#include "gateway_bacnet.hpp"

#include "gateway_bacnet_stack_port.h"

#include "esp_log.h"
#include "freertos/semphr.h"

#include <algorithm>
#include <map>
#include <optional>
#include <set>
#include <string_view>
#include <utility>

namespace gateway {

namespace {

constexpr const char* kTag = "gateway_bacnet";
constexpr TickType_t kPollDelayTicks = pdMS_TO_TICKS(10);
constexpr TickType_t kValueRefreshTicks = pdMS_TO_TICKS(2000);
constexpr uint32_t kReliabilityCommunicationFailure = 12;

class LockGuard {
 public:
  explicit LockGuard(SemaphoreHandle_t lock) : lock_(lock) {
    if (lock_ != nullptr) {
      xSemaphoreTakeRecursive(lock_, portMAX_DELAY);
    }
  }

  ~LockGuard() {
    if (lock_ != nullptr) {
      xSemaphoreGiveRecursive(lock_);
    }
  }

 private:
  SemaphoreHandle_t lock_;
};

constexpr uint32_t kMaxBacnetInstance = 4194303;
GatewayBacnetServer* g_server = nullptr;

gateway_bacnet_object_kind_t ToBacnetKind(BridgeObjectType type) {
  switch (type) {
    case BridgeObjectType::analogInput:
      return GW_BACNET_OBJECT_ANALOG_INPUT;
    case BridgeObjectType::analogValue:
      return GW_BACNET_OBJECT_ANALOG_VALUE;
    case BridgeObjectType::analogOutput:
      return GW_BACNET_OBJECT_ANALOG_OUTPUT;
    case BridgeObjectType::binaryInput:
      return GW_BACNET_OBJECT_BINARY_INPUT;
    case BridgeObjectType::binaryValue:
      return GW_BACNET_OBJECT_BINARY_VALUE;
    case BridgeObjectType::binaryOutput:
      return GW_BACNET_OBJECT_BINARY_OUTPUT;
    case BridgeObjectType::multiStateInput:
      return GW_BACNET_OBJECT_MULTI_STATE_INPUT;
    case BridgeObjectType::multiStateValue:
      return GW_BACNET_OBJECT_MULTI_STATE_VALUE;
    case BridgeObjectType::multiStateOutput:
      return GW_BACNET_OBJECT_MULTI_STATE_OUTPUT;
    case BridgeObjectType::holdingRegister:
      return GW_BACNET_OBJECT_ANALOG_VALUE;
    case BridgeObjectType::inputRegister:
      return GW_BACNET_OBJECT_ANALOG_INPUT;
    case BridgeObjectType::coil:
      return GW_BACNET_OBJECT_BINARY_OUTPUT;
    case BridgeObjectType::discreteInput:
      return GW_BACNET_OBJECT_BINARY_INPUT;
    default:
      return GW_BACNET_OBJECT_UNKNOWN;
  }
}

BridgeObjectType FromBacnetKind(gateway_bacnet_object_kind_t kind) {
  switch (kind) {
    case GW_BACNET_OBJECT_ANALOG_INPUT:
      return BridgeObjectType::analogInput;
    case GW_BACNET_OBJECT_ANALOG_VALUE:
      return BridgeObjectType::analogValue;
    case GW_BACNET_OBJECT_ANALOG_OUTPUT:
      return BridgeObjectType::analogOutput;
    case GW_BACNET_OBJECT_BINARY_INPUT:
      return BridgeObjectType::binaryInput;
    case GW_BACNET_OBJECT_BINARY_VALUE:
      return BridgeObjectType::binaryValue;
    case GW_BACNET_OBJECT_BINARY_OUTPUT:
      return BridgeObjectType::binaryOutput;
    case GW_BACNET_OBJECT_MULTI_STATE_INPUT:
      return BridgeObjectType::multiStateInput;
    case GW_BACNET_OBJECT_MULTI_STATE_VALUE:
      return BridgeObjectType::multiStateValue;
    case GW_BACNET_OBJECT_MULTI_STATE_OUTPUT:
      return BridgeObjectType::multiStateOutput;
    default:
      return BridgeObjectType::unknown;
  }
}

bool IsSupportedObjectType(BridgeObjectType type) {
  return ToBacnetKind(type) != GW_BACNET_OBJECT_UNKNOWN;
}

std::string ObjectName(const GatewayBacnetObjectBinding& binding) {
  if (!binding.name.empty()) {
    return binding.name;
  }
  if (!binding.model_id.empty()) {
    return "DALI " + binding.model_id;
  }
  return "DALI BACnet " + std::to_string(binding.object_instance);
}

DaliValue StackWriteValueToDali(const gateway_bacnet_write_value_t& value) {
  switch (value.kind) {
    case GW_BACNET_WRITE_VALUE_REAL:
      return DaliValue(value.real_value);
    case GW_BACNET_WRITE_VALUE_BOOLEAN:
      return DaliValue(value.boolean_value);
    case GW_BACNET_WRITE_VALUE_UNSIGNED:
      return DaliValue(static_cast<int>(value.unsigned_value));
    default:
      return DaliValue();
  }
}

bool DaliValueToStackPresentValue(BridgeObjectType object_type, const DaliValue& value,
                                  gateway_bacnet_write_value_t* out) {
  if (out == nullptr) {
    return false;
  }
  switch (ToBacnetKind(object_type)) {
    case GW_BACNET_OBJECT_ANALOG_INPUT:
    case GW_BACNET_OBJECT_ANALOG_VALUE:
    case GW_BACNET_OBJECT_ANALOG_OUTPUT: {
      const auto parsed = value.asDouble();
      if (!parsed.has_value()) {
        return false;
      }
      *out = gateway_bacnet_write_value_t{GW_BACNET_WRITE_VALUE_REAL,
                                          parsed.value(),
                                          false,
                                          0};
      return true;
    }
    case GW_BACNET_OBJECT_BINARY_INPUT:
    case GW_BACNET_OBJECT_BINARY_VALUE:
    case GW_BACNET_OBJECT_BINARY_OUTPUT: {
      const auto parsed = value.asBool();
      if (!parsed.has_value()) {
        return false;
      }
      *out = gateway_bacnet_write_value_t{GW_BACNET_WRITE_VALUE_BOOLEAN,
                                          0.0,
                                          parsed.value(),
                                          0};
      return true;
    }
    case GW_BACNET_OBJECT_MULTI_STATE_INPUT:
    case GW_BACNET_OBJECT_MULTI_STATE_VALUE:
    case GW_BACNET_OBJECT_MULTI_STATE_OUTPUT: {
      const auto parsed = value.asInt();
      if (!parsed.has_value()) {
        return false;
      }
      const uint32_t unsigned_value = parsed.value() <= 0
                                          ? 1
                                          : static_cast<uint32_t>(parsed.value());
      *out = gateway_bacnet_write_value_t{GW_BACNET_WRITE_VALUE_UNSIGNED,
                                          0.0,
                                          false,
                                          unsigned_value};
      return true;
    }
    default:
      return false;
  }
}

void HandleStackWrite(gateway_bacnet_object_kind_t object_kind, uint32_t object_instance,
                      const gateway_bacnet_write_value_t* value, void*) {
  if (g_server == nullptr || value == nullptr) {
    return;
  }
  g_server->handleWrite(FromBacnetKind(object_kind), object_instance, StackWriteValueToDali(*value));
}

}  // namespace

struct GatewayBacnetServer::ChannelRegistration {
  uint8_t gateway_id{0};
  GatewayBacnetServerConfig config;
  std::vector<GatewayBacnetObjectBinding> bindings;
  GatewayBacnetWriteCallback write_callback;
  GatewayBacnetReadCallback read_callback;
};

struct GatewayBacnetServer::RuntimeBinding {
  uint8_t gateway_id{0};
  BridgeObjectType object_type{BridgeObjectType::unknown};
  uint32_t object_instance{0};
  std::string model_id;
  std::string property{"presentValue"};
  bool out_of_service{false};
  uint32_t reliability{0};
  bool readable{false};
  GatewayBacnetWriteCallback write_callback;
  GatewayBacnetReadCallback read_callback;
};

GatewayBacnetServer& GatewayBacnetServer::instance() {
  static GatewayBacnetServer server;
  return server;
}

GatewayBacnetServer::GatewayBacnetServer() : lock_(xSemaphoreCreateRecursiveMutex()) {
  g_server = this;
}

GatewayBacnetServer::~GatewayBacnetServer() {
  if (lock_ != nullptr) {
    vSemaphoreDelete(lock_);
    lock_ = nullptr;
  }
}

bool GatewayBacnetServer::configCompatible(const GatewayBacnetServerConfig& config) const {
  LockGuard guard(lock_);
  return !started_ || (active_config_.udp_port == config.udp_port &&
                       active_config_.device_instance == config.device_instance);
}

GatewayBacnetServerStatus GatewayBacnetServer::status() const {
  LockGuard guard(lock_);
  return GatewayBacnetServerStatus{started_,
                                   active_config_.device_instance,
                                   active_config_.udp_port,
                                   channels_.size(),
                                   runtime_bindings_.size()};
}

esp_err_t GatewayBacnetServer::registerChannel(
    uint8_t gateway_id, const GatewayBacnetServerConfig& config,
    std::vector<GatewayBacnetObjectBinding> bindings,
  GatewayBacnetWriteCallback write_callback,
  GatewayBacnetReadCallback read_callback) {
  if (write_callback == nullptr) {
    return ESP_ERR_INVALID_ARG;
  }

  bindings.erase(std::remove_if(bindings.begin(), bindings.end(), [](const auto& binding) {
                   return !IsSupportedObjectType(binding.object_type) ||
                          binding.object_instance > kMaxBacnetInstance;
                 }),
                 bindings.end());

  LockGuard guard(lock_);
  if (started_ && !configCompatible(config)) {
    return ESP_ERR_INVALID_STATE;
  }

  auto channel = std::find_if(channels_.begin(), channels_.end(), [gateway_id](const auto& item) {
    return item.gateway_id == gateway_id;
  });
  if (bindings.empty() && !started_ && channel == channels_.end()) {
    return ESP_ERR_NOT_FOUND;
  }
  ChannelRegistration registration{gateway_id, config, std::move(bindings),
                                   std::move(write_callback), std::move(read_callback)};
  if (channel == channels_.end()) {
    channels_.push_back(std::move(registration));
  } else {
    *channel = std::move(registration);
  }

  esp_err_t err = startStackLocked(config);
  if (err != ESP_OK) {
    return err;
  }
  return rebuildObjectsLocked();
}

esp_err_t GatewayBacnetServer::startStackLocked(const GatewayBacnetServerConfig& config) {
  if (started_) {
    return ESP_OK;
  }

  active_config_ = config;
  if (active_config_.device_name.empty()) {
    active_config_.device_name = "DALI Gateway";
  }
  if (active_config_.udp_port == 0) {
    active_config_.udp_port = 47808;
  }
  if (active_config_.task_stack_size < 6144) {
    active_config_.task_stack_size = 6144;
  }

  if (!gateway_bacnet_stack_start(active_config_.device_instance, active_config_.device_name.c_str(),
                                  active_config_.udp_port, HandleStackWrite, this)) {
    ESP_LOGE(kTag, "failed to initialize BACnet/IP port %u", active_config_.udp_port);
    return ESP_FAIL;
  }

  const BaseType_t created = xTaskCreate(&GatewayBacnetServer::TaskEntry, "gw_bacnet_ip",
                                         active_config_.task_stack_size, this,
                                         active_config_.task_priority, &task_handle_);
  if (created != pdPASS) {
    task_handle_ = nullptr;
    gateway_bacnet_stack_cleanup();
    return ESP_ERR_NO_MEM;
  }

  started_ = true;
  gateway_bacnet_stack_send_i_am();
  ESP_LOGI(kTag, "BACnet/IP server started device=%lu port=%u",
           static_cast<unsigned long>(active_config_.device_instance), active_config_.udp_port);
  return ESP_OK;
}

esp_err_t GatewayBacnetServer::rebuildObjectsLocked() {
  runtime_bindings_.clear();
  std::set<std::pair<BridgeObjectType, uint32_t>> used_objects;

  if (!gateway_bacnet_stack_clear_objects()) {
    return ESP_FAIL;
  }

  for (const auto& channel : channels_) {
    for (const auto& binding : channel.bindings) {
      const auto key = std::make_pair(binding.object_type, binding.object_instance);
      if (used_objects.find(key) != used_objects.end()) {
        ESP_LOGE(kTag, "duplicate BACnet object type=%d instance=%lu",
                 static_cast<int>(binding.object_type),
                 static_cast<unsigned long>(binding.object_instance));
        return ESP_ERR_INVALID_STATE;
      }
      used_objects.insert(key);

      const std::string name = ObjectName(binding);
      if (!gateway_bacnet_stack_upsert_object(ToBacnetKind(binding.object_type),
                                              binding.object_instance, name.c_str(),
                                              binding.model_id.c_str(),
                                              binding.out_of_service,
                                              binding.reliability)) {
        return ESP_FAIL;
      }
      runtime_bindings_.push_back(RuntimeBinding{channel.gateway_id,
                                                 binding.object_type,
                                                 binding.object_instance,
                                                 binding.model_id,
                                                 binding.property.empty() ? "presentValue"
                                                                          : binding.property,
                                                 binding.out_of_service,
                                                 binding.reliability,
                                                 binding.readable,
                                                 channel.write_callback,
                                                 channel.read_callback});
    }
  }

  ESP_LOGI(kTag, "BACnet/IP object table updated objects=%u",
           static_cast<unsigned>(runtime_bindings_.size()));
  return ESP_OK;
}

bool GatewayBacnetServer::handleWrite(BridgeObjectType object_type, uint32_t object_instance,
                                      const DaliValue& value) {
  GatewayBacnetWriteCallback callback;
  std::string property;
  std::string model_id;
  uint8_t gateway_id = 0;
  {
    LockGuard guard(lock_);
    const auto binding = std::find_if(runtime_bindings_.begin(), runtime_bindings_.end(),
                                      [object_type, object_instance](const auto& item) {
                                        return item.object_type == object_type &&
                                               item.object_instance == object_instance;
                                      });
    if (binding == runtime_bindings_.end()) {
      ESP_LOGW(kTag, "write for unmapped BACnet object type=%d instance=%lu",
               static_cast<int>(object_type), static_cast<unsigned long>(object_instance));
      return false;
    }
    callback = binding->write_callback;
    property = binding->property;
    model_id = binding->model_id;
    gateway_id = binding->gateway_id;
  }

  const bool ok = callback != nullptr && callback(object_type, object_instance, property, value);
  if (!ok) {
    ESP_LOGW(kTag, "gateway=%u BACnet write failed model=%s object=%lu",
             gateway_id, model_id.c_str(), static_cast<unsigned long>(object_instance));
  }
  return ok;
}

void GatewayBacnetServer::refreshPresentValues() {
  std::vector<RuntimeBinding> bindings;
  {
    LockGuard guard(lock_);
    bindings = runtime_bindings_;
  }

  for (const auto& binding : bindings) {
    const auto object_kind = ToBacnetKind(binding.object_type);
    if (object_kind == GW_BACNET_OBJECT_UNKNOWN) {
      continue;
    }
    if (!binding.readable || binding.read_callback == nullptr) {
      LockGuard guard(lock_);
      gateway_bacnet_stack_set_object_state(object_kind, binding.object_instance,
                                            binding.out_of_service, binding.reliability);
      continue;
    }

    gateway_bacnet_write_value_t stack_value = {};
    const auto value = binding.read_callback(binding.object_type, binding.object_instance,
                                             binding.property);
    const bool converted = value.has_value() &&
                           DaliValueToStackPresentValue(binding.object_type, value.value(),
                                                        &stack_value);
    LockGuard guard(lock_);
    const bool ok = converted && gateway_bacnet_stack_set_present_value(
                                     object_kind, binding.object_instance, &stack_value);
    gateway_bacnet_stack_set_object_state(
        object_kind, binding.object_instance, binding.out_of_service || !ok,
        ok ? binding.reliability : kReliabilityCommunicationFailure);
  }
}

void GatewayBacnetServer::TaskEntry(void* arg) {
  static_cast<GatewayBacnetServer*>(arg)->taskLoop();
}

void GatewayBacnetServer::taskLoop() {
  TickType_t last_timer = xTaskGetTickCount();
  TickType_t last_refresh = last_timer;

  while (true) {
    const TickType_t now = xTaskGetTickCount();
    const TickType_t elapsed = now - last_timer;
    uint16_t elapsed_ms = 0;
    if (elapsed >= pdMS_TO_TICKS(1000)) {
      elapsed_ms = static_cast<uint16_t>(elapsed * portTICK_PERIOD_MS);
      last_timer = now;
    }
    bool refresh_due = false;
    {
      LockGuard guard(lock_);
      gateway_bacnet_stack_poll(elapsed_ms);
      if ((now - last_refresh) >= kValueRefreshTicks) {
        refresh_due = true;
      }
    }
    if (refresh_due) {
      refreshPresentValues();
      last_refresh = now;
    }
    vTaskDelay(kPollDelayTicks);
  }
}

}  // namespace gateway