% @doc tetris
%
% manages state for a single game of tetris
%
% sends parent process messages `{tetris, String}` where String is an encoded
% JSON blob meant to be sent to the page script in /priv/static/js/ts/tetris.ts
%
% Refs:
% 1. https://www.erlang.org/docs/24/man/gen_server
-module(fd_tetris).

-behavior(gen_server).

-export([
    %% caller context
    start_link/0,
    %% process context
    %% gen_server callbacks
    init/1, handle_call/3, handle_cast/2, handle_info/2,
    code_change/3, terminate/2
]).

-include("$zx_include/zx_logger.hrl").


-record(s, {parent :: pid()}).

-type state() :: #s{}.

%%-----------------------------------------------------------------------------
%% caller context below this line
%%-----------------------------------------------------------------------------

-spec ws_msg(Tetris, Message) -> ok
    when Tetris  :: pid(),
         Message :: fd_ws:ws_msg().

ws_msg(Tetris, Msg) ->
    gen_server:cast(Tetris, {ws_msg, Msg}).


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


%%-----------------------------------------------------------------------------
%% process context below this line
%%-----------------------------------------------------------------------------

%% gen_server callbacks

-spec init(Args) -> {ok, State}
    when Args   :: [Parent],
         Parent :: pid(),
         State  :: state().

init([Parent]) ->
    tell("~tp:~tp starting fd_tetris with parent ~p", [?MODULE, self(), Parent]),
    self() ! {poop, 0},
    InitState = #s{parent = Parent},
    {ok, InitState}.


handle_call(Unexpected, From, State) ->
    tell("~tp:~tp unexpected call from ~tp: ~tp", [?MODULE, self(), From, Unexpected]),
    {noreply, State}.


handle_cast(Unexpected, State) ->
    tell("~tp:~tp unexpected cast: ~tp", [?MODULE, self(), Unexpected]),
    {noreply, State}.


handle_info({poop, N}, State = #s{parent = Parent}) ->
    Parent ! {tetris, io_lib:format("poop~p", [N])},
    erlang:send_after(1_000, self(), {poop, N+1}),
    {noreply, State};
handle_info(Unexpected, State) ->
    tell("~tp:~tp unexpected info: ~tp", [?MODULE, self(), Unexpected]),
    {noreply, State}.


code_change(_, State, _) ->
    {ok, State}.

terminate(_, _) ->
    ok.