# AUTO-GENERATED FILE - DO NOT EDIT
# This file was automatically generated by the XDK build tool.
# Any manual changes will be overwritten on the next generation.

defmodule Xdk.Streaming do
  @moduledoc """
  Low-level NDJSON streaming helper for the X API.

  Used internally by `Xdk.Stream` to consume newline-delimited JSON
  streams (filtered stream, sample stream, etc.).
  """

  @spec ndjson_stream(Xdk.t(), atom(), String.t(), keyword()) :: Enumerable.t()
  def ndjson_stream(%Xdk{} = client, method, path, opts \\ []) do
    finch = Xdk.require_finch!(client)
    request = Xdk.build_finch_request(client, method, path, opts)
    idle_timeout = Keyword.get(opts, :idle_timeout, 30_000)

    parent = self()

    Stream.resource(
      fn ->
        ref = make_ref()

        pid =
          spawn_link(fn ->
            result =
              Finch.stream(
                request,
                finch,
                _buffer = "",
                fn
                  {:status, _status}, buf ->
                    buf

                  {:headers, _headers}, buf ->
                    buf

                  {:data, data}, buf ->
                    buf = buf <> data
                    {lines, rest} = split_lines(buf)

                    for line <- lines do
                      case parse_line(line) do
                        :heartbeat -> :ok
                        {:ok, event} -> send(parent, {ref, {:event, event}})
                        {:error, err} -> send(parent, {ref, {:decode_error, err, line}})
                      end
                    end

                    rest
                end,
                Keyword.get(opts, :request_opts, client.request_opts)
              )

            case result do
              {:ok, _} -> send(parent, {ref, :done})
              {:error, reason} -> send(parent, {ref, {:stream_error, reason}})
            end
          end)

        %{ref: ref, pid: pid}
      end,
      fn %{ref: ref} = state ->
        receive do
          {^ref, {:event, event}} -> {[{:ok, event}], state}
          {^ref, {:decode_error, err, line}} -> {[{:error, {:decode, err, line}}], state}
          {^ref, {:stream_error, reason}} -> {[{:error, {:stream, reason}}], state}
          {^ref, :done} -> {:halt, state}
        after
          idle_timeout -> {[{:error, :idle_timeout}], %{state | ref: ref}}
        end
      end,
      fn %{pid: pid} ->
        if Process.alive?(pid), do: Process.exit(pid, :shutdown)
        :ok
      end
    )
  end

  defp split_lines(buf) do
    case String.split(buf, "\n") do
      [single] -> {[], single}
      parts -> {Enum.slice(parts, 0..-2//1), List.last(parts)}
    end
  end

  defp parse_line(line) do
    line = String.trim(line)

    if line == "" do
      :heartbeat
    else
      Jason.decode(line)
    end
  end
end