//  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 <unordered_map>

#include "rocksdb/file_checksum.h"

#include "util/coding.h"

#include "util/crc32c.h"

#include "util/math.h"

namespace ROCKSDB_NAMESPACE {

// Converts a 32-bit checksum value (e.g. a CRC32C) to its hex string

// representation, matching the on-disk/backup-metadata encoding. Shared by the

// backup and copy engines.

inline std::string ChecksumInt32ToHex(uint32_t checksum_value) {

  std::string checksum_str;

  PutFixed32(&checksum_str, EndianSwapValue(checksum_value));

  return Slice(checksum_str).ToString(/*hex=*/true);

}

// This is the class to generate the file checksum based on Crc32. It

// will be used as the default checksum method for SST file checksum

class FileChecksumGenCrc32c : public FileChecksumGenerator {

 public:

  FileChecksumGenCrc32c(const FileChecksumGenContext& /*context*/) {

    checksum_ = 0;

  }

  void Update(const char* data, size_t n) override {

    checksum_ = crc32c::Extend(checksum_, data, n);

  }

  void Finalize() override {

    assert(checksum_str_.empty());

    // Store as big endian raw bytes

    PutFixed32(&checksum_str_, EndianSwapValue(checksum_));

  }

  std::string GetChecksum() const override {

    assert(!checksum_str_.empty());

    return checksum_str_;

  }

  const char* Name() const override { return "FileChecksumCrc32c"; }

 private:

  uint32_t checksum_;

  std::string checksum_str_;

};

class FileChecksumGenCrc32cFactory : public FileChecksumGenFactory {

 public:

  std::unique_ptr<FileChecksumGenerator> CreateFileChecksumGenerator(

      const FileChecksumGenContext& context) override {

    if (context.requested_checksum_func_name.empty() ||

        context.requested_checksum_func_name == "FileChecksumCrc32c") {

      return std::unique_ptr<FileChecksumGenerator>(

          new FileChecksumGenCrc32c(context));

    } else {

      return nullptr;

    }

  }

  static const char* kClassName() { return "FileChecksumGenCrc32cFactory"; }

  const char* Name() const override { return kClassName(); }

};

// The default implementaion of FileChecksumList

class FileChecksumListImpl : public FileChecksumList {

 public:

  FileChecksumListImpl() {}

  void reset() override;

  size_t size() const override;

  Status GetAllFileChecksums(

      std::vector<uint64_t>* file_numbers, std::vector<std::string>* checksums,

      std::vector<std::string>* checksum_func_names) override;

  Status SearchOneFileChecksum(uint64_t file_number, std::string* checksum,

                               std::string* checksum_func_name) override;

  Status InsertOneFileChecksum(uint64_t file_number,

                               const std::string& checksum,

                               const std::string& checksum_func_name) override;

  Status RemoveOneFileChecksum(uint64_t file_number) override;

 private:

  // Key is the file number, the first portion of the value is checksum, the

  // second portion of the value is checksum function name.

  std::unordered_map<uint64_t, std::pair<std::string, std::string>>

      checksum_map_;

};

}  // namespace ROCKSDB_NAMESPACE