%%--------------------------------------------------------------------
%% Copyright (c) 2020-2023 EMQ Technologies Co., Ltd. All Rights Reserved.
%%
%% Licensed under the Apache License, Version 2.0 (the "License");
%% you may not use this file except in compliance with the License.
%% You may obtain a copy of the License at
%%
%%     http://www.apache.org/licenses/LICENSE-2.0
%%
%% Unless required by applicable law or agreed to in writing, software
%% distributed under the License is distributed on an "AS IS" BASIS,
%% WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
%% See the License for the specific language governing permissions and
%% limitations under the License.
%%--------------------------------------------------------------------

-module(emqx_observer_cli).

-export([
    enable/0,
    disable/0
]).

-export([cmd/1]).

%%--------------------------------------------------------------------
%% enable/disable
%%--------------------------------------------------------------------
enable() ->
    emqx_ctl:register_command(observer, {?MODULE, cmd}, []).

disable() ->
    emqx_ctl:unregister_command(observer).

cmd(["status"]) ->
    observer_cli:start();
cmd(["bin_leak"]) ->
    lists:foreach(
        fun(Row) -> emqx_ctl:print("~p~n", [Row]) end,
        recon:bin_leak(100)
    );
cmd(["load", Mod]) ->
    Module = list_to_existing_atom(Mod),
    Nodes = nodes(),
    Res = remote_load(Nodes, Module),
    emqx_ctl:print("Loaded ~p module on ~p: ~p~n", [Module, Nodes, Res]);
cmd(_) ->
    emqx_ctl:usage([
        {"observer status", "Start observer in the current console"},
        {"observer bin_leak",
            "Force all processes to perform garbage collection "
            "and prints the top-100 processes that freed the "
            "biggest amount of binaries, potentially highlighting leaks."},
        {"observer load Mod", "Ensure a module is loaded in all EMQX nodes in the cluster"}
    ]).

%% recon:remote_load/1 has a bug, when nodes() returns [], it is
%% taken by recon as a node name.
%% before OTP 23, the call returns a 'badrpc' tuple
%% after OTP 23, it crashes with 'badarg' error
remote_load([], _Module) -> ok;
remote_load(Nodes, Module) -> recon:remote_load(Nodes, Module).