defmodule HostKit.DSL.Systemd do
  @moduledoc "DSL helpers for core systemd resources."

  defmacro systemd_service(name, opts \\ [], do: block) do
    quote do
      HostKit.DSL.Systemd.Scope.start_service(unquote(name), unquote(opts))
      unquote(block)
      HostKit.DSL.Scope.add_resource(HostKit.DSL.Systemd.Scope.finish_service())
    end
  end

  defmacro systemd_timer(name, opts \\ [], do: block) do
    quote do
      HostKit.DSL.Systemd.Scope.start_timer(unquote(name), unquote(opts))
      unquote(block)
      HostKit.DSL.Scope.add_resource(HostKit.DSL.Systemd.Scope.finish_timer())
    end
  end

  defmacro daemon(do: block) do
    quote do
      systemd_service unit_name() do
        unquote(block)
      end
    end
  end

  defmacro daemon(opts, do: block) when is_list(opts) do
    quote do
      systemd_service Keyword.get(unquote(opts), :unit, unit_name()),
                      Keyword.delete(unquote(opts), :unit) do
        unquote(block)
      end
    end
  end

  defmacro daemon(name, opts \\ [], do: block) do
    quote do
      systemd_service HostKit.DSL.Systemd.service_unit_name(unquote(name)), unquote(opts) do
        unquote(block)
      end
    end
  end

  defmacro job(name, opts \\ [], do: block) do
    quote do
      systemd_service HostKit.DSL.Systemd.service_unit_name(unquote(name)), unquote(opts) do
        unquote(block)
      end
    end
  end

  defmacro schedule(name, opts \\ [], do: block) do
    quote do
      systemd_timer HostKit.DSL.Systemd.timer_unit_name(unquote(name)), unquote(opts) do
        unquote(block)
      end
    end
  end

  defmacro unit(opts) do
    quote do
      HostKit.DSL.Systemd.Scope.put_unit(unquote(opts))
    end
  end

  defmacro service(opts) do
    quote do
      HostKit.DSL.Systemd.Scope.put_service(
        HostKit.DSL.Systemd.normalize_account_refs(unquote(opts))
      )
    end
  end

  defmacro run(opts) do
    quote do
      HostKit.DSL.Systemd.Scope.put_service(
        HostKit.DSL.Systemd.normalize_account_refs(unquote(opts))
      )
    end
  end

  defmacro timer(opts) do
    quote do
      HostKit.DSL.Systemd.Scope.put_timer(unquote(opts))
    end
  end

  defmacro every(interval) do
    quote do
      HostKit.DSL.Systemd.Scope.put_timer(
        :on_calendar,
        HostKit.Systemd.Calendar.name(unquote(interval))
      )
    end
  end

  defmacro daily(opts) do
    quote do
      HostKit.DSL.Systemd.Scope.put_timer(
        :on_calendar,
        HostKit.Systemd.Calendar.daily_at(Keyword.fetch!(unquote(opts), :at))
      )
    end
  end

  defmacro weekly(day, opts) do
    quote do
      HostKit.DSL.Systemd.Scope.put_timer(
        :on_calendar,
        HostKit.Systemd.Calendar.weekly_at(unquote(day), Keyword.fetch!(unquote(opts), :at))
      )
    end
  end

  defmacro monthly(opts) do
    quote do
      opts = unquote(opts)

      HostKit.DSL.Systemd.Scope.put_timer(
        :on_calendar,
        HostKit.Systemd.Calendar.monthly_at(Keyword.fetch!(opts, :day), Keyword.fetch!(opts, :at))
      )
    end
  end

  defmacro jitter(value) do
    quote do
      HostKit.DSL.Systemd.Scope.put_timer(:randomized_delay_sec, unquote(value))
    end
  end

  defmacro repeat_after(value) do
    quote do
      HostKit.DSL.Systemd.Scope.put_timer(:on_unit_active_sec, unquote(value))
    end
  end

  defmacro after_boot(value) do
    quote do
      HostKit.DSL.Systemd.Scope.put_timer(:on_boot_sec, unquote(value))
    end
  end

  defmacro persistent(value) do
    quote do
      HostKit.DSL.Systemd.Scope.put_timer(:persistent, unquote(value))
    end
  end

  defmacro on_boot(value) do
    quote do
      HostKit.DSL.Systemd.Scope.put_timer(:on_boot_sec, unquote(value))
    end
  end

  defmacro description(value) do
    quote do
      HostKit.DSL.Systemd.Scope.put_unit(:description, unquote(value))
    end
  end

  defmacro after_units(values) do
    quote do
      HostKit.DSL.Systemd.Scope.put_unit(:after, unquote(values))
    end
  end

  defmacro after_target(targets) do
    quote do
      HostKit.DSL.Systemd.Scope.put_unit(:after, HostKit.Systemd.Target.names(unquote(targets)))
    end
  end

  defmacro wants(values) do
    quote do
      HostKit.DSL.Systemd.Scope.put_unit(:wants, HostKit.Systemd.Target.names(unquote(values)))
    end
  end

  defmacro requires(values) do
    quote do
      HostKit.DSL.Systemd.Scope.put_unit(:requires, HostKit.Systemd.Target.names(unquote(values)))
    end
  end

  defmacro service_user(value) do
    quote do
      HostKit.DSL.Systemd.Scope.put_service(:user, HostKit.Account.name!(unquote(value)))
    end
  end

  defmacro service_group(value) do
    quote do
      HostKit.DSL.Systemd.Scope.put_service(:group, HostKit.Account.name!(unquote(value)))
    end
  end

  defmacro working_directory(value) do
    quote do
      HostKit.DSL.Systemd.Scope.put_service(:working_directory, unquote(value))
    end
  end

  defmacro environment_file(value) do
    quote do
      HostKit.DSL.Systemd.Scope.put_service(:environment_file, unquote(value))
    end
  end

  defmacro exec_start(value) do
    quote do
      HostKit.DSL.Systemd.Scope.put_service(:exec_start, unquote(value))
    end
  end

  defmacro exec(value) do
    quote do
      HostKit.DSL.Systemd.Scope.put_service(:exec_start, unquote(value))
    end
  end

  defmacro exec_stop(value) do
    quote do
      HostKit.DSL.Systemd.Scope.put_service(:exec_stop, unquote(value))
    end
  end

  defmacro restart(value) do
    quote do
      HostKit.DSL.Systemd.Scope.put_service(:restart, unquote(value))
    end
  end

  defmacro restart_sec(value) do
    quote do
      HostKit.DSL.Systemd.Scope.put_service(:restart_sec, unquote(value))
    end
  end

  defmacro install(opts) do
    quote do
      HostKit.DSL.Systemd.Scope.put_install(unquote(opts))
    end
  end

  defmacro wanted_by(targets) do
    quote do
      HostKit.DSL.Systemd.Scope.put_install(
        :wanted_by,
        HostKit.Systemd.Target.names(unquote(targets))
      )
    end
  end

  defmacro hardening(level) do
    quote do
      HostKit.DSL.Systemd.Scope.apply_hardening(unquote(level))
    end
  end

  defmacro read_write_paths(paths) do
    quote do
      HostKit.DSL.Systemd.Scope.put_service(:read_write_paths, unquote(paths))
    end
  end

  def service_unit_name(name), do: unit_name(name, ".service")
  def timer_unit_name(name), do: unit_name(name, ".timer")

  defp unit_name(name, suffix) when is_atom(name) do
    identity = HostKit.Naming.identity_segment(name)

    :unit
    |> HostKit.DSL.Scope.prefixed(identity)
    |> HostKit.Naming.systemd_unit(suffix)
  end

  defp unit_name(name, suffix), do: HostKit.Naming.systemd_unit(name, suffix)

  def normalize_account_refs(opts) when is_list(opts) do
    opts
    |> Keyword.update(:user, nil, &HostKit.Account.name!/1)
    |> Keyword.update(:group, nil, &HostKit.Account.name!/1)
    |> Enum.reject(&match?({_key, nil}, &1))
  end
end