iot/apps/iot/src/iot_host.erl

%%%-------------------------------------------------------------------
%%% @author aresei
%%% @copyright (C) 2023, <COMPANY>
%%% @doc
%%%
%%% @end
%%% Created : 12. 3月 2023 21:27
%%%-------------------------------------------------------------------
-module(iot_host).
-author("aresei").
-include("iot.hrl").

-behaviour(gen_server).

%% API
-export([test/1]).
-export([start_link/2, get_name/1, get_pid/1, publish/4]).

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

-define(SERVER, ?MODULE).

-record(state, {
    host :: #host{},
    emqx_pid :: pid(),
    is_connected = false :: boolean()
}).

test(Id) when is_binary(Id) ->
    Pid = get_pid(<<"1">>),
    publish(Pid, <<"/host/", Id/binary>>, <<"hello world">>, 1).

%%%===================================================================
%%% API
%%%===================================================================
get_pid(HostId) when is_binary(HostId) ->
    Name = get_name(HostId),
    global:whereis_name(Name).

get_name(HostId) when is_binary(HostId) ->
    binary_to_atom(<<"iot_host:", HostId/binary>>).

publish(Pid, Topic, Message, Qos) when is_pid(Pid), is_binary(Topic) ->
    gen_server:call(Pid, {publish, Topic, Message, Qos}).

%% @doc Spawns the server and registers the local name (unique)
-spec(start_link(Name :: atom(), Host :: #host{}) ->
    {ok, Pid :: pid()} | ignore | {error, Reason :: term()}).
start_link(Name, Host = #host{}) ->
    gen_server:start_link({global, Name}, ?MODULE, [Host], []).

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

%% @private
%% @doc Initializes the server
-spec(init(Args :: term()) ->
    {ok, State :: #state{}} | {ok, State :: #state{}, timeout() | hibernate} |
    {stop, Reason :: term()} | ignore).
init([Host = #host{host_id = HostId}]) ->
    lager:debug("[iot_host] host is: ~p", [Host]),
    %% 建立到emqx服务器的连接
    {ok, Props} = application:get_env(iot, emqx_server),
    EMQXHost = proplists:get_value(host, Props),
    EMQXPort = proplists:get_value(port, Props, 18080),
    Username = proplists:get_value(username, Props),
    Password = proplists:get_value(password, Props),
    RetryInterval = proplists:get_value(retry_interval, Props, 5),
    Keepalive = proplists:get_value(keepalive, Props, 86400),
    Opts = [
        {host, EMQXHost},
        {port, EMQXPort},
        {owner, self()},
        {tcp_opts, []},
        {username, Username},
        {password, Password},
        {keepalive, Keepalive},
        {retry_interval, RetryInterval}
    ],

    case emqtt:start_link(Opts) of
        {ok, ConnPid} ->
            lager:debug("[iot_host] connect success, pid: ~p", [ConnPid]),
            %% 监听和host相关的全部事件
            {ok, _} = emqtt:connect(ConnPid),
            Topics = [
                {<<"/host/", HostId/binary>>, qos1}
            ],
            SubscribeResult = emqtt:subscribe(ConnPid, Topics),
            lager:debug("subscribe result is: ~p", [SubscribeResult]),

            {ok, #state{host = Host, is_connected = true, emqx_pid = ConnPid}};
        ignore ->
            lager:debug("[iot_host] connect emqx get ignore"),
            {stop, ignore};
        {error, Reason} ->
            lager:debug("[iot_host] connect emqx get error: ~p", [Reason]),
            {stop, Reason}
    end.

%% @private
%% @doc Handling call messages
-spec(handle_call(Request :: term(), From :: {pid(), Tag :: term()},
    State :: #state{}) ->
    {reply, Reply :: term(), NewState :: #state{}} |
    {reply, Reply :: term(), NewState :: #state{}, timeout() | hibernate} |
    {noreply, NewState :: #state{}} |
    {noreply, NewState :: #state{}, timeout() | hibernate} |
    {stop, Reason :: term(), Reply :: term(), NewState :: #state{}} |
    {stop, Reason :: term(), NewState :: #state{}}).
handle_call({publish, Topic, Message, Qos}, _From, State = #state{emqx_pid = ConnPid}) ->
    Result = emqtt:publish(ConnPid, Topic, #{}, Message, [{qos, Qos}]),
    {reply, Result, State}.

%% @private
%% @doc Handling cast messages
-spec(handle_cast(Request :: term(), State :: #state{}) ->
    {noreply, NewState :: #state{}} |
    {noreply, NewState :: #state{}, timeout() | hibernate} |
    {stop, Reason :: term(), NewState :: #state{}}).
handle_cast(_Request, State = #state{}) ->
    {noreply, State}.

%% @private
%% @doc Handling all non call/cast messages
-spec(handle_info(Info :: timeout() | term(), State :: #state{}) ->
    {noreply, NewState :: #state{}} |
    {noreply, NewState :: #state{}, timeout() | hibernate} |
    {stop, Reason :: term(), NewState :: #state{}}).
handle_info({disconnect, ReasonCode, Properties}, State = #state{host = #host{host_id = HostId}}) ->
    lager:debug("[iot_host] host: ~p, Recv a DISONNECT packet - ReasonCode: ~p, Properties: ~p", [HostId, ReasonCode, Properties]),
    {stop, disconnected, State};
handle_info({publish, Message = #{packet_id := PacketId, payload := Payload}}, State = #state{emqx_pid = ConnPid, host = #host{host_id = HostId}}) ->
    lager:debug("[iot_host] host: ~p, Recv a publish packet: ~p, payload: ~p", [HostId, Message, Payload]),
    % emqtt:pubrec(ConnPid, PacketId),
    {noreply, State};
handle_info({puback, #{packet_id := PacketId, reason_code := ReasonCode}}, State = #state{host = #host{host_id = HostId}}) ->
    lager:debug("[iot_host] host: ~p, receive puback packet_id: ~p, reason_code: ~p", [HostId, PacketId, ReasonCode]),
    {noreply, State};

handle_info(Info, State = #state{host = #host{host_id = HostId}}) ->
    lager:debug("host_id: ~p, get info: ~p", [HostId, Info]),
    {noreply, State}.

%% @private
%% @doc This function is called by a gen_server when it is about to
%% terminate. It should be the opposite of Module:init/1 and do any
%% necessary cleaning up. When it returns, the gen_server terminates
%% with Reason. The return value is ignored.
-spec(terminate(Reason :: (normal | shutdown | {shutdown, term()} | term()),
    State :: #state{}) -> term()).
terminate(_Reason, _State = #state{emqx_pid = ConnPid}) ->
    {ok, _Props, _ReasonCode} = emqtt:unsubscribe(ConnPid, #{}, <<"hello">>),
    ok = emqtt:disconnect(ConnPid),
    ok = emqtt:stop(ConnPid),
    ok.

%% @private
%% @doc Convert process state when code is changed
-spec(code_change(OldVsn :: term() | {down, term()}, State :: #state{},
    Extra :: term()) ->
    {ok, NewState :: #state{}} | {error, Reason :: term()}).
code_change(_OldVsn, State = #state{}, _Extra) ->
    {ok, State}.

%%%===================================================================
%%% Internal functions
%%%===================================================================