%%%-------------------------------------------------------------------
%%% @author anlicheng
%%% @copyright (C) 2025, <COMPANY>
%%% @doc
%%% 1. 需要管理服务的整个生命周期，包括: 启动，停止
%%% 2. 需要监控服务的状态，通过port的方式
%%% 3. 服务的启动和关闭，需要在更高的层级控制
%%% @end
%%% Created : 18. 4月 2025 16:50
%%%-------------------------------------------------------------------
-module(efka_service).
-author("anlicheng").
-include("efka_tables.hrl").

-behaviour(gen_server).

%% API
-export([start_link/2]).
-export([get_name/1, get_pid/1, attach_channel/2]).
-export([metric_data/4, send_event/3]).

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

-record(state, {
    service_id :: binary(),
    %% 通道id信息
    channel_pid :: pid() | undefined
}).

%%%===================================================================
%%% API
%%%===================================================================

-spec get_name(ServiceId :: binary()) -> atom().
get_name(ServiceId) when is_binary(ServiceId) ->
    list_to_atom("efka_service:" ++ binary_to_list(ServiceId)).

-spec get_pid(ServiceId :: binary()) -> undefined | pid().
get_pid(ServiceId) when is_binary(ServiceId) ->
    whereis(get_name(ServiceId)).

-spec metric_data(Pid :: pid(), DeviceUUID :: binary(), RouteKey :: binary(), Metric :: binary()) -> no_return().
metric_data(Pid, DeviceUUID, RouteKey, Metric) when is_pid(Pid), is_binary(DeviceUUID), is_binary(RouteKey),  is_binary(Metric) ->
    gen_server:cast(Pid, {metric_data, DeviceUUID, RouteKey, Metric}).

-spec send_event(Pid :: pid(), EventType :: integer(), Params :: binary()) -> no_return().
send_event(Pid, EventType, Params) when is_pid(Pid), is_integer(EventType), is_binary(Params) ->
    gen_server:cast(Pid, {send_event, EventType, Params}).

-spec attach_channel(pid(), pid()) -> ok | {error, Reason :: binary()}.
attach_channel(Pid, ChannelPid) when is_pid(Pid), is_pid(ChannelPid) ->
    gen_server:call(Pid, {attach_channel, ChannelPid}).

%% @doc Spawns the server and registers the local name (unique)
-spec(start_link(Name :: atom(), Service :: binary()) ->
    {ok, Pid :: pid()} | ignore | {error, Reason :: term()}).
start_link(Name, ServiceId) when is_atom(Name), is_binary(ServiceId) ->
    gen_server:start_link({local, Name}, ?MODULE, [ServiceId], []).

%%%===================================================================
%%% 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([ServiceId]) ->
    %% supervisor进程通过exit(ChildPid, shutdown)调用的时候，确保terminate函数被调用
    lager:debug("[efka_service] service_id: ~p, started", [ServiceId]),
    {ok, #state{service_id = ServiceId}}.

%% @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{}}).
%% 绑定channel
handle_call({attach_channel, ChannelPid}, _From, State = #state{channel_pid = OldChannelPid, service_id = ServiceId}) ->
    case is_pid(OldChannelPid) andalso is_process_alive(OldChannelPid) of
        false ->
            erlang:monitor(process, ChannelPid),
            lager:debug("[efka_service] service_id: ~p, channel attched", [ServiceId]),
            {reply, ok, State#state{channel_pid = ChannelPid}};
        true ->
            {reply, {error, <<"channel exists">>}, State}
    end;

handle_call(_Request, _From, State = #state{}) ->
    {reply, ok, 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({metric_data, DeviceUUID, RouteKey, Metric}, State = #state{service_id = ServiceId}) ->
    lager:debug("[efka_service] metric_data service_id: ~p, device_uuid: ~p, route_key: ~p, metric data: ~p", [ServiceId, DeviceUUID, RouteKey, Metric]),
    efka_remote_agent:metric_data(ServiceId, DeviceUUID, RouteKey, Metric),
    {noreply, State};

handle_cast({send_event, EventType, Params}, State = #state{service_id = ServiceId}) ->
    efka_remote_agent:event(ServiceId, EventType, Params),
    lager:debug("[efka_service] send_event, service_id: ~p, event_type: ~p, params: ~p", [ServiceId, EventType, Params]),
    {noreply, 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{}}).
%% 处理channel进程的退出
handle_info({'DOWN', _Ref, process, ChannelPid, Reason}, State = #state{channel_pid = ChannelPid, service_id = ServiceId}) ->
    lager:debug("[efka_service] service_id: ~p, channel exited: ~p", [ServiceId, Reason]),
    {noreply, State#state{channel_pid = undefined}}.

%% @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{service_id = ServiceId}) ->
    lager:debug("[efka_service] service_id: ~p, terminate with reason: ~p", [ServiceId, Reason]),
    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
%%%===================================================================