%% -------------------------------------------------------------------
%%
%% Copyright (c) 2017 Christopher S. Meiklejohn.  All Rights Reserved.
%%
%% This file is provided to you 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(partisan_connection_cache).
-author("Christopher S. Meiklejohn <christopher.meiklejohn@gmail.com>").

-include("partisan.hrl").

-export([update/1,
         dispatch/1]).

update(Connections) ->
    ets:delete_all_objects(?CACHE),

    dict:fold(fun(K, V, _AccIn) ->
                      true = ets:insert(?CACHE, [{K, V}])
              end, [], Connections).

dispatch({forward_message, Name, ServerRef, Message}) ->
    %% Find a connection for the remote node, if we have one.
    case ets:lookup(?CACHE, Name) of
        [] ->
            %% Trap back to gen_server.
            {error, trap};
        [{Name, Pids}] ->
            Pid = lists:nth(rand_compat:uniform(length(Pids)), Pids),
            gen_server:cast(Pid, {send_message, {forward_message, ServerRef, Message}})
    end.