defmodule ToweropsWeb.Api.V1.ActivityController do
  @moduledoc "API controller for the organization activity feed."
  use ToweropsWeb, :controller

  alias Towerops.ActivityFeed

  def index(conn, params) do
    organization_id = conn.assigns.current_organization_id

    opts =
      []
      |> maybe_add(:limit, parse_int(params["limit"], 50))
      |> maybe_add_types(params["types"])

    items = ActivityFeed.list_org_activity(organization_id, opts)

    json(conn, %{data: items})
  end

  defp maybe_add(opts, key, value), do: Keyword.put(opts, key, value)

  defp maybe_add_types(opts, nil), do: opts

  # Allowlist of activity types the API accepts. Anything else is dropped
  # silently. Using a hard list avoids `String.to_existing_atom/1` which
  # would convert any string that happens to match an internal atom
  # somewhere in the BEAM — that produces unpredictable filter behavior
  # and grows the atom table from user input.
  @allowed_types ~w(config_change alert_fired alert_resolved device_event sync device_added)a

  defp maybe_add_types(opts, types) when is_binary(types) do
    type_atoms =
      types
      |> String.split(",")
      |> Enum.map(&String.trim/1)
      |> Enum.flat_map(&allowed_type/1)

    Keyword.put(opts, :types, type_atoms)
  end

  defp maybe_add_types(opts, _), do: opts

  defp allowed_type(str) do
    Enum.filter(@allowed_types, fn t -> Atom.to_string(t) == str end)
  end

  defp parse_int(nil, default), do: default

  defp parse_int(val, default) when is_binary(val) do
    case Integer.parse(val) do
      {n, _} -> n
      :error -> default
    end
  end

  defp parse_int(val, _default) when is_integer(val), do: val
end