%%--------------------------------------------------------------------
%% Copyright (c) 2012-2017 Feng Lee <feng@emqtt.io>.
%%
%% 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(emqttd_opts).

-export([merge/2]).

%% @doc Merge Options
merge(Defaults, Options) ->
    lists:foldl(
        fun({Opt, Val}, Acc) ->
                case lists:keymember(Opt, 1, Acc) of
                    true  -> lists:keyreplace(Opt, 1, Acc, {Opt, Val});
                    false -> [{Opt, Val}|Acc]
                end;
            (Opt, Acc) ->
                case lists:member(Opt, Acc) of
                    true  -> Acc;
                    false -> [Opt | Acc]
                end
        end, Defaults, Options).