-module(simple_tcp).
-behaviour(gen_server).

%% API
-export([start_link/1, stop/0, start/0, start/1]).

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

-define(SERVER, ?MODULE).
-define(DEFAULT_PORT, 1055).

-record(state, {port, lsock}).

start_link({port, Port}) ->
    gen_server:start_link(?MODULE, [{port, Port}], []);

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

start({port, Port}) ->
    simple_tcp_sup:start_child({port, Port});

start({socket, Socket}) ->
    simple_tcp_sup:start_child({socket, Socket}).

start() ->
    start({port, ?DEFAULT_PORT}).

stop() ->
    gen_server:cast(?SERVER, stop).

% Callback functions
init([{port, Port}]) ->
    {ok, LSock} = gen_tcp:listen(Port, [{active, true},{reuseaddr, true}]),
    init([{socket, LSock}]);

init([{socket, Socket}]) ->
    io:fwrite("Starting server with socket: ~p~n", [self()]),
    {ok, Port} = inet:port(Socket),
    {ok, #state{port=Port, lsock=Socket}, 0}.

handle_call(_Msg, _From, State) ->
    {noreply, State}.

handle_cast(stop, State) ->
    {stop, ok, State}.

handle_info({tcp, Socket, RawData}, State) ->
    gen_tcp:send(Socket, io_lib:fwrite("Received raw data: ~p~n", [RawData])),
    {noreply, State};

handle_info({tcp_error, _Socket, Reason}, State) ->
    io:fwrite("Error: ~p~n", [Reason]),
    {stop, normal, State};

handle_info(timeout, #state{lsock = LSock} = State) ->
    case gen_tcp:accept(LSock) of
        {ok, Sock} ->
            io:fwrite("Accepting connection...~p~n", [self()]),
            start({socket, LSock}),
            {noreply, #state{lsock=Sock}};

        {error, Reason} ->
            io:fwrite("Error: ~p, ~p~n", [Reason, self()]),
            {stop, normal, State}
    end;

handle_info({tcp_closed, _Port}, State) ->
    io:fwrite("Socket closed: ~p~n", [self()]),
    simple_tcp_sup:kill_child(self()),
    {stop, normal, State}.

terminate(_Reason, _State) ->
    io:fwrite("Shutting down server: ~p~n", [self()]),
    ok.

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