zen_websocket

defmodule ZenWebsocket.Helpers.Deribit do
  @moduledoc """
  Helper functions for Deribit-specific WebSocket operations.
  """

  require Logger

  @doc """
  Handles Deribit test_request heartbeat messages.
  """
  @spec handle_heartbeat(map(), map()) :: map()
  def handle_heartbeat(%{"params" => %{"type" => "test_request"}}, state) do
    Logger.info("🚨 [DERIBIT TEST_REQUEST] Auto-responding...")
    now = System.monotonic_time(:millisecond)

    # Emit heartbeat interval telemetry if we have a previous timestamp
    # Note: This measures time between heartbeat responses (heartbeat regularity),
    # not true round-trip time which would require tracking when requests are sent
    if state.last_heartbeat_at do
      rtt_ms = now - state.last_heartbeat_at

      :telemetry.execute(
        [:zen_websocket, :heartbeat, :pong],
        %{rtt_ms: rtt_ms},
        %{type: :deribit_test_request}
      )
    end

    # Send immediate test response
    response =
      Jason.encode!(%{
        jsonrpc: "2.0",
        method: "public/test",
        params: %{}
      })

    Logger.info("📤 [HEARTBEAT RESPONSE] #{DateTime.to_string(DateTime.utc_now())}")
    Logger.info("   ✅ Sending automatic public/test response")

    :ok = :gun.ws_send(state.gun_pid, state.stream_ref, {:text, response})

    # Update heartbeat tracking
    %{
      state
      | active_heartbeats: MapSet.put(state.active_heartbeats, :deribit_test_request),
        last_heartbeat_at: now,
        heartbeat_failures: 0
    }
  end

  @doc false
  # Catch-all clause for non-test_request heartbeat messages
  def handle_heartbeat(_msg, state), do: state

  @doc """
  Sends Deribit heartbeat ping message.
  """
  @spec send_heartbeat(map()) :: map()
  def send_heartbeat(state) do
    message =
      Jason.encode!(%{
        jsonrpc: "2.0",
        method: "public/test",
        params: %{}
      })

    :ok = :gun.ws_send(state.gun_pid, state.stream_ref, {:text, message})

    %{state | last_heartbeat_at: System.monotonic_time(:millisecond)}
  end
end