A simple example plugin for the skopjehacklab KIKA

It connects to ourJSON service that counts the number of devices in the
Skopje Hacklab network.

extra/prisutni.erl

@@ -0,0 +1,83 @@
+-module(plugins.prisutni).
+-author("gorgi.kosev@gmail.com").
+
+-behaviour(gen_event).
+-export([init/1, handle_event/2, terminate/2, handle_call/2, handle_info/2, code_change/3]).
+
+
+-import(ircbot_lib).
+
+-import(ejson).
+-import(proplists).
+-import(httpc).
+-import(inets).
+
+
+init(_Args) ->
+    inets:start(),
+    {ok, ok}.
+
+
+handle_event(Msg, State) ->
+    case Msg of
+        % explicit command to fetch prisutni.spodeli.org
+        {in, Ref, [_Nick, _Name, <<"PRIVMSG">>, <<"#lugola">>, <<"!prisutni">>]} ->
+            fetch("http://prisutni.spodeli.org/status?limit=1", Ref, <<"#lugola">>),
+            {ok, State};
+       _ ->
+            {ok, State}
+    end.
+handle_call(_Request, State) -> {ok, ok, State}.
+handle_info(_Info, State) -> {ok, State}.
+code_change(_OldVsn, State, _Extra) -> {ok, State}.
+terminate(_Args, _State) -> ok.
+
+
+
+% Fetch the json, but not more than 10kbytes
+%% The function gets spawned as a separate process, and fails silently on any
+%% error.
+fetch(Url, Ref, Channel) ->
+    F = fun(Answer) -> Ref:privmsg(Channel, Answer) end,
+    spawn(fun() -> fetcher(Url, F) end).
+
+fetcher(Url, Callback) ->
+    Headers = [{"User-Agent", "Mozilla/5.0 (erlang-irc-bot)"}],
+    {ok, RequestId} = httpc:request(get, {Url, Headers}, [], [{sync, false}, {stream, self}]),
+    receive_chunk(RequestId, Callback, [], 10000).
+
+%% callback function called as chunks from http are received
+%% when enough data is received (Len =< 0) process the json
+
+receive_chunk(_RequestId, Callback, Body, Len) when Len =< 0 ->
+    {Json} = ejson:decode(Body),
+    [{Counter}|_] = proplists:get_value(<<"counters">>, Json),
+    Count = proplists:get_value(<<"count">>, Counter),
+    CountS = integer_to_list(Count),
+    People = proplists:get_value(<<"present">>, Json),
+
+    case {Count, People} of
+        {0, _} ->
+            Callback(<<"во хаклаб нема никој :(">>);
+        {_, []} ->
+            Callback([<<"во хаклаб има ">>, CountS, <<" уреди">>]);
+        _ ->
+            Names = [ proplists:get_value(<<"name">>, Person) || {Person} <- People ],
+            Callback([<<"Присутни: ">>, ircbot_lib:iolist_join(Names, ", "), <<". Вкупно уреди: ">>, CountS])
+    end;
+
+receive_chunk(RequestId, Callback, Body, Len)  ->
+    receive
+        {http,{RequestId, stream_start, _Headers}} ->
+            receive_chunk(RequestId, Callback, Body, Len);
+
+        {http,{RequestId, stream, Data}} ->
+            Size = size(Data),
+            receive_chunk(RequestId, Callback, Body ++ [Data], Len - Size);
+
+        {http,{RequestId, stream_end, _Headers}} ->
+            receive_chunk(RequestId, Callback, Body, 0)
+    after 10000 ->
+        ok
+    end.
+