%% -*- erlang-indent-level: 4;indent-tabs-mode: nil -*-
%% ex: ts=4 sw=4 et
%% -------------------------------------------------------------------
%%
%% rebar: Erlang Build Tools
%%
%% Copyright (c) 2009 Dave Smith (dizzyd@dizzyd.com)
%%
%% Permission is hereby granted, free of charge, to any person obtaining a copy
%% of this software and associated documentation files (the "Software"), to deal
%% in the Software without restriction, including without limitation the rights
%% to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
%% copies of the Software, and to permit persons to whom the Software is
%% furnished to do so, subject to the following conditions:
%%
%% The above copyright notice and this permission notice shall be included in
%% all copies or substantial portions of the Software.
%%
%% THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
%% IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
%% FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
%% AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
%% LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
%% OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
%% THE SOFTWARE.
%% -------------------------------------------------------------------
-module(rebar_deps).

-include("rebar.hrl").

-export([preprocess/2,
         postprocess/2,
         compile/2,
         setup_env/1,
         'check-deps'/2,
         'get-deps'/2,
         'update-deps'/2,
         'delete-deps'/2,
         'list-deps'/2]).


-record(dep, { dir,
               app,
               vsn_regex,
               source }).

%% ===================================================================
%% Public API
%% ===================================================================

preprocess(Config, _) ->
    %% Side effect to set deps_dir globally for all dependencies from
    %% top level down. Means the root deps_dir is honoured or the default
    %% used globally since it will be set on the first time through here
    Config1 = set_shared_deps_dir(Config, get_shared_deps_dir(Config, [])),

    %% Get the list of deps for the current working directory and identify those
    %% deps that are available/present.
    Deps = rebar_config:get_local(Config1, deps, []),
    {Config2, {AvailableDeps, MissingDeps}} = find_deps(Config1, find, Deps),

    ?DEBUG("Available deps: ~p\n", [AvailableDeps]),
    ?DEBUG("Missing deps  : ~p\n", [MissingDeps]),

    %% Add available deps to code path
    Config3 = update_deps_code_path(Config2, AvailableDeps),

    %% If skip_deps=true, mark each dep dir as a skip_dir w/ the core so that
    %% the current command doesn't run on the dep dir. However, pre/postprocess
    %% WILL run (and we want it to) for transitivity purposes.
    NewConfig = case rebar_config:get_global(Config3, skip_deps, false) of
                    "true" ->
                        lists:foldl(
                          fun(#dep{dir = Dir}, C) ->
                                  rebar_config:set_skip_dir(C, Dir)
                          end, Config3, AvailableDeps);
                    _ ->
                        Config3
                end,

    %% Return all the available dep directories for process
    {ok, NewConfig, dep_dirs(AvailableDeps)}.

postprocess(Config, _) ->
    case rebar_config:get_xconf(Config, ?MODULE, undefined) of
        undefined ->
            {ok, []};
        Dirs ->
            NewConfig = rebar_config:erase_xconf(Config, ?MODULE),
            {ok, NewConfig, Dirs}
    end.

compile(Config, AppFile) ->
    'check-deps'(Config, AppFile).

%% set REBAR_DEPS_DIR and ERL_LIBS environment variables
setup_env(Config) ->
    {true, DepsDir} = get_deps_dir(Config),
    %% include rebar's DepsDir in ERL_LIBS
    Separator = case os:type() of
                    {win32, nt} ->
                        ";";
                    _ ->
                        ":"
                end,
    ERL_LIBS = case os:getenv("ERL_LIBS") of
                   false ->
                       {"ERL_LIBS", DepsDir};
                   PrevValue ->
                       {"ERL_LIBS", DepsDir ++ Separator ++ PrevValue}
               end,
    [{"REBAR_DEPS_DIR", DepsDir}, ERL_LIBS].

'check-deps'(Config, _) ->
    %% Get the list of immediate (i.e. non-transitive) deps that are missing
    Deps = rebar_config:get_local(Config, deps, []),
    case find_deps(Config, find, Deps) of
        {Config1, {_, []}} ->
            %% No missing deps
            {ok, Config1};
        {_Config1, {_, MissingDeps}} ->
            lists:foreach(fun (#dep{app=App, vsn_regex=Vsn, source=Src}) ->
                                  ?CONSOLE("Dependency not available: "
                                           "~p-~s (~p)\n", [App, Vsn, Src])
                          end, MissingDeps),
            ?FAIL
    end.

'get-deps'(Config, _) ->
    %% Determine what deps are available and missing
    Deps = rebar_config:get_local(Config, deps, []),
    {Config1, {_AvailableDeps, MissingDeps}} = find_deps(Config, find, Deps),
    MissingDeps1 = [D || D <- MissingDeps, D#dep.source =/= undefined],

    %% For each missing dep with a specified source, try to pull it.
    {Config2, PulledDeps} =
        lists:foldl(fun(D, {C, PulledDeps0}) ->
                            {C1, D1} = use_source(C, D),
                            {C1, [D1 | PulledDeps0]}
                    end, {Config1, []}, MissingDeps1),

    %% Add each pulled dep to our list of dirs for post-processing. This yields
    %% the necessary transitivity of the deps
    {ok, save_dep_dirs(Config2, lists:reverse(PulledDeps))}.

'update-deps'(Config, _) ->
    %% Determine what deps are required
    RawDeps = rebar_config:get_local(Config, deps, []),
    {Config1, Deps} = find_deps(Config, read, RawDeps),

    %% Update each dep
    UpdatedDeps = [update_source(Config1, D)
                   || D <- Deps, D#dep.source =/= undefined],

    %% Add each updated dep to our list of dirs for post-processing. This yields
    %% the necessary transitivity of the deps
    {ok, save_dep_dirs(Config1, UpdatedDeps)}.

'delete-deps'(Config, _) ->
    %% Delete all the available deps in our deps/ directory, if any
    {true, DepsDir} = get_deps_dir(Config),
    Deps = rebar_config:get_local(Config, deps, []),
    {Config1, {AvailableDeps, _}} = find_deps(Config, find, Deps),
    _ = [delete_dep(D)
         || D <- AvailableDeps,
            lists:prefix(DepsDir, D#dep.dir)],
    {ok, Config1}.

'list-deps'(Config, _) ->
    Deps = rebar_config:get_local(Config, deps, []),
    case find_deps(Config, find, Deps) of
        {Config1, {AvailDeps, []}} ->
            lists:foreach(fun(Dep) -> print_source(Dep) end, AvailDeps),
            {ok, Config1};
        {_, MissingDeps} ->
            ?ABORT("Missing dependencies: ~p\n", [MissingDeps])
    end.

%% ===================================================================
%% Internal functions
%% ===================================================================

%% Added because of trans deps,
%% need all deps in same dir and should be the one set by the root rebar.config
%% Sets a default if root config has no deps_dir set
set_shared_deps_dir(Config, []) ->
    GlobalDepsDir = rebar_config:get_global(Config, deps_dir, "deps"),
    DepsDir = rebar_config:get_local(Config, deps_dir, GlobalDepsDir),
    rebar_config:set_xconf(Config, deps_dir, DepsDir);
set_shared_deps_dir(Config, _DepsDir) ->
    Config.

get_shared_deps_dir(Config, Default) ->
    rebar_config:get_xconf(Config, deps_dir, Default).

get_deps_dir(Config) ->
    get_deps_dir(Config, "").

get_deps_dir(Config, App) ->
    BaseDir = rebar_config:get_xconf(Config, base_dir, []),
    DepsDir = get_shared_deps_dir(Config, "deps"),
    {true, filename:join([BaseDir, DepsDir, App])}.

dep_dirs(Deps) ->
    [D#dep.dir || D <- Deps].

save_dep_dirs(Config, Deps) ->
    rebar_config:set_xconf(Config, ?MODULE, dep_dirs(Deps)).

get_lib_dir(App) ->
    %% Find App amongst the reachable lib directories
    %% Returns either the found path or a tagged tuple with a boolean
    %% to match get_deps_dir's return type
    case code:lib_dir(App) of
        {error, bad_name} -> {false, bad_name};
        Path -> {true, Path}
    end.

update_deps_code_path(Config, []) ->
    Config;
update_deps_code_path(Config, [Dep | Rest]) ->
    Config2 =
        case is_app_available(Config, Dep#dep.app,
                              Dep#dep.vsn_regex, Dep#dep.dir) of
            {Config1, {true, _}} ->
                Dir = filename:join(Dep#dep.dir, "ebin"),
                ok = filelib:ensure_dir(filename:join(Dir, "dummy")),
                ?DEBUG("Adding ~s to code path~n", [Dir]),
                true = code:add_patha(Dir),
                Config1;
            {Config1, {false, _}} ->
                Config1
        end,
    update_deps_code_path(Config2, Rest).

find_deps(Config, find=Mode, Deps) ->
    find_deps(Config, Mode, Deps, {[], []});
find_deps(Config, read=Mode, Deps) ->
    find_deps(Config, Mode, Deps, []).

find_deps(Config, find, [], {Avail, Missing}) ->
    {Config, {lists:reverse(Avail), lists:reverse(Missing)}};
find_deps(Config, read, [], Deps) ->
    {Config, lists:reverse(Deps)};
find_deps(Config, Mode, [App | Rest], Acc) when is_atom(App) ->
    find_deps(Config, Mode, [{App, ".*", undefined} | Rest], Acc);
find_deps(Config, Mode, [{App, VsnRegex} | Rest], Acc) when is_atom(App) ->
    find_deps(Config, Mode, [{App, VsnRegex, undefined} | Rest], Acc);
find_deps(Config, Mode, [{App, VsnRegex, Source} | Rest], Acc) ->
    Dep = #dep { app = App,
                 vsn_regex = VsnRegex,
                 source = Source },
    {Config1, {Availability, FoundDir}} = find_dep(Config, Dep),
    find_deps(Config1, Mode, Rest,
              acc_deps(Mode, Availability, Dep, FoundDir, Acc));
find_deps(_Config, _Mode, [Other | _Rest], _Acc) ->
    ?ABORT("Invalid dependency specification ~p in ~s\n",
           [Other, rebar_utils:get_cwd()]).

find_dep(Config, Dep) ->
    %% Find a dep based on its source,
    %% e.g. {git, "https://github.com/mochi/mochiweb.git", "HEAD"}
    %% Deps with a source must be found (or fetched) locally.
    %% Those without a source may be satisfied from lib dir (get_lib_dir).
    find_dep(Config, Dep, Dep#dep.source).

find_dep(Config, Dep, undefined) ->
    %% 'source' is undefined.  If Dep is not satisfied locally,
    %% go ahead and find it amongst the lib_dir's.
    case find_dep_in_dir(Config, Dep, get_deps_dir(Config, Dep#dep.app)) of
        {_Config1, {avail, _Dir}} = Avail ->
            Avail;
        {Config1, {missing, _}} ->
            find_dep_in_dir(Config1, Dep, get_lib_dir(Dep#dep.app))
    end;
find_dep(Config, Dep, _Source) ->
    %% _Source is defined.  Regardless of what it is, we must find it
    %% locally satisfied or fetch it from the original source
    %% into the project's deps
    find_dep_in_dir(Config, Dep, get_deps_dir(Config, Dep#dep.app)).

find_dep_in_dir(Config, _Dep, {false, Dir}) ->
    {Config, {missing, Dir}};
find_dep_in_dir(Config, Dep, {true, Dir}) ->
    App = Dep#dep.app,
    VsnRegex = Dep#dep.vsn_regex,
    case is_app_available(Config, App, VsnRegex, Dir) of
        {Config1, {true, _AppFile}} -> {Config1, {avail, Dir}};
        {Config1, {false, _}}       -> {Config1, {missing, Dir}}
    end.

acc_deps(find, avail, Dep, AppDir, {Avail, Missing}) ->
    {[Dep#dep { dir = AppDir } | Avail], Missing};
acc_deps(find, missing, Dep, AppDir, {Avail, Missing}) ->
    {Avail, [Dep#dep { dir = AppDir } | Missing]};
acc_deps(read, _, Dep, AppDir, Acc) ->
    [Dep#dep { dir = AppDir } | Acc].

delete_dep(D) ->
    case filelib:is_dir(D#dep.dir) of
        true ->
            ?INFO("Deleting dependency: ~s\n", [D#dep.dir]),
            rebar_file_utils:rm_rf(D#dep.dir);
        false ->
            ok
    end.

require_source_engine(Source) ->
    true = source_engine_avail(Source),
    ok.

is_app_available(Config, App, VsnRegex, Path) ->
    ?DEBUG("is_app_available, looking for App ~p with Path ~p~n", [App, Path]),
    case rebar_app_utils:is_app_dir(Path) of
        {true, AppFile} ->
            case rebar_app_utils:app_name(Config, AppFile) of
                {Config1, App} ->
                    {Config2, Vsn} = rebar_app_utils:app_vsn(Config1, AppFile),
                    ?INFO("Looking for ~s-~s ; found ~s-~s at ~s\n",
                          [App, VsnRegex, App, Vsn, Path]),
                    case re:run(Vsn, VsnRegex, [{capture, none}]) of
                        match ->
                            {Config2, {true, Path}};
                        nomatch ->
                            ?WARN("~s has version ~p; requested regex was ~s\n",
                                  [AppFile, Vsn, VsnRegex]),
                            {Config2,
                             {false, {version_mismatch,
                                      {AppFile,
                                       {expected, VsnRegex}, {has, Vsn}}}}}
                    end;
                {Config1, OtherApp} ->
                    ?WARN("~s has application id ~p; expected ~p\n",
                          [AppFile, OtherApp, App]),
                    {Config1,
                     {false, {name_mismatch,
                              {AppFile, {expected, App}, {has, OtherApp}}}}}
            end;
        false ->
            ?WARN("Expected ~s to be an app dir (containing ebin/*.app), "
                  "but no .app found.\n", [Path]),
            {Config, {false, {missing_app_file, Path}}}
    end.

use_source(Config, Dep) ->
    use_source(Config, Dep, 3).

use_source(_Config, Dep, 0) ->
    ?ABORT("Failed to acquire source from ~p after 3 tries.\n",
           [Dep#dep.source]);
use_source(Config, Dep, Count) ->
    case filelib:is_dir(Dep#dep.dir) of
        true ->
            %% Already downloaded -- verify the versioning matches the regex
            case is_app_available(Config, Dep#dep.app,
                                  Dep#dep.vsn_regex, Dep#dep.dir) of
                {Config1, {true, _}} ->
                    Dir = filename:join(Dep#dep.dir, "ebin"),
                    ok = filelib:ensure_dir(filename:join(Dir, "dummy")),
                    %% Available version matches up -- we're good to go;
                    %% add the app dir to our code path
                    true = code:add_patha(Dir),
                    {Config1, Dep};
                {_Config1, {false, Reason}} ->
                    %% The app that was downloaded doesn't match up (or had
                    %% errors or something). For the time being, abort.
                    ?ABORT("Dependency dir ~s failed application validation "
                           "with reason:~n~p.\n", [Dep#dep.dir, Reason])
            end;
        false ->
            ?CONSOLE("Pulling ~p from ~p\n", [Dep#dep.app, Dep#dep.source]),
            require_source_engine(Dep#dep.source),
            {true, TargetDir} = get_deps_dir(Config, Dep#dep.app),
            download_source(TargetDir, Dep#dep.source),
            use_source(Config, Dep#dep { dir = TargetDir }, Count-1)
    end.

download_source(AppDir, {hg, Url, Rev}) ->
    ok = filelib:ensure_dir(AppDir),
    rebar_utils:sh(?FMT("hg clone -U ~s ~s", [Url, filename:basename(AppDir)]),
                   [{cd, filename:dirname(AppDir)}]),
    rebar_utils:sh(?FMT("hg update ~s", [Rev]), [{cd, AppDir}]);
download_source(AppDir, {git, Url}) ->
    download_source(AppDir, {git, Url, {branch, "HEAD"}});
download_source(AppDir, {git, Url, ""}) ->
    download_source(AppDir, {git, Url, {branch, "HEAD"}});
download_source(AppDir, {git, Url, {branch, Branch}}) ->
    ok = filelib:ensure_dir(AppDir),
    rebar_utils:sh(?FMT("git clone -n ~s ~s", [Url, filename:basename(AppDir)]),
                   [{cd, filename:dirname(AppDir)}]),
    rebar_utils:sh(?FMT("git checkout -q origin/~s", [Branch]), [{cd, AppDir}]);
download_source(AppDir, {git, Url, {tag, Tag}}) ->
    ok = filelib:ensure_dir(AppDir),
    rebar_utils:sh(?FMT("git clone -n ~s ~s", [Url, filename:basename(AppDir)]),
                   [{cd, filename:dirname(AppDir)}]),
    rebar_utils:sh(?FMT("git checkout -q ~s", [Tag]), [{cd, AppDir}]);
download_source(AppDir, {git, Url, Rev}) ->
    ok = filelib:ensure_dir(AppDir),
    rebar_utils:sh(?FMT("git clone -n ~s ~s", [Url, filename:basename(AppDir)]),
                   [{cd, filename:dirname(AppDir)}]),
    rebar_utils:sh(?FMT("git checkout -q ~s", [Rev]), [{cd, AppDir}]);
download_source(AppDir, {bzr, Url, Rev}) ->
    ok = filelib:ensure_dir(AppDir),
    rebar_utils:sh(?FMT("bzr branch -r ~s ~s ~s",
                        [Rev, Url, filename:basename(AppDir)]),
                   [{cd, filename:dirname(AppDir)}]);
download_source(AppDir, {svn, Url, Rev}) ->
    ok = filelib:ensure_dir(AppDir),
    rebar_utils:sh(?FMT("svn checkout -r ~s ~s ~s",
                        [Rev, Url, filename:basename(AppDir)]),
                   [{cd, filename:dirname(AppDir)}]);
download_source(AppDir, {rsync, Url}) ->
    ok = filelib:ensure_dir(AppDir),
    rebar_utils:sh(?FMT("rsync -az --delete ~s/ ~s", [Url, AppDir]), []).

update_source(Config, Dep) ->
    %% It's possible when updating a source, that a given dep does not have a
    %% VCS directory, such as when a source archive is built of a project, with
    %% all deps already downloaded/included. So, verify that the necessary VCS
    %% directory exists before attempting to do the update.
    {true, AppDir} = get_deps_dir(Config, Dep#dep.app),
    case has_vcs_dir(element(1, Dep#dep.source), AppDir) of
        true ->
            ?CONSOLE("Updating ~p from ~p\n", [Dep#dep.app, Dep#dep.source]),
            require_source_engine(Dep#dep.source),
            update_source1(AppDir, Dep#dep.source),
            Dep;
        false ->
            ?WARN("Skipping update for ~p: "
                  "no VCS directory available!\n", [Dep]),
            Dep
    end.

update_source1(AppDir, {git, Url}) ->
    update_source1(AppDir, {git, Url, {branch, "HEAD"}});
update_source1(AppDir, {git, Url, ""}) ->
    update_source1(AppDir, {git, Url, {branch, "HEAD"}});
update_source1(AppDir, {git, _Url, {branch, Branch}}) ->
    ShOpts = [{cd, AppDir}],
    rebar_utils:sh("git fetch origin", ShOpts),
    rebar_utils:sh(?FMT("git checkout -q origin/~s", [Branch]), ShOpts);
update_source1(AppDir, {git, _Url, {tag, Tag}}) ->
    ShOpts = [{cd, AppDir}],
    rebar_utils:sh("git fetch --tags origin", ShOpts),
    rebar_utils:sh(?FMT("git checkout -q ~s", [Tag]), ShOpts);
update_source1(AppDir, {git, _Url, Refspec}) ->
    ShOpts = [{cd, AppDir}],
    rebar_utils:sh("git fetch origin", ShOpts),
    rebar_utils:sh(?FMT("git checkout -q ~s", [Refspec]), ShOpts);
update_source1(AppDir, {svn, _Url, Rev}) ->
    rebar_utils:sh(?FMT("svn up -r ~s", [Rev]), [{cd, AppDir}]);
update_source1(AppDir, {hg, _Url, Rev}) ->
    rebar_utils:sh(?FMT("hg pull -u -r ~s", [Rev]), [{cd, AppDir}]);
update_source1(AppDir, {bzr, _Url, Rev}) ->
    rebar_utils:sh(?FMT("bzr update -r ~s", [Rev]), [{cd, AppDir}]);
update_source1(AppDir, {rsync, Url}) ->
    rebar_utils:sh(?FMT("rsync -az --delete ~s/ ~s",[Url,AppDir]),[]).

%% ===================================================================
%% Source helper functions
%% ===================================================================

source_engine_avail(Source) ->
    Name = element(1, Source),
    source_engine_avail(Name, Source).

source_engine_avail(Name, Source)
  when Name == hg; Name == git; Name == svn; Name == bzr; Name == rsync ->
    case vcs_client_vsn(Name) >= required_vcs_client_vsn(Name) of
        true ->
            true;
        false ->
            ?ABORT("Rebar requires version ~p or higher of ~s to process ~p\n",
                   [required_vcs_client_vsn(Name), Name, Source])
    end.

vcs_client_vsn(false, _VsnArg, _VsnRegex) ->
    false;
vcs_client_vsn(Path, VsnArg, VsnRegex) ->
    {ok, Info} = rebar_utils:sh(Path ++ VsnArg, [{env, [{"LANG", "C"}]},
                                                 {use_stdout, false}]),
    case re:run(Info, VsnRegex, [{capture, all_but_first, list}]) of
        {match, Match} ->
            list_to_tuple([list_to_integer(S) || S <- Match]);
        _ ->
            false
    end.

required_vcs_client_vsn(hg)    -> {1, 1};
required_vcs_client_vsn(git)   -> {1, 5};
required_vcs_client_vsn(bzr)   -> {2, 0};
required_vcs_client_vsn(svn)   -> {1, 6};
required_vcs_client_vsn(rsync) -> {2, 0}.

vcs_client_vsn(hg) ->
    vcs_client_vsn(rebar_utils:find_executable("hg"), " --version",
                   "version (\\d+).(\\d+)");
vcs_client_vsn(git) ->
    vcs_client_vsn(rebar_utils:find_executable("git"), " --version",
                   "git version (\\d+).(\\d+)");
vcs_client_vsn(bzr) ->
    vcs_client_vsn(rebar_utils:find_executable("bzr"), " --version",
                   "Bazaar \\(bzr\\) (\\d+).(\\d+)");
vcs_client_vsn(svn) ->
    vcs_client_vsn(rebar_utils:find_executable("svn"), " --version",
                   "svn, version (\\d+).(\\d+)");
vcs_client_vsn(rsync) ->
    vcs_client_vsn(rebar_utils:find_executable("rsync"), " --version",
                   "rsync  version (\\d+).(\\d+)").

has_vcs_dir(git, Dir) ->
    filelib:is_dir(filename:join(Dir, ".git"));
has_vcs_dir(hg, Dir) ->
    filelib:is_dir(filename:join(Dir, ".hg"));
has_vcs_dir(bzr, Dir) ->
    filelib:is_dir(filename:join(Dir, ".bzr"));
has_vcs_dir(svn, Dir) ->
    filelib:is_dir(filename:join(Dir, ".svn"))
        orelse filelib:is_dir(filename:join(Dir, "_svn"));
has_vcs_dir(rsync, _) ->
    true;
has_vcs_dir(_, _) ->
    true.

print_source(#dep{app=App, source=Source}) ->
    ?CONSOLE("~s~n", [format_source(App, Source)]).

format_source(App, {git, Url}) ->
    ?FMT("~p BRANCH ~s ~s", [App, "HEAD", Url]);
format_source(App, {git, Url, ""}) ->
    ?FMT("~p BRANCH ~s ~s", [App, "HEAD", Url]);
format_source(App, {git, Url, {branch, Branch}}) ->
    ?FMT("~p BRANCH ~s ~s", [App, Branch, Url]);
format_source(App, {git, Url, {tag, Tag}}) ->
    ?FMT("~p TAG ~s ~s", [App, Tag, Url]);
format_source(App, {_, Url, Rev}) ->
    ?FMT("~p REV ~s ~s", [App, Rev, Url]);
format_source(App, undefined) ->
    ?FMT("~p", [App]).