Improve BitcoinityReader.

It sends a pong message back, but I'm not sure it's
having an effect

src/bitcoinity_payload.hpp

@@ -44,6 +44,8 @@ class BitcoinityPayload {
 public:
 	static constexpr std::string_view JsonKeyPayload = "payload";
 
+	BitcoinityPayload() = default;
+
 	BitcoinityPayload(
 		simdjson::padded_string&& body_p,
 		simdjson::ondemand::parser&& parser_p

src/bitcoinity_reader.cpp

@@ -37,6 +37,7 @@ namespace {
 	}
 
 	BitcoinityMessage to_bitcoinity_message (const std::string& message) {
+		typedef std::optional<std::string> OptionalString;
 		if (message.empty())
 			throw BitcoinityError("Unable to make a BitcoinityMessage from an empty message");
 
@@ -56,7 +57,8 @@ namespace {
 		auto ref_result = doc[JsonKeyRef];
 		if (ref_result.error())
 			throw BitcoinityMissingKeyError({std::string(JsonKeyRef)}, message);
-		std::string_view ref = (ref_result.is_null() ? std::string_view{} : ref_result.value());
+		OptionalString ref =
+			(ref_result.is_null() ? OptionalString{} : OptionalString{static_cast<std::string_view>(ref_result.value())});
 
 		auto topic_result = doc[JsonKeyTopic];
 		if (topic_result.error())
@@ -66,11 +68,20 @@ namespace {
 		return BitcoinityMessage{
 			BitcoinityPayload{std::move(body), std::move(parser)},
 			std::move(ref),
-			std::move(event),
-			std::move(topic)
+			std::string(event),
+			std::string(topic)
 		};
 	}
 
+	BitcoinityMessage wait_for_event (WebsocketReader& ws, std::string_view event, int max_messages) {
+		do {
+			auto resp = to_bitcoinity_message(ws.read());
+			if (resp.event == event)
+				return resp;
+		} while (--max_messages > 0);
+		return BitcoinityMessage{};
+	}
+
 	void init_bitcoinity (WebsocketReader& ws, std::string_view exchange, std::string_view currency) {
 		//thanks to blueagain from #javascript libera.chat for helping figuring
 		//out the websocket address and the correct sequence of messages to
@@ -81,9 +92,11 @@ namespace {
 		//3) {"topic":"webs:markets_bitfinex_USD","event":"phx_join","payload":{},"ref":"3"}
 		//See docs/bitcoinity/sample_communication.md for a real world example
 
+		constexpr int MaxDiscardedReplies = 5;
+
 		{
 			ws.write(R"({"topic":"all","event":"phx_join","payload":{},"ref":"1"})");
-			auto resp = to_bitcoinity_message(ws.read());
+			auto resp = wait_for_event(ws, "phx_reply", MaxDiscardedReplies);
 			if (resp.event != "phx_reply" or resp.payload.get_string_or_empty("status") != "ok" or not resp.ref or *resp.ref != "1")
 				throw BitcoinityError("Server responded to message 1 \"" +
 					std::string{resp.event} + "\" with status \"" +
@@ -93,7 +106,7 @@ namespace {
 
 		{
 			ws.write(R"({"topic":"webs:markets","event":"phx_join","payload":{},"ref":"2"})");
-			auto resp = to_bitcoinity_message(ws.read());
+			auto resp = wait_for_event(ws, "phx_reply", MaxDiscardedReplies);
 			if (resp.event != "phx_reply" or resp.payload.get_string_or_empty("status") != "ok" or not resp.ref or *resp.ref != "2")
 				throw BitcoinityError("Server responded to message 2 \"" +
 					std::string{resp.event} + "\" with status \"" +
@@ -106,7 +119,7 @@ namespace {
 				R"({"topic":"webs:markets_)" + std::string{exchange} + "_" +
 				std::string{currency} + R"(","event":"phx_join","payload":{},"ref":"3"})"
 			);
-			auto resp = to_bitcoinity_message(ws.read());
+			auto resp = wait_for_event(ws, "phx_reply", MaxDiscardedReplies);
 			if (resp.event != "phx_reply" or resp.payload.get_string_or_empty("status") != "ok" or not resp.ref or *resp.ref != "3")
 				throw BitcoinityError("Server responded to message 3 \"" +
 					std::string{resp.event} + "\" with status \"" +
@@ -146,9 +159,9 @@ const std::string& BitcoinityMissingKeyError::json() const noexcept {
 
 BitcoinityMessage::BitcoinityMessage (
 	BitcoinityPayload&& payload_p,
-	std::optional<std::string_view> ref_p,
-	std::string_view event_p,
-	std::string_view topic_p
+	std::optional<std::string> ref_p,
+	std::string event_p,
+	std::string topic_p
 ) :
 	payload(std::move(payload_p)),
 	ref(std::move(ref_p)),
@@ -168,6 +181,26 @@ BitcoinityReader::BitcoinityReader(const std::string& user_agent, std::string_vi
 }
 
 BitcoinityMessage BitcoinityReader::read() {
-	return to_bitcoinity_message(WebsocketReader::read());
+	do {
+		auto response = to_bitcoinity_message(WebsocketReader::read());
+		if (response.event == "ping") {
+			//received something like
+			//  {"event":"ping","payload":{"token":"wassup"},"ref":null,"topic":"all"}
+			std::string reply = R"({"event":"pong","payload":{"token":")";
+			reply += response.payload.get_string_or_empty("token");
+			reply += R"("},"ref":)";
+			if (response.ref)
+				reply += "\"" + std::string{*response.ref} + "\"";
+			else
+				reply += "null";
+			reply += R"(,"topic":")";
+			reply += response.topic;
+			reply += R"("})";
+			WebsocketReader::write(reply);
+		}
+		else {
+			return response;
+		}
+	} while(true);
 }
 } //namespace duck

src/bitcoinity_reader.hpp

@@ -43,17 +43,18 @@ private:
 };
 
 struct BitcoinityMessage {
+	BitcoinityMessage() = default;
 	BitcoinityMessage (
 		BitcoinityPayload&& payload_p,
-		std::optional<std::string_view> ref_p,
-		std::string_view event_p,
-		std::string_view topic_p
+		std::optional<std::string> ref_p,
+		std::string event_p,
+		std::string topic_p
 	);
 
 	BitcoinityPayload payload;
-	std::optional<std::string_view> ref;
-	std::string_view event;
-	std::string_view topic;
+	std::optional<std::string> ref;
+	std::string event;
+	std::string topic;
 };
 
 class BitcoinityReader : private WebsocketReader {