fix: delayed message api doc (#5569)

* fix: delayed message api doc & add delayed message internal & remaning params

apps/emqx_modules/src/emqx_delayed.erl

@@ -50,7 +50,7 @@
         , delete_delayed_message/1
         ]).
 
--record(delayed_message, {key, msg}).
+-record(delayed_message, {key, delayed, msg}).
 
 -define(TAB, ?MODULE).
 -define(SERVER, ?MODULE).
@@ -78,19 +78,19 @@ on_message_publish(Msg = #message{
                             timestamp = Ts
                            }) ->
     [Delay, Topic1] = binary:split(Topic, <<"/">>),
-    PubAt = case binary_to_integer(Delay) of
+    {PubAt, Delayed} = case binary_to_integer(Delay) of
                 Interval when Interval < ?MAX_INTERVAL ->
-                    Interval + erlang:round(Ts / 1000);
+                    {Interval + erlang:round(Ts / 1000), Interval};
                 Timestamp ->
                     %% Check malicious timestamp?
                     case (Timestamp - erlang:round(Ts / 1000)) > ?MAX_INTERVAL of
                         true  -> error(invalid_delayed_timestamp);
-                        false -> Timestamp
+                        false -> {Timestamp, Timestamp - erlang:round(Ts / 1000)}
                     end
             end,
     PubMsg = Msg#message{topic = Topic1},
     Headers = PubMsg#message.headers,
-    case store(#delayed_message{key = {PubAt, Id}, msg = PubMsg}) of
+    case store(#delayed_message{key = {PubAt, Id}, delayed = Delayed, msg = PubMsg}) of
         ok -> ok;
         {error, Error} ->
             ?LOG(error, "Store delayed message fail: ~p", [Error])
@@ -128,15 +128,22 @@ list(Params) ->
 format_delayed(Delayed) ->
     format_delayed(Delayed, false).
 
-format_delayed(#delayed_message{key = {TimeStamp, Id},
+format_delayed(#delayed_message{key = {ExpectTimeStamp, Id}, delayed = Delayed,
             msg = #message{topic = Topic,
                            from = From,
                            headers = #{username := Username},
                            qos = Qos,
+                           timestamp = PublishTimeStamp,
                            payload = Payload}}, WithPayload) ->
+    PublishTime = to_rfc3339(PublishTimeStamp div 1000),
+    ExpectTime = to_rfc3339(ExpectTimeStamp),
+    RemainingTime = ExpectTimeStamp - erlang:system_time(second),
     Result = #{
         id => emqx_guid:to_hexstr(Id),
-        publish_time => list_to_binary(calendar:system_time_to_rfc3339(TimeStamp, [{unit, second}])),
+        publish_at => PublishTime,
+        delayed_interval => Delayed,
+        delayed_remaining => RemainingTime,
+        expected_at => ExpectTime,
         topic => Topic,
         qos => Qos,
         from_clientid => From,
@@ -149,6 +156,9 @@ format_delayed(#delayed_message{key = {TimeStamp, Id},
             Result
     end.
 
+to_rfc3339(Timestamp) ->
+    list_to_binary(calendar:system_time_to_rfc3339(Timestamp, [{unit, second}])).
+
 get_delayed_message(Id0) ->
     Id = emqx_guid:from_hexstr(Id0),
     Ms = [{{delayed_message,{'_',Id},'_'},[],['$_']}],

apps/emqx_modules/src/emqx_delayed_api.erl

@@ -59,12 +59,15 @@ properties() ->
             [?PAYLOAD_TOO_LARGE, ?MAX_PAYLOAD_LENGTH]),
     properties([
         {id, integer, <<"Message Id (MQTT message id hash)">>},
-        {publish_time, string, <<"publish time, rfc 3339">>},
+        {publish_at, string, <<"Client publish message time, rfc 3339">>},
+        {delayed_interval, integer, <<"Delayed interval, second">>},
+        {delayed_remaining, integer, <<"Delayed remaining, second">>},
+        {expected_at, string, <<"Expect publish time, rfc 3339">>},
         {topic, string, <<"Topic">>},
         {qos, string, <<"QoS">>},
         {payload, string, iolist_to_binary(PayloadDesc)},
-        {form_clientid, string, <<"Form ClientId">>},
-        {form_username, string, <<"Form Username">>}
+        {from_clientid, string, <<"From ClientId">>},
+        {from_username, string, <<"From Username">>}
     ]).
 
 parameters() ->

apps/emqx_modules/test/emqx_delayed_SUITE.erl

@@ -21,7 +21,7 @@
 -compile(export_all).
 -compile(nowarn_export_all).
 
--record(delayed_message, {key, msg}).
+-record(delayed_message, {key, delayed, msg}).
 
 -include_lib("common_test/include/ct.hrl").
 -include_lib("eunit/include/eunit.hrl").