.Message{
      topic: "__absinthe__:control",
      event: "phx_leave",
      payload: payload,
      ref: nil,
      join_ref: id
    }
  end

  #[msg.join_ref, msg.ref, msg.topic, msg.event, msg.payload]  
  defp phoenix2gql(_join_ref, ref, "__absinthe__:control", "subs_ack", %{subscriptionId: _subscription_id} = payload) do
    %{ "type" => "data", "id" => ref, "payload" => %{data: payload}}
  end

  defp phoenix2gql(join_ref, _ref, "__absinthe__:control", "phx_reply", payload) do
    %{ "type" => "connection_ack", "id" => join_ref, "payload" => payload }
  end

  defp phoenix2gql(_, ref, "__absinthe__:control", "phx_message", payload) do
    %{ "type" => "data", "id" => ref, "payload" => payload }
  end

  defp phoenix2gql(_, ref, "__absinthe__:control", "phx_error", payload) do
    %{ "type" => "error", "id" => ref, "payload" => payload }
  end

  defp phoenix2gql(_, ref, _msg_topic, "subscription:data", payload) do
    %{ "type" => "data", "id" => ref, "payload" => payload }
  end
end