%% @doc: Updates the cached date in the ETS-table
-module(elli_date_server).
-behaviour(gen_server).

%% API
-export([start_link/0,
         rfc1123/0]).

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


-record(state, {}).

%%%===================================================================
%%% API
%%%===================================================================

start_link() -> gen_server:start_link({local, ?MODULE}, ?MODULE, [], []).

rfc1123() ->
    case ets:lookup(?MODULE, rfc1123) of
        [{rfc1123, Date}] -> Date;
        []                -> <<"">>
    end.

%%%===================================================================
%%% gen_server callbacks
%%%===================================================================

init([]) ->
    ?MODULE = ets:new(?MODULE, [named_table, protected, {read_concurrency, true}]),
    handle_info(update_date, #state{}),
    timer:send_interval(1000, update_date),
    {ok, #state{}}.

handle_call(_, _From, State) -> {reply, ok, State}.

handle_cast(_, State) -> {noreply, State}.

handle_info(update_date, State) ->
    Date = list_to_binary(httpd_util:rfc1123_date()),
    ets:insert(?MODULE, {rfc1123, Date}),
    {noreply, State}.

terminate(_Reason, _State) -> ok.

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