defmodule Kuu do
  @moduledoc """
  Elixir binding for the kuu CLI-argument-definition spec (early placeholder).

  kuu is a language-agnostic specification (https://github.com/kawaz/kuu).
  This version delegates to the `kuu-cli` reference binary found on PATH;
  a native implementation is planned to grow under this name.
  """

  @version Mix.Project.config()[:version]

  def version, do: @version

  @doc "Run kuu-cli with raw arguments. Returns {:ok, stdout} | {:error, reason}."
  def run(args) when is_list(args) do
    case System.find_executable("kuu-cli") do
      nil ->
        {:error,
         "kuu-cli not found on PATH. Install it from https://github.com/kawaz/kuu-cli " <>
           "(this early version of the kuu package delegates to the reference CLI)"}

      exe ->
        case System.cmd(exe, args, stderr_to_stdout: false) do
          {out, 0} -> {:ok, out}
          {err, _} -> {:error, "kuu-cli failed: #{err}"}
        end
    end
  end

  @doc "Parse args against a kuu wire-format definition (JSON string)."
  def parse(definition_json, args) when is_binary(definition_json) and is_list(args) do
    path = Path.join(System.tmp_dir!(), "kuu-def-#{System.unique_integer([:positive])}.json")
    File.write!(path, definition_json)

    try do
      run(["parse", path, "--" | args])
    after
      File.rm(path)
    end
  end
end