bb

# SPDX-FileCopyrightText: 2025 James Harton
#
# SPDX-License-Identifier: Apache-2.0

defmodule BB.JointSupervisor do
  @moduledoc """
  Supervisor for a joint and its child link.

  Supervises:
  - Joint sensors
  - Joint actuators
  - Child link supervisor (if joint has a child link)
  """

  alias BB.Dsl.Info

  @doc """
  Starts the joint supervisor.

  ## Arguments

  - `robot_module` - The robot module (e.g., `MyRobot`)
  - `joint` - The `BB.Dsl.Joint` struct
  - `path` - The path to this joint (e.g., `[:base_link]`)
  - `opts` - Options passed through to child processes
  """
  @spec start_link({module, BB.Dsl.Joint.t(), [atom], Keyword.t()}) ::
          Supervisor.on_start()
  def start_link({robot_module, joint, path, opts}) do
    settings = Info.settings(robot_module)
    sup_mod = settings.supervisor_module || Supervisor

    children = build_children(robot_module, joint, path, opts)
    sup_mod.start_link(children, strategy: :one_for_one)
  end

  @doc false
  def child_spec({robot_module, joint, path, opts}) do
    %{
      id: joint.name,
      start: {__MODULE__, :start_link, [{robot_module, joint, path, opts}]},
      type: :supervisor
    }
  end

  defp build_children(robot_module, joint, path, opts) do
    joint_path = path ++ [joint.name]

    sensor_children =
      Enum.map(joint.sensors, fn sensor ->
        BB.Process.child_spec(robot_module, sensor.name, sensor.child_spec, joint_path)
      end)

    actuator_children =
      Enum.map(joint.actuators, fn actuator ->
        BB.Process.child_spec(robot_module, actuator.name, actuator.child_spec, joint_path)
      end)

    link_child =
      if joint.link do
        [{BB.LinkSupervisor, {robot_module, joint.link, joint_path, opts}}]
      else
        []
      end

    sensor_children ++ actuator_children ++ link_child
  end
end