// Passive SECS/GEM equipment: a small simulated tool. Drives the E30 control
// state machine, owns an in-memory data dictionary (SVIDs, DVIDs, ECIDs,
// CEIDs, alarms, recipes), answers the GEM SxFy core, and emits S6F11 +
// S5F1 primaries when host-subscribed events fire.

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

#include "secsgem/endpoint.hpp"
#include "secsgem/gem/control_state.hpp"
#include "secsgem/gem/data_model.hpp"
#include "secsgem/gem/messages.hpp"
#include "secsgem/secs2/item.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;
}

constexpr const char* kModelName = "SECSGEM-SIM";
constexpr const char* kSoftRev = "0.1.0";

// SVIDs
constexpr uint32_t kSvidControlState  = 1;
constexpr uint32_t kSvidClock         = 2;
constexpr uint32_t kSvidEventsEnabled = 3;

// ECIDs
constexpr uint32_t kEcidTimeFormat       = 10;
constexpr uint32_t kEcidEstablishTimeout = 11;

// CEIDs
constexpr uint32_t kCeidControlStateChanged = 100;
constexpr uint32_t kCeidAlarmSetEvent       = 200;
constexpr uint32_t kCeidProcessStarted      = 300;

// ALIDs
constexpr uint32_t kAlarmChillerTempHigh = 1;
constexpr uint32_t kAlarmDoorOpen        = 2;

void populate(gem::EquipmentDataModel& m, const gem::ControlStateMachine& sm) {
  m.add_status_variable(
      {kSvidControlState, "ControlState", "", s2::Item::ascii(gem::control_state_name(sm.state()))});
  m.add_status_variable({kSvidClock, "Clock", "", s2::Item::ascii(m.current_time_string())});
  m.add_status_variable({kSvidEventsEnabled, "EventsEnabled", "", s2::Item::boolean(true)});

  m.add_equipment_constant({kEcidTimeFormat, "TimeFormat", "code",
                            s2::Item::u4(uint32_t{1}), s2::Item::u4(uint32_t{1}), "0", "1"});
  m.add_equipment_constant({kEcidEstablishTimeout, "EstablishCommTimeout", "sec",
                            s2::Item::u4(uint32_t{10}), s2::Item::u4(uint32_t{10}), "1", "60"});

  m.register_event({kCeidControlStateChanged, "ControlStateChanged"});
  m.register_event({kCeidAlarmSetEvent, "AlarmSetEvent"});
  m.register_event({kCeidProcessStarted, "ProcessStarted"});

  m.add_alarm({kAlarmChillerTempHigh, "Chiller Temp High", 4});
  m.add_alarm({kAlarmDoorOpen, "Door Open", 1});

  m.add_process_program("RECIPE-A", "STEP CHAMBER ARGON 30s\nSTEP CHAMBER NITROGEN 60s\nEND");
  m.add_process_program("RECIPE-B", "STEP HEATER 800C 120s\nEND");
}

void refresh_dynamic_svids(gem::EquipmentDataModel& m, const gem::ControlStateMachine& sm) {
  m.set_status_value(kSvidControlState, s2::Item::ascii(gem::control_state_name(sm.state())));
  m.set_status_value(kSvidClock, s2::Item::ascii(m.current_time_string()));
}

}  // namespace

int main(int argc, char** argv) {
  Server::Config cfg;
  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")));

  asio::io_context io;
  Server server(io, cfg);

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

  auto sm = std::make_shared<gem::ControlStateMachine>();
  auto model = std::make_shared<gem::EquipmentDataModel>();
  populate(*model, *sm);

  auto active_conn = std::make_shared<std::weak_ptr<Connection>>();

  // Emit a CEID via S6F11 to the currently-active host connection, if any
  // and if the host has subscribed to that CEID via S2F37.
  auto emit_event = [&io, active_conn, model, logfn](uint32_t ceid) {
    asio::post(io, [active_conn, model, logfn, ceid]() {
      auto conn = active_conn->lock();
      if (!conn) return;
      if (!model->is_event_enabled(ceid)) {
        logfn("CEID " + std::to_string(ceid) + " not enabled; suppressed");
        return;
      }
      auto reports = model->compose_reports_for(ceid);
      logfn("emit S6F11 CEID=" + std::to_string(ceid) + " (" +
            std::to_string(reports.size()) + " reports)");
      conn->send_request(gem::s6f11_event_report(0, ceid, reports),
                         [logfn, ceid](std::error_code ec, const s2::Message&) {
                           if (ec)
                             logfn("CEID " + std::to_string(ceid) + " emit failed: " + ec.message());
                         });
    });
  };

  // Equipment-initiated alarm set: emits S5F1 (if alarm enabled) and the
  // AlarmSetEvent CEID (if event enabled).
  auto emit_alarm_set = [&io, active_conn, model, logfn, emit_event](uint32_t alid) {
    asio::post(io, [active_conn, model, logfn, emit_event, alid]() {
      auto conn = active_conn->lock();
      if (!conn) return;
      auto alarm = model->alarm(alid);
      if (!alarm) return;
      auto alcd = model->alarm_set(alid);
      if (!alcd) return;
      if (!model->alarm_enabled(alid)) {
        logfn("alarm " + std::to_string(alid) + " not enabled; suppressed");
      } else {
        logfn("emit S5F1 alarm set ALID=" + std::to_string(alid));
        conn->send_request(gem::s5f1_alarm_report(*alcd, alid, alarm->text),
                           [](std::error_code, const s2::Message&) {});
      }
      emit_event(kCeidAlarmSetEvent);
    });
  };

  sm->set_state_change_handler(
      [logfn, emit_event](gem::ControlState from, gem::ControlState to, gem::ControlEvent ev) {
        logfn(std::string("control: ") + gem::control_state_name(from) + " -> " +
              gem::control_state_name(to) + "  (" + gem::control_event_name(ev) + ")");
        emit_event(kCeidControlStateChanged);
      });

  server.on_connection([sm, model, logfn, active_conn, emit_event,
                        emit_alarm_set](std::shared_ptr<Connection> conn) {
    *active_conn = conn;

    conn->set_closed_handler([active_conn, logfn](const std::string&) {
      active_conn->reset();
    });

    conn->set_selected_handler([logfn, sm]() {
      logfn(std::string("host is online; control=") + gem::control_state_name(sm->state()));
    });

    // Host commands are registered here so they can capture emit_event /
    // emit_alarm_set without static globals.
    model->register_command("START", [logfn, emit_event](const auto& params) {
      logfn("RCMD START (" + std::to_string(params.size()) + " params)");
      emit_event(kCeidProcessStarted);
      return gem::HostCmdAck::Accept;
    });
    model->register_command("STOP",
                            [](const auto&) { return gem::HostCmdAck::Accept; });
    model->register_command("PAUSE",
                            [](const auto&) { return gem::HostCmdAck::CannotDoNow; });
    model->register_command("FAULT", [logfn, emit_alarm_set](const auto&) {
      logfn("RCMD FAULT triggers alarm 1");
      emit_alarm_set(kAlarmChillerTempHigh);
      return gem::HostCmdAck::Accept;
    });

    conn->set_message_handler([sm, model, logfn](const s2::Message& msg)
                                  -> std::optional<s2::Message> {
      const uint8_t s = msg.stream, f = msg.function;

      // ---- S1: equipment status ----------------------------------------
      if (s == 1 && f == 1) {
        logfn("S1F1; replying S1F2");
        return gem::s1f2_on_line_data(kModelName, kSoftRev);
      }
      if (s == 1 && f == 3) {
        refresh_dynamic_svids(*model, *sm);
        auto svids = gem::parse_s1f3(msg);
        if (!svids) return s2::Message(1, 0, false);
        std::vector<std::optional<s2::Item>> values;
        if (svids->empty()) {
          for (const auto& sv : model->all_status_variables()) values.push_back(sv.value);
        } else {
          for (auto id : *svids) {
            auto sv = model->status_variable(id);
            values.push_back(sv ? std::optional<s2::Item>(sv->value) : std::nullopt);
          }
        }
        logfn("S1F3; replying S1F4 (" + std::to_string(values.size()) + " values)");
        return gem::s1f4_selected_status_data(values);
      }
      if (s == 1 && f == 11) {
        logfn("S1F11; replying S1F12 (status namelist)");
        return gem::s1f12_status_namelist_data(model->all_status_variables());
      }
      if (s == 1 && f == 13) {
        logfn("S1F13; replying S1F14 (COMMACK=0)");
        return gem::s1f14_establish_comms_ack(gem::CommAck::Accept, kModelName, kSoftRev);
      }
      if (s == 1 && f == 15) {
        auto ack = sm->on_host_request_offline();
        logfn(std::string("S1F15; replying S1F16 (OFLACK=") +
              std::to_string(static_cast<int>(ack)) + ")");
        return gem::s1f16_offline_ack(ack);
      }
      if (s == 1 && f == 17) {
        auto ack = sm->on_host_request_online();
        logfn(std::string("S1F17; replying S1F18 (ONLACK=") +
              std::to_string(static_cast<int>(ack)) + ")");
        return gem::s1f18_online_ack(ack);
      }

      // ---- S2: equipment control + reports -----------------------------
      if (s == 2 && f == 13) {
        auto ids = gem::parse_u4_list_body(msg);
        if (!ids) return s2::Message(2, 0, false);
        std::vector<s2::Item> values;
        for (auto id : *ids) {
          auto ec = model->equipment_constant(id);
          values.push_back(ec ? ec->value : s2::Item::list({}));
        }
        logfn("S2F13; replying S2F14 (" + std::to_string(values.size()) + " values)");
        return gem::s2f14_ec_data(values);
      }
      if (s == 2 && f == 15) {
        auto sets = gem::parse_s2f15(msg);
        if (!sets) return gem::s2f16_ec_ack(gem::EquipmentAck::Denied_OutOfRange);
        auto eac = gem::EquipmentAck::Accept;
        for (const auto& [id, val] : *sets) {
          auto r = model->set_equipment_constant_value(id, val);
          if (r != gem::EquipmentAck::Accept) eac = r;
        }
        logfn(std::string("S2F15; replying S2F16 (EAC=") +
              std::to_string(static_cast<int>(eac)) + ")");
        return gem::s2f16_ec_ack(eac);
      }
      if (s == 2 && f == 17) {
        logfn("S2F17; replying S2F18 (clock)");
        return gem::s2f18_date_time_data(model->current_time_string());
      }
      if (s == 2 && f == 29) {
        auto ids = gem::parse_u4_list_body(msg);
        std::vector<gem::EquipmentConstant> ecs;
        if (ids && ids->empty()) {
          ecs = model->all_equipment_constants();
        } else if (ids) {
          for (auto id : *ids) {
            auto ec = model->equipment_constant(id);
            if (ec) ecs.push_back(*ec);
          }
        }
        logfn("S2F29; replying S2F30 (" + std::to_string(ecs.size()) + " EC entries)");
        return gem::s2f30_ec_namelist_data(ecs);
      }
      if (s == 2 && f == 31) {
        auto t = gem::parse_s2f31(msg);
        auto ack = t ? model->set_time_string(*t) : gem::TimeAck::Error;
        logfn(std::string("S2F31; replying S2F32 (TIACK=") +
              std::to_string(static_cast<int>(ack)) + ")");
        return gem::s2f32_date_time_ack(ack);
      }
      if (s == 2 && f == 33) {
        auto req = gem::parse_s2f33(msg);
        auto ack = req ? model->define_reports(req->reports)
                       : gem::DefineReportAck::InvalidFormat;
        logfn(std::string("S2F33; replying S2F34 (DRACK=") +
              std::to_string(static_cast<int>(ack)) + ")");
        return gem::s2f34_define_report_ack(ack);
      }
      if (s == 2 && f == 35) {
        auto req = gem::parse_s2f35(msg);
        auto ack = req ? model->link_event_reports(req->links) : gem::LinkEventAck::InvalidFormat;
        logfn(std::string("S2F35; replying S2F36 (LRACK=") +
              std::to_string(static_cast<int>(ack)) + ")");
        return gem::s2f36_link_event_report_ack(ack);
      }
      if (s == 2 && f == 37) {
        auto req = gem::parse_s2f37(msg);
        auto ack = req ? model->enable_events(req->enable, req->ceids)
                       : gem::EnableEventAck::UnknownCeid;
        logfn(std::string("S2F37 ") + (req && req->enable ? "enable" : "disable") +
              "; replying S2F38 (ERACK=" + std::to_string(static_cast<int>(ack)) + ")");
        return gem::s2f38_enable_event_ack(ack);
      }
      if (s == 2 && f == 41) {
        auto cmd = gem::parse_s2f41(msg);
        if (!cmd) return gem::s2f42_host_command_ack(gem::HostCmdAck::ParameterInvalid);
        auto ack = model->dispatch_command(cmd->rcmd, cmd->params);
        logfn("S2F41 RCMD=" + cmd->rcmd + "; replying S2F42 (HCACK=" +
              std::to_string(static_cast<int>(ack)) + ")");
        return gem::s2f42_host_command_ack(ack);
      }

      // ---- S5: alarms --------------------------------------------------
      if (s == 5 && f == 3) {
        auto req = gem::parse_s5f3(msg);
        auto ack = req ? model->set_alarm_enabled(req->alid, req->enable)
                       : gem::AlarmAck::Error;
        logfn(std::string("S5F3 ALID=") + (req ? std::to_string(req->alid) : "?") +
              (req && req->enable ? " enable" : " disable") +
              "; replying S5F4 (ACKC5=" + std::to_string(static_cast<int>(ack)) + ")");
        return gem::s5f4_enable_alarm_ack(ack);
      }
      if (s == 5 && f == 5) {
        auto ids = gem::parse_u4_list_body(msg);
        std::vector<gem::Alarm> alarms;
        if (ids && ids->empty()) {
          alarms = model->all_alarms();
        } else if (ids) {
          for (auto id : *ids) {
            auto a = model->alarm(id);
            if (a) alarms.push_back(*a);
          }
        }
        logfn("S5F5; replying S5F6 (" + std::to_string(alarms.size()) + " alarms)");
        return gem::s5f6_list_alarms_data(alarms, [model](uint32_t id) {
          return model->alarm_active(id);
        });
      }

      // ---- S7: process programs ----------------------------------------
      if (s == 7 && f == 3) {
        auto pp = gem::parse_s7f3(msg);
        if (!pp) return gem::s7f4_process_program_ack(gem::ProcessProgramAck::LengthError);
        model->add_process_program(pp->ppid, pp->ppbody);
        logfn("S7F3 PPID=" + pp->ppid + " (" + std::to_string(pp->ppbody.size()) +
              " bytes); replying S7F4 (ACKC7=0)");
        return gem::s7f4_process_program_ack(gem::ProcessProgramAck::Accept);
      }
      if (s == 7 && f == 5) {
        auto ppid = gem::parse_s7f5(msg);
        if (!ppid) return gem::s7f6_process_program_data("", "");
        auto body = model->process_program(*ppid);
        logfn("S7F5 PPID=" + *ppid + (body ? "; replying S7F6" : "; PPID not found"));
        return gem::s7f6_process_program_data(*ppid, body ? *body : "");
      }
      if (s == 7 && f == 19) {
        auto list = model->process_program_list();
        logfn("S7F19; replying S7F20 (" + std::to_string(list.size()) + " PPIDs)");
        return gem::s7f20_current_eppd_data(list);
      }

      // ---- S10: terminal services --------------------------------------
      if (s == 10 && f == 1) {
        auto td = gem::parse_terminal_display(msg);
        if (td) logfn("TERMINAL[" + std::to_string(td->tid) + "] " + td->text);
        return gem::s10f2_terminal_display_ack(gem::TerminalAck::Accepted);
      }

      // Unhandled primaries expecting a reply get SxF0 (abort).
      if (msg.reply_expected) {
        logfn("unhandled " + msg.sml() + "; replying S" + std::to_string(s) + "F0");
        return s2::Message(s, 0, false);
      }
      return std::nullopt;
    });
  });

  server.start();
  io.run();
  return 0;
}