%% A remote manager is a gen_server for coordination of remotes for
%% all tokens.

%% Spawn one remote per configured p11p module per configured virtual
%% token. Provide a lookup service for servers that need a remote to
%% send a request to, by keeping track of which module is current for
%% a given vtoken.

-module(p11p_remote_manager).

-behaviour(gen_server).

%% API.
-export([start_link/0]).
-export([port_for_token/1]).			% For servers.
-export([p11init_done/1, timeout/0]).		% For remotes.

%% Genserver callbacks.
-export([init/1, handle_call/3, handle_cast/2, handle_info/2, terminate/2,
         code_change/3]).

%% Records and types.
-record(token, {
	  p11init_done = false :: boolean(),
	  remotes :: [port()]		      % Active remote in hd().
	 }).

-record(state, {
	  tokens :: #{string() => #token{}}
	 }).

-define(P11KITREMOTE_PATH, "/home/linus/usr/libexec/p11-kit/p11-kit-remote").

%% API implementation.
-spec start_link() -> {ok, pid()} | {error, term()}.
start_link() ->
    gen_server:start_link({local, ?MODULE}, ?MODULE, [], []).

port_for_token(_Token) ->
    todo.
p11init_done(_Done) ->
    todo.
timeout() ->
    todo.

%% Genserver callbacks.
init([]) ->
    {ok, #state{tokens = init_tokens(p11p_config:tokens())}}.

handle_call(Request, _From, State) ->
    lager:debug("Unhandled call: ~p~n", [Request]),
    {reply, unhandled, State}.

handle_cast(Request, State) ->
    lager:debug("Unhandled cast: ~p~n", [Request]),
    {noreply, State}.

handle_info({Port, {exit_status, Status}}, State) ->
    lager:info("~p: process exited with ~p", [Port, Status]),
    {stop, child_exit, State};
handle_info(Info, State) ->
    lager:debug("Unhandled info: ~p~n", [Info]),
    {noreply, State}.

terminate(_Reason, _State) ->
    ok.

code_change(_OldVersion, State, _Extra) ->
    {ok, State}.

%% Private functions
-spec init_tokens([any()]) -> #{string() => #token{}}.
init_tokens(ConfTokens) ->
    init_tokens(ConfTokens, #{}).
init_tokens([], Acc)->
    Acc;
init_tokens([H|T], Acc)->
    init_tokens(T, Acc#{p11p_config:nameof(H) => new_token(H)}).

new_token(ConfToken) ->
    Remotes = start_remotes(p11p_config:modules_for_token(p11p_config:nameof(ConfToken))),
    #token{remotes = Remotes}.

start_remotes(ConfModules) ->
    start_remotes(ConfModules, []).
start_remotes([], Acc) ->
    lists:reverse(Acc);
start_remotes([H|T], Acc) ->
    ModPath = p11p_config:module_path(H),
    Port = start_remote(ModPath),
    start_remotes(T, [Port | Acc]).

start_remote(ModPath) ->
    Port = open_port({spawn_executable, ?P11KITREMOTE_PATH},
		     [stream, exit_status, {args, [ModPath, "-v"]}]),
    lager:debug("~s: New port: ~p", [?P11KITREMOTE_PATH, Port]),
    Port.