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

#include "chromeos/ash/components/report/device_metrics/churn/observation_impl.h"

#include "ash/constants/ash_features.h"
#include "chromeos/ash/components/report/device_metrics/churn/active_status.h"
#include "chromeos/ash/components/report/prefs/fresnel_pref_names.h"
#include "chromeos/ash/components/report/utils/device_metadata_utils.h"
#include "chromeos/ash/components/report/utils/network_utils.h"
#include "chromeos/ash/components/report/utils/psm_utils.h"
#include "chromeos/ash/components/report/utils/time_utils.h"
#include "chromeos/ash/components/report/utils/uma_utils.h"
#include "components/prefs/pref_service.h"
#include "services/network/public/cpp/resource_request.h"
#include "services/network/public/cpp/shared_url_loader_factory.h"
#include "services/network/public/cpp/simple_url_loader.h"
#include "third_party/private_membership/src/private_membership_rlwe.pb.h"

namespace psm_rlwe = private_membership::rlwe;

namespace ash::report::device_metrics {

namespace {

// PSM use case enum for churn monthly observation use case.
constexpr psm_rlwe::RlweUseCase kPsmUseCase =
    psm_rlwe::RlweUseCase::CROS_FRESNEL_CHURN_MONTHLY_OBSERVATION;

}  // namespace

ObservationImpl::ObservationImpl(UseCaseParameters* params)
    : UseCase(params),
      active_status_(std::make_unique<ActiveStatus>(params->GetLocalState())) {}

ObservationImpl::~ObservationImpl() = default;

void ObservationImpl::Run(base::OnceCallback<void()> callback) {
  callback_ = std::move(callback);

  if (!IsDevicePingRequired()) {
    utils::RecordIsDevicePingRequired(utils::PsmUseCase::kObservation, false);
    std::move(callback_).Run();
    return;
  }

  utils::RecordIsDevicePingRequired(utils::PsmUseCase::kObservation, true);

  // Perform check membership if the local state pref has default value.
  // This is done to avoid duplicate check in if the device pinged already.
  if (base::FeatureList::IsEnabled(
          features::kDeviceActiveClientChurnObservationCheckMembership) &&
      (GetLastPingTimestamp() == base::Time::UnixEpoch() ||
       GetLastPingTimestamp() == base::Time())) {
    CheckMembershipOprf();
  } else {
    CheckIn();
  }
}

base::WeakPtr<ObservationImpl> ObservationImpl::GetWeakPtr() {
  return weak_factory_.GetWeakPtr();
}

std::optional<FresnelImportDataRequest>
ObservationImpl::GenerateImportRequestBodyForTesting() {
  return GenerateImportRequestBody();
}

void ObservationImpl::CheckMembershipOprf() {
  PsmClientManager* psm_client_manager = GetParams()->GetPsmClientManager();

  psm_client_manager->SetPsmRlweClient(kPsmUseCase, GetPsmIdentifiersToQuery());

  if (!psm_client_manager->GetPsmRlweClient()) {
    LOG(ERROR) << "Check membership failed since the PSM RLWE client could "
               << "not be initialized.";
    std::move(callback_).Run();
    return;
  }

  // Generate PSM Oprf request body.
  const auto status_or_oprf_request = psm_client_manager->CreateOprfRequest();
  if (!status_or_oprf_request.ok()) {
    LOG(ERROR) << "Failed to create OPRF request.";
    std::move(callback_).Run();
    return;
  }

  psm_rlwe::PrivateMembershipRlweOprfRequest oprf_request =
      status_or_oprf_request.value();

  // Wrap PSM Oprf request body by FresnelPsmRlweOprfRequest proto.
  // This proto is expected by the Fresnel service.
  report::FresnelPsmRlweOprfRequest fresnel_oprf_request;
  *fresnel_oprf_request.mutable_rlwe_oprf_request() = oprf_request;

  std::string request_body;
  fresnel_oprf_request.SerializeToString(&request_body);

  auto resource_request =
      utils::GenerateResourceRequest(utils::GetOprfRequestURL());

  url_loader_ = network::SimpleURLLoader::Create(
      std::move(resource_request), GetCheckMembershipTrafficTag());
  url_loader_->AttachStringForUpload(request_body, "application/x-protobuf");
  url_loader_->SetTimeoutDuration(utils::GetOprfRequestTimeout());
  url_loader_->DownloadToString(
      GetParams()->GetUrlLoaderFactory().get(),
      base::BindOnce(&ObservationImpl::OnCheckMembershipOprfComplete,
                     weak_factory_.GetWeakPtr()),
      utils::GetMaxFresnelResponseSizeBytes());
}

void ObservationImpl::OnCheckMembershipOprfComplete(
    std::optional<std::string> response_body) {
  // Use RAII to reset |url_loader_| after current function scope.
  auto url_loader = std::move(url_loader_);

  int net_code = url_loader->NetError();
  utils::RecordNetErrorCode(utils::PsmUseCase::kObservation,
                            utils::PsmRequest::kOprf, net_code);

  // Convert serialized response body to oprf response protobuf.
  FresnelPsmRlweOprfResponse psm_oprf_response;
  if (!response_body.has_value() ||
      !psm_oprf_response.ParseFromString(*response_body)) {
    LOG(ERROR) << "Oprf response net code = " << net_code;
    LOG(ERROR) << "Response body was not set or could not be parsed into "
               << "FresnelPsmRlweOprfResponse proto. "
               << "Is response body set = " << response_body.has_value();
    std::move(callback_).Run();
    return;
  }

  if (!psm_oprf_response.has_rlwe_oprf_response()) {
    LOG(ERROR) << "Oprf response net code = " << net_code;
    LOG(ERROR) << "FresnelPsmRlweOprfResponse is missing the actual oprf "
                  "response from server.";
    std::move(callback_).Run();
    return;
  }

  psm_rlwe::PrivateMembershipRlweOprfResponse oprf_response =
      psm_oprf_response.rlwe_oprf_response();

  CheckMembershipQuery(oprf_response);
}

void ObservationImpl::CheckMembershipQuery(
    const psm_rlwe::PrivateMembershipRlweOprfResponse& oprf_response) {
  PsmClientManager* psm_client_manager = GetParams()->GetPsmClientManager();

  // Generate PSM Query request body.
  const auto status_or_query_request =
      psm_client_manager->CreateQueryRequest(oprf_response);
  if (!status_or_query_request.ok()) {
    LOG(ERROR) << "Failed to create Query request.";
    std::move(callback_).Run();
    return;
  }

  psm_rlwe::PrivateMembershipRlweQueryRequest query_request =
      status_or_query_request.value();

  // Wrap PSM Query request body by FresnelPsmRlweQueryRequest proto.
  // This proto is expected by the Fresnel service.
  report::FresnelPsmRlweQueryRequest fresnel_query_request;
  *fresnel_query_request.mutable_rlwe_query_request() = query_request;

  std::string request_body;
  fresnel_query_request.SerializeToString(&request_body);

  auto resource_request =
      utils::GenerateResourceRequest(utils::GetQueryRequestURL());

  url_loader_ = network ::SimpleURLLoader ::Create(
      std::move(resource_request), GetCheckMembershipTrafficTag());
  url_loader_->AttachStringForUpload(request_body, "application/x-protobuf");
  url_loader_->SetTimeoutDuration(utils::GetQueryRequestTimeout());
  url_loader_->DownloadToString(
      GetParams()->GetUrlLoaderFactory().get(),
      base::BindOnce(&ObservationImpl::OnCheckMembershipQueryComplete,
                     weak_factory_.GetWeakPtr()),
      utils::GetMaxFresnelResponseSizeBytes());
}

void ObservationImpl::OnCheckMembershipQueryComplete(
    std::optional<std::string> response_body) {
  // Use RAII to reset |url_loader_| after current function scope.
  auto url_loader = std::move(url_loader_);

  int net_code = url_loader->NetError();
  utils::RecordNetErrorCode(utils::PsmUseCase::kObservation,
                            utils::PsmRequest::kQuery, net_code);

  // Convert serialized response body to fresnel query response protobuf.
  FresnelPsmRlweQueryResponse psm_query_response;
  if (!response_body.has_value() ||
      !psm_query_response.ParseFromString(*response_body)) {
    LOG(ERROR) << "Query response net code = " << net_code;
    LOG(ERROR) << "Response body was not set or could not be parsed into "
               << "FresnelPsmRlweQueryResponse proto. "
               << "Is response body set = " << response_body.has_value();
    std::move(callback_).Run();
    return;
  }

  if (!psm_query_response.has_rlwe_query_response()) {
    LOG(ERROR) << "Query response net code = " << net_code;
    LOG(ERROR) << "FresnelPsmRlweQueryResponse is missing the actual query "
                  "response from server.";
    std::move(callback_).Run();
    return;
  }

  psm_rlwe::PrivateMembershipRlweQueryResponse query_response =
      psm_query_response.rlwe_query_response();
  auto status_or_response =
      GetParams()->GetPsmClientManager()->ProcessQueryResponse(query_response);

  if (!status_or_response.ok()) {
    LOG(ERROR) << "Failed to process query response.";
    std::move(callback_).Run();
    return;
  }

  psm_rlwe::RlweMembershipResponses rlwe_membership_responses =
      status_or_response.value();

  // TODO: Update logic below here to handle observation check membership...
  if (rlwe_membership_responses.membership_responses_size() == 0) {
    LOG(ERROR) << "Check Membership for Observation should query for greater "
               << "than 0 memberships. Size = "
               << rlwe_membership_responses.membership_responses_size();
    std::move(callback_).Run();
    return;
  }

  LOG(ERROR)
      << "TODO: Implement logic to find last ping Observation use case. ";
  private_membership::MembershipResponse membership_response =
      rlwe_membership_responses.membership_responses(0).membership_response();

  bool is_psm_id_member = membership_response.is_member();

  if (is_psm_id_member) {
    LOG(ERROR) << "Check in ping was already sent this month.";
    SetLastPingTimestamp(GetParams()->GetActiveTs());
    std::move(callback_).Run();
    return;
  }

  CheckIn();
}

void ObservationImpl::CheckIn() {
  std::optional<FresnelImportDataRequest> import_request =
      GenerateImportRequestBody();
  if (!import_request.has_value()) {
    LOG(ERROR) << "Failed to create the import request body.";
    std::move(callback_).Run();
    return;
  }

  std::string request_body;
  import_request.value().SerializeToString(&request_body);

  auto resource_request =
      utils::GenerateResourceRequest(utils::GetImportRequestURL());

  url_loader_ = network::SimpleURLLoader::Create(std::move(resource_request),
                                                 GetCheckInTrafficTag());
  url_loader_->AttachStringForUpload(request_body, "application/x-protobuf");
  url_loader_->SetTimeoutDuration(utils::GetImportRequestTimeout());
  url_loader_->DownloadToString(
      GetParams()->GetUrlLoaderFactory().get(),
      base::BindOnce(&ObservationImpl::OnCheckInComplete,
                     weak_factory_.GetWeakPtr()),
      utils::GetMaxFresnelResponseSizeBytes());
}

void ObservationImpl::OnCheckInComplete(
    std::optional<std::string> response_body) {
  // Use RAII to reset |url_loader_| after current function scope.
  auto url_loader = std::move(url_loader_);

  int net_code = url_loader->NetError();
  utils::RecordNetErrorCode(utils::PsmUseCase::kObservation,
                            utils::PsmRequest::kImport, net_code);

  if (net_code == net::OK) {
    UpdateLocalStateOnCheckInSuccess();
  } else {
    LOG(ERROR) << "Failed to check in successfully. Net code = " << net_code;
  }

  // Check-in completed - use case is done running.
  std::move(callback_).Run();
}

base::Time ObservationImpl::GetLastPingTimestamp() {
  return GetParams()->GetLocalState()->GetTime(
      ash::report::prefs::kDeviceActiveChurnObservationMonthlyPingTimestamp);
}

void ObservationImpl::SetLastPingTimestamp(base::Time ts) {
  GetParams()->GetLocalState()->SetTime(
      ash::report::prefs::kDeviceActiveChurnObservationMonthlyPingTimestamp,
      ts);
}

std::vector<psm_rlwe::RlwePlaintextId>
ObservationImpl::GetPsmIdentifiersToQuery() {
  // TODO: implement methods to generate PSM id.
  std::vector<psm_rlwe::RlwePlaintextId> query_psm_ids = {};
  return query_psm_ids;
}

std::optional<FresnelImportDataRequest>
ObservationImpl::GenerateImportRequestBody() {
  FresnelImportDataRequest import_request;
  import_request.set_use_case(kPsmUseCase);

  // Certain metadata is passed by chrome, since it's not available in ash.
  version_info::Channel version_channel =
      GetParams()->GetChromeDeviceParams().chrome_channel;
  ash::report::MarketSegment market_segment =
      GetParams()->GetChromeDeviceParams().market_segment;

  DeviceMetadata* device_metadata = import_request.mutable_device_metadata();
  device_metadata->set_chrome_milestone(utils::GetChromeMilestone());
  device_metadata->set_hardware_id(utils::GetFullHardwareClass());
  device_metadata->set_chromeos_channel(
      utils::GetChromeChannel(version_channel));
  device_metadata->set_market_segment(market_segment);

  // Generate metadata for the 3 non-imported observation periods relative to
  // the last cohort ping month, tracking sending status with booleans.
  PrefService* local_state = GetParams()->GetLocalState();
  if (!local_state->GetBoolean(
          prefs::kDeviceActiveLastKnownIsActiveCurrentPeriodMinus0)) {
    FresnelImportData* import_data = import_request.add_import_data();
    std::optional<FresnelImportData> period_0_data =
        GenerateObservationImportData(0);

    if (!period_0_data.has_value()) {
      LOG(ERROR) << "Failed to generate import data request body since period 0"
                 << " could not be generated. ";
      return std::nullopt;
    }
    *import_data = period_0_data.value();
  }

  if (!local_state->GetBoolean(
          prefs::kDeviceActiveLastKnownIsActiveCurrentPeriodMinus1)) {
    FresnelImportData* import_data = import_request.add_import_data();
    std::optional<FresnelImportData> period_1_data =
        GenerateObservationImportData(1);

    if (!period_1_data.has_value()) {
      LOG(ERROR) << "Failed to generate import data request body since period 1"
                 << " could not be generated. ";
      return std::nullopt;
    }
    *import_data = period_1_data.value();
  }

  if (!local_state->GetBoolean(
          prefs::kDeviceActiveLastKnownIsActiveCurrentPeriodMinus2)) {
    FresnelImportData* import_data = import_request.add_import_data();
    std::optional<FresnelImportData> period_2_data =
        GenerateObservationImportData(2);

    if (!period_2_data.has_value()) {
      LOG(ERROR) << "Failed to generate import data request body since period 2"
                 << " could not be generated. ";
      return std::nullopt;
    }
    *import_data = period_2_data.value();
  }

  return import_request;
}

std::optional<FresnelImportData> ObservationImpl::GenerateObservationImportData(
    int period) {
  DCHECK(period >= 0 && period <= 2) << "Period must be in [0,2] range.";
  FresnelImportData import_data;

  base::Time active_ts = GetParams()->GetActiveTs();
  std::optional<base::Time> last_month_ts = utils::GetPreviousMonth(active_ts);
  std::optional<base::Time> two_months_ago_ts =
      utils::GetPreviousMonth(last_month_ts.value_or(base::Time()));
  std::optional<base::Time> next_month_ts = utils::GetNextMonth(active_ts);
  std::optional<base::Time> two_months_later_ts =
      utils::GetNextMonth(next_month_ts.value_or(base::Time()));

  if (!last_month_ts.has_value() || !two_months_ago_ts.has_value() ||
      !next_month_ts.has_value() || !two_months_later_ts.has_value()) {
    LOG(ERROR) << "Failed to get observation periods.";
    return std::nullopt;
  }

  std::string cur_month = utils::TimeToYYYYMMString(active_ts);

  std::string window_id;
  if (period == 0) {
    window_id = cur_month + "-" +
                utils::TimeToYYYYMMString(two_months_later_ts.value());
  } else if (period == 1) {
    window_id = utils::TimeToYYYYMMString(last_month_ts.value()) + "-" +
                utils::TimeToYYYYMMString(next_month_ts.value());
  } else if (period == 2) {
    window_id =
        utils::TimeToYYYYMMString(two_months_ago_ts.value()) + "-" + cur_month;
  }

  std::optional<psm_rlwe::RlwePlaintextId> psm_id =
      utils::GeneratePsmIdentifier(GetParams()->GetHighEntropySeed(),
                                   psm_rlwe::RlweUseCase_Name(kPsmUseCase),
                                   window_id);
  std::optional<ChurnObservationMetadata> observation_metadata =
      active_status_->CalculateObservationMetadata(active_ts, period);

  if (window_id.empty() || !psm_id.has_value() ||
      !observation_metadata.has_value()) {
    LOG(ERROR) << "Failed to generate observation import data for period = "
               << period;
    return std::nullopt;
  }

  // Finch flag is disabled by default.
  if (base::FeatureList::IsEnabled(
          features::kDeviceActiveClientChurnObservationNewDeviceMetadata)) {
    std::optional<base::Time> first_active_week_ts =
        utils::GetFirstActiveWeek();

    if (!first_active_week_ts.has_value() ||
        first_active_week_ts.value() == base::Time() ||
        first_active_week_ts.value() == base::Time::UnixEpoch()) {
      LOG(ERROR) << "Failed to retrieve first active week from VPD. "
                    "Setting first active and last powerwash week to UNKNOWN.";
      observation_metadata->set_first_active_week("UNKNOWN");
      observation_metadata->set_last_powerwash_week("UNKNOWN");
    } else {
      int max_days_in_4_months = 31 * 4;
      bool within_date_range = utils::IsFirstActiveUnderNDaysAgo(
          active_ts, first_active_week_ts.value(), max_days_in_4_months);

      // Privacy approved 4 months of first active week history.
      // Reference b/316402479.
      if (within_date_range) {
        observation_metadata->set_first_active_week(
            utils::ConvertTimeToISO8601String(first_active_week_ts.value()));

        // Last powerwash week is read from preserved file and stored in
        // |ReportControllerInitializer|.
        observation_metadata->set_last_powerwash_week(
            GetParams()->GetChromeDeviceParams().last_powerwash_week);
      }
    }
  }

  import_data.set_plaintext_id(psm_id.value().sensitive_id());
  import_data.set_window_identifier(window_id);
  import_data.set_is_pt_window_identifier(true);

  ChurnObservationMetadata* observation_metadata_src =
      import_data.mutable_churn_observation_metadata();
  *observation_metadata_src = observation_metadata.value();
  return import_data;
}

void ObservationImpl::UpdateLocalStateOnCheckInSuccess() {
  PrefService* local_state = GetParams()->GetLocalState();

  local_state->SetBoolean(
      prefs::kDeviceActiveLastKnownIsActiveCurrentPeriodMinus0, true);
  local_state->SetBoolean(
      prefs::kDeviceActiveLastKnownIsActiveCurrentPeriodMinus1, true);
  local_state->SetBoolean(
      prefs::kDeviceActiveLastKnownIsActiveCurrentPeriodMinus2, true);
  SetLastPingTimestamp(GetParams()->GetActiveTs());
}

bool ObservationImpl::IsDevicePingRequired() {
  base::Time last_ping_ts = GetLastPingTimestamp();
  base::Time cur_ping_ts = GetParams()->GetActiveTs();

  // Safety check to avoid against clock drift, or unexpected timestamps.
  // Check should make sure that we are not reporting window id's for
  // a month previous to one that we reported already.
  if (last_ping_ts >= cur_ping_ts) {
    return false;
  }

  base::Time last_ping_cohort_ts = GetParams()->GetLocalState()->GetTime(
      prefs::kDeviceActiveChurnCohortMonthlyPingTimestamp);
  std::string cur_ping_month = utils::TimeToYYYYMMString(cur_ping_ts);
  return cur_ping_month != utils::TimeToYYYYMMString(last_ping_ts) &&
         cur_ping_month == utils::TimeToYYYYMMString(last_ping_cohort_ts);
}

}  // namespace ash::report::device_metrics