-module(er_xdg_pipe_menu_watcher_tests).

-include_lib("eunit/include/eunit.hrl").

%% Exercises the real debounce-timer-reset-then-invalidate wiring by
%% sending the watcher a synthetic message of the exact shape `fs'
%% delivers, rather than waiting on a real inotify event -- `fs'
%% itself is treated as out of scope for this test.
debounced_event_invalidates_cache_test() ->
    Root = mk_tmp_dir(),
    AppDir = filename:join(Root, "applications"),
    ok = file:make_dir(AppDir),
    write_desktop(AppDir, "foo.desktop", "Foo", "foo"),
    PrevDebounce = application:get_env(er_xdg_pipe_menu, debounce_ms),
    application:set_env(er_xdg_pipe_menu, debounce_ms, 20),
    with_env(
        [{"XDG_DATA_HOME", Root}, {"XDG_DATA_DIRS", "/does-not-exist-eunit"}],
        fun() ->
            {ok, CachePid} = er_xdg_pipe_menu_cache:start_link(),
            {ok, WatcherPid} = er_xdg_pipe_menu_watcher:start_link(),

            write_desktop(AppDir, "bar.desktop", "Bar", "bar"),
            WatcherPid ! {self(), {fs, file_event}, {"dummy", [modified]}},
            timer:sleep(100),

            Menu = er_xdg_pipe_menu_cache:get_menu(),
            stop(WatcherPid),
            stop(CachePid),
            ?assert(binary:match(Menu, <<"Bar">>) =/= nomatch)
        end
    ),
    ok = rm_rf(Root),
    restore_env(er_xdg_pipe_menu, debounce_ms, PrevDebounce).

%% -- helpers ----------------------------------------------------------------

%% start_link/0 links the started process to us (the test process);
%% unlink before killing it so the kill signal doesn't propagate back
%% and take the test process down with it.
stop(Pid) ->
    unlink(Pid),
    true = erlang:exit(Pid, kill).

restore_env(App, Key, undefined) -> application:unset_env(App, Key);
restore_env(App, Key, {ok, Value}) -> application:set_env(App, Key, Value).

with_env(Vars, Fun) ->
    Saved = [{Name, os:getenv(Name)} || {Name, _} <- Vars],
    try
        lists:foreach(fun({Name, Value}) -> set_env(Name, Value) end, Vars),
        Fun()
    after
        lists:foreach(fun({Name, Value}) -> set_env(Name, Value) end, Saved)
    end.

set_env(Name, false) -> os:unsetenv(Name);
set_env(Name, Value) -> os:putenv(Name, Value).

write_desktop(Dir, FileName, Name, Exec) ->
    ok = file:write_file(
        filename:join(Dir, FileName),
        iolist_to_binary(["[Desktop Entry]\nName=", Name, "\nExec=", Exec, "\n"])
    ).

mk_tmp_dir() ->
    Path = filename:join(
        test_tmp_dir(), "eunit-watcher-" ++ integer_to_list(erlang:unique_integer([positive]))
    ),
    ok = file:make_dir(Path),
    Path.

test_tmp_dir() ->
    case os:getenv("TMPDIR") of
        false -> "/tmp";
        Dir -> Dir
    end.

rm_rf(Path) ->
    case filelib:is_dir(Path) of
        true ->
            {ok, Entries} = file:list_dir(Path),
            lists:foreach(fun(E) -> rm_rf(filename:join(Path, E)) end, Entries),
            file:del_dir(Path);
        false ->
            file:delete(Path)
    end.