aprs.me/lib/aprs/packets.ex

defmodule Aprs.Packets do
  @moduledoc """
  The Packets context.
  """

  import Ecto.Query, warn: false

  alias Aprs.Packet
  alias Aprs.Repo

  @doc """
  Stores a packet in the database.

  ## Parameters
    * `packet_data` - Map containing packet data to be stored
  """
  def store_packet(packet_data) do
    require Logger

    # Convert to map if it's a struct, or use as is if already a map
    packet_attrs =
      case packet_data do
        %Packet{} = packet ->
          packet
          |> Map.from_struct()
          |> Map.delete(:__meta__)

        %{} ->
          packet_data
      end

    # Convert data_type to string if it's an atom
    packet_attrs =
      case packet_attrs do
        %{data_type: data_type} when is_atom(data_type) ->
          Map.put(packet_attrs, :data_type, to_string(data_type))

        _ ->
          packet_attrs
      end

    # Make sure received_at is set with explicit UTC DateTime
    current_time = DateTime.truncate(DateTime.utc_now(), :microsecond)
    packet_attrs = Map.put(packet_attrs, :received_at, current_time)

    # Extract position data
    {lat, lon} = extract_position(packet_attrs)

    # Set position fields if found
    packet_attrs =
      if lat && lon do
        packet_attrs
        |> Map.put(:lat, lat)
        |> Map.put(:lon, lon)
        |> Map.put(:has_position, true)
        |> Map.put(:region, "#{Float.round(lat, 1)},#{Float.round(lon, 1)}")
      else
        # Set region based on callsign if no position
        sender_region = if packet_attrs[:sender], do: String.slice(packet_attrs.sender || "", 0, 3), else: "unknown"
        Map.put(packet_attrs, :region, "call:#{sender_region}")
      end

    # Insert the packet
    %Packet{}
    |> Packet.changeset(packet_attrs)
    |> Repo.insert()
  end

  # Extracts position data from packet, checking various possible locations
  defp extract_position(packet_data) do
    cond do
      # Check for lat/lon at top level
      not is_nil(packet_data[:lat]) and not is_nil(packet_data[:lon]) ->
        {to_float(packet_data.lat), to_float(packet_data.lon)}

      # Check data_extended struct or map
      not is_nil(packet_data[:data_extended]) ->
        data_extended = packet_data.data_extended

        cond do
          # Standard position format
          is_map(data_extended) and not is_nil(data_extended[:latitude]) and not is_nil(data_extended[:longitude]) ->
            {to_float(data_extended.latitude), to_float(data_extended.longitude)}

          # MicE packet format with components
          is_map(data_extended) and data_extended.__struct__ == Parser.Types.MicE ->
            mic_e = data_extended

            if is_number(mic_e.lat_degrees) and is_number(mic_e.lat_minutes) and
                 is_number(mic_e.lon_degrees) and is_number(mic_e.lon_minutes) do
              # Convert MicE components to decimal degrees
              lat = mic_e.lat_degrees + mic_e.lat_minutes / 60.0
              lat = if mic_e.lat_direction == :south, do: -lat, else: lat

              lon = mic_e.lon_degrees + mic_e.lon_minutes / 60.0
              lon = if mic_e.lon_direction == :west, do: -lon, else: lon

              {lat, lon}
            else
              {nil, nil}
            end

          true ->
            {nil, nil}
        end

      true ->
        {nil, nil}
    end
  end

  @doc """
  Gets packets for replay.

  ## Parameters
    * `opts` - Map of options for filtering and pagination:
      * `:lat` - Latitude for center point filtering
      * `:lon` - Longitude for center point filtering
      * `:radius` - Radius in kilometers for filtering
      * `:callsign` - Filter by callsign
      * `:region` - Filter by region
      * `:start_time` - Start time for replay (DateTime)
      * `:end_time` - End time for replay (DateTime)
      * `:limit` - Maximum number of packets to return
      * `:page` - Page number for pagination
  """
  def get_packets_for_replay(opts \\ %{}) do
    base_query = from(p in Packet, order_by: [asc: p.received_at], where: p.has_position == true)

    query =
      base_query
      |> filter_by_time(opts)
      |> filter_by_region(opts)
      |> filter_by_callsign(opts)
      |> filter_by_map_bounds(opts)
      |> limit_results(opts)

    Repo.all(query)
  end

  @doc """
  Gets historical packet count for a map area.
  """
  def get_historical_packet_count(opts \\ %{}) do
    base_query = from(p in Packet, select: count(p.id), where: p.has_position == true)

    query =
      base_query
      |> filter_by_time(opts)
      |> filter_by_region(opts)
      |> filter_by_callsign(opts)
      |> filter_by_map_bounds(opts)

    Repo.one(query)
  end

  # Query building helpers
  # Handle both start_time and end_time
  defp filter_by_time(query, %{start_time: start_time, end_time: end_time}) do
    # Ensure we prioritize packets from the last hour
    one_hour_ago = DateTime.add(DateTime.utc_now(), -3600, :second)
    effective_start_time = if DateTime.before?(start_time, one_hour_ago), do: one_hour_ago, else: start_time

    from p in query,
      where: p.received_at >= ^effective_start_time and p.received_at <= ^end_time
  end

  # Handle only start_time
  defp filter_by_time(query, %{start_time: start_time}) do
    from p in query, where: p.received_at >= ^start_time
  end

  # Handle only end_time
  defp filter_by_time(query, %{end_time: end_time}) do
    from p in query, where: p.received_at <= ^end_time
  end

  # Default case
  defp filter_by_time(query, _), do: query

  @doc """
  Get packets only from the last hour for current display.
  This is used for initial map loading to show only recent packets.
  """
  def get_recent_packets(opts \\ %{}) do
    # Always limit to the last hour
    one_hour_ago = DateTime.add(DateTime.utc_now(), -3600, :second)

    # Merge the one-hour limit with any other filters
    opts_with_time = Map.put(opts, :start_time, one_hour_ago)

    get_packets_for_replay(opts_with_time)
  end

  @doc """
  Retrieves a continuous stream of stored packets for replay in chronological order.

  This function returns a Stream that can be used to process packets in chronological
  order, preserving the timing between packets.

  ## Parameters
    * `opts` - The same options as `get_packets_for_replay/1`
      * `:playback_speed` - Speed multiplier (1.0 = real-time, 2.0 = 2x speed, etc.)

  ## Returns
    * Stream of packets with timing information
  """
  def stream_packets_for_replay(opts \\ %{}) do
    packets = get_packets_for_replay(opts)
    playback_speed = Map.get(opts, :playback_speed, 1.0)

    # Return a stream that emits packets with their original timing
    Stream.unfold({packets, nil}, fn
      {[], _} ->
        nil

      {[packet | rest], nil} ->
        {{0, packet}, {rest, packet}}

      {[next | rest], prev} ->
        # Calculate delay between packets in milliseconds, then convert to seconds
        delay_ms = DateTime.diff(next.received_at, prev.received_at, :millisecond)
        adjusted_delay = delay_ms / (playback_speed * 1000)
        {{adjusted_delay, next}, {rest, next}}
    end)
  end

  defp filter_by_region(query, %{region: region}) do
    from p in query, where: p.region == ^region
  end

  defp filter_by_region(query, _), do: query

  defp filter_by_callsign(query, %{callsign: callsign}) do
    pattern = "%#{callsign}%"
    from p in query, where: ilike(p.sender, ^pattern) or ilike(p.base_callsign, ^pattern)
  end

  defp filter_by_callsign(query, _), do: query

  defp filter_by_map_bounds(query, %{bounds: [min_lon, min_lat, max_lon, max_lat]})
       when not is_nil(min_lon) and not is_nil(min_lat) and not is_nil(max_lon) and not is_nil(max_lat) do
    from p in query,
      where: p.has_position == true,
      where: p.lat >= ^min_lat and p.lat <= ^max_lat,
      where: p.lon >= ^min_lon and p.lon <= ^max_lon
  end

  defp filter_by_map_bounds(query, _), do: query

  defp limit_results(query, %{limit: limit, page: page}) when not is_nil(limit) and not is_nil(page) do
    offset = (page - 1) * limit
    from p in query, limit: ^limit, offset: ^offset
  end

  defp limit_results(query, %{limit: limit}) when not is_nil(limit) do
    from p in query, limit: ^limit
  end

  defp limit_results(query, _), do: query

  @doc """
  Configure packet retention policy.

  Packets are retained based on these rules:
  - Default retention is 30 days (configurable via :packet_retention_days)
  - Returns the number of packets deleted
  """
  def clean_old_packets do
    retention_days = Application.get_env(:aprs, :packet_retention_days, 30)
    cutoff_time = DateTime.add(DateTime.utc_now(), -retention_days * 86_400, :second)

    {deleted_count, _} = Repo.delete_all(from(p in Packet, where: p.received_at < ^cutoff_time))

    deleted_count
  end

  # Helper to convert various types to float
  defp to_float(value) when is_float(value), do: value
  defp to_float(value) when is_integer(value), do: value * 1.0
  defp to_float(%Decimal{} = value), do: Decimal.to_float(value)

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

  defp to_float(_), do: nil

  # Get packets from last hour only - used to initialize the map
  def get_last_hour_packets do
    one_hour_ago = DateTime.add(DateTime.utc_now(), -3600, :second)

    Packet
    |> where([p], p.has_position == true)
    |> where([p], p.received_at >= ^one_hour_ago)
    |> order_by([p], asc: p.received_at)
    |> limit(500)
    |> Repo.all()
  end
end