#include "bluetooth_proxy.h"

#include "esphome/core/log.h"
#include "esphome/core/macros.h"
#include "esphome/core/application.h"
#include <cstring>

#ifdef USE_ESP32

namespace esphome::bluetooth_proxy {

static const char *const TAG = "bluetooth_proxy";

// Batch size for BLE advertisements to maximize WiFi efficiency
// Each advertisement is up to 80 bytes when packaged (including protocol overhead)
// Most advertisements are 20-30 bytes, allowing even more to fit per packet
// 16 advertisements × 80 bytes (worst case) = 1280 bytes out of ~1320 bytes usable payload
// This achieves ~97% WiFi MTU utilization while staying under the limit
static constexpr size_t FLUSH_BATCH_SIZE = 16;

// Verify BLE advertisement data array size matches the BLE specification (31 bytes adv + 31 bytes scan response)
static_assert(sizeof(((api::BluetoothLERawAdvertisement *) nullptr)->data) == 62,
              "BLE advertisement data array size mismatch");

BluetoothProxy::BluetoothProxy() { global_bluetooth_proxy = this; }

void BluetoothProxy::setup() {
  // Pre-allocate response object
  this->response_ = std::make_unique<api::BluetoothLERawAdvertisementsResponse>();

  // Reserve capacity but start with size 0
  // Reserve 50% since we'll grow naturally and flush at FLUSH_BATCH_SIZE
  this->response_->advertisements.reserve(FLUSH_BATCH_SIZE / 2);

  // Don't pre-allocate pool - let it grow only if needed in busy environments
  // Many devices in quiet areas will never need the overflow pool

  this->connections_free_response_.limit = this->connections_.size();
  this->connections_free_response_.free = this->connections_.size();

  this->parent_->add_scanner_state_callback([this](esp32_ble_tracker::ScannerState state) {
    if (this->api_connection_ != nullptr) {
      this->send_bluetooth_scanner_state_(state);
    }
  });
}

void BluetoothProxy::send_bluetooth_scanner_state_(esp32_ble_tracker::ScannerState state) {
  api::BluetoothScannerStateResponse resp;
  resp.state = static_cast<api::enums::BluetoothScannerState>(state);
  resp.mode = this->parent_->get_scan_active() ? api::enums::BluetoothScannerMode::BLUETOOTH_SCANNER_MODE_ACTIVE
                                               : api::enums::BluetoothScannerMode::BLUETOOTH_SCANNER_MODE_PASSIVE;
  this->api_connection_->send_message(resp, api::BluetoothScannerStateResponse::MESSAGE_TYPE);
}

#ifdef USE_ESP32_BLE_DEVICE
bool BluetoothProxy::parse_device(const esp32_ble_tracker::ESPBTDevice &device) {
  // This method should never be called since bluetooth_proxy always uses raw advertisements
  // but we need to provide an implementation to satisfy the virtual method requirement
  return false;
}
#endif

bool BluetoothProxy::parse_devices(const esp32_ble::BLEScanResult *scan_results, size_t count) {
  if (!api::global_api_server->is_connected() || this->api_connection_ == nullptr)
    return false;

  auto &advertisements = this->response_->advertisements;

  for (size_t i = 0; i < count; i++) {
    auto &result = scan_results[i];
    uint8_t length = result.adv_data_len + result.scan_rsp_len;

    // Check if we need to expand the vector
    if (this->advertisement_count_ >= advertisements.size()) {
      if (this->advertisement_pool_.empty()) {
        // No room in pool, need to allocate
        advertisements.emplace_back();
      } else {
        // Pull from pool
        advertisements.push_back(std::move(this->advertisement_pool_.back()));
        this->advertisement_pool_.pop_back();
      }
    }

    // Fill in the data directly at current position
    auto &adv = advertisements[this->advertisement_count_];
    adv.address = esp32_ble::ble_addr_to_uint64(result.bda);
    adv.rssi = result.rssi;
    adv.address_type = result.ble_addr_type;
    adv.data_len = length;
    std::memcpy(adv.data, result.ble_adv, length);

    this->advertisement_count_++;

    ESP_LOGV(TAG, "Queuing raw packet from %02X:%02X:%02X:%02X:%02X:%02X, length %d. RSSI: %d dB", result.bda[0],
             result.bda[1], result.bda[2], result.bda[3], result.bda[4], result.bda[5], length, result.rssi);

    // Flush if we have reached FLUSH_BATCH_SIZE
    if (this->advertisement_count_ >= FLUSH_BATCH_SIZE) {
      this->flush_pending_advertisements();
    }
  }

  return true;
}

void BluetoothProxy::flush_pending_advertisements() {
  if (this->advertisement_count_ == 0 || !api::global_api_server->is_connected() || this->api_connection_ == nullptr)
    return;

  auto &advertisements = this->response_->advertisements;

  // Return any items beyond advertisement_count_ to the pool
  if (advertisements.size() > this->advertisement_count_) {
    // Move unused items back to pool
    this->advertisement_pool_.insert(this->advertisement_pool_.end(),
                                     std::make_move_iterator(advertisements.begin() + this->advertisement_count_),
                                     std::make_move_iterator(advertisements.end()));

    // Resize to actual count
    advertisements.resize(this->advertisement_count_);
  }

  // Send the message
  this->api_connection_->send_message(*this->response_, api::BluetoothLERawAdvertisementsResponse::MESSAGE_TYPE);

  // Reset count - existing items will be overwritten in next batch
  this->advertisement_count_ = 0;
}

void BluetoothProxy::dump_config() {
  ESP_LOGCONFIG(TAG, "Bluetooth Proxy:");
  ESP_LOGCONFIG(TAG,
                "  Active: %s\n"
                "  Connections: %d",
                YESNO(this->active_), this->connections_.size());
}

void BluetoothProxy::loop() {
  if (!api::global_api_server->is_connected() || this->api_connection_ == nullptr) {
    for (auto *connection : this->connections_) {
      if (connection->get_address() != 0 && !connection->disconnect_pending()) {
        connection->disconnect();
      }
    }
    return;
  }

  // Flush any pending BLE advertisements that have been accumulated but not yet sent
  uint32_t now = App.get_loop_component_start_time();

  // Flush accumulated advertisements every 100ms
  if (now - this->last_advertisement_flush_time_ >= 100) {
    this->flush_pending_advertisements();
    this->last_advertisement_flush_time_ = now;
  }
}

esp32_ble_tracker::AdvertisementParserType BluetoothProxy::get_advertisement_parser_type() {
  return esp32_ble_tracker::AdvertisementParserType::RAW_ADVERTISEMENTS;
}

BluetoothConnection *BluetoothProxy::get_connection_(uint64_t address, bool reserve) {
  for (auto *connection : this->connections_) {
    if (connection->get_address() == address)
      return connection;
  }

  if (!reserve)
    return nullptr;

  for (auto *connection : this->connections_) {
    if (connection->get_address() == 0) {
      connection->send_service_ = DONE_SENDING_SERVICES;
      connection->set_address(address);
      // All connections must start at INIT
      // We only set the state if we allocate the connection
      // to avoid a race where multiple connection attempts
      // are made.
      connection->set_state(espbt::ClientState::INIT);
      return connection;
    }
  }

  return nullptr;
}

void BluetoothProxy::bluetooth_device_request(const api::BluetoothDeviceRequest &msg) {
  switch (msg.request_type) {
    case api::enums::BLUETOOTH_DEVICE_REQUEST_TYPE_CONNECT_V3_WITH_CACHE:
    case api::enums::BLUETOOTH_DEVICE_REQUEST_TYPE_CONNECT_V3_WITHOUT_CACHE:
    case api::enums::BLUETOOTH_DEVICE_REQUEST_TYPE_CONNECT: {
      auto *connection = this->get_connection_(msg.address, true);
      if (connection == nullptr) {
        ESP_LOGW(TAG, "No free connections available");
        this->send_device_connection(msg.address, false);
        return;
      }
      if (connection->state() == espbt::ClientState::CONNECTED ||
          connection->state() == espbt::ClientState::ESTABLISHED) {
        ESP_LOGW(TAG, "[%d] [%s] Connection already established", connection->get_connection_index(),
                 connection->address_str().c_str());
        this->send_device_connection(msg.address, true);
        this->send_connections_free();
        return;
      } else if (connection->state() == espbt::ClientState::SEARCHING) {
        ESP_LOGW(TAG, "[%d] [%s] Connection request ignored, already searching for device",
                 connection->get_connection_index(), connection->address_str().c_str());
        return;
      } else if (connection->state() == espbt::ClientState::DISCOVERED) {
        ESP_LOGW(TAG, "[%d] [%s] Connection request ignored, device already discovered",
                 connection->get_connection_index(), connection->address_str().c_str());
        return;
      } else if (connection->state() == espbt::ClientState::READY_TO_CONNECT) {
        ESP_LOGW(TAG, "[%d] [%s] Connection request ignored, waiting in line to connect",
                 connection->get_connection_index(), connection->address_str().c_str());
        return;
      } else if (connection->state() == espbt::ClientState::CONNECTING) {
        if (connection->disconnect_pending()) {
          ESP_LOGW(TAG, "[%d] [%s] Connection request while pending disconnect, cancelling pending disconnect",
                   connection->get_connection_index(), connection->address_str().c_str());
          connection->cancel_pending_disconnect();
          return;
        }
        ESP_LOGW(TAG, "[%d] [%s] Connection request ignored, already connecting", connection->get_connection_index(),
                 connection->address_str().c_str());
        return;
      } else if (connection->state() == espbt::ClientState::DISCONNECTING) {
        ESP_LOGW(TAG, "[%d] [%s] Connection request ignored, device is disconnecting",
                 connection->get_connection_index(), connection->address_str().c_str());
        return;
      } else if (connection->state() != espbt::ClientState::INIT) {
        ESP_LOGW(TAG, "[%d] [%s] Connection already in progress", connection->get_connection_index(),
                 connection->address_str().c_str());
        return;
      }
      if (msg.request_type == api::enums::BLUETOOTH_DEVICE_REQUEST_TYPE_CONNECT_V3_WITH_CACHE) {
        connection->set_connection_type(espbt::ConnectionType::V3_WITH_CACHE);
        ESP_LOGI(TAG, "[%d] [%s] Connecting v3 with cache", connection->get_connection_index(),
                 connection->address_str().c_str());
      } else if (msg.request_type == api::enums::BLUETOOTH_DEVICE_REQUEST_TYPE_CONNECT_V3_WITHOUT_CACHE) {
        connection->set_connection_type(espbt::ConnectionType::V3_WITHOUT_CACHE);
        ESP_LOGI(TAG, "[%d] [%s] Connecting v3 without cache", connection->get_connection_index(),
                 connection->address_str().c_str());
      } else {
        connection->set_connection_type(espbt::ConnectionType::V1);
        ESP_LOGI(TAG, "[%d] [%s] Connecting v1", connection->get_connection_index(), connection->address_str().c_str());
      }
      if (msg.has_address_type) {
        uint64_to_bd_addr(msg.address, connection->remote_bda_);
        connection->set_remote_addr_type(static_cast<esp_ble_addr_type_t>(msg.address_type));
        connection->set_state(espbt::ClientState::DISCOVERED);
      } else {
        connection->set_state(espbt::ClientState::SEARCHING);
      }
      this->send_connections_free();
      break;
    }
    case api::enums::BLUETOOTH_DEVICE_REQUEST_TYPE_DISCONNECT: {
      auto *connection = this->get_connection_(msg.address, false);
      if (connection == nullptr) {
        this->send_device_connection(msg.address, false);
        this->send_connections_free();
        return;
      }
      if (connection->state() != espbt::ClientState::IDLE) {
        connection->disconnect();
      } else {
        connection->set_address(0);
        this->send_device_connection(msg.address, false);
        this->send_connections_free();
      }
      break;
    }
    case api::enums::BLUETOOTH_DEVICE_REQUEST_TYPE_PAIR: {
      auto *connection = this->get_connection_(msg.address, false);
      if (connection != nullptr) {
        if (!connection->is_paired()) {
          auto err = connection->pair();
          if (err != ESP_OK) {
            this->send_device_pairing(msg.address, false, err);
          }
        } else {
          this->send_device_pairing(msg.address, true);
        }
      }
      break;
    }
    case api::enums::BLUETOOTH_DEVICE_REQUEST_TYPE_UNPAIR: {
      esp_bd_addr_t address;
      uint64_to_bd_addr(msg.address, address);
      esp_err_t ret = esp_ble_remove_bond_device(address);
      this->send_device_pairing(msg.address, ret == ESP_OK, ret);
      break;
    }
    case api::enums::BLUETOOTH_DEVICE_REQUEST_TYPE_CLEAR_CACHE: {
      esp_bd_addr_t address;
      uint64_to_bd_addr(msg.address, address);
      esp_err_t ret = esp_ble_gattc_cache_clean(address);
      api::BluetoothDeviceClearCacheResponse call;
      call.address = msg.address;
      call.success = ret == ESP_OK;
      call.error = ret;

      this->api_connection_->send_message(call, api::BluetoothDeviceClearCacheResponse::MESSAGE_TYPE);

      break;
    }
  }
}

void BluetoothProxy::bluetooth_gatt_read(const api::BluetoothGATTReadRequest &msg) {
  auto *connection = this->get_connection_(msg.address, false);
  if (connection == nullptr) {
    ESP_LOGW(TAG, "Cannot read GATT characteristic, not connected");
    this->send_gatt_error(msg.address, msg.handle, ESP_GATT_NOT_CONNECTED);
    return;
  }

  auto err = connection->read_characteristic(msg.handle);
  if (err != ESP_OK) {
    this->send_gatt_error(msg.address, msg.handle, err);
  }
}

void BluetoothProxy::bluetooth_gatt_write(const api::BluetoothGATTWriteRequest &msg) {
  auto *connection = this->get_connection_(msg.address, false);
  if (connection == nullptr) {
    ESP_LOGW(TAG, "Cannot write GATT characteristic, not connected");
    this->send_gatt_error(msg.address, msg.handle, ESP_GATT_NOT_CONNECTED);
    return;
  }

  auto err = connection->write_characteristic(msg.handle, msg.data, msg.response);
  if (err != ESP_OK) {
    this->send_gatt_error(msg.address, msg.handle, err);
  }
}

void BluetoothProxy::bluetooth_gatt_read_descriptor(const api::BluetoothGATTReadDescriptorRequest &msg) {
  auto *connection = this->get_connection_(msg.address, false);
  if (connection == nullptr) {
    ESP_LOGW(TAG, "Cannot read GATT descriptor, not connected");
    this->send_gatt_error(msg.address, msg.handle, ESP_GATT_NOT_CONNECTED);
    return;
  }

  auto err = connection->read_descriptor(msg.handle);
  if (err != ESP_OK) {
    this->send_gatt_error(msg.address, msg.handle, err);
  }
}

void BluetoothProxy::bluetooth_gatt_write_descriptor(const api::BluetoothGATTWriteDescriptorRequest &msg) {
  auto *connection = this->get_connection_(msg.address, false);
  if (connection == nullptr) {
    ESP_LOGW(TAG, "Cannot write GATT descriptor, not connected");
    this->send_gatt_error(msg.address, msg.handle, ESP_GATT_NOT_CONNECTED);
    return;
  }

  auto err = connection->write_descriptor(msg.handle, msg.data, true);
  if (err != ESP_OK) {
    this->send_gatt_error(msg.address, msg.handle, err);
  }
}

void BluetoothProxy::bluetooth_gatt_send_services(const api::BluetoothGATTGetServicesRequest &msg) {
  auto *connection = this->get_connection_(msg.address, false);
  if (connection == nullptr || !connection->connected()) {
    ESP_LOGW(TAG, "Cannot get GATT services, not connected");
    this->send_gatt_error(msg.address, 0, ESP_GATT_NOT_CONNECTED);
    return;
  }
  if (!connection->service_count_) {
    ESP_LOGW(TAG, "[%d] [%s] No GATT services found", connection->connection_index_, connection->address_str().c_str());
    this->send_gatt_services_done(msg.address);
    return;
  }
  if (connection->send_service_ ==
      DONE_SENDING_SERVICES)  // Only start sending services if we're not already sending them
    connection->send_service_ = 0;
}

void BluetoothProxy::bluetooth_gatt_notify(const api::BluetoothGATTNotifyRequest &msg) {
  auto *connection = this->get_connection_(msg.address, false);
  if (connection == nullptr) {
    ESP_LOGW(TAG, "Cannot notify GATT characteristic, not connected");
    this->send_gatt_error(msg.address, msg.handle, ESP_GATT_NOT_CONNECTED);
    return;
  }

  auto err = connection->notify_characteristic(msg.handle, msg.enable);
  if (err != ESP_OK) {
    this->send_gatt_error(msg.address, msg.handle, err);
  }
}

void BluetoothProxy::subscribe_api_connection(api::APIConnection *api_connection, uint32_t flags) {
  if (this->api_connection_ != nullptr) {
    ESP_LOGE(TAG, "Only one API subscription is allowed at a time");
    return;
  }
  this->api_connection_ = api_connection;
  this->parent_->recalculate_advertisement_parser_types();

  this->send_bluetooth_scanner_state_(this->parent_->get_scanner_state());
}

void BluetoothProxy::unsubscribe_api_connection(api::APIConnection *api_connection) {
  if (this->api_connection_ != api_connection) {
    ESP_LOGV(TAG, "API connection is not subscribed");
    return;
  }
  this->api_connection_ = nullptr;
  this->parent_->recalculate_advertisement_parser_types();
}

void BluetoothProxy::send_device_connection(uint64_t address, bool connected, uint16_t mtu, esp_err_t error) {
  if (this->api_connection_ == nullptr)
    return;
  api::BluetoothDeviceConnectionResponse call;
  call.address = address;
  call.connected = connected;
  call.mtu = mtu;
  call.error = error;
  this->api_connection_->send_message(call, api::BluetoothDeviceConnectionResponse::MESSAGE_TYPE);
}
void BluetoothProxy::send_connections_free() {
  if (this->api_connection_ != nullptr) {
    this->send_connections_free(this->api_connection_);
  }
}

void BluetoothProxy::send_connections_free(api::APIConnection *api_connection) {
  api_connection->send_message(this->connections_free_response_, api::BluetoothConnectionsFreeResponse::MESSAGE_TYPE);
}

void BluetoothProxy::send_gatt_services_done(uint64_t address) {
  if (this->api_connection_ == nullptr)
    return;
  api::BluetoothGATTGetServicesDoneResponse call;
  call.address = address;
  this->api_connection_->send_message(call, api::BluetoothGATTGetServicesDoneResponse::MESSAGE_TYPE);
}

void BluetoothProxy::send_gatt_error(uint64_t address, uint16_t handle, esp_err_t error) {
  if (this->api_connection_ == nullptr)
    return;
  api::BluetoothGATTErrorResponse call;
  call.address = address;
  call.handle = handle;
  call.error = error;
  this->api_connection_->send_message(call, api::BluetoothGATTWriteResponse::MESSAGE_TYPE);
}

void BluetoothProxy::send_device_pairing(uint64_t address, bool paired, esp_err_t error) {
  api::BluetoothDevicePairingResponse call;
  call.address = address;
  call.paired = paired;
  call.error = error;

  this->api_connection_->send_message(call, api::BluetoothDevicePairingResponse::MESSAGE_TYPE);
}

void BluetoothProxy::send_device_unpairing(uint64_t address, bool success, esp_err_t error) {
  api::BluetoothDeviceUnpairingResponse call;
  call.address = address;
  call.success = success;
  call.error = error;

  this->api_connection_->send_message(call, api::BluetoothDeviceUnpairingResponse::MESSAGE_TYPE);
}

void BluetoothProxy::bluetooth_scanner_set_mode(bool active) {
  if (this->parent_->get_scan_active() == active) {
    return;
  }
  ESP_LOGD(TAG, "Setting scanner mode to %s", active ? "active" : "passive");
  this->parent_->set_scan_active(active);
  this->parent_->stop_scan();
  this->parent_->set_scan_continuous(
      true);  // Set this to true to automatically start scanning again when it has cleaned up.
}

BluetoothProxy *global_bluetooth_proxy = nullptr;  // NOLINT(cppcoreguidelines-avoid-non-const-global-variables)

}  // namespace esphome::bluetooth_proxy

#endif  // USE_ESP32