//  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 <cassert>

#include <cstdint>

#include <iosfwd>

#include <memory>

#include <string>

#include <unordered_set>

#include "rocksdb/rocksdb_namespace.h"

namespace ROCKSDB_NAMESPACE {

// SharedBlobFileMetaData represents the immutable part of blob files' metadata,

// like the blob file number, total number and size of blobs, or checksum

// method and value. There is supposed to be one object of this class per blob

// file (shared across all versions that include the blob file in question);

// hence, the type is neither copyable nor movable. A blob file can be marked

// obsolete when the corresponding SharedBlobFileMetaData object is destroyed.

class SharedBlobFileMetaData {

 public:

  static std::shared_ptr<SharedBlobFileMetaData> Create(

      uint64_t blob_file_number, uint64_t total_blob_count,

      uint64_t total_blob_bytes, std::string checksum_method,

      std::string checksum_value) {

    return std::shared_ptr<SharedBlobFileMetaData>(new SharedBlobFileMetaData(

        blob_file_number, total_blob_count, total_blob_bytes,

        std::move(checksum_method), std::move(checksum_value)));

  }

  template <typename Deleter>

  static std::shared_ptr<SharedBlobFileMetaData> Create(

      uint64_t blob_file_number, uint64_t total_blob_count,

      uint64_t total_blob_bytes, std::string checksum_method,

      std::string checksum_value, Deleter deleter) {

    return std::shared_ptr<SharedBlobFileMetaData>(

        new SharedBlobFileMetaData(blob_file_number, total_blob_count,

                                   total_blob_bytes, std::move(checksum_method),

                                   std::move(checksum_value)),

        deleter);

  }

  SharedBlobFileMetaData(const SharedBlobFileMetaData&) = delete;

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

  SharedBlobFileMetaData(SharedBlobFileMetaData&&) = delete;

  SharedBlobFileMetaData& operator=(SharedBlobFileMetaData&&) = delete;

  uint64_t GetBlobFileSize() const;

  uint64_t GetBlobFileNumber() const { return blob_file_number_; }

  uint64_t GetTotalBlobCount() const { return total_blob_count_; }

  uint64_t GetTotalBlobBytes() const { return total_blob_bytes_; }

  const std::string& GetChecksumMethod() const { return checksum_method_; }

  const std::string& GetChecksumValue() const { return checksum_value_; }

  std::string DebugString() const;

 private:

  SharedBlobFileMetaData(uint64_t blob_file_number, uint64_t total_blob_count,

                         uint64_t total_blob_bytes, std::string checksum_method,

                         std::string checksum_value)

      : blob_file_number_(blob_file_number),

        total_blob_count_(total_blob_count),

        total_blob_bytes_(total_blob_bytes),

        checksum_method_(std::move(checksum_method)),

        checksum_value_(std::move(checksum_value)) {

    assert(checksum_method_.empty() == checksum_value_.empty());

  }

  uint64_t blob_file_number_;

  uint64_t total_blob_count_;

  uint64_t total_blob_bytes_;

  std::string checksum_method_;

  std::string checksum_value_;

};

std::ostream& operator<<(std::ostream& os,

                         const SharedBlobFileMetaData& shared_meta);

// BlobFileMetaData contains the part of the metadata for blob files that can

// vary across versions, like the amount of garbage in the blob file. In

// addition, BlobFileMetaData objects point to and share the ownership of the

// SharedBlobFileMetaData object for the corresponding blob file. Similarly to

// SharedBlobFileMetaData, BlobFileMetaData are not copyable or movable. They

// are meant to be jointly owned by the versions in which the blob file has the

// same (immutable *and* mutable) state.

class BlobFileMetaData {

 public:

  using LinkedSsts = std::unordered_set<uint64_t>;

  static std::shared_ptr<BlobFileMetaData> Create(

      std::shared_ptr<SharedBlobFileMetaData> shared_meta,

      LinkedSsts linked_ssts, uint64_t garbage_blob_count,

      uint64_t garbage_blob_bytes) {

    return std::shared_ptr<BlobFileMetaData>(

        new BlobFileMetaData(std::move(shared_meta), std::move(linked_ssts),

                             garbage_blob_count, garbage_blob_bytes));

  }

  BlobFileMetaData(const BlobFileMetaData&) = delete;

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

  BlobFileMetaData(BlobFileMetaData&&) = delete;

  BlobFileMetaData& operator=(BlobFileMetaData&&) = delete;

  const std::shared_ptr<SharedBlobFileMetaData>& GetSharedMeta() const {

    return shared_meta_;

  }

  uint64_t GetBlobFileSize() const {

    assert(shared_meta_);

    return shared_meta_->GetBlobFileSize();

  }

  uint64_t GetBlobFileNumber() const {

    assert(shared_meta_);

    return shared_meta_->GetBlobFileNumber();

  }

  uint64_t GetTotalBlobCount() const {

    assert(shared_meta_);

    return shared_meta_->GetTotalBlobCount();

  }

  uint64_t GetTotalBlobBytes() const {

    assert(shared_meta_);

    return shared_meta_->GetTotalBlobBytes();

  }

  const std::string& GetChecksumMethod() const {

    assert(shared_meta_);

    return shared_meta_->GetChecksumMethod();

  }

  const std::string& GetChecksumValue() const {

    assert(shared_meta_);

    return shared_meta_->GetChecksumValue();

  }

  const LinkedSsts& GetLinkedSsts() const { return linked_ssts_; }

  uint64_t GetGarbageBlobCount() const { return garbage_blob_count_; }

  uint64_t GetGarbageBlobBytes() const { return garbage_blob_bytes_; }

  std::string DebugString() const;

 private:

  BlobFileMetaData(std::shared_ptr<SharedBlobFileMetaData> shared_meta,

                   LinkedSsts linked_ssts, uint64_t garbage_blob_count,

                   uint64_t garbage_blob_bytes)

      : shared_meta_(std::move(shared_meta)),

        linked_ssts_(std::move(linked_ssts)),

        garbage_blob_count_(garbage_blob_count),

        garbage_blob_bytes_(garbage_blob_bytes) {

    assert(shared_meta_);

    assert(garbage_blob_count_ <= shared_meta_->GetTotalBlobCount());

    assert(garbage_blob_bytes_ <= shared_meta_->GetTotalBlobBytes());

  }

  std::shared_ptr<SharedBlobFileMetaData> shared_meta_;

  LinkedSsts linked_ssts_;

  uint64_t garbage_blob_count_;

  uint64_t garbage_blob_bytes_;

};

std::ostream& operator<<(std::ostream& os, const BlobFileMetaData& meta);

}  // namespace ROCKSDB_NAMESPACE