// 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.

#include "db/version_edit.h"

#include "db/version_set.h"

#include "util/coding.h"

namespace leveldb {

// Tag numbers for serialized VersionEdit.  These numbers are written to

// disk and should not be changed.

enum Tag {

  kComparator = 1,

  kLogNumber = 2,

  kNextFileNumber = 3,

  kLastSequence = 4,

  kCompactPointer = 5,

  kDeletedFile = 6,

  kNewFile = 7,

  // 8 was used for large value refs

  kPrevLogNumber = 9

};

void VersionEdit::Clear() {

  comparator_.clear();

  log_number_ = 0;

  prev_log_number_ = 0;

  last_sequence_ = 0;

  next_file_number_ = 0;

  has_comparator_ = false;

  has_log_number_ = false;

  has_prev_log_number_ = false;

  has_next_file_number_ = false;

  has_last_sequence_ = false;

  compact_pointers_.clear();

  deleted_files_.clear();

  new_files_.clear();

}

void VersionEdit::EncodeTo(std::string* dst) const {

  if (has_comparator_) {

    PutVarint32(dst, kComparator);

    PutLengthPrefixedSlice(dst, comparator_);

  }

  if (has_log_number_) {

    PutVarint32(dst, kLogNumber);

    PutVarint64(dst, log_number_);

  }

  if (has_prev_log_number_) {

    PutVarint32(dst, kPrevLogNumber);

    PutVarint64(dst, prev_log_number_);

  }

  if (has_next_file_number_) {

    PutVarint32(dst, kNextFileNumber);

    PutVarint64(dst, next_file_number_);

  }

  if (has_last_sequence_) {

    PutVarint32(dst, kLastSequence);

    PutVarint64(dst, last_sequence_);

  }

  for (size_t i = 0; i < compact_pointers_.size(); i++) {

    PutVarint32(dst, kCompactPointer);

    PutVarint32(dst, compact_pointers_[i].first);  // level

    PutLengthPrefixedSlice(dst, compact_pointers_[i].second.Encode());

  }

  for (const auto& deleted_file_kvp : deleted_files_) {

    PutVarint32(dst, kDeletedFile);

    PutVarint32(dst, deleted_file_kvp.first);   // level

    PutVarint64(dst, deleted_file_kvp.second);  // file number

  }

  for (size_t i = 0; i < new_files_.size(); i++) {

    const FileMetaData& f = new_files_[i].second;

    PutVarint32(dst, kNewFile);

    PutVarint32(dst, new_files_[i].first);  // level

    PutVarint64(dst, f.number);

    PutVarint64(dst, f.file_size);

    PutLengthPrefixedSlice(dst, f.smallest.Encode());

    PutLengthPrefixedSlice(dst, f.largest.Encode());

  }

}

static bool GetInternalKey(Slice* input, InternalKey* dst) {

  Slice str;

  if (GetLengthPrefixedSlice(input, &str)) {

    return dst->DecodeFrom(str);

  } else {

    return false;

  }

}

static bool GetLevel(Slice* input, int* level) {

  uint32_t v;

  if (GetVarint32(input, &v) && v < config::kNumLevels) {

    *level = v;

    return true;

  } else {

    return false;

  }

}

Status VersionEdit::DecodeFrom(const Slice& src) {

  Clear();

  Slice input = src;

  const char* msg = nullptr;

  uint32_t tag;

  // Temporary storage for parsing

  int level;

  uint64_t number;

  FileMetaData f;

  Slice str;

  InternalKey key;

  while (msg == nullptr && GetVarint32(&input, &tag)) {

    switch (tag) {

      case kComparator:

        if (GetLengthPrefixedSlice(&input, &str)) {

          comparator_ = str.ToString();

          has_comparator_ = true;

        } else {

          msg = "comparator name";

        }

        break;

      case kLogNumber:

        if (GetVarint64(&input, &log_number_)) {

          has_log_number_ = true;

        } else {

          msg = "log number";

        }

        break;

      case kPrevLogNumber:

        if (GetVarint64(&input, &prev_log_number_)) {

          has_prev_log_number_ = true;

        } else {

          msg = "previous log number";

        }

        break;

      case kNextFileNumber:

        if (GetVarint64(&input, &next_file_number_)) {

          has_next_file_number_ = true;

        } else {

          msg = "next file number";

        }

        break;

      case kLastSequence:

        if (GetVarint64(&input, &last_sequence_)) {

          has_last_sequence_ = true;

        } else {

          msg = "last sequence number";

        }

        break;

      case kCompactPointer:

        if (GetLevel(&input, &level) && GetInternalKey(&input, &key)) {

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

        } else {

          msg = "compaction pointer";

        }

        break;

      case kDeletedFile:

        if (GetLevel(&input, &level) && GetVarint64(&input, &number)) {

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

        } else {

          msg = "deleted file";

        }

        break;

      case kNewFile:

        if (GetLevel(&input, &level) && GetVarint64(&input, &f.number) &&

            GetVarint64(&input, &f.file_size) &&

            GetInternalKey(&input, &f.smallest) &&

            GetInternalKey(&input, &f.largest)) {

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

        } else {

          msg = "new-file entry";

        }

        break;

      default:

        msg = "unknown tag";

        break;

    }

  }

  if (msg == nullptr && !input.empty()) {

    msg = "invalid tag";

  }

  Status result;

  if (msg != nullptr) {

    result = Status::Corruption("VersionEdit", msg);

  }

  return result;

}

std::string VersionEdit::DebugString() const {

  std::string r;

  r.append("VersionEdit {");

  if (has_comparator_) {

    r.append("\n  Comparator: ");

    r.append(comparator_);

  }

  if (has_log_number_) {

    r.append("\n  LogNumber: ");

    AppendNumberTo(&r, log_number_);

  }

  if (has_prev_log_number_) {

    r.append("\n  PrevLogNumber: ");

    AppendNumberTo(&r, prev_log_number_);

  }

  if (has_next_file_number_) {

    r.append("\n  NextFile: ");

    AppendNumberTo(&r, next_file_number_);

  }

  if (has_last_sequence_) {

    r.append("\n  LastSeq: ");

    AppendNumberTo(&r, last_sequence_);

  }

  for (size_t i = 0; i < compact_pointers_.size(); i++) {

    r.append("\n  CompactPointer: ");

    AppendNumberTo(&r, compact_pointers_[i].first);

    r.append(" ");

    r.append(compact_pointers_[i].second.DebugString());

  }

  for (const auto& deleted_files_kvp : deleted_files_) {

    r.append("\n  RemoveFile: ");

    AppendNumberTo(&r, deleted_files_kvp.first);

    r.append(" ");

    AppendNumberTo(&r, deleted_files_kvp.second);

  }

  for (size_t i = 0; i < new_files_.size(); i++) {

    const FileMetaData& f = new_files_[i].second;

    r.append("\n  AddFile: ");

    AppendNumberTo(&r, new_files_[i].first);

    r.append(" ");

    AppendNumberTo(&r, f.number);

    r.append(" ");

    AppendNumberTo(&r, f.file_size);

    r.append(" ");

    r.append(f.smallest.DebugString());

    r.append(" .. ");

    r.append(f.largest.DebugString());

  }

  r.append("\n}\n");

  return r;

}

}  // namespace leveldb