// HSMS-GS integration test: drives a passive equipment with TWO MES
// sessions (device_id 1 + 2) over a single TCP connection through the
// Server/Client high-level API customers actually use.  Each MES gets
// its own router + selected handler + send path.
//
// This is the "two MES, one tool" pattern that the codebase advertises
// in COMPLIANCE.md §1 ("HSMS-GS (general-session) ✅") and that
// INTEGRATION.md §7 mentions.  Until now there was no end-to-end test
// covering the Server/Client integration — only direct Connection
// wire tests in test_hsms_gs.cpp.

#include <doctest/doctest.h>

#include <asio.hpp>
#include <chrono>
#include <memory>
#include <optional>
#include <string>

#include "secsgem/endpoint.hpp"
#include "secsgem/gem/messages.hpp"
#include "secsgem/secs2/message.hpp"

using namespace secsgem;
using namespace std::chrono_literals;
namespace s2 = secsgem::secs2;
namespace gem = secsgem::gem;

namespace {

template <typename Pred>
void run_until(asio::io_context& io, Pred pred,
               std::chrono::seconds budget = 10s) {
  asio::steady_timer cap(io);
  cap.expires_after(budget);
  cap.async_wait([&io](std::error_code ec) {
    if (!ec) io.stop();
  });
  asio::steady_timer poll(io);
  std::function<void(std::error_code)> tick = [&](std::error_code ec) {
    if (ec) return;
    if (pred()) { io.stop(); return; }
    poll.expires_after(1ms);
    poll.async_wait(tick);
  };
  poll.expires_after(1ms);
  poll.async_wait(tick);
  io.run();
  io.restart();
}

}  // namespace

TEST_CASE("HSMS-GS integration: two MES sessions on one Server, distinct dispatch") {
  asio::io_context io;

  // Pick an OS-allocated port for the test.
  asio::ip::tcp::acceptor probe(
      io, asio::ip::tcp::endpoint(asio::ip::address_v4::loopback(), 0));
  const auto port = probe.local_endpoint().port();
  probe.close();

  // Equipment: passive Server bound to the primary session (device_id=1)
  // by construction, then add_session(2) for the second MES.  Each
  // session has its own router (different MDLN/SOFTREV so we can tell
  // them apart on the wire).
  Server::Config sc;
  sc.port = port;
  sc.device_id = 1;
  Server server(io, sc);

  std::shared_ptr<Connection> equipment_conn;
  int sess1_messages = 0;
  int sess2_messages = 0;

  server.on_connection([&](std::shared_ptr<Connection> conn) {
    equipment_conn = conn;
    conn->add_session(2);

    conn->set_session_message_handler(
        1, [&sess1_messages](const s2::Message& m)
               -> std::optional<s2::Message> {
          ++sess1_messages;
          if (m.stream == 1 && m.function == 1)
            return gem::s1f2_on_line_data("EQUIP-SESS-1", "1.0");
          return std::nullopt;
        });

    conn->set_session_message_handler(
        2, [&sess2_messages](const s2::Message& m)
               -> std::optional<s2::Message> {
          ++sess2_messages;
          if (m.stream == 1 && m.function == 1)
            return gem::s1f2_on_line_data("EQUIP-SESS-2", "2.0");
          return std::nullopt;
        });
  });
  server.start();

  // Active host running TWO sessions over a single TCP connection.
  // Mirrors the multi-MES "one tool, two factory schedulers" pattern.
  Client::Config cc;
  cc.host = "127.0.0.1";
  cc.port = port;
  cc.device_id = 1;
  cc.timers.linktest = 0ms;
  Client client(io, cc);

  std::shared_ptr<Connection> host_conn;
  bool sess1_selected = false;
  bool sess2_selected = false;

  client.on_connection([&](std::shared_ptr<Connection> conn) {
    host_conn = conn;
    conn->add_session(2);
    conn->set_session_selected_handler(1, [&] { sess1_selected = true; });
    conn->set_session_selected_handler(2, [&] { sess2_selected = true; });
  });
  client.start();

  // Both sessions go through Select.req individually (Active mode
  // walk-list: session 1 first, then session 2 once 1 is SELECTED).
  run_until(io, [&] { return sess1_selected && sess2_selected; });
  REQUIRE(sess1_selected);
  REQUIRE(sess2_selected);
  REQUIRE(equipment_conn);
  REQUIRE(host_conn);

  // Host sends S1F1 on session 1 → expects MDLN "EQUIP-SESS-1".
  std::optional<s2::Message> sess1_reply;
  host_conn->send_request(1, s2::Message(1, 1, true),
                           [&](std::error_code ec, const s2::Message& m) {
                             if (!ec) sess1_reply = m;
                           });

  // Host sends S1F1 on session 2 → expects MDLN "EQUIP-SESS-2".
  std::optional<s2::Message> sess2_reply;
  host_conn->send_request(2, s2::Message(1, 1, true),
                           [&](std::error_code ec, const s2::Message& m) {
                             if (!ec) sess2_reply = m;
                           });

  run_until(io,
            [&] { return sess1_reply.has_value() && sess2_reply.has_value(); });

  REQUIRE(sess1_reply.has_value());
  REQUIRE(sess2_reply.has_value());
  CHECK(sess1_reply->stream == 1);
  CHECK(sess1_reply->function == 2);
  CHECK(sess2_reply->stream == 1);
  CHECK(sess2_reply->function == 2);

  // Both routers fired, each on its own session — no cross-talk.
  CHECK(sess1_messages == 1);
  CHECK(sess2_messages == 1);

  // The replies have different MDLNs proving the per-session
  // dispatch returned distinct payloads.
  const auto sml1 = sess1_reply->sml();
  const auto sml2 = sess2_reply->sml();
  CHECK(sml1.find("EQUIP-SESS-1") != std::string::npos);
  CHECK(sml2.find("EQUIP-SESS-2") != std::string::npos);

  host_conn->separate();
}