-module(rps_nickserv).
-behaviour(gen_server).
-export([init/1, handle_call/3, handle_cast/2, handle_info/2, terminate/2, code_change/3]).
-export([start_link/0, nick/2, nick/3, whois/1, whois/2]).
start_link() ->
    gen_server:start_link({local, ?MODULE}, ?MODULE, [], []).
init([]) ->
    {ok, dict:new()}.
handle_call({nick, Who, Nickname}, _From, Nicknames) ->
    io:format("~w registered as ~s.~n", [Who, Nickname]),
    {reply, ok, dict:store(Who, Nickname, Nicknames)};
handle_call({whois, Who}, _From, Nicknames) ->
    N = case dict:find(Who, Nicknames) of
            {ok, Nickname} -> Nickname;
            error -> Who
        end,
    {reply, N, Nicknames}.
handle_cast(_Msg, State) -> {noreply, State}.
handle_info(_Msg, State) -> {noreply, State}.
terminate(_Reason, _State) -> ok.
code_change(_OldVersion, State, _Extra) -> {ok, State}.
nick(Who, Nickname) ->
    nick(?MODULE, Who, Nickname).
nick(Pid, Who, Nickname) ->
    gen_server:call(Pid, {nick, Who, Nickname}).
whois(Who) ->
    whois(?MODULE, Who).
whois(Pid, Who) ->
    gen_server:call(Pid, {whois, Who}).