// Copyright 2023 Google LLC
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     https://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

#include <arpa/inet.h>
#include <netinet/in.h>
#include <sys/socket.h>
#include <cstring>
#include <memory>
#include <random>

#include "internal/platform/implementation/linux/dbus.h"
#include "internal/platform/implementation/linux/network_manager.h"
#include "internal/platform/implementation/linux/utils.h"
#include "internal/platform/implementation/linux/wifi_hotspot.h"
#include "internal/platform/implementation/linux/wifi_hotspot_server_socket.h"
#include "internal/platform/implementation/linux/wifi_hotspot_socket.h"
#include "internal/platform/implementation/linux/wifi_medium.h"
#include "internal/platform/implementation/wifi.h"
#include "internal/platform/logging.h"

namespace nearby {
namespace linux {
std::unique_ptr<api::WifiHotspotSocket>
NetworkManagerWifiHotspotMedium::ConnectToService(
    absl::string_view ip_address, int port,
    CancellationFlag *cancellation_flag) {
  if (!ConnectedToWifi()) {
    LOG(ERROR)
        << __func__
        << ": Cannot connect to service without an active WiFi hotspot";
    return nullptr;
  }

  int sock = socket(AF_INET, SOCK_STREAM, 0);
  if (sock < 0) {
    LOG(ERROR) << __func__
                       << ": Error opening socket: " << std::strerror(errno);
    return nullptr;
  }

  LOG(INFO) << __func__ << ": Connecting to " << ip_address << ":"
                       << port;
  struct sockaddr_in addr {};
  addr.sin_addr.s_addr = inet_addr(std::string(ip_address).c_str());
  addr.sin_family = AF_INET;
  addr.sin_port = htons(port);

  auto ret =
      connect(sock, reinterpret_cast<struct sockaddr *>(&addr), sizeof(addr));
  if (ret < 0) {
    LOG(ERROR) << __func__ << ": Error connecting to socket: "
                       << std::strerror(errno);
    return nullptr;
  }

  return std::make_unique<WifiHotspotSocket>(sock);
}

std::unique_ptr<api::WifiHotspotServerSocket>
NetworkManagerWifiHotspotMedium::ListenForService(int port) {
  if (!WifiHotspotActive()) {
    LOG(ERROR)
        << __func__
        << ": Cannot connect to service without an active WiFi hotspot";
    return nullptr;
  }

  auto active_connection = wireless_device_->GetActiveConnection();
  if (active_connection == nullptr) {
    return nullptr;
  }

  auto ip4addresses = active_connection->GetIP4Addresses();
  if (ip4addresses.empty()) {
    LOG(ERROR)
        << __func__
        << "Could not find any IPv4 addresses for active connection "
        << active_connection->getObjectPath();
    return nullptr;
  }

  auto sock = socket(AF_INET, SOCK_STREAM, 0);
  if (sock < 0) {
    LOG(ERROR) << __func__
                       << ": Error opening socket: " << std::strerror(errno);
    return nullptr;
  }

  struct sockaddr_in addr;
  addr.sin_family = AF_INET;
  addr.sin_addr.s_addr = inet_addr(ip4addresses[0].c_str());
  addr.sin_port = htons(port);

  auto ret =
      bind(sock, reinterpret_cast<struct sockaddr *>(&addr), sizeof(addr));
  if (ret < 0) {
    LOG(ERROR) << __func__
                       << ": Error binding to socket: " << std::strerror(errno);
    return nullptr;
  }

  LOG(INFO) << __func__ << ": Listening for services on "
                       << ip4addresses[0] << ":" << port << " on device "
                       << wireless_device_->getObjectPath();

  ret = listen(sock, 0);
  if (ret < 0) {
    LOG(ERROR) << __func__ << ": Error listening on socket: "
                       << std::strerror(errno);
    return nullptr;
  }

  return std::make_unique<NetworkManagerWifiHotspotServerSocket>(
      sock, std::move(active_connection), network_manager_);
}

bool NetworkManagerWifiHotspotMedium::StartWifiHotspot(
    HotspotCredentials *hotspot_credentials) {
  if (WifiHotspotActive()) {
    LOG(ERROR) << __func__ << ": " << wireless_device_->getObjectPath()
                       << ": cannot start WiFi hotspot, a hotspot is already "
                          "active on this device";
    return false;
  }

  std::string ssid = RandSSID();
  hotspot_credentials->SetSSID(ssid);

  std::string password = RandWPAPassphrase();
  hotspot_credentials->SetPassword(password);

  auto connection_id = NewUuidStr();
  if (!connection_id.has_value()) {
    LOG(ERROR) << __func__ << ": could not generate a connection UUID";
    return false;
  }

  std::map<std::string, std::map<std::string, sdbus::Variant>>
      connection_settings{
          {
              "connection",
              {{"uuid", *connection_id},
               {"id", "Google Nearby Hotspot"},
               {"type", "802-11-wireless"},
               {"zone", "Public"}},
          },
          {"802-11-wireless",
           {{"assigned-mac-address", "random"},
            {"ap-isolation", networkmanager::constants::kNMTernaryFalse},
            {"mode", "ap"},
            {"ssid", std::vector<uint8_t>(ssid.begin(), ssid.end())},
            {"security", "802-11-wireless-security"}}},
          {"802-11-wireless-security",
           {{"pmf",
             networkmanager::constants::setting::kWirelessSecurityPMFDisable},
            {"key-mgmt", "wpa-psk"},
            {"psk", password}}},
          {"ipv4", {{"method", "shared"}}},
          {"ipv6",
           {
               {"addr-gen-mode", networkmanager::constants::setting::
                                     kIP6ConfigAddrGenModeStablePrivacy},
               {"method", "shared"},
           }}};
  std::unique_ptr<networkmanager::ActiveConnection> active_conn;
  try {
    auto [path, active_path, result] =
        network_manager_->AddAndActivateConnection2(
            connection_settings, wireless_device_->getObjectPath(), "/",
            {{"persist", "volatile"}, {"bind-activation", "dbus-client"}});
    active_conn = std::make_unique<networkmanager::ActiveConnection>(
        system_bus_, active_path);
  } catch (const sdbus::Error &e) {
    DBUS_LOG_METHOD_CALL_ERROR(network_manager_, "AddAndActivateConnection2",
                               e);
    return false;
  }

  auto [reason, timeout] = active_conn->WaitForConnection();
  if (timeout) {
    LOG(ERROR)
        << __func__ << ": "
        << ": timed out while waiting for connection "
        << active_conn->getObjectPath()
        << " to be activated, last NMActiveConnectionStateReason: "
        << reason->ToString();
    DisconnectWifiHotspot();
    return false;
  }

  LOG(INFO) << __func__ << ": Started a WiFi hotspot on device "
                    << wireless_device_->getObjectPath() << " at "
                    << active_conn->getObjectPath();
  return true;
}

bool NetworkManagerWifiHotspotMedium::StopWifiHotspot() {
  if (!WifiHotspotActive()) {
    LOG(ERROR)
        << __func__ << ": " << wireless_device_->getObjectPath()
        << ": Cannot stop WiFi hotspot as a WiFi hotspot is not active";
  }

  // Get the active connection object for the hotspot AP.
  sdbus::ObjectPath active_ap_path;

  try {
    active_ap_path = wireless_device_->ActiveAccessPoint();
    if (active_ap_path.empty()) {
      LOG(ERROR) << __func__ << ": No active access points on "
                         << wireless_device_->getObjectPath();
      return false;
    }
  } catch (const sdbus::Error &e) {
    DBUS_LOG_PROPERTY_GET_ERROR(wireless_device_, "ActiveAccessPoint", e);
  }

  auto object_manager = networkmanager::ObjectManager(system_bus_);
  auto active_connection = wireless_device_->GetActiveConnection();
  if (active_connection == nullptr) {
    LOG(ERROR)
        << __func__
        << ": Could not find an active connection using the access point "
        << active_ap_path;
    return false;
  }

  LOG(INFO) << __func__ << ": " << wireless_device_->getObjectPath()
                    << ": Deactivating active connection "
                    << active_connection->getObjectPath();

  try {
    network_manager_->DeactivateConnection(active_connection->getObjectPath());
  } catch (const sdbus::Error &e) {
    DBUS_LOG_METHOD_CALL_ERROR(network_manager_, "DeactivateConnection", e);
    return false;
  }

  return true;
}

bool NetworkManagerWifiHotspotMedium::ConnectWifiHotspot(
    HotspotCredentials *hotspot_credentials) {
  if (hotspot_credentials == nullptr) {
    LOG(ERROR) << __func__ << ": hotspot_credentials cannot be null";
    return false;
  }

  auto ssid = hotspot_credentials->GetSSID();
  auto password = hotspot_credentials->GetPassword();

  return wireless_device_->ConnectToNetwork(ssid, password,
                                            api::WifiAuthType::kWpaPsk) ==
         api::WifiConnectionStatus::kConnected;
}

bool NetworkManagerWifiHotspotMedium::DisconnectWifiHotspot() {
  if (!ConnectedToWifi()) {
    LOG(ERROR) << __func__ << ": Not connected to a WiFi hotspot";
    return false;
  }

  auto active_connection = wireless_device_->GetActiveConnection();
  if (active_connection == nullptr) {
    return false;
  }

  try {
    network_manager_->DeactivateConnection(active_connection->getObjectPath());
  } catch (const sdbus::Error &e) {
    DBUS_LOG_METHOD_CALL_ERROR(network_manager_, "DeactivateConnection", e);
    return false;
  }

  return true;
}

bool NetworkManagerWifiHotspotMedium::WifiHotspotActive() {
  try {
    auto mode = wireless_device_->Mode();
    return mode == networkmanager::constants::kNM80211ModeAP;
  } catch (const sdbus::Error &e) {
    DBUS_LOG_PROPERTY_GET_ERROR(wireless_device_, "Mode", e);
    return false;
  }
}

bool NetworkManagerWifiHotspotMedium::ConnectedToWifi() {
  try {
    auto mode = wireless_device_->Mode();
    return mode == networkmanager::constants::kNM80211ModeInfra;
  } catch (const sdbus::Error &e) {
    DBUS_LOG_PROPERTY_GET_ERROR(wireless_device_, "Mode", e);
    return false;
  }
}

}  // namespace linux
}  // namespace nearby