// Copyright (c) 2011 The LevelDB Authors. All rights reserved.

// Use of this source code is governed by a BSD-style license that can be

// found in the LICENSE file. See the AUTHORS file for names of contributors.

#ifndef STORAGE_LEVELDB_DB_VERSION_EDIT_H_

#define STORAGE_LEVELDB_DB_VERSION_EDIT_H_

#include <set>

#include <utility>

#include <vector>

#include "db/dbformat.h"

namespace leveldb {

class VersionSet;

struct FileMetaData {

  FileMetaData() : refs(0), allowed_seeks(1 << 30), file_size(0) {}

  int refs;

  int allowed_seeks;  // Seeks allowed until compaction

  uint64_t number;

  uint64_t file_size;    // File size in bytes

  InternalKey smallest;  // Smallest internal key served by table

  InternalKey largest;   // Largest internal key served by table

};

class VersionEdit {

 public:

  VersionEdit() { Clear(); }

  ~VersionEdit() = default;

  void Clear();

  void SetComparatorName(const Slice& name) {

    has_comparator_ = true;

    comparator_ = name.ToString();

  }

  void SetLogNumber(uint64_t num) {

    has_log_number_ = true;

    log_number_ = num;

  }

  void SetPrevLogNumber(uint64_t num) {

    has_prev_log_number_ = true;

    prev_log_number_ = num;

  }

  void SetNextFile(uint64_t num) {

    has_next_file_number_ = true;

    next_file_number_ = num;

  }

  void SetLastSequence(SequenceNumber seq) {

    has_last_sequence_ = true;

    last_sequence_ = seq;

  }

  void SetCompactPointer(int level, const InternalKey& key) {

    compact_pointers_.push_back(std::make_pair(level, key));

  }

  // Add the specified file at the specified number.

  // REQUIRES: This version has not been saved (see VersionSet::SaveTo)

  // REQUIRES: "smallest" and "largest" are smallest and largest keys in file

  void AddFile(int level, uint64_t file, uint64_t file_size,

               const InternalKey& smallest, const InternalKey& largest) {

    FileMetaData f;

    f.number = file;

    f.file_size = file_size;

    f.smallest = smallest;

    f.largest = largest;

    new_files_.push_back(std::make_pair(level, f));

  }

  // Delete the specified "file" from the specified "level".

  void RemoveFile(int level, uint64_t file) {

    deleted_files_.insert(std::make_pair(level, file));

  }

  void EncodeTo(std::string* dst) const;

  Status DecodeFrom(const Slice& src);

  std::string DebugString() const;

 private:

  friend class VersionSet;

  typedef std::set<std::pair<int, uint64_t>> DeletedFileSet;

  std::string comparator_;

  uint64_t log_number_;

  uint64_t prev_log_number_;

  uint64_t next_file_number_;

  SequenceNumber last_sequence_;

  bool has_comparator_;

  bool has_log_number_;

  bool has_prev_log_number_;

  bool has_next_file_number_;

  bool has_last_sequence_;

  std::vector<std::pair<int, InternalKey>> compact_pointers_;

  DeletedFileSet deleted_files_;

  std::vector<std::pair<int, FileMetaData>> new_files_;

};

}  // namespace leveldb

#endif  // STORAGE_LEVELDB_DB_VERSION_EDIT_H_