%% 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([remote_for_token/1]).			% For servers.
-export([p11init_done/1, timeout/1]).		% For remotes.
-export([send/2]).				% Experiment

%% 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 :: [pid()]		      % Active remote in hd().
	 }).

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

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

-spec remote_for_token(string()) -> pid().
remote_for_token(TokName) ->
    gen_server:call(?MODULE, {remote_for_token, TokName}).
p11init_done(_Done) ->
    todo.
timeout(_TokName) ->
    todo.

send(TokName, Data) ->
    gen_server:cast(?MODULE, {send, TokName, Data}).

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

handle_call({remote_for_token, TokName}, _From, State) ->
    #{TokName := Token} = State#state.tokens,
    {reply, hd(Token#token.remotes), State};
handle_call(Request, _From, State) ->
    lager:debug("Unhandled call: ~p~n", [Request]),
    {reply, unhandled, State}.

handle_cast({send, TokName, Data}, State) ->
    #{TokName := Token} = State#state.tokens,
    ServerPort = hd(Token#token.remotes),
    ServerPort ! {self(), {command, Data}}, % TODO: Use synchronous port_command()?
    {noreply, 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("~p: Unhandled info: ~p~n", [self(), Info]),
    {noreply, State}.

terminate(_Reason, _State) ->
    ok.

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

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

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

start_remotes(TokName, ConfModules) ->
    start_remotes(TokName, ConfModules, []).
start_remotes(_, [], Acc) ->
    %%lists:reverse(Acc);
    Acc;
start_remotes(TokName, [H|T], Acc) ->
    ModName = p11p_config:nameof(H),
    ServName = "p11p_remote:" ++ TokName ++ ":" ++ ModName,
    ModPath = p11p_config:module_path(H),
    {ok, Pid} = p11p_remote:start_link(list_to_atom(ServName), TokName, ModPath),
    start_remotes(TokName, T, [Pid | Acc]).