defmodule Localiser.Domain.Sensors do
  import Ecto.Query

  alias Localiser.Repo
  alias Localiser.Domain.Schema.Sensor
  alias Localiser.Domain.Schema.SensorCalibration

  def list_sensors do
    Sensor
    |> Repo.all()
    |> Repo.preload(:room)
    |> Enum.map(&populate_floor_coords/1)
  end

  def list_unplaced do
    Sensor |> where([s], is_nil(s.room_id)) |> Repo.all()
  end

  def any_placed?, do: Repo.exists?(from s in Sensor, where: not is_nil(s.room_id))

  def list_sensors_for_room(room_id) do
    Sensor
    |> where([s], s.room_id == ^room_id)
    |> Repo.all()
  end

  def list_sensors_for_floor(floor_id) do
    Sensor
    |> join(:inner, [s], r in assoc(s, :room))
    |> where([_s, r], r.floor_id == ^floor_id)
    |> Repo.all()
  end

  def get_sensor!(id) do
    Sensor
    |> Repo.get!(id)
    |> Repo.preload(:room)
    |> populate_floor_coords()
  end

  def get_sensor_by_sensor_id(sensor_id) do
    Repo.get_by(Sensor, sensor_id: sensor_id)
  end

  def create_sensor(attrs) do
    %Sensor{}
    |> Sensor.changeset(attrs)
    |> Repo.insert()
  end

  def update_sensor(%Sensor{} = sensor, attrs) do
    sensor
    |> Sensor.changeset(attrs)
    |> Repo.update()
  end

  def factory_reset(%Sensor{} = sensor) do
    Localiser.MQTT.Connection.publish(cmd_topic(sensor), Jason.encode!(%{action: "factory_reset"}))
    {:ok, sensor}
  end

  # Pushes new WiFi and/or MQTT broker settings to the sensor. The sensor will
  # apply the changes and restart. All keys are optional — omit any you don't
  # want to change. Valid keys: "ssid", "password", "mqtt_host", "mqtt_port".
  def reconfigure_settings(%Sensor{} = sensor, config) do
    payload = Map.merge(
      %{"action" => "reconfigure_settings"},
      Map.new(config, fn
        {"mqtt_broker", v} -> {"mqtt_host", v}
        entry -> entry
      end)
    )
    Localiser.MQTT.Connection.publish(cmd_topic(sensor), Jason.encode!(payload))
    {:ok, sensor}
  end

  def delete_sensor(%Sensor{} = sensor) do
    factory_reset(sensor)
    Repo.delete(sensor)
  end

  def enroll_sensor(%Sensor{} = sensor, room_id) do
    sensor
    |> Sensor.changeset(%{room_id: room_id})
    |> Repo.update()
  end

  def add_calibration(%Sensor{} = sensor, attrs) do
    attrs = Map.put(attrs, :sensor_id, sensor.id)

    %SensorCalibration{}
    |> SensorCalibration.changeset(attrs)
    |> Repo.insert()
  end

  def list_calibrations(%Sensor{} = sensor) do
    SensorCalibration
    |> where([c], c.sensor_id == ^sensor.id)
    |> order_by([c], desc: c.calibrated_at)
    |> Repo.all()
  end

  def latest_calibration(%Sensor{} = sensor) do
    SensorCalibration
    |> where([c], c.sensor_id == ^sensor.id)
    |> order_by([c], desc: c.calibrated_at)
    |> limit(1)
    |> Repo.one()
  end

  # Sensor lifecycle / enrollment helpers

  @enrollment_timeout_ms Application.compile_env(:localiser, :enrollment_timeout_ms, 10_000)

  # Called by the phone app to indicate a sensor is about to come online.
  # Creates an unconfirmed sensor record and starts a timeout Task.
  def expect_sensor(sensor_id) do
    result =
      %Sensor{}
      |> Sensor.changeset(%{sensor_id: sensor_id, confirmed: false})
      |> Repo.insert(
        on_conflict: [set: [confirmed: false, updated_at: DateTime.utc_now()]],
        conflict_target: :sensor_id,
        returning: true
      )

    case result do
      {:ok, sensor} ->
        Phoenix.PubSub.broadcast(Localiser.PubSub, "sensors", {:sensor_expected, sensor})
        Task.start(fn ->
          Process.sleep(@enrollment_timeout_ms)
          fresh = Repo.get_by(Sensor, sensor_id: sensor_id)
          if fresh && !fresh.confirmed do
            Phoenix.PubSub.broadcast(Localiser.PubSub, "sensors", {:sensor_enrollment_timeout, sensor_id})
          end
        end)
        {:ok, sensor}

      error ->
        error
    end
  end

  # Called when an ESP board self-announces on MQTT. Inserts a new unplaced sensor
  # record, or marks it confirmed if the sensor_id already exists.
  def upsert_announced(sensor_id) do
    result =
      %Sensor{}
      |> Sensor.changeset(%{sensor_id: sensor_id, confirmed: true})
      |> Repo.insert(
        on_conflict: [set: [confirmed: true, updated_at: DateTime.utc_now()]],
        conflict_target: :sensor_id,
        returning: true
      )

    case result do
      {:ok, sensor} ->
        Phoenix.PubSub.broadcast(Localiser.PubSub, "sensors", {:sensor_announced, sensor})
        {:ok, sensor}

      error ->
        error
    end
  end

  # Places (or re-places) a sensor at a specific position within a room.
  # Broadcasts {:sensor_enrolled, sensor, room} for Sensor.Supervisor / Sensor.Server.
  def place_sensor(%Sensor{} = sensor, room_id, {x, y}) do
    with {:ok, sensor} <- update_sensor(sensor, %{room_id: room_id, x: x, y: y}) do
      room = Repo.preload(sensor, :room).room
      sensor = populate_floor_coords(%{sensor | room: room})
      Phoenix.PubSub.broadcast(Localiser.PubSub, "sensors", {:sensor_enrolled, sensor, room})
      {:ok, sensor}
    end
  end

  # Removes a sensor from the room layout without deleting the DB record.
  # Broadcasts {:sensor_unenrolled, sensor_id} for Sensor.Supervisor.
  def remove_from_layout(%Sensor{} = sensor) do
    with {:ok, sensor} <- update_sensor(sensor, %{room_id: nil, x: nil, y: nil}) do
      Phoenix.PubSub.broadcast(Localiser.PubSub, "sensors", {:sensor_unenrolled, sensor.sensor_id})
      {:ok, sensor}
    end
  end

  defp cmd_topic(sensor), do: "localiser/sensor/#{sensor.sensor_id}/cmd"

  defp populate_floor_coords(%Sensor{room: nil} = sensor), do: sensor

  defp populate_floor_coords(%Sensor{room: room} = sensor) do
    %{sensor |
      floor_x: (room.x || 0.0) + (sensor.x || 0.0),
      floor_y: (room.y || 0.0) + (sensor.y || 0.0)
    }
  end
end