Make a little system to replace the InputBox message queue with something more generic

Common/System/Message.cpp

@@ -0,0 +1,55 @@
+#include "Common/System/Message.h"
+#include "Common/System/System.h"
+#include "Common/Log.h"
+
+RequestManager g_RequestManager;
+
+const char *RequestTypeAsString(SystemRequestType type) {
+	switch (type) {
+	case SystemRequestType::INPUT_TEXT_MODAL: return "INPUT_TEXT_MODAL";
+	default: return "N/A";
+	}
+}
+
+bool RequestManager::MakeSystemRequest(SystemRequestType type, RequestCallback callback, const char *param1, const char *param2) {
+	int requestId = idCounter_++;
+	if (!System_MakeRequest(type, requestId, param1, param2)) {
+		return false;
+	}
+
+	if (!callback) {
+		// We don't expect a response, this is a one-directional request. We're thus done.
+		return true;
+	}
+
+	std::lock_guard<std::mutex> guard(callbackMutex_);
+	callbackMap_[requestId] = callback;
+	return true;
+}
+
+void RequestManager::PostSystemResponse(int requestId, const char *responseString, int responseValue) {
+	std::lock_guard<std::mutex> guard(callbackMutex_);
+	auto iter = callbackMap_.find(requestId);
+	if (iter == callbackMap_.end()) {
+		// Unexpected!
+		ERROR_LOG(SYSTEM, "PostSystemResponse: Unexpected request ID %d for %s (responseString=%s)", requestId, responseString);
+		return;
+	}
+
+	std::lock_guard<std::mutex> responseGuard(responseMutex_);
+	PendingResponse response;
+	response.callback = iter->second;
+	response.responseString = responseString;
+	response.responseValue = responseValue;
+	pendingResponses_.push_back(response);
+}
+
+void RequestManager::ProcessRequests() {
+	std::lock_guard<std::mutex> guard(responseMutex_);
+	for (auto &iter : pendingResponses_) {
+		if (iter.callback) {
+			iter.callback(iter.responseString.c_str(), iter.responseValue);
+		}
+	}
+	pendingResponses_.clear();
+}