%%%-------------------------------------------------------------------
%%% @author licheng5
%%% @copyright (C) 2020, <COMPANY>
%%% @doc
%%%
%%% @end
%%% Created : 10. 12月 2020 上午11:17
%%%-------------------------------------------------------------------
-module(tcp_channel).
-author("licheng5").
-behaviour(gen_server).

%% 心跳包监测机制
-define(PING_TICKER, 15000).

%% API
-export([start_link/2]).
-export([publish_command/4, send_event/3, stop/2, move_network/3]).

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

-record(state, {
    transport,
    socket,
    %% 标记是否已经注册
    is_registered = false,
    %% 记录ping的次数
    ping_counter = 0,
    %% 发送消息对应的id
    packet_id = 1 :: integer(),
    %% 请求响应的对应关系
    inflight = #{}
}).

%% 向通道中写入消息
-spec publish_command(Pid :: pid(), ReceiverPid :: pid(), CommandType :: integer(), Msg :: binary()) -> Ref :: reference().
publish_command(Pid, ReceiverPid, CommandType, Msg) when is_pid(Pid), is_pid(ReceiverPid), is_integer(CommandType), is_binary(Msg) ->
    Ref = make_ref(),
    Pid ! {publish_command, ReceiverPid, Ref, CommandType, Msg},
    Ref.

%% 网络迁移是一种特殊的指令信息，需要单独处理
-spec move_network(Pid :: pid(), ReceiverPid :: pid(), NetworkPid :: pid()) -> Ref :: reference().
move_network(Pid, ReceiverPid, NetworkPid) when is_pid(Pid), is_pid(ReceiverPid), is_pid(NetworkPid) ->
    Ref = make_ref(),
    Pid ! {move_network, ReceiverPid, Ref, NetworkPid},
    Ref.

%% 向通道中写入消息
-spec send_event(Pid :: pid(), EventType :: integer(), Event :: binary()) -> no_return().
send_event(Pid, EventType, Event) when is_pid(Pid), is_integer(EventType), is_binary(Event) ->
    Pid ! {send_event, EventType, Event}.

%% 关闭方法
-spec stop(Pid :: pid(), Reason :: any()) -> no_return().
stop(undefined, _Reason) ->
    ok;
stop(Pid, Reason) when is_pid(Pid) ->
    Pid ! {stop, Reason}.

%%--------------------------------------------------------------------
%% esockd callback
%%--------------------------------------------------------------------

start_link(Transport, Sock) ->
    {ok, proc_lib:spawn_link(?MODULE, init, [[Transport, Sock]])}.

init([Transport, Sock]) ->
    efka_logger:debug("[sdlan_channel] get a new connection: ~p", [Sock]),
    case Transport:wait(Sock) of
        {ok, NewSock} ->
            Transport:setopts(Sock, [{active, true}]),
            erlang:start_timer(?PING_TICKER, self(), ping_ticker),
            gen_server:enter_loop(?MODULE, [], #state{transport = Transport, socket = NewSock});
        {error, Reason} ->
            {stop, Reason}
    end.

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

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

%% 网络流量统计
handle_info({tcp, _Sock, <<Body/binary>>}, State = #state{is_registered = true}) ->
    % #sdl_flows{forward_num = ForwardNum, p2p_num = P2PNum, inbound_num = InboundNum} = sdlan_pb:decode_msg(Body, sdl_flows),
    efka_logger:debug("[sdlan_channel] body: ~p", [Body]),
    {noreply, State};

handle_info({tcp_error, Sock, Reason}, State = #state{socket = Sock}) ->
    efka_logger:notice("[sdlan_channel] tcp_error: ~p", [Reason]),
    {stop, normal, State};

handle_info({tcp_closed, Sock}, State = #state{socket = Sock}) ->
    efka_logger:notice("[sdlan_channel] tcp_closed", []),
    {stop, normal, State};

%% 关闭当前通道
handle_info({stop, Reason}, State) ->
    {stop, Reason, State};

handle_info(Info, State) ->
    efka_logger:warning("[sdlan_channel] get a unknown message: ~p, channel will closed", [Info]),
    {noreply, State}.

terminate(Reason, #state{}) ->
    efka_logger:warning("[sdlan_channel] stop with reason: ~p", [Reason]),
    ok.

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

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%% helper methods
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%