add '--dbg-server' command-line argument & add debugging server draft

src/devtools/DebuggingServer.cpp

@@ -0,0 +1,77 @@
+#include "DebuggingServer.hpp"
+
+#include "engine/Engine.hpp"
+#include "network/Network.hpp"
+#include "debug/Logger.hpp"
+
+using namespace devtools;
+
+static debug::Logger logger("debug-server");
+
+static network::Server& create_tcp_server(
+    DebuggingServer& dbgServer, Engine& engine, int port
+) {
+    auto& network = engine.getNetwork();
+    u64id_t serverId = network.openTcpServer(
+        port,
+        [&network, &dbgServer](u64id_t sid, u64id_t id) {
+            auto& connection = *network.getConnection(id, true);
+            connection.setPrivate(true);
+            logger.info() << "connected client " << id << ": "
+                          << connection.getAddress() << ":"
+                          << connection.getPort();
+            dbgServer.setClient(connection);
+        }
+    );
+    auto& server = *network.getServer(serverId, true);
+    server.setPrivate(true);
+
+    auto& tcpServer = dynamic_cast<network::TcpServer&>(server);
+    tcpServer.setMaxClientsConnected(1);
+
+    logger.info() << "tcp debugging server open at port " << server.getPort();
+
+    return tcpServer;
+}
+
+static network::Server& create_server(
+    DebuggingServer& dbgServer, Engine& engine, const std::string& serverString
+) {
+    logger.info() << "starting debugging server";
+
+    size_t sepPos = serverString.find(':');
+    if (sepPos == std::string::npos) {
+        throw std::runtime_error("invalid debugging server configuration string");
+    }
+    auto transport = serverString.substr(0, sepPos);
+    if (transport == "tcp") {
+        int port;
+        try {
+            port = std::stoi(serverString.substr(sepPos + 1));
+        } catch (const std::exception& err) {
+            throw std::runtime_error("invalid tcp port");
+        }
+        return create_tcp_server(dbgServer, engine, port);
+    } else {
+        throw std::runtime_error(
+            "unsupported debugging server transport '" + transport + "'"
+        );
+    }
+}
+
+DebuggingServer::DebuggingServer(
+    Engine& engine, const std::string& serverString
+)
+    : engine(engine),
+      server(create_server(*this, engine, serverString)),
+      client(nullptr) {
+}
+
+DebuggingServer::~DebuggingServer() {
+    logger.info() << "stopping debugging server";
+}
+
+
+bool DebuggingServer::update() {
+    return false;
+}