//  Copyright (c) 2011-present, Facebook, Inc.  All rights reserved.

//  This source code is licensed under both the GPLv2 (found in the

//  COPYING file in the root directory) and Apache 2.0 License

//  (found in the LICENSE.Apache file in the root directory).

#pragma once

#include <cstdint>

#include <memory>

#include <string>

#include "db/blob/blob_log_format.h"

#include "rocksdb/slice.h"

#include "rocksdb/statistics.h"

#include "rocksdb/status.h"

#include "rocksdb/types.h"

namespace ROCKSDB_NAMESPACE {

class WritableFileWriter;

class SystemClock;

/**

 * BlobLogWriter is the blob log stream writer. It provides an append-only

 * abstraction for writing blob data.

 *

 *

 * Look at blob_db_format.h to see the details of the record formats.

 */

class BlobLogWriter {

 public:

  // Create a writer that will append data to "*dest".

  // "*dest" must be initially empty.

  // "*dest" must remain live while this BlobLogWriter is in use.

  BlobLogWriter(std::unique_ptr<WritableFileWriter>&& dest, SystemClock* clock,

                Statistics* statistics, uint64_t log_number, bool use_fsync,

                bool do_flush, uint64_t boffset = 0);

  // No copying allowed

  BlobLogWriter(const BlobLogWriter&) = delete;

  BlobLogWriter& operator=(const BlobLogWriter&) = delete;

  ~BlobLogWriter();

  static void ConstructBlobHeader(std::string* buf, const Slice& key,

                                  const Slice& val, uint64_t expiration);

  Status AddRecord(const WriteOptions& write_options, const Slice& key,

                   const Slice& val, uint64_t* key_offset,

                   uint64_t* blob_offset);

  Status AddRecord(const WriteOptions& write_options, const Slice& key,

                   const Slice& val, uint64_t expiration, uint64_t* key_offset,

                   uint64_t* blob_offset);

  Status EmitPhysicalRecord(const WriteOptions& write_options,

                            const std::string& headerbuf, const Slice& key,

                            const Slice& val, uint64_t* key_offset,

                            uint64_t* blob_offset);

  Status AppendFooter(const WriteOptions& write_options, BlobLogFooter& footer,

                      std::string* checksum_method,

                      std::string* checksum_value);

  Status WriteHeader(const WriteOptions& write_options, BlobLogHeader& header);

  WritableFileWriter* file() { return dest_.get(); }

  const WritableFileWriter* file() const { return dest_.get(); }

  uint64_t get_log_number() const { return log_number_; }

  Status Sync(const WriteOptions& write_options);

 private:

  std::unique_ptr<WritableFileWriter> dest_;

  SystemClock* clock_;

  Statistics* statistics_;

  uint64_t log_number_;

  uint64_t block_offset_;  // Current offset in block

  bool use_fsync_;

  bool do_flush_;

 public:

  enum ElemType { kEtNone, kEtFileHdr, kEtRecord, kEtFileFooter };

  ElemType last_elem_type_;

};

}  // namespace ROCKSDB_NAMESPACE