defmodule ReleaseManager.Plugin.Nerves do
  use ReleaseManager.Plugin

  @system_libs "/staging/usr/lib/erlang/lib"

  def before_release(%Config{version: version} = config) do
    case System.get_env("NERVES_SYSTEM") do
      nil -> config
      system ->
        info "Modifying release for Nerves System #{Mix.Project.config[:target]}"

        relx_config = config.relx_config

        vm_args_file = 'releases/#{version}/vm.args'
        vm_args =
          relx_config[:overlay]
          |> Enum.find(fn(
            {_, _, ^vm_args_file}) -> true
            _ -> false
          end)
        overlay =
        case vm_args do
          nil ->
            default_vm_args =
              Mix.Project.deps_paths[:nerves]
              |> Path.join("template/_iex.vm.args")
              |> String.to_char_list
            [{:copy, default_vm_args, vm_args_file} | relx_config[:overlay]]
          _ -> relx_config[:overlay]
        end
        relx_config
        |> Enum.reject(fn
          {:include_erts, _} -> true
          {:system_libs, _} -> true
          {:overlay, _} -> true
          _ -> false
        end)
        system_libs = String.to_char_list(Path.join(system, @system_libs))
        relx_config = [{:include_erts, false} | relx_config]
        relx_config = [{:system_libs, system_libs} | relx_config]
        relx_config = [{:overlay, overlay} | relx_config]

        config = %{config | relx_config: relx_config}
    end
  end

  def after_release(_),     do: nil
  def after_package(_),     do: nil
  def after_cleanup(_args), do: nil
end