%% Create an AF_UNIX socket and accept connections. On connect, spawn
%% another p11p_server process.

-module(p11p_server).
-behaviour(gen_server).

%% API.
-export([start_link/1]).

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

%% Records and types.
-include("p11p_defs.hrl").
-record(state, {
	  sockpath :: string(),		       % FIXME: filename(3erl)
	  socket :: gen_tcp:socket()
	 }).

%% API.
-spec start_link(gen_tcp:socket()) -> {ok, pid()} | {error, term()}.
start_link(Args) ->
    lager:debug("~p: p11p_server:start_link enter", [self()]),
    gen_server:start_link(?MODULE, Args, []).

%% Genserver callbacks.
init([SocketPath, Socket]) ->
    lager:debug("~p: p11p_server:init: ~s", [self(), SocketPath]),
    process_flag(trap_exit, true),		% We want terminate().
    gen_server:cast(self(), accept), % Perform accept in gen-server loop.
    {ok, #state{sockpath = SocketPath, socket = Socket}}.

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

handle_cast(accept, State = #state{sockpath = SocketPath, socket = ListenSocket}) ->
    %% Blocking until client connects or timeout fires. Without a
    %% timeout our supervisor cannot terminate us.
    case gen_tcp:accept(ListenSocket, 900) of
	{ok, Sock} ->
	    %% TODO: authz
	    lager:debug("~p: ~p: new connection accepted", [self(), Sock]),
	    p11p_server_sup:start_server([SocketPath, ListenSocket]), % Start a new acceptor.
	    {noreply, State#state{socket = Sock}}; % Use the new socket.
	{error, timeout} ->
	    gen_server:cast(self(), accept),	% Try again.
	    {noreply, State};
	{error, closed} ->
	    lager:debug("~p: listening socket closed", [self()]),
	    {stop, normal, State}
    end;
handle_cast(Request, State) ->
    lager:debug("Unhandled cast: ~p~n", [Request]),
    {noreply, State}.

handle_info({tcp, Port, Data}, State) ->
    lager:debug("~p: received: ~s", [self(), Data]),
    case Data of
	<<"q\n">> ->
	    gen_tcp:send(Port, "ok, bye\n"),	%DEBUG
	    {stop, {shutdown, quit_by_client}, State};
	_ ->
	    gen_tcp:send(Port, "ok, thanks: " ++ Data),	%DEBUG
	    {noreply, State}
    end;
handle_info({tcp_closed, Port}, State) ->
    lager:debug("~p: ~p: closed", [self(), Port]),
    {stop, {shutdown, close_by_client}, State};
handle_info(Info, State) ->
    lager:debug("Unhandled info: ~p~n", [Info]),
    {noreply, State}.

terminate(_Reason, #state{sockpath = _SocketPath, socket = Socket}) ->
    lager:debug("~p: ~p: terminated", [self(), Socket]),
    gen_tcp:close(Socket),
    ok.

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

%% Private functions.