defmodule WeewxProxy.Modbus.Deye do
  @moduledoc false

  require Logger

  use Tortoise311.Handler

  alias WeewxProxy.{Publisher, Utils}

  # Callbacks

  @impl true
  def init(_opts) do
    _ = Logger.info("Initializing handler")
    {:ok, nil}
  end

  @impl true
  def connection(:up, state) do
    _ = Logger.info("Connection has been established")
    {:ok, state}
  end

  @impl true
  def connection(:down, state) do
    _ = Logger.warning("Connection has been dropped")
    {:ok, state}
  end

  @impl true
  def connection(:terminating, state) do
    _ = Logger.warning("Connection is terminating")
    {:ok, state}
  end

  @impl true
  def subscription(:up, topic, state) do
    _ = Logger.info("Subscribed to `#{topic}'")
    {:ok, state}
  end

  @impl true
  def subscription({:warn, [requested: req, accepted: qos]}, topic, state) do
    _ = Logger.warning("Subscribed to `#{topic}'; requested #{req} but got accepted with QoS #{qos}")
    {:ok, state}
  end

  @impl true
  def subscription({:error, reason}, topic, state) do
    _ = Logger.error("Error subscribing to `#{topic}'; #{inspect(reason)}")
    {:ok, state}
  end

  @impl true
  def subscription(:down, topic, state) do
    _ = Logger.info("Unsubscribed from `#{topic}'")
    {:ok, state}
  end

  @impl true
  def handle_message(topic, publish, state) do
    full_topic = Enum.join(topic, "/")
    parsed_message = parse_message(full_topic, publish)

    state = handle_reading(full_topic, parsed_message, state)

    {:ok, state}
  end

  @impl true
  def terminate(reason, _state) do
    _ = Logger.warning("Client has been terminated with reason: `#{inspect(reason)}'")
    :ok
  end

  # Helper

  @spec parse_message(String.t(), String.t()) :: float() | nil
  defp parse_message(topic, message) when topic in ["deye/day_energy", "deye/ac/active_power"] do
    Utils.parse_float(message)
  end

  defp parse_message(_topic, _message), do: nil

  @spec handle_reading(String.t(), float() | nil, {:day | :active, float()}) :: {:day | :active, float()} | nil
  defp handle_reading(_topic, nil, state), do: state

  defp handle_reading("deye/day_energy", reading, {:active, active}) do
    timestamp = DateTime.utc_now() |> DateTime.to_unix()

    data = %{
      dateTime: timestamp,
      solarEnergyDay: reading * 1000.0,
      solarEnergyActive: active
    }

    :ok = Publisher.publish("weewx/ingest_si", data)

    nil
  end

  defp handle_reading("deye/day_energy", reading, _other) do
    {:day, reading}
  end

  defp handle_reading("deye/ac/active_power", reading, {:day, day}) do
    timestamp = DateTime.utc_now() |> DateTime.to_unix()

    data = %{
      dateTime: timestamp,
      solarEnergyDay: day * 1000.0,
      solarEnergyActive: reading
    }

    :ok = Publisher.publish("weewx/ingest_si", data)

    nil
  end

  defp handle_reading("deye/ac/active_power", reading, _other) do
    {:active, reading}
  end
end