// Copyright 2018 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include "components/consent_auditor/consent_sync_bridge_impl.h"

#include <set>
#include <utility>
#include <vector>

#include "base/big_endian.h"
#include "base/bind.h"
#include "base/bind_helpers.h"
#include "base/location.h"
#include "base/logging.h"
#include "base/stl_util.h"
#include "base/strings/string_number_conversions.h"
#include "build/build_config.h"
#include "components/sync/model/data_type_activation_request.h"
#include "components/sync/model/entity_change.h"
#include "components/sync/model/metadata_batch.h"
#include "components/sync/model/mutable_data_batch.h"
#include "components/sync/protocol/sync.pb.h"

namespace consent_auditor {

using sync_pb::UserConsentSpecifics;
using syncer::EntityChange;
using syncer::EntityChangeList;
using syncer::EntityData;
using syncer::MetadataBatch;
using syncer::MetadataChangeList;
using syncer::ModelError;
using syncer::ModelTypeChangeProcessor;
using syncer::ModelTypeStore;
using syncer::ModelTypeSyncBridge;
using syncer::MutableDataBatch;
using syncer::OnceModelTypeStoreFactory;
using IdList = ModelTypeStore::IdList;
using Record = ModelTypeStore::Record;
using RecordList = ModelTypeStore::RecordList;
using WriteBatch = ModelTypeStore::WriteBatch;

namespace {

std::string GetStorageKeyFromSpecifics(const UserConsentSpecifics& specifics) {
  // Force Big Endian, this means newly created keys are last in sort order,
  // which allows leveldb to append new writes, which it is best at.
  // TODO(skym): Until we force |event_time_usec| to never conflict, this has
  // the potential for errors.
  std::string key(8, 0);
  base::WriteBigEndian(&key[0], specifics.client_consent_time_usec());
  return key;
}

std::unique_ptr<EntityData> MoveToEntityData(
    std::unique_ptr<UserConsentSpecifics> specifics) {
  auto entity_data = std::make_unique<EntityData>();
  entity_data->non_unique_name =
      base::NumberToString(specifics->client_consent_time_usec());
  entity_data->specifics.set_allocated_user_consent(specifics.release());
  return entity_data;
}

}  // namespace

ConsentSyncBridgeImpl::ConsentSyncBridgeImpl(
    OnceModelTypeStoreFactory store_factory,
    std::unique_ptr<ModelTypeChangeProcessor> change_processor)
    : ModelTypeSyncBridge(std::move(change_processor)),
      weak_ptr_factory_(this) {
  std::move(store_factory)
      .Run(syncer::USER_CONSENTS,
           base::BindOnce(&ConsentSyncBridgeImpl::OnStoreCreated,
                          weak_ptr_factory_.GetWeakPtr()));
}

ConsentSyncBridgeImpl::~ConsentSyncBridgeImpl() {
  if (!deferred_consents_while_initializing_.empty())
    LOG(ERROR) << "Non-empty event queue at shutdown!";
}

std::unique_ptr<MetadataChangeList>
ConsentSyncBridgeImpl::CreateMetadataChangeList() {
  return WriteBatch::CreateMetadataChangeList();
}

base::Optional<ModelError> ConsentSyncBridgeImpl::MergeSyncData(
    std::unique_ptr<MetadataChangeList> metadata_change_list,
    EntityChangeList entity_data) {
  DCHECK(entity_data.empty());
  DCHECK(change_processor()->IsTrackingMetadata());
  DCHECK(!change_processor()->TrackedAccountId().empty());
  ReadAllDataAndResubmit();
  return ApplySyncChanges(std::move(metadata_change_list),
                          std::move(entity_data));
}

base::Optional<ModelError> ConsentSyncBridgeImpl::ApplySyncChanges(
    std::unique_ptr<MetadataChangeList> metadata_change_list,
    EntityChangeList entity_changes) {
  std::unique_ptr<WriteBatch> batch = store_->CreateWriteBatch();
  for (const std::unique_ptr<EntityChange>& change : entity_changes) {
    DCHECK_EQ(EntityChange::ACTION_DELETE, change->type());
    batch->DeleteData(change->storage_key());
  }

  batch->TakeMetadataChangesFrom(std::move(metadata_change_list));
  store_->CommitWriteBatch(std::move(batch),
                           base::BindOnce(&ConsentSyncBridgeImpl::OnCommit,
                                          weak_ptr_factory_.GetWeakPtr()));
  return {};
}

void ConsentSyncBridgeImpl::GetData(StorageKeyList storage_keys,
                                    DataCallback callback) {
  store_->ReadData(
      storage_keys,
      base::BindOnce(&ConsentSyncBridgeImpl::OnReadData,
                     weak_ptr_factory_.GetWeakPtr(), std::move(callback)));
}

void ConsentSyncBridgeImpl::GetAllDataForDebugging(DataCallback callback) {
  store_->ReadAllData(base::BindOnce(&ConsentSyncBridgeImpl::OnReadAllData,
                                     weak_ptr_factory_.GetWeakPtr(),
                                     std::move(callback)));
}

std::string ConsentSyncBridgeImpl::GetClientTag(const EntityData& entity_data) {
  return GetStorageKey(entity_data);
}

std::string ConsentSyncBridgeImpl::GetStorageKey(
    const EntityData& entity_data) {
  return GetStorageKeyFromSpecifics(entity_data.specifics.user_consent());
}

void ConsentSyncBridgeImpl::ApplyStopSyncChanges(
    std::unique_ptr<MetadataChangeList> delete_metadata_change_list) {
  // Sync can only be stopped after initialization.
  DCHECK(deferred_consents_while_initializing_.empty());

  if (delete_metadata_change_list) {
    // Preserve all consents in the store, but delete their metadata, because it
    // may become invalid when the sync is reenabled. It is important to report
    // all user consents, thus, they are persisted for some time even after
    // signout. We will try to resubmit these consents once the sync is enabled
    // again. This may lead to same consent being submitted multiple times, but
    // this is allowed.
    std::unique_ptr<WriteBatch> batch = store_->CreateWriteBatch();
    batch->TakeMetadataChangesFrom(std::move(delete_metadata_change_list));

    store_->CommitWriteBatch(std::move(batch),
                             base::BindOnce(&ConsentSyncBridgeImpl::OnCommit,
                                            weak_ptr_factory_.GetWeakPtr()));
  }
}

void ConsentSyncBridgeImpl::ReadAllDataAndResubmit() {
  DCHECK(!change_processor()->TrackedAccountId().empty());
  DCHECK(change_processor()->IsTrackingMetadata());
  DCHECK(store_);
  store_->ReadAllData(
      base::BindOnce(&ConsentSyncBridgeImpl::OnReadAllDataToResubmit,
                     weak_ptr_factory_.GetWeakPtr()));
}

void ConsentSyncBridgeImpl::OnReadAllDataToResubmit(
    const base::Optional<ModelError>& error,
    std::unique_ptr<RecordList> data_records) {
  if (change_processor()->TrackedAccountId().empty()) {
    // Meanwhile the sync has been disabled. We will try next time.
    return;
  }
  DCHECK(change_processor()->IsTrackingMetadata());

  if (error) {
    change_processor()->ReportError(*error);
    return;
  }

  std::unique_ptr<WriteBatch> batch = store_->CreateWriteBatch();

  for (const Record& r : *data_records) {
    auto specifics = std::make_unique<UserConsentSpecifics>();
    if (specifics->ParseFromString(r.value)) {
      if (specifics->account_id() == change_processor()->TrackedAccountId()) {
        change_processor()->Put(r.id, MoveToEntityData(std::move(specifics)),
                                batch->GetMetadataChangeList());
      }
    }
  }

  store_->CommitWriteBatch(std::move(batch),
                           base::BindOnce(&ConsentSyncBridgeImpl::OnCommit,
                                          weak_ptr_factory_.GetWeakPtr()));
}

void ConsentSyncBridgeImpl::RecordConsent(
    std::unique_ptr<UserConsentSpecifics> specifics) {
  // TODO(vitaliii): Sanity-check specifics->account_id() against
  // change_processor()->TrackedAccountId(), maybe DCHECK.
  DCHECK(!specifics->account_id().empty());
  if (store_) {
    RecordConsentImpl(std::move(specifics));
    return;
  }
  deferred_consents_while_initializing_.push_back(std::move(specifics));
}

// static
std::string ConsentSyncBridgeImpl::GetStorageKeyFromSpecificsForTest(
    const UserConsentSpecifics& specifics) {
  return GetStorageKeyFromSpecifics(specifics);
}

std::unique_ptr<ModelTypeStore> ConsentSyncBridgeImpl::StealStoreForTest() {
  return std::move(store_);
}

void ConsentSyncBridgeImpl::RecordConsentImpl(
    std::unique_ptr<UserConsentSpecifics> specifics) {
  DCHECK(store_);

  std::string storage_key = GetStorageKeyFromSpecifics(*specifics);
  std::unique_ptr<WriteBatch> batch = store_->CreateWriteBatch();
  batch->WriteData(storage_key, specifics->SerializeAsString());

  if (specifics->account_id() == change_processor()->TrackedAccountId()) {
    change_processor()->Put(storage_key, MoveToEntityData(std::move(specifics)),
                            batch->GetMetadataChangeList());
  }

  store_->CommitWriteBatch(std::move(batch),
                           base::BindOnce(&ConsentSyncBridgeImpl::OnCommit,
                                          weak_ptr_factory_.GetWeakPtr()));
}

base::WeakPtr<syncer::ModelTypeControllerDelegate>
ConsentSyncBridgeImpl::GetControllerDelegate() {
  return change_processor()->GetControllerDelegate();
}

void ConsentSyncBridgeImpl::ProcessQueuedEvents() {
  for (std::unique_ptr<sync_pb::UserConsentSpecifics>& event :
       deferred_consents_while_initializing_) {
    RecordConsentImpl(std::move(event));
  }
  deferred_consents_while_initializing_.clear();
}

void ConsentSyncBridgeImpl::OnStoreCreated(
    const base::Optional<ModelError>& error,
    std::unique_ptr<ModelTypeStore> store) {
  if (error) {
    change_processor()->ReportError(*error);
    return;
  }

  store_ = std::move(store);
  store_->ReadAllMetadata(
      base::BindOnce(&ConsentSyncBridgeImpl::OnReadAllMetadata,
                     weak_ptr_factory_.GetWeakPtr()));
}

void ConsentSyncBridgeImpl::OnReadAllMetadata(
    const base::Optional<ModelError>& error,
    std::unique_ptr<MetadataBatch> metadata_batch) {
  if (error) {
    change_processor()->ReportError(*error);
  } else {
    change_processor()->ModelReadyToSync(std::move(metadata_batch));
    if (!change_processor()->TrackedAccountId().empty()) {
      // We resubmit all data in case the client crashed immediately after
      // MergeSyncData(), where submissions are supposed to happen and
      // metadata populated. This would be simpler if MergeSyncData() were
      // asynchronous.
      ReadAllDataAndResubmit();
    }
    ProcessQueuedEvents();
  }
}

void ConsentSyncBridgeImpl::OnCommit(const base::Optional<ModelError>& error) {
  if (error) {
    change_processor()->ReportError(*error);
  }
}

void ConsentSyncBridgeImpl::OnReadData(
    DataCallback callback,
    const base::Optional<ModelError>& error,
    std::unique_ptr<RecordList> data_records,
    std::unique_ptr<IdList> missing_id_list) {
  OnReadAllData(std::move(callback), error, std::move(data_records));
}

void ConsentSyncBridgeImpl::OnReadAllData(
    DataCallback callback,
    const base::Optional<ModelError>& error,
    std::unique_ptr<RecordList> data_records) {
  if (error) {
    change_processor()->ReportError(*error);
    return;
  }

  auto batch = std::make_unique<MutableDataBatch>();
  for (const Record& r : *data_records) {
    auto specifics = std::make_unique<UserConsentSpecifics>();

    if (specifics->ParseFromString(r.value)) {
      DCHECK_EQ(r.id, GetStorageKeyFromSpecifics(*specifics));
      batch->Put(r.id, MoveToEntityData(std::move(specifics)));
    } else {
      change_processor()->ReportError(
          {FROM_HERE, "Failed deserializing user events."});
      return;
    }
  }
  std::move(callback).Run(std::move(batch));
}

}  // namespace consent_auditor