defmodule Actors.Registry.ActorRegistry do
  @moduledoc false
  use GenServer
  require Logger

  alias Actors.Registry.HostActor
  alias Eigr.Functions.Protocol.Actors.{Actor, ActorId}
  alias Spawn.Cluster.StateHandoff

  def child_spec(state \\ []) do
    %{
      id: __MODULE__,
      start: {__MODULE__, :start_link, [state]},
      shutdown: 10_000,
      restart: :transient
    }
  end

  @impl true
  def init(state) do
    Process.flag(:trap_exit, true)
    :ok = :net_kernel.monitor_nodes(true, node_type: :visible)
    {:ok, state}
  end

  @impl true
  def handle_info({:nodeup, node, _node_type}, state) do
    Logger.debug("Received :nodeup event from #{inspect(node)}")

    {:noreply, state}
  end

  def handle_info({:nodedown, node, _node_type}, state) do
    Logger.debug("Received :nodedown event from #{inspect(node)}")
    {:noreply, state}
  end

  @impl true
  def handle_call({:get, _system_name, actor_name}, from, state) do
    spawn(fn ->
      case StateHandoff.get(actor_name) do
        nil ->
          GenServer.reply(from, {:not_found, []})

        hosts ->
          Enum.filter(hosts, fn ac -> ac.actor.id.name == actor_name end)
          |> Enum.random()
          |> then(fn
            nil ->
              GenServer.reply(from, {:not_found, []})

            node_host ->
              GenServer.reply(from, {:ok, node_host})
          end)
      end
    end)

    {:noreply, state}
  end

  def handle_call({:register, hosts}, _from, state) do
    Enum.each(hosts, fn %HostActor{
                          node: node,
                          actor: %Actor{id: %ActorId{name: name} = _id} = _actor
                        } = host ->
      case StateHandoff.get(name) do
        nil ->
          StateHandoff.set(name, [host])

        hosts ->
          filtered_list =
            Enum.filter(hosts, fn ac -> ac.node == node and ac.actor.id.name == name end)

          if length(filtered_list) <= 0 do
            updated_hosts = hosts ++ [host]
            StateHandoff.set(name, updated_hosts)
          end
      end
    end)

    {:reply, :ok, state}
  end

  @impl true
  def terminate(_reason, _state) do
    Logger.debug("Stopping ActorRegistry...")
    _node = Node.self()
    # StateHandoff.clean(node)
  end

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

  @doc """
  Register `member` entities to the ActorRegistry.
  Returns `Cluster` with all Host members.
  ## Examples
      iex> hosts = [%HostActor{node: Node.self(), actor: actor, opts: []}}]
      iex> ActorRegistry.register(hosts)
      :ok
  """
  @doc since: "0.1.0"
  @spec register(list(HostActor.t())) :: :ok
  def register(hosts) do
    GenServer.call(__MODULE__, {:register, hosts})
  end

  @doc """
  Fetch current entities of the service.
  Returns `Member` with Host and specific actor.
  ## Examples
      iex> ActorRegistry.lookup("spawn-system", "joe")
      {:ok,
       %Actors.Registry.Member{
         id: :"spawn_a2@127.0.0.1",
         host_function: %Actors.Registry.HostActor{
           actors: [
             %Eigr.Functions.Protocol.Actors.Actor{
               name: "jose",
               persistent: true,
               state: %Eigr.Functions.Protocol.Actors.ActorState{
                 tags: %{},
                 state: nil,
                 __unknown_fields__: []
               },
               snapshot_strategy: %Eigr.Functions.Protocol.Actors.ActorSnapshotStrategy{
                 strategy: {:timeout,
                   %Eigr.Functions.Protocol.Actors.TimeoutStrategy{
                     timeout: 2000,
                     __unknown_fields__: []
                   }},
                 __unknown_fields__: []
               },
               deactivation_strategy: %Eigr.Functions.Protocol.Actors.ActorDeactivationStrategy{
                 strategy: {:timeout,
                   %Eigr.Functions.Protocol.Actors.TimeoutStrategy{
                     timeout: 30000,
                     __unknown_fields__: []
                   }},
                 __unknown_fields__: []
               },
               __unknown_fields__: []
             }
           ],
           opts: [host_interface: SpawnSdk.Interface]
         }
      }}
  """
  @doc since: "0.1.0"
  @spec lookup(String.t(), String.t()) :: {:ok, Member.t()} | {:not_found, []}
  def lookup(system_name, actor_name) do
    GenServer.call(__MODULE__, {:get, system_name, actor_name})
  end
end