towerops/lib/towerops_web/live/graph_live/show.ex

defmodule ToweropsWeb.GraphLive.Show do
  @moduledoc false
  use ToweropsWeb, :live_view

  alias Towerops.Agents
  alias Towerops.Devices
  alias Towerops.Monitoring
  alias Towerops.Snmp

  require Logger

  # Maximum live data points (5 minutes at 1 second intervals)
  @max_live_points 300

  @impl true
  def mount(_params, _session, socket) do
    {:ok, socket}
  end

  @impl true
  def handle_params(%{"id" => device_id, "sensor_type" => sensor_type} = params, _, socket) do
    organization = socket.assigns.current_scope.organization

    with {:ok, device} <- find_device(device_id),
         :ok <- verify_device_access(device, organization) do
      socket = initialize_graph_view(socket, device_id, sensor_type, params)
      {:noreply, socket}
    else
      {:error, :not_found} ->
        {:noreply,
         socket
         |> put_flash(:error, "Device not found")
         |> push_navigate(to: ~p"/devices")}

      {:error, :access_denied} ->
        {:noreply,
         socket
         |> put_flash(:error, "You don't have access to this device")
         |> push_navigate(to: ~p"/devices")}
    end
  end

  defp find_device(device_id) do
    case Devices.get_device(device_id) do
      nil -> {:error, :not_found}
      device -> {:ok, device}
    end
  end

  defp verify_device_access(device, organization) do
    if device.organization_id == organization.id do
      :ok
    else
      {:error, :access_denied}
    end
  end

  defp initialize_graph_view(socket, device_id, sensor_type, params) do
    maybe_subscribe_to_device(socket, device_id)

    range = Map.get(params, "range", "24h")
    interface_id = Map.get(params, "interface_id")
    sensor_id = Map.get(params, "sensor_id")
    storage_id = Map.get(params, "storage_id")

    # Check if device has agent assignment
    has_agent = Agents.get_device_assignment(device_id) != nil

    socket
    |> assign(:device_id, device_id)
    |> assign(:sensor_type, sensor_type)
    |> assign(:range, range)
    |> assign(:interface_id, interface_id)
    |> assign(:sensor_id, sensor_id)
    |> assign(:storage_id, storage_id)
    |> assign(:is_live_mode, range == "live")
    |> assign(:has_agent_assignment, has_agent)
    |> maybe_start_live_polling()
    |> load_graph_data()
  end

  defp maybe_subscribe_to_device(socket, device_id) do
    _ =
      if connected?(socket) do
        Phoenix.PubSub.subscribe(Towerops.PubSub, "device:#{device_id}")
      end

    :ok
  end

  @impl true
  def handle_event("change_range", %{"range" => range}, socket) do
    params = build_graph_params(socket.assigns, range)

    {:noreply,
     push_patch(socket,
       to: ~p"/devices/#{socket.assigns.device_id}/graph/#{socket.assigns.sensor_type}?#{params}"
     )}
  end

  defp build_graph_params(assigns, range) do
    base_params = %{"range" => range}

    base_params =
      if assigns.interface_id do
        Map.put(base_params, "interface_id", assigns.interface_id)
      else
        base_params
      end

    base_params =
      if assigns.sensor_id do
        Map.put(base_params, "sensor_id", assigns.sensor_id)
      else
        base_params
      end

    if assigns.storage_id do
      Map.put(base_params, "storage_id", assigns.storage_id)
    else
      base_params
    end
  end

  # Private functions

  defp load_graph_data(socket) do
    if socket.assigns.is_live_mode do
      load_live_mode_graph_data(socket)
    else
      # Historical mode - existing logic
      device_id = socket.assigns.device_id
      sensor_type = socket.assigns.sensor_type
      range = socket.assigns.range

      device = Devices.get_device!(device_id)
      {chart_data, title_suffix} = load_chart_data_for_type(socket.assigns, range)

      {title, unit, auto_scale} = get_chart_config(sensor_type)
      chart_title = if title_suffix, do: "#{title} - #{title_suffix}", else: title
      show_zero_line = sensor_type == "traffic"

      # Calculate max/min values from chart data
      {max_value, min_value} = calculate_chart_stats(chart_data)

      socket
      |> assign(:device, device)
      |> assign(:page_title, "#{device.name} - #{chart_title}")
      |> assign(:chart_title, chart_title)
      |> assign(:chart_data, chart_data)
      |> assign(:unit, unit)
      |> assign(:auto_scale, auto_scale)
      |> assign(:show_zero_line, show_zero_line)
      |> assign(:max_value, max_value)
      |> assign(:min_value, min_value)
    end
  end

  defp load_live_mode_graph_data(socket) do
    device_id = socket.assigns.device_id
    sensor_type = socket.assigns.sensor_type
    device = Devices.get_device!(device_id)
    {title, unit, auto_scale} = get_chart_config(sensor_type)

    title_suffix = get_title_suffix(socket.assigns)
    chart_title = if title_suffix, do: "#{title} - #{title_suffix}", else: title

    socket
    |> assign(:device, device)
    |> assign(:page_title, "#{device.name} - #{chart_title} (Live)")
    |> assign(:chart_title, chart_title)
    |> assign(:chart_data, Jason.encode!(%{datasets: []}))
    |> assign(:unit, unit)
    |> assign(:auto_scale, auto_scale)
    |> assign(:show_zero_line, sensor_type == "traffic")
    |> assign(:max_value, nil)
    |> assign(:min_value, nil)
  end

  defp get_title_suffix(assigns) do
    cond do
      assigns[:sensor_id] -> get_sensor_name(assigns[:sensor_id])
      assigns[:interface_id] && assigns[:sensor_type] == "traffic" -> get_interface_name(assigns[:interface_id])
      assigns[:storage_id] && assigns[:sensor_type] == "storage_volume" -> get_storage_name(assigns[:storage_id])
      true -> nil
    end
  end

  defp load_chart_data_for_type(%{sensor_type: "latency", device_id: device_id}, range) do
    {load_latency_chart_data(device_id, range), nil}
  end

  defp load_chart_data_for_type(%{sensor_type: "traffic", interface_id: interface_id}, range)
       when not is_nil(interface_id) do
    {load_interface_traffic_chart_data(interface_id, range), get_interface_name(interface_id)}
  end

  defp load_chart_data_for_type(%{sensor_type: "traffic", device_id: device_id}, range) do
    {load_traffic_chart_data(device_id, range), nil}
  end

  defp load_chart_data_for_type(%{sensor_type: "storage_volume", storage_id: storage_id}, range)
       when not is_nil(storage_id) do
    {load_storage_chart_data(storage_id, range), get_storage_name(storage_id)}
  end

  defp load_chart_data_for_type(%{sensor_id: sensor_id}, range) when not is_nil(sensor_id) do
    {load_single_sensor_chart_data(sensor_id, range), get_sensor_name(sensor_id)}
  end

  defp load_chart_data_for_type(%{sensor_type: sensor_type, device_id: device_id}, range) do
    sensor_types = get_sensor_types_for_chart(sensor_type)
    {load_sensor_chart_data(device_id, sensor_types, range), nil}
  end

  defp get_sensor_types_for_chart("processors"), do: ["cpu_load"]
  defp get_sensor_types_for_chart("memory"), do: ["memory_usage"]
  defp get_sensor_types_for_chart("storage"), do: ["disk_usage"]
  defp get_sensor_types_for_chart("temperature"), do: ["temperature", "cpu_temperature", "celsius"]
  defp get_sensor_types_for_chart("voltage"), do: ["voltage", "volts"]
  defp get_sensor_types_for_chart("traffic"), do: nil
  # For unknown sensor types, use the type directly (supports count, pppoe_sessions, etc.)
  defp get_sensor_types_for_chart(sensor_type), do: [sensor_type]

  defp get_chart_config("latency"), do: {"ICMP Latency", "ms", true}
  defp get_chart_config("processors"), do: {"Processor Usage", "%", false}
  defp get_chart_config("memory"), do: {"Memory Usage", "%", false}
  defp get_chart_config("storage"), do: {"Storage Usage", "%", false}
  defp get_chart_config("storage_volume"), do: {"Storage Usage", "%", false}
  defp get_chart_config("temperature"), do: {"Temperature", "°C", true}
  defp get_chart_config("voltage"), do: {"Voltage", "V", true}
  defp get_chart_config("traffic"), do: {"Overall Traffic", "bps", true}
  defp get_chart_config("count"), do: {"Count", "", true}
  defp get_chart_config("pppoe_sessions"), do: {"PPPoE Sessions", "", true}
  defp get_chart_config("connections"), do: {"Connections", "", true}
  defp get_chart_config("wireless"), do: {"Wireless Metrics", "", true}
  # Humanize unknown sensor types for title
  defp get_chart_config(sensor_type), do: {humanize_sensor_type(sensor_type), "", true}

  defp humanize_sensor_type(sensor_type) do
    sensor_type
    |> String.replace("_", " ")
    |> String.split()
    |> Enum.map_join(" ", &String.capitalize/1)
  end

  defp load_sensor_chart_data(device_id, sensor_types, range) do
    case Snmp.get_device_with_associations(device_id) do
      nil ->
        nil

      device ->
        build_sensor_chart_json(device, sensor_types, range)
    end
  end

  defp load_single_sensor_chart_data(sensor_id, range) do
    case Snmp.get_sensor(sensor_id) do
      nil ->
        nil

      sensor ->
        since = get_datetime_from_range(range)
        limit = get_limit_for_range(range)
        dataset = sensor_to_dataset(sensor, since, limit)

        # Return nil if no data points (empty readings)
        if Enum.empty?(dataset.data) do
          nil
        else
          Jason.encode!(%{datasets: [dataset]})
        end
    end
  end

  defp get_sensor_name(sensor_id) do
    case Snmp.get_sensor(sensor_id) do
      nil -> nil
      sensor -> sensor.sensor_descr
    end
  end

  defp load_storage_chart_data(storage_id, range) do
    case Snmp.get_storage(storage_id) do
      nil ->
        nil

      storage ->
        since = get_datetime_from_range(range)
        limit = get_limit_for_range(range)
        dataset = storage_to_dataset(storage, since, limit)
        Jason.encode!(%{datasets: [dataset]})
    end
  end

  defp get_storage_name(storage_id) do
    case Snmp.get_storage(storage_id) do
      nil -> nil
      storage -> storage.description || "Storage #{storage.storage_index}"
    end
  end

  defp storage_to_dataset(storage, since, limit) do
    readings =
      storage.id
      |> Snmp.get_storage_readings(since: since, limit: limit)
      |> Enum.reverse()

    %{
      label: storage.description || "Storage #{storage.storage_index}",
      data: Enum.map(readings, &storage_reading_to_chart_point/1)
    }
  end

  defp storage_reading_to_chart_point(reading) do
    %{
      x: DateTime.to_unix(reading.checked_at, :millisecond),
      y: if(reading.usage_percent, do: Float.round(reading.usage_percent, 1))
    }
  end

  defp build_sensor_chart_json(device, sensor_types, range) do
    sensors =
      device.sensors
      |> Enum.filter(&(&1.sensor_type in sensor_types))
      |> Enum.sort_by(& &1.sensor_index)

    if Enum.empty?(sensors) do
      nil
    else
      since = get_datetime_from_range(range)
      limit = get_limit_for_range(range)
      datasets = Enum.map(sensors, &sensor_to_dataset(&1, since, limit))
      Jason.encode!(%{datasets: datasets})
    end
  end

  defp sensor_to_dataset(sensor, since, limit) do
    readings =
      sensor.id
      |> Snmp.get_sensor_readings(since: since, limit: limit)
      |> Enum.reverse()

    %{
      label: sensor.sensor_descr,
      data: Enum.map(readings, &reading_to_chart_point/1)
    }
  end

  defp reading_to_chart_point(reading) do
    %{
      x: DateTime.to_unix(reading.checked_at, :millisecond),
      y: if(reading.value, do: Float.round(reading.value, 1))
    }
  end

  defp get_datetime_from_range("1h"), do: DateTime.add(DateTime.utc_now(), -1, :hour)
  defp get_datetime_from_range("6h"), do: DateTime.add(DateTime.utc_now(), -6, :hour)
  defp get_datetime_from_range("12h"), do: DateTime.add(DateTime.utc_now(), -12, :hour)
  defp get_datetime_from_range("24h"), do: DateTime.add(DateTime.utc_now(), -24, :hour)
  defp get_datetime_from_range("7d"), do: DateTime.add(DateTime.utc_now(), -7, :day)
  defp get_datetime_from_range("30d"), do: DateTime.add(DateTime.utc_now(), -30, :day)
  defp get_datetime_from_range(_), do: DateTime.add(DateTime.utc_now(), -24, :hour)

  defp get_limit_for_range("1h"), do: 360
  defp get_limit_for_range("6h"), do: 720
  defp get_limit_for_range("12h"), do: 1440
  defp get_limit_for_range("24h"), do: 2880
  defp get_limit_for_range("7d"), do: 10_080
  defp get_limit_for_range("30d"), do: 43_200
  defp get_limit_for_range(_), do: 2880

  defp load_traffic_chart_data(device_id, range) do
    case Snmp.get_device_with_associations(device_id) do
      nil -> nil
      device -> build_traffic_chart_json(device, range)
    end
  end

  defp load_interface_traffic_chart_data(interface_id, range) do
    case Snmp.get_interface(interface_id) do
      nil -> nil
      interface -> build_interface_traffic_chart_json(interface, range)
    end
  end

  defp get_interface_name(interface_id) do
    case Snmp.get_interface(interface_id) do
      nil -> "Unknown Interface"
      interface -> interface.if_name || interface.if_descr || "Interface #{interface.if_index}"
    end
  end

  defp load_latency_chart_data(device_id, range) do
    since = get_datetime_from_range(range)
    limit = get_limit_for_range(range)

    checks =
      device_id
      |> Monitoring.get_latency_data(since: since, limit: limit)
      |> Enum.reverse()

    if Enum.empty?(checks) do
      nil
    else
      dataset = %{
        label: "ICMP Latency",
        data: Enum.map(checks, &latency_check_to_chart_point/1)
      }

      Jason.encode!(%{datasets: [dataset]})
    end
  end

  defp latency_check_to_chart_point(check) do
    %{
      x: DateTime.to_unix(check.checked_at, :millisecond),
      y: check.response_time_ms
    }
  end

  # Calculate max and min values from chart data
  defp calculate_chart_stats(nil), do: {nil, nil}

  defp calculate_chart_stats(chart_data) when is_binary(chart_data) do
    case Jason.decode(chart_data) do
      {:ok, %{"datasets" => datasets}} ->
        extract_min_max_from_datasets(datasets)

      _ ->
        {nil, nil}
    end
  end

  defp extract_min_max_from_datasets(datasets) do
    values = Enum.flat_map(datasets, &extract_values_from_dataset/1)

    case values do
      [] -> {nil, nil}
      _ -> {Enum.max(values), Enum.min(values)}
    end
  end

  defp extract_values_from_dataset(%{"data" => data}) when is_list(data) do
    Enum.flat_map(data, &extract_y_value/1)
  end

  defp extract_values_from_dataset(_), do: []

  defp extract_y_value(%{"y" => y}) when is_number(y), do: [y]
  defp extract_y_value(_), do: []

  defp build_traffic_chart_json(device, range) do
    if Enum.empty?(device.interfaces), do: nil, else: build_traffic_datasets(device, range)
  end

  defp build_traffic_datasets(device, range) do
    since = get_datetime_from_range(range)
    limit = get_limit_for_range(range)
    active_interfaces = Enum.filter(device.interfaces, &(&1.if_oper_status == "up"))

    if Enum.empty?(active_interfaces), do: nil, else: encode_interface_datasets(active_interfaces, since, limit)
  end

  defp encode_interface_datasets(interfaces, since, limit) do
    datasets = build_per_interface_datasets(interfaces, since, limit)
    if Enum.empty?(datasets), do: nil, else: Jason.encode!(%{datasets: datasets})
  end

  defp build_per_interface_datasets(interfaces, since, limit) do
    Enum.flat_map(interfaces, fn interface ->
      stats =
        interface.id
        |> Snmp.get_interface_stats(since: since, limit: limit)
        |> Enum.reverse()

      if Enum.empty?(stats) do
        []
      else
        interface_name = interface.if_name || interface.if_descr
        in_data = calculate_interface_traffic_data(stats, :inbound)
        out_data = calculate_interface_traffic_data(stats, :outbound)

        [
          %{label: "#{interface_name} Out", data: out_data},
          %{label: "#{interface_name} In", data: in_data}
        ]
      end
    end)
  end

  defp build_interface_traffic_chart_json(interface, range) do
    since = get_datetime_from_range(range)
    limit = get_limit_for_range(range)

    stats =
      interface.id
      |> Snmp.get_interface_stats(since: since, limit: limit)
      |> Enum.reverse()

    if Enum.empty?(stats) do
      nil
    else
      in_data = calculate_interface_traffic_data(stats, :inbound)
      out_data = calculate_interface_traffic_data(stats, :outbound)

      datasets = [
        %{label: "Outbound", data: out_data},
        %{label: "Inbound", data: in_data}
      ]

      Jason.encode!(%{datasets: datasets})
    end
  end

  defp calculate_interface_traffic_data(stats, :inbound) do
    stats
    |> Enum.chunk_every(2, 1, :discard)
    |> Enum.map(fn [stat1, stat2] ->
      # Skip if octets are nil
      if is_nil(stat1.if_in_octets) or is_nil(stat2.if_in_octets) do
        nil
      else
        time_diff = stat2.checked_at |> DateTime.diff(stat1.checked_at, :second) |> max(1)

        bps =
          ((stat2.if_in_octets - stat1.if_in_octets) * 8 / time_diff)
          |> max(0)
          |> :erlang.float()
          |> Float.round(2)

        %{
          x: DateTime.to_unix(stat2.checked_at, :millisecond),
          y: -bps
        }
      end
    end)
    |> Enum.reject(&is_nil/1)
  end

  defp calculate_interface_traffic_data(stats, :outbound) do
    stats
    |> Enum.chunk_every(2, 1, :discard)
    |> Enum.map(fn [stat1, stat2] ->
      # Skip if octets are nil
      if is_nil(stat1.if_out_octets) or is_nil(stat2.if_out_octets) do
        nil
      else
        time_diff = stat2.checked_at |> DateTime.diff(stat1.checked_at, :second) |> max(1)

        bps =
          ((stat2.if_out_octets - stat1.if_out_octets) * 8 / time_diff)
          |> max(0)
          |> :erlang.float()
          |> Float.round(2)

        %{
          x: DateTime.to_unix(stat2.checked_at, :millisecond),
          y: bps
        }
      end
    end)
    |> Enum.reject(&is_nil/1)
  end

  # Format value with unit for display
  defp format_value(value, "bps") do
    abs_value = abs(value)

    cond do
      abs_value >= 1_000_000_000 ->
        "#{Float.round(abs_value / 1_000_000_000, 2)} Gbps"

      abs_value >= 1_000_000 ->
        "#{Float.round(abs_value / 1_000_000, 2)} Mbps"

      abs_value >= 1_000 ->
        "#{Float.round(abs_value / 1_000, 2)} Kbps"

      true ->
        "#{Float.round(abs_value, 2)} bps"
    end
  end

  # For counts (empty unit), format as integer
  defp format_value(value, "") do
    "#{round(value)}"
  end

  # For other units, format with one decimal place
  defp format_value(value, unit) do
    "#{Float.round(value, 1)}#{unit}"
  end

  # Live polling functions

  # Start/stop live polling based on mode
  defp maybe_start_live_polling(socket) do
    if socket.assigns[:is_live_mode] && connected?(socket) do
      cancel_live_polling_timer(socket)

      socket
      |> assign(:live_data_buffer, %{})
      |> assign(:live_data_points, 0)
      |> schedule_live_poll()
    else
      cancel_live_polling_timer(socket)
    end
  end

  # Schedule next poll in 1 second
  defp schedule_live_poll(socket) do
    timer_ref = Process.send_after(self(), :live_poll, 1_000)
    assign(socket, :live_poll_timer, timer_ref)
  end

  # Cancel existing timer
  defp cancel_live_polling_timer(socket) do
    case Map.get(socket.assigns, :live_poll_timer) do
      nil ->
        socket

      timer_ref ->
        Process.cancel_timer(timer_ref)
        assign(socket, :live_poll_timer, nil)
    end
  end

  # Handle device status changes from PubSub
  @impl true
  def handle_info({:device_status_changed, _device_id, _new_status, _response_time}, socket) do
    # Reload device to get updated status
    device = Devices.get_device(socket.assigns.device_id)
    {:noreply, assign(socket, :device, device)}
  end

  # Handle sensor updates from PubSub
  @impl true
  def handle_info({:state_sensors_updated, _device_id}, socket) do
    {:noreply, load_graph_data(socket)}
  end

  # Handle neighbor updates from PubSub (ignored - not relevant to graphs)
  @impl true
  def handle_info({:neighbors_updated, _device_id}, socket) do
    {:noreply, socket}
  end

  # Handle live poll event
  @impl true
  def handle_info(:live_poll, socket) do
    if socket.assigns[:is_live_mode] do
      socket = perform_live_poll(socket)
      {:noreply, schedule_live_poll(socket)}
    else
      {:noreply, socket}
    end
  end

  # Perform SNMP polling and update buffer
  defp perform_live_poll(socket) do
    device_id = socket.assigns.device_id

    # Verify device still exists and access is valid
    case Devices.get_device(device_id) do
      nil ->
        socket
        |> put_flash(:error, "Device no longer exists")
        |> push_navigate(to: ~p"/devices")

      device ->
        organization = socket.assigns.current_scope.organization

        if device.organization_id == organization.id do
          poll_and_update_buffer(socket, device)
        else
          socket
          |> put_flash(:error, "Access to device revoked")
          |> push_navigate(to: ~p"/devices")
        end
    end
  end

  # Poll sensors and update buffer
  defp poll_and_update_buffer(socket, device) do
    now = DateTime.utc_now()
    timestamp_ms = DateTime.to_unix(now, :millisecond)

    # Check if device has agent assignment
    has_agent = socket.assigns[:has_agent_assignment] || false

    Logger.info("Live poll for device #{device.name}: has_agent=#{has_agent}")

    new_points =
      if has_agent do
        # Request agent to poll NOW and wait for result
        Logger.info("Requesting live poll from agent")
        request_agent_live_poll_and_wait(device.id, socket.assigns)
      else
        # Do direct SNMP polling for specific sensors only
        Logger.info("Using direct SNMP for live polling")
        client_opts = build_snmp_client_opts(device)
        poll_sensors_for_live_mode(socket.assigns, client_opts, timestamp_ms)
      end

    Logger.info("Live poll fetched #{length(new_points)} data points: #{inspect(new_points)}")

    # Update buffer with new points (rolling window)
    {updated_buffer, point_count} =
      update_live_data_buffer(
        socket.assigns.live_data_buffer,
        socket.assigns.live_data_points,
        new_points
      )

    # Push update to client
    socket
    |> assign(:live_data_buffer, updated_buffer)
    |> assign(:live_data_points, point_count)
    |> push_event("live_data_update", %{
      timestamp: timestamp_ms,
      points: new_points
    })
  end

  # Request live poll from agent and wait for response
  defp request_agent_live_poll_and_wait(device_id, assigns) do
    case Agents.get_device_assignment(device_id) do
      nil ->
        []

      assignment ->
        # Generate unique reply topic for this request
        reply_topic = "live_poll_reply:#{:erlang.unique_integer([:positive])}"

        # Subscribe to reply topic
        :ok = Phoenix.PubSub.subscribe(Towerops.PubSub, reply_topic)

        # Get sensors we're interested in
        sensors = get_sensors_for_live_mode(assigns)
        sensor_oids = Enum.map(sensors, & &1.sensor_oid)

        # Broadcast live poll request with reply topic and sensor OIDs
        Phoenix.PubSub.broadcast(
          Towerops.PubSub,
          "agent:#{assignment.agent_token_id}:live_poll",
          {:live_poll_requested, device_id, sensor_oids, reply_topic}
        )

        # Wait for response with timeout
        receive do
          {:live_poll_result, oid_values} ->
            # Process the OID values into data points
            process_live_poll_oids(sensors, oid_values)
        after
          3000 ->
            Logger.warning("Live poll timeout waiting for agent response")
            []
        end
    end
  end

  # Convert OID values from agent into data points
  defp process_live_poll_oids(sensors, oid_values) do
    timestamp_ms = DateTime.to_unix(DateTime.utc_now(), :millisecond)

    sensors
    |> Enum.map(&build_live_poll_data_point(&1, oid_values, timestamp_ms))
    |> Enum.reject(&is_nil/1)
  end

  defp build_live_poll_data_point(sensor, oid_values, timestamp_ms) do
    with value when not is_nil(value) <- Map.get(oid_values, sensor.sensor_oid),
         parsed_value when not is_nil(parsed_value) <- parse_sensor_value(value) do
      final_value = parsed_value / sensor.sensor_divisor

      %{
        sensor_id: sensor.id,
        label: sensor.sensor_descr,
        value: Float.round(final_value, 1),
        timestamp: timestamp_ms
      }
    else
      _ -> nil
    end
  end

  defp parse_sensor_value(value) when is_float(value), do: value
  defp parse_sensor_value(value) when is_integer(value), do: value / 1.0

  defp parse_sensor_value(value) when is_binary(value) do
    case Float.parse(value) do
      {float, _} -> float
      :error -> nil
    end
  end

  defp parse_sensor_value(_), do: nil

  # Build SNMP client options
  defp build_snmp_client_opts(device) do
    snmp_config = Devices.get_snmp_config(device)

    [
      ip: device.ip_address,
      community: snmp_config.community,
      version: snmp_config.version,
      port: device.snmp_port || 161,
      # Increased for live polling - devices may be slow to respond
      timeout: 3000
    ]
  end

  # Poll sensors in parallel
  defp poll_sensors_for_live_mode(assigns, client_opts, timestamp_ms) do
    sensors = get_sensors_for_live_mode(assigns)

    sensors
    |> Task.async_stream(
      fn sensor ->
        case poll_single_sensor(sensor, client_opts) do
          {:ok, value} ->
            %{
              sensor_id: sensor.id,
              label: sensor.sensor_descr,
              value: Float.round(value, 1),
              timestamp: timestamp_ms
            }

          {:error, _reason} ->
            # Skip failed polls - chart will show gap
            nil
        end
      end,
      max_concurrency: 10,
      # Give SNMP client (3000ms timeout) enough time plus overhead
      timeout: 4000,
      on_timeout: :kill_task
    )
    |> Enum.reduce([], fn
      {:ok, nil}, acc -> acc
      {:ok, point}, acc -> [point | acc]
      {:exit, _reason}, acc -> acc
    end)
  end

  # Get sensors based on graph type
  defp get_sensors_for_live_mode(%{sensor_id: sensor_id}) when not is_nil(sensor_id) do
    case Snmp.get_sensor(sensor_id) do
      nil -> []
      sensor -> [sensor]
    end
  end

  defp get_sensors_for_live_mode(%{sensor_type: sensor_type, device_id: device_id}) do
    sensor_types = get_sensor_types_for_chart(sensor_type)
    device = Snmp.get_device_with_associations(device_id)

    device.sensors
    |> Enum.filter(&(&1.sensor_type in sensor_types))
    |> Enum.sort_by(& &1.sensor_index)
  end

  # Poll single sensor via SNMP
  defp poll_single_sensor(sensor, client_opts) do
    case Snmp.Client.get(client_opts, sensor.sensor_oid) do
      {:ok, raw_value} when is_number(raw_value) ->
        value = raw_value / sensor.sensor_divisor
        {:ok, value}

      {:ok, _non_numeric} ->
        {:error, :non_numeric}

      {:error, reason} ->
        {:error, reason}
    end
  end

  # Update live data buffer with rolling window
  defp update_live_data_buffer(buffer, current_count, new_points) do
    updated_buffer =
      Enum.reduce(new_points, buffer, fn point, acc ->
        sensor_buffer = Map.get(acc, point.sensor_id, [])

        # Add new point at the front
        new_buffer = [
          %{x: point.timestamp, y: point.value} | sensor_buffer
        ]

        # Trim to max size
        trimmed_buffer =
          if current_count >= @max_live_points do
            Enum.take(new_buffer, @max_live_points)
          else
            new_buffer
          end

        Map.put(acc, point.sensor_id, trimmed_buffer)
      end)

    new_count = min(current_count + 1, @max_live_points)
    {updated_buffer, new_count}
  end

  # Cleanup on LiveView termination
  @impl true
  def terminate(_reason, socket) do
    cancel_live_polling_timer(socket)
    :ok
  end
end