// Minimal interop driver: connect, HSMS-select, S1F13, S1F1, S1F3,
// separate.  Exits 0 if every step succeeds, non-zero on the first
// failure.  Used by the interop harness to validate that our active
// (host) HSMS implementation talks to a third-party passive equipment
// — in particular, secsgem-py running as GemEquipmentHandler.

#include <asio.hpp>
#include <chrono>
#include <cstdint>
#include <iostream>
#include <memory>
#include <string>
#include <system_error>

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

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

namespace {

std::string arg(int argc, char** argv, const std::string& key, const std::string& def) {
  for (int i = 1; i + 1 < argc; ++i)
    if (key == argv[i]) return argv[i + 1];
  return def;
}

int exit_code = 1;

}  // namespace

int main(int argc, char** argv) {
  Client::Config cfg;
  cfg.host = arg(argc, argv, "--host", "127.0.0.1");
  cfg.port = static_cast<uint16_t>(std::stoi(arg(argc, argv, "--port", "5000")));
  cfg.device_id = static_cast<uint16_t>(std::stoi(arg(argc, argv, "--device", "0")));
  cfg.timers.linktest = std::chrono::milliseconds(0);

  asio::io_context io;
  Client client(io, cfg);

  auto logfn = [](const std::string& m) { std::cout << "[probe] " << m << std::endl; };
  client.on_log(logfn);

  // Bail out after 15s so a stuck handshake doesn't hang the test.
  asio::steady_timer deadline(io);
  deadline.expires_after(std::chrono::seconds(15));
  deadline.async_wait([&](std::error_code ec) {
    if (!ec) { logfn("DEADLINE reached, aborting"); io.stop(); }
  });

  client.on_connection([&](std::shared_ptr<Connection> conn) {
    auto fail = [&io, logfn, conn](const char* where, std::error_code ec) {
      logfn(std::string("FAIL ") + where + ": " + ec.message());
      conn->close(where);
      io.stop();
    };

    // The equipment will also send us its own S1F13 once SELECTED — we
    // need to reply with S1F14, otherwise the equipment's transaction
    // times out.  Same for any unsolicited primary we don't care about.
    conn->set_message_handler(
        [logfn](const s2::Message& msg) -> std::optional<s2::Message> {
          if (msg.stream == 1 && msg.function == 13) {
            logfn("<- equipment S1F13, replying S1F14");
            return gem::s1f14_establish_comms_ack(
                gem::CommAck::Accept, {"INTEROP-PROBE", "0.0.1"});
          }
          if (msg.reply_expected) return s2::Message(msg.stream, 0, false);
          return std::nullopt;
        });

    // Drive the probe sequence only after SELECT completes, otherwise
    // our outbound S1F13 races the HSMS Select.req and the equipment
    // rejects it.
    conn->set_selected_handler([&, conn, logfn, fail]() {
    // Step 1: S1F13 establish communications.
    conn->send_request(
        gem::s1f13_establish_comms("INTEROP-PROBE", "0.0.1"),
        [&, conn, logfn, fail](std::error_code ec, const s2::Message& reply) {
          if (ec) { fail("S1F13", ec); return; }
          logfn("OK S1F13->S1F14");

          // Step 2: S1F1 Are You There.
          conn->send_request(
              gem::s1f1_are_you_there(),
              [&, conn, logfn, fail](std::error_code ec2, const s2::Message& reply2) {
                if (ec2) { fail("S1F1", ec2); return; }
                logfn("OK S1F1->S1F2");

                // Step 3: S1F3 with empty SVID list (= "all").
                conn->send_request(
                    gem::s1f3_selected_status_request({}),
                    [&, conn, logfn, fail](std::error_code ec3,
                                            const s2::Message& reply3) {
                      if (ec3) { fail("S1F3", ec3); return; }
                      logfn(std::string("OK S1F3->S1F4 body=") + reply3.sml());

                      exit_code = 0;
                      logfn("ALL PROBES PASSED");
                      conn->separate();
                      // Give separate a beat to flush.
                      auto t = std::make_shared<asio::steady_timer>(io);
                      t->expires_after(std::chrono::milliseconds(200));
                      t->async_wait([t, &io](std::error_code) { io.stop(); });
                    });
              });
        });
    });  // set_selected_handler
  });

  client.start();
  io.run();
  return exit_code;
}