defmodule ProxmoxAgent.Shell do
  @moduledoc """
  Thin wrapper over System.cmd for testability. Collectors accept an optional
  :runner function of this shape so tests can inject fixture-backed fakes.
  """

  @type result :: {:ok, String.t()} | {:error, term()}

  @spec run(String.t(), [String.t()]) :: result
  def run(command, args) do
    start = System.monotonic_time(:microsecond)
    result = do_run(command, args)
    duration_us = System.monotonic_time(:microsecond) - start
    ProxmoxAgent.Diagnostics.log_command(command, args, result, duration_us)
    result
  end

  defp do_run(command, args) do
    try do
      case System.cmd(command, args, stderr_to_stdout: true) do
        {output, 0} -> {:ok, output}
        {output, code} -> {:error, {:nonzero_exit, code, output}}
      end
    rescue
      e in ErlangError ->
        case e.original do
          :enoent -> {:error, {:enoent, command}}
          other -> {:error, {:system_error, other}}
        end
    end
  end
end