/*
    This file is part of TON Blockchain Library.

    TON Blockchain Library is free software: you can redistribute it and/or modify
    it under the terms of the GNU Lesser General Public License as published by
    the Free Software Foundation, either version 2 of the License, or
    (at your option) any later version.

    TON Blockchain Library is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU Lesser General Public License for more details.

    You should have received a copy of the GNU Lesser General Public License
    along with TON Blockchain Library.  If not, see <http://www.gnu.org/licenses/>.

    Copyright 2017-2020 Telegram Systems LLP
*/
#include "td/db/RocksDb.h"

#include "rocksdb/db.h"
#include "rocksdb/table.h"
#include "rocksdb/statistics.h"
#include "rocksdb/write_batch.h"
#include "rocksdb/utilities/optimistic_transaction_db.h"
#include "rocksdb/utilities/transaction.h"

namespace td {
namespace {
static Status from_rocksdb(rocksdb::Status status) {
  if (status.ok()) {
    return Status::OK();
  }
  return Status::Error(status.ToString());
}
static Slice from_rocksdb(rocksdb::Slice slice) {
  return Slice(slice.data(), slice.size());
}
static rocksdb::Slice to_rocksdb(Slice slice) {
  return rocksdb::Slice(slice.data(), slice.size());
}
}  // namespace

Status RocksDb::destroy(Slice path) {
  return from_rocksdb(rocksdb::DestroyDB(path.str(), {}));
}

RocksDb::RocksDb(RocksDb &&) = default;
RocksDb &RocksDb::operator=(RocksDb &&) = default;

RocksDb::~RocksDb() {
  if (!db_) {
    return;
  }
  end_snapshot().ensure();
}

RocksDb RocksDb::clone() const {
  return RocksDb{db_, options_};
}

Result<RocksDb> RocksDb::open(std::string path, RocksDbOptions options) {
  rocksdb::OptimisticTransactionDB *db;
  {
    rocksdb::Options db_options;

    static auto default_cache = rocksdb::NewLRUCache(1 << 30);
    if (options.block_cache == nullptr) {
      options.block_cache = default_cache;
    }

    rocksdb::BlockBasedTableOptions table_options;
    table_options.block_cache = options.block_cache;
    db_options.table_factory.reset(rocksdb::NewBlockBasedTableFactory(table_options));

    db_options.use_direct_reads = options.use_direct_reads;
    db_options.manual_wal_flush = true;
    db_options.create_if_missing = true;
    db_options.max_background_compactions = 4;
    db_options.max_background_flushes = 2;
    db_options.bytes_per_sync = 1 << 20;
    db_options.writable_file_max_buffer_size = 2 << 14;
    db_options.statistics = options.statistics;
    rocksdb::OptimisticTransactionDBOptions occ_options;
    occ_options.validate_policy = rocksdb::OccValidationPolicy::kValidateSerial;
    rocksdb::ColumnFamilyOptions cf_options(db_options);
    std::vector<rocksdb::ColumnFamilyDescriptor> column_families;
    column_families.push_back(rocksdb::ColumnFamilyDescriptor(rocksdb::kDefaultColumnFamilyName, cf_options));
    std::vector<rocksdb::ColumnFamilyHandle *> handles;
    TRY_STATUS(from_rocksdb(rocksdb::OptimisticTransactionDB::Open(db_options, occ_options, std::move(path),
                                                                   column_families, &handles, &db)));
    CHECK(handles.size() == 1);
    // i can delete the handle since DBImpl is always holding a reference to
    // default column family
    delete handles[0];
  }
  return RocksDb(std::shared_ptr<rocksdb::OptimisticTransactionDB>(db), std::move(options));
}

std::shared_ptr<rocksdb::Statistics> RocksDb::create_statistics() {
  return rocksdb::CreateDBStatistics();
}

std::string RocksDb::statistics_to_string(const std::shared_ptr<rocksdb::Statistics> statistics) {
  return statistics->ToString();
}

void RocksDb::reset_statistics(const std::shared_ptr<rocksdb::Statistics> statistics) {
  statistics->Reset();
}

std::shared_ptr<rocksdb::Cache> RocksDb::create_cache(size_t capacity) {
  return rocksdb::NewLRUCache(capacity);
}

std::unique_ptr<KeyValueReader> RocksDb::snapshot() {
  auto res = std::make_unique<RocksDb>(clone());
  res->begin_snapshot().ensure();
  return std::move(res);
}

std::string RocksDb::stats() const {
  std::string out;
  db_->GetProperty("rocksdb.stats", &out);
  //db_->GetProperty("rocksdb.cur-size-all-mem-tables", &out);
  return out;
}

Result<RocksDb::GetStatus> RocksDb::get(Slice key, std::string &value) {
  //LOG(ERROR) << "GET";
  rocksdb::Status status;
  if (snapshot_) {
    rocksdb::ReadOptions options;
    options.snapshot = snapshot_.get();
    status = db_->Get(options, to_rocksdb(key), &value);
  } else if (transaction_) {
    status = transaction_->Get({}, to_rocksdb(key), &value);
  } else {
    status = db_->Get({}, to_rocksdb(key), &value);
  }
  if (status.ok()) {
    return GetStatus::Ok;
  }
  if (status.code() == rocksdb::Status::kNotFound) {
    return GetStatus::NotFound;
  }
  return from_rocksdb(status);
}

Status RocksDb::set(Slice key, Slice value) {
  if (write_batch_) {
    return from_rocksdb(write_batch_->Put(to_rocksdb(key), to_rocksdb(value)));
  }
  if (transaction_) {
    return from_rocksdb(transaction_->Put(to_rocksdb(key), to_rocksdb(value)));
  }
  return from_rocksdb(db_->Put({}, to_rocksdb(key), to_rocksdb(value)));
}

Status RocksDb::erase(Slice key) {
  if (write_batch_) {
    return from_rocksdb(write_batch_->Delete(to_rocksdb(key)));
  }
  if (transaction_) {
    return from_rocksdb(transaction_->Delete(to_rocksdb(key)));
  }
  return from_rocksdb(db_->Delete({}, to_rocksdb(key)));
}

Result<size_t> RocksDb::count(Slice prefix) {
  rocksdb::ReadOptions options;
  options.snapshot = snapshot_.get();
  std::unique_ptr<rocksdb::Iterator> iterator;
  if (snapshot_ || !transaction_) {
    iterator.reset(db_->NewIterator(options));
  } else {
    iterator.reset(transaction_->GetIterator(options));
  }

  size_t res = 0;
  for (iterator->Seek(to_rocksdb(prefix)); iterator->Valid(); iterator->Next()) {
    if (from_rocksdb(iterator->key()).truncate(prefix.size()) != prefix) {
      break;
    }
    res++;
  }
  if (!iterator->status().ok()) {
    return from_rocksdb(iterator->status());
  }
  return res;
}

Status RocksDb::for_each(std::function<Status(Slice, Slice)> f) {
  rocksdb::ReadOptions options;
  options.snapshot = snapshot_.get();
  std::unique_ptr<rocksdb::Iterator> iterator;
  if (snapshot_ || !transaction_) {
    iterator.reset(db_->NewIterator(options));
  } else {
    iterator.reset(transaction_->GetIterator(options));
  }

  iterator->SeekToFirst();
  for (; iterator->Valid(); iterator->Next()) {
    auto key = from_rocksdb(iterator->key());
    auto value = from_rocksdb(iterator->value());
    TRY_STATUS(f(key, value));
  }
  if (!iterator->status().ok()) {
    return from_rocksdb(iterator->status());
  }
  return Status::OK();
}

Status RocksDb::begin_write_batch() {
  CHECK(!transaction_);
  write_batch_ = std::make_unique<rocksdb::WriteBatch>();
  return Status::OK();
}

Status RocksDb::begin_transaction() {
  CHECK(!write_batch_);
  rocksdb::WriteOptions options;
  options.sync = true;
  transaction_.reset(db_->BeginTransaction(options, {}));
  return Status::OK();
}

Status RocksDb::commit_write_batch() {
  CHECK(write_batch_);
  auto write_batch = std::move(write_batch_);
  rocksdb::WriteOptions options;
  options.sync = true;
  return from_rocksdb(db_->Write(options, write_batch.get()));
}

Status RocksDb::commit_transaction() {
  CHECK(transaction_);
  auto transaction = std::move(transaction_);
  return from_rocksdb(transaction->Commit());
}

Status RocksDb::abort_write_batch() {
  CHECK(write_batch_);
  write_batch_.reset();
  return Status::OK();
}

Status RocksDb::abort_transaction() {
  CHECK(transaction_);
  transaction_.reset();
  return Status::OK();
}

Status RocksDb::flush() {
  return from_rocksdb(db_->Flush({}));
}

Status RocksDb::begin_snapshot() {
  snapshot_.reset(db_->GetSnapshot());
  return td::Status::OK();
}

Status RocksDb::end_snapshot() {
  if (snapshot_) {
    db_->ReleaseSnapshot(snapshot_.release());
  }
  return td::Status::OK();
}

RocksDb::RocksDb(std::shared_ptr<rocksdb::OptimisticTransactionDB> db, RocksDbOptions options)
    : db_(std::move(db)), options_(options) {
}
}  // namespace td