From a7bbc6ff8c63e0eea8710889d93281a2458fd7bf Mon Sep 17 00:00:00 2001
From: "Timur A. Fatkhullin" <timur@sao.ru>
Date: Wed, 1 Jul 2026 18:26:09 +0300
Subject: [PATCH] ...

---
 include/snipplib/network/snplib_network.h | 89 ++++++++++++-----------
 1 file changed, 45 insertions(+), 44 deletions(-)

diff --git a/include/snipplib/network/snplib_network.h b/include/snipplib/network/snplib_network.h
index 00cbc25..cd68793 100644
--- a/include/snipplib/network/snplib_network.h
+++ b/include/snipplib/network/snplib_network.h
@@ -2,7 +2,6 @@
 
 #include <set>
 #include "../concepts/snplib_concepts.h"
-#include "../containers/snplib_hvec.h"
 
 namespace snplib
 {
@@ -23,6 +22,21 @@ concept snplib_net_endpoint_c = requires(T t, const T t_const) {
 };
 
 
+
+template <typename T>
+concept snplib_net_message_c = requires(T t) {
+    { t.toBytes() } -> snplib_output_char_range_c;
+
+    // can be constructed from contiguous byte range
+    requires(
+        requires {
+            { T::fromBytes(std::declval<std::span<const char>>()) } -> std::same_as<T>;
+        } ||
+        requires {
+            { T::fromBytes(std::declval<std::span<char>>()) } -> std::same_as<T>;
+        });
+};
+
 template <typename T>
 concept snplib_net_connection_c = requires(T t) {
     // static constexpr member
@@ -46,7 +60,8 @@ concept snplib_net_session_c = std::derived_from<T, std::enable_shared_from_this
 
     snplib_net_connection_c<typename T::connection_t>;
 
-    { t.startSession(std::declval<typename T::connection_t>()) } -> snplib_async_retval_c;
+    // { t.startSession(std::declval<typename T::connection_t>()) } -> snplib_async_retval_c;
+    t.startSession(std::declval<typename T::connection_t>());
 
     t.stopSession();
 };
@@ -58,73 +73,67 @@ concept snplib_net_listener_c = requires(T t) {
     std::formattable<decltype(T::id), char>;
     []() { [[maybe_unused]] static constexpr auto val = T::id; }();
 
-    snplib_net_session_c<typename T::session_t>;
+    snplib_net_connection_c<typename T::connection_t>;
 
-    { t.accept() } -> snplib_async_retval_c<typename T::session_t>;
+    { t.accept() } -> snplib_async_retval_c<typename T::connection_t>;
 
-    // { t.accept() } -> snplib_expected_c;  // must return std::expected<snplib_net_session_c, snplib_error_c>
+    { t.startListen() } -> snplib_error_c;
 
-    // snplib_net_session_c<typename std::invoke_result_t<decltype(t.accept)>::value_type>;
-
-    { t.start() } -> snplib_error_c;
-
-    t.stop();
+    t.stopListen();
 };
 
 
-struct snplib_netserver_iface_t {
-    virtual ~snplib_netserver_iface_t() = default;
-
-    template <std::derived_from<snplib_netserver_iface_t> SelfT, snplib_net_listener_c LT>
-    auto start(this SelfT&& self, LT&& listener)
-    {
-        return std::forward<SelfT>(self).start(std::forward<LT>(listener));
-    }
-
-protected:
-    snplib_netserver_iface_t() = default;
-};
-
 template <typename T>
-concept snplib_netserver_c = std::derived_from<T, snplib_netserver_iface_t> && requires(T t) {
+concept snplib_netserver_c = requires(T t) {
     // static constexpr member
     std::formattable<decltype(T::id), char>;
     []() { [[maybe_unused]] static constexpr auto val = T::id; }();
 
 
     // start/stop all listeners
-    { t.start() } -> snplib_error_c;
+    t.startServer();
 
-    { t.stop() } -> snplib_error_c;
+    t.stopServer();
 
-    { t.disconnectClients() } -> snplib_error_c;
+    t.disconnectClients();
+    // { t.startServer() } -> snplib_error_c;
+
+    // { t.stopServer() } -> snplib_error_c;
+
+    // { t.disconnectClients() } -> snplib_error_c;
 };
 
 
 
 /*                          SINGLE-PROTO*/
 
-template <snplib_net_listener_c ListenerT>
+template <snplib_net_listener_c ListenerT, snplib_net_session_c SessionT>
+    requires std::same_as<typename ListenerT::connection_t, typename SessionT::connection_t>
 class snplib_generic_netserver_t
 {
 public:
-    typedef std::error_code error_t;
-
-    using session_t = typename ListenerT::session_t;
+    // typedef std::error_code error_t;
 
     snplib_generic_netserver_t(std::unique_ptr<ListenerT> listener) : _listener(std::move(listener)) {}
 
-    error_t start()
+    auto startServer()
     {
         auto err = _listener->start();
         if (err) {
-            return snplib_deduced_error(err, std::make_error_code(std::errc::io_error));
+            co_return std::unexpect(snplib_deduced_error(err, std::make_error_code(std::errc::io_error)));
         }
 
-        startListen();
+        while (true) {
+            auto connection = co_await _listener->accept();
+            if (connection) {
+                auto sptr = std::make_shared<SessionT>();
+                _sessions.insert(sptr);
+                sptr->start(std::move(connection.value()));
+            }
+        }
     }
 
-    error_t stop()
+    error_t stopServer()
     {
         _listener->stop();
 
@@ -133,15 +142,7 @@ public:
 
 protected:
     std::unique_ptr<ListenerT> _listener{};
-    std::set<std::weak_ptr<session_t>> _sessions{};
-
-    void startListen()
-    {
-        auto sess = co_await _listener->accept();
-        if (sess) {
-            _sessions.insert(sess);
-        }
-    }
+    std::set<std::weak_ptr<SessionT>> _sessions{};
 };