// Copyright 2023 The ChromiumOS Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include "secagentd/device_user.h"

#include <cstddef>
#include <string>
#include <utility>
#include <vector>

#include "absl/status/status.h"
#include "absl/status/statusor.h"
#include "base/functional/bind.h"
#include "base/memory/scoped_refptr.h"
#include "base/no_destructor.h"
#include "base/strings/strcat.h"
#include "bindings/chrome_device_policy.pb.h"
#include "bindings/device_management_backend.pb.h"
#include "brillo/errors/error.h"
#include "metrics/metrics_library.h"

namespace secagentd {

DeviceUser::DeviceUser(
    std::unique_ptr<org::chromium::SessionManagerInterfaceProxyInterface>
        session_manager)
    : weak_ptr_factory_(this), session_manager_(std::move(session_manager)) {}

void DeviceUser::RegisterSessionChangeHandler() {
  session_manager_->RegisterSessionStateChangedSignalHandler(
      base::BindRepeating(&DeviceUser::OnSessionStateChange,
                          weak_ptr_factory_.GetWeakPtr()),
      base::BindOnce(&DeviceUser::HandleRegistrationResult,
                     weak_ptr_factory_.GetWeakPtr()));
}

std::string DeviceUser::GetDeviceUser() {
  return device_user_;
}

void DeviceUser::HandleRegistrationResult(const std::string& interface,
                                          const std::string& signal,
                                          bool success) {
  if (!success) {
    LOG(ERROR) << "Callback registration failed for dbus signal: " << signal
               << " on interface: " << interface;
    device_user_ = "Unknown";
  } else {
    UpdateDeviceId();
    UpdateDeviceUser();
  }
}

void DeviceUser::OnSessionStateChange(const std::string& state) {
  if (state == "started") {
    UpdateDeviceId();
    // When a user logs in for the first time there is a delay for their
    // ID to be added. Add a slight delay so the ID can appear.
    base::SequencedTaskRunner::GetCurrentDefault()->PostDelayedTask(
        FROM_HERE,
        base::BindOnce(&DeviceUser::UpdateDeviceUser,
                       weak_ptr_factory_.GetWeakPtr()),
        base::Seconds(2));
  } else if (state == "stopping" || state == "stopped") {
    device_user_ = "";
  }
}

void DeviceUser::UpdateDeviceId() {
  if (device_id_ != "") {
    return;
  }

  auto response = RetrievePolicy(login_manager::ACCOUNT_TYPE_DEVICE, "");
  if (!response.ok()) {
    LOG(ERROR) << response.status();
    return;
  }

  auto device_policy = response.value();
  if (device_policy.device_affiliation_ids_size() >= 1) {
    device_id_ = device_policy.device_affiliation_ids()[0];
    if (device_policy.user_affiliation_ids_size() > 1) {
      // There should only be 1 ID in the list.
      LOG(ERROR) << "Greater than 1 Device ID. Count = "
                 << device_policy.user_affiliation_ids_size();
    }
  }
}

void DeviceUser::UpdateDeviceUser() {
  // Check if guest session is active.
  bool is_guest = false;
  brillo::ErrorPtr error;
  if (!session_manager_->IsGuestSessionActive(&is_guest, &error) ||
      error.get()) {
    device_user_ = "Unknown";
    // Do not exit method because possible that it is user session.
    LOG(ERROR) << "Failed to deterimine if guest session "
               << error->GetMessage();
  } else if (is_guest) {
    device_user_ = "GuestUser";
    return;
  }

  // Retrieve the device username.
  std::string username;
  std::string sanitized;
  if (!session_manager_->RetrievePrimarySession(&username, &sanitized,
                                                &error) ||
      error.get()) {
    device_user_ = "Unknown";
    LOG(ERROR) << "Failed to retrieve primary session " << error->GetMessage();
    return;
  } else {
    // No active session.
    if (username.empty()) {
      // Only set as empty when Guest session retrieval succeeds.
      if (device_user_ != "Unknown") {
        device_user_ = "";
      }
      return;
    }
    // Retrieve user policy information.
    auto response = RetrievePolicy(login_manager::ACCOUNT_TYPE_USER, username);
    if (!response.ok()) {
      device_user_ = "Unknown";
      LOG(ERROR) << response.status();
      return;
    } else {
      auto user_policy = response.value();
      // Fill in device_user if user is affiliated.
      if (IsAffiliated(user_policy)) {
        device_user_ = username;
      } else {
        // TODO(b/277796550): Make count stable across reboots.
        device_user_ = "UnaffiliatedUser";
      }
    }
  }
}

absl::StatusOr<enterprise_management::PolicyData> DeviceUser::RetrievePolicy(
    login_manager::PolicyAccountType account_type,
    const std::string& account_id) {
  login_manager::PolicyDescriptor descriptor;
  descriptor.set_account_type(account_type);
  descriptor.set_account_id(account_id);
  descriptor.set_domain(login_manager::POLICY_DOMAIN_CHROME);
  std::string account_type_string =
      account_type == login_manager::PolicyAccountType::ACCOUNT_TYPE_DEVICE
          ? "device"
          : "user";

  brillo::ErrorPtr error;
  std::vector<uint8_t> out_blob;
  std::string descriptor_string = descriptor.SerializeAsString();
  if (!session_manager_->RetrievePolicyEx(
          std::vector<uint8_t>(descriptor_string.begin(),
                               descriptor_string.end()),
          &out_blob, &error) ||
      error.get()) {
    return absl::InternalError("Failed to retrieve " + account_type_string +
                               " policy " + error->GetMessage());
  }
  enterprise_management::PolicyFetchResponse response;
  if (!response.ParseFromArray(out_blob.data(), out_blob.size())) {
    return absl::InternalError("Failed to parse policy response for " +
                               account_type_string);
  }

  enterprise_management::PolicyData policy_data;
  if (!policy_data.ParseFromArray(response.policy_data().data(),
                                  response.policy_data().size())) {
    return absl::InternalError("Failed to parse policy data for " +
                               account_type_string);
  }

  return policy_data;
}

bool DeviceUser::IsAffiliated(
    const enterprise_management::PolicyData& user_policy) {
  std::string user_id = "unset";
  if (user_policy.user_affiliation_ids_size() >= 1) {
    user_id = user_policy.user_affiliation_ids()[0];
    if (user_policy.user_affiliation_ids_size() > 1) {
      // There should only be 1 ID in the list.
      LOG(ERROR) << "Greater than 1 User ID. Count = "
                 << user_policy.user_affiliation_ids_size();
    }
  }

  return user_id == device_id_;
}

}  // namespace secagentd