defmodule Grizzly.ZWave.Commands.AssociationReport do
  @moduledoc """
  Report the destinations for the given association group

  Params:

    * `:grouping_identifier` - the grouping identifier for the the association
      group (required)
    * `:max_nodes_supported` - the max number of destinations for the
      association group (required)
    * `:reports_to_follow` - if the full destination list is too long for one
      report this field reports the number of follow up reports (optional
      default `0`)
    * `:nodes` - the destination nodes in the association group (required)
  """

  @behaviour Grizzly.ZWave.Command

  alias Grizzly.ZWave
  alias Grizzly.ZWave.Command
  alias Grizzly.ZWave.CommandClasses.Association

  @default_params [reports_to_follow: 0]

  @type param ::
          {:grouping_identifier, byte()}
          | {:max_nodes_supported, byte()}
          | {:reports_to_follow, byte()}
          | {:nodes, [ZWave.node_id()]}

  @impl true
  @spec new([param]) :: {:ok, Command.t()}
  def new(params) do
    # TODO: validate params
    command = %Command{
      name: :association_report,
      command_byte: 0x03,
      command_class: Association,
      params: Keyword.merge(@default_params, params),
      impl: __MODULE__
    }

    {:ok, command}
  end

  @impl true
  @spec encode_params(Command.t()) :: binary()
  def encode_params(command) do
    gi = Command.param!(command, :grouping_identifier)
    max_nodes = Command.param!(command, :max_nodes_supported)
    reports_to_follow = Command.param!(command, :reports_to_follow)
    nodes_bin = :erlang.list_to_binary(Command.param!(command, :nodes))
    <<gi, max_nodes, reports_to_follow>> <> nodes_bin
  end

  @impl true
  @spec decode_params(binary()) :: {:ok, [param]}
  def decode_params(<<gi, max_nodes, reports_to_follow, nodes_bin::binary>>) do
    {:ok,
     [
       grouping_identifier: gi,
       max_nodes_supported: max_nodes,
       reports_to_follow: reports_to_follow,
       nodes: :erlang.binary_to_list(nodes_bin)
     ]}
  end
end