From dfadae0b59b321029c806b714daa252ba5797282 Mon Sep 17 00:00:00 2001
From: Tristan Sloughter <t@crashfast.com>
Date: Sat, 6 Oct 2018 12:14:51 -0600
Subject: [PATCH] convert annotations to string values in zipkin reporter

---
 src/oc_reporter_zipkin.erl | 38 +++++++++++++++++++++++++++++++++++++-
 1 file changed, 37 insertions(+), 1 deletion(-)

diff --git a/src/oc_reporter_zipkin.erl b/src/oc_reporter_zipkin.erl
index 1c2db7b..1a518e8 100644
--- a/src/oc_reporter_zipkin.erl
+++ b/src/oc_reporter_zipkin.erl
@@ -66,10 +66,46 @@ zipkin_span(Span, LocalEndpoint) ->
        <<"shared">> => false, %% TODO: get from attributes?
        <<"localEndpoint">> => LocalEndpoint,
        %% <<"remoteEndpoint">> =>  %% TODO: get from attributes?
-       <<"annotations">> => [],
+       <<"annotations">> => to_annotations(Span#span.time_events),
        <<"tags">> => to_tags(Span#span.attributes) %% TODO: merge with oc_tags?
      }.
 
+to_annotations(TimeEvents) ->
+    to_annotations(TimeEvents, []).
+
+to_annotations([], Annotations) ->
+    Annotations;
+to_annotations([{Timestamp, #annotation{description=Description,
+                                        attributes=Attributes}} | Rest], Annotations) ->
+    to_annotations(Rest, [#{<<"timestamp">> => wts:to_absolute(Timestamp),
+                            <<"value">> => annotation_value(Description, Attributes)} | Annotations]);
+to_annotations([{Timestamp, MessageEvent=#message_event{}} | Rest], Annotations) ->
+    to_annotations(Rest, [#{<<"timestamp">> => wts:to_absolute(Timestamp),
+                            <<"value">> => annotation_value(MessageEvent)} | Annotations]).
+
+annotation_value(Description, Attributes) ->
+    AttrString = lists:join(", ", [[Key, "=", to_string(Value)] ||
+                                      {Key, Value} <- maps:to_list(Attributes)]),
+    iolist_to_binary([Description, " Attributes:{", AttrString,"}"]).
+
+annotation_value(#message_event{type=Type,
+                                id=Id,
+                                uncompressed_size=UncompressedSize,
+                                compressed_size=CompressedSize}) ->
+    iolist_to_binary(["MessageEvent:{type=", atom_to_binary(Type, utf8),
+                      ", id=", integer_to_binary(Id),
+                      ", uncompressed_size=", integer_to_binary(UncompressedSize),
+                      ", compressed_size=", integer_to_binary(CompressedSize), "}"]).
+
+
+to_string(Value) when is_function(Value) ->
+    to_string(Value());
+to_string(Value) when is_list(Value) ;
+                      is_binary(Value) ->
+    Value;
+to_string(Value) ->
+    io_lib:format("~p", [Value]).
+
 to_tag(_Name, Value) when is_function(Value) ->
     Value();
 to_tag(_Name, Value) when is_list(Value) ->