## This Source Code Form is subject to the terms of the Mozilla Public
## License, v. 2.0. If a copy of the MPL was not distributed with this
## file, You can obtain one at https://mozilla.org/MPL/2.0/.
##
## Copyright (c) 2007-2020 VMware, Inc. or its affiliates.  All rights reserved.

defmodule RabbitMQ.CLI.Ctl.RpcStream do
  alias RabbitMQ.CLI.Ctl.InfoKeys

  def receive_list_items(node, mod, fun, args, timeout, info_keys) do
    receive_list_items(node, [{mod, fun, args}], timeout, info_keys, 1)
  end

  def receive_list_items(node, mod, fun, args, timeout, info_keys, chunks) do
    receive_list_items(node, [{mod, fun, args}], timeout, info_keys, chunks)
  end

  def receive_list_items(_node, _mfas, _timeout, _info_keys, 0) do
    nil
  end

  def receive_list_items(node, mfas, timeout, info_keys, chunks_init) do
    receive_list_items_with_fun(node, mfas, timeout, info_keys, chunks_init, fn v -> v end)
  end

  def receive_list_items_with_fun(node, mfas, timeout, info_keys, chunks_init, response_fun) do
    pid = Kernel.self()
    ref = Kernel.make_ref()
    for {m, f, a} <- mfas, do: init_items_stream(node, m, f, a, timeout, pid, ref)

    Stream.unfold(
      {chunks_init, :continue},
      fn
        :finished ->
          response_fun.(nil)

        {chunks, :continue} ->
          received =
            receive do
              {^ref, :finished} when chunks === 1 ->
                nil

              {^ref, :finished} ->
                {[], {chunks - 1, :continue}}

              {^ref, {:timeout, t}} ->
                {{:error, {:badrpc, {:timeout, t / 1000}}}, :finished}

              {^ref, []} ->
                {[], {chunks, :continue}}

              {^ref, :error, {:badrpc, :timeout}} ->
                {{:error, {:badrpc, {:timeout, timeout / 1000}}}, :finished}

              {^ref, result, :continue} ->
                {result, {chunks, :continue}}

              {:error, _} = error ->
                {error, :finished}

              {^ref, :error, error} ->
                {{:error, simplify_emission_error(error)}, :finished}

              {:DOWN, _mref, :process, _pid, :normal} ->
                {[], {chunks, :continue}}

              {:DOWN, _mref, :process, _pid, reason} ->
                {{:error, simplify_emission_error(reason)}, :finished}
            end

          response_fun.(received)
      end
    )
    |> display_list_items(info_keys)
  end

  def simplify_emission_error({:badrpc, {:EXIT, {{:nocatch, error}, error_details}}}) do
    {error, error_details}
  end

  def simplify_emission_error({{:nocatch, error}, error_details}) do
    {error, error_details}
  end

  def simplify_emission_error(other) do
    other
  end

  defp display_list_items(items, info_keys) do
    items
    |> Stream.filter(fn
      [] -> false
      _ -> true
    end)
    |> Stream.map(fn
      {:error, error} ->
        error

      # here item is a list of keyword lists:
      [[{_, _} | _] | _] = item ->
        Enum.map(item, fn i -> InfoKeys.info_for_keys(i, info_keys) end)

      item ->
        InfoKeys.info_for_keys(item, info_keys)
    end)
  end

  defp init_items_stream(_node, _mod, _fun, _args, 0, pid, ref) do
    set_stream_timeout(pid, ref, 0)
  end

  defp init_items_stream(node, mod, fun, args, timeout, pid, ref) do
    :rabbit_control_misc.spawn_emitter_caller(node, mod, fun, args, ref, pid, timeout)
    set_stream_timeout(pid, ref, timeout)
  end

  defp set_stream_timeout(_, _, :infinity) do
    :ok
  end

  defp set_stream_timeout(pid, ref, timeout) do
    Process.send_after(pid, {ref, {:timeout, timeout}}, timeout)
  end
end
