#!/usr/bin/env escript
%% vim:ft=erlang:sw=2:et:

main(["show-rel"]) ->
  Rel = get_rel(),
  io:format("~p.~n", [Rel]);
main(["gen-boot"]) ->
  generate_rel(),
  generate_boot().

get_rel() ->
  ok = application:load(rabbit),
  Apps0 = get_apps(rabbit),
  Apps1 = lists:sort(
            fun
              (_, rabbitmq_prelaunch) -> false;
              (rabbitmq_prelaunch, _) -> true;
              (_, mnesia)             -> true;
              (mnesia, _)             -> false;
              (A, B)                  -> A =< B
            end, Apps0),
  Apps = [{App, get_vsn(App)} || App <- Apps1],

  ERTSVersion = erlang:system_info(version),
  RabbitVersion = get_vsn(rabbit),

  {release,
   {"RabbitMQ", RabbitVersion},
   {erts, ERTSVersion},
   Apps}.

get_apps(App) ->
  ok = load_app(App),
  {ok, DirectDeps} = application:get_key(App, applications),
  lists:umerge(
    [lists:usort(get_apps(Dep)) || Dep <- DirectDeps] ++
    [lists:usort([kernel, stdlib, sasl, App, mnesia])]).

load_app(App) ->
  case application:load(App) of
    ok                             -> ok;
    {error, {already_loaded, App}} -> ok
  end.

generate_rel() ->
  Rel = get_rel(),
  io:format("~p.~n", [Rel]),
  Output = io_lib:format("~p.~n", [Rel]),
  ok = file:write_file("rabbit.rel", Output).

generate_boot() ->
  Options = [local, {path, code:get_path()}],
  ok = systools:make_script("rabbit", Options).

get_vsn(App) ->
  load_app(App),
  {ok, Vsn} = application:get_key(App, vsn),
  Vsn.