//  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).

//

// 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.

#pragma once

#include <stdint.h>

#include <vector>

#include "rocksdb/slice.h"

#include "rocksdb/table.h"

#include "table/block_based/data_block_hash_index.h"

namespace ROCKSDB_NAMESPACE {

class BlockBuilder {

 public:

  BlockBuilder(const BlockBuilder&) = delete;

  void operator=(const BlockBuilder&) = delete;

  explicit BlockBuilder(int block_restart_interval,

                        bool use_delta_encoding = true,

                        bool use_value_delta_encoding = false,

                        BlockBasedTableOptions::DataBlockIndexType index_type =

                            BlockBasedTableOptions::kDataBlockBinarySearch,

                        double data_block_hash_table_util_ratio = 0.75,

                        size_t ts_sz = 0,

                        bool persist_user_defined_timestamps = true,

                        bool is_user_key = false);

  // Reset the contents as if the BlockBuilder was just constructed.

  void Reset();

  // Swap the contents in BlockBuilder with buffer, then reset the BlockBuilder.

  void SwapAndReset(std::string& buffer);

  // REQUIRES: Finish() has not been called since the last call to Reset().

  // REQUIRES: Unless a range tombstone block, key is larger than any previously

  //           added key

  // DO NOT mix with AddWithLastKey() between Resets. For efficiency, use

  // AddWithLastKey() in contexts where previous added key is already known

  // and delta encoding might be used.

  void Add(const Slice& key, const Slice& value,

           const Slice* const delta_value = nullptr);

  // A faster version of Add() if the previous key is already known for all

  // Add()s.

  // REQUIRES: Finish() has not been called since the last call to Reset().

  // REQUIRES: Unless a range tombstone block, key is larger than any previously

  //           added key

  // REQUIRES: if AddWithLastKey has been called since last Reset(), last_key

  // is the key from most recent AddWithLastKey. (For convenience, last_key

  // is ignored on first call after creation or Reset().)

  // DO NOT mix with Add() between Resets.

  void AddWithLastKey(const Slice& key, const Slice& value,

                      const Slice& last_key,

                      const Slice* const delta_value = nullptr);

  // Finish building the block and return a slice that refers to the

  // block contents.  The returned slice will remain valid for the

  // lifetime of this builder or until Reset() is called.

  Slice Finish();

  // Returns an estimate of the current (uncompressed) size of the block

  // we are building.

  inline size_t CurrentSizeEstimate() const {

    return estimate_ + (data_block_hash_index_builder_.Valid()

                            ? data_block_hash_index_builder_.EstimateSize()

                            : 0);

  }

  // Returns an estimated block size after appending key and value.

  size_t EstimateSizeAfterKV(const Slice& key, const Slice& value) const;

  // Return true iff no entries have been added since the last Reset()

  bool empty() const { return buffer_.empty(); }

 private:

  inline void AddWithLastKeyImpl(const Slice& key, const Slice& value,

                                 const Slice& last_key,

                                 const Slice* const delta_value,

                                 size_t buffer_size);

  inline const Slice MaybeStripTimestampFromKey(std::string* key_buf,

                                                const Slice& key);

  const int block_restart_interval_;

  // TODO(myabandeh): put it into a separate IndexBlockBuilder

  const bool use_delta_encoding_;

  // Refer to BlockIter::DecodeCurrentValue for format of delta encoded values

  const bool use_value_delta_encoding_;

  // Size in bytes for the user-defined timestamp to strip in a user key.

  // This is non-zero if there is user-defined timestamp in the user key and it

  // should not be persisted.

  const size_t strip_ts_sz_;

  // Whether the keys provided to build this block are user keys. If not,

  // the keys are internal keys. This will affect how timestamp stripping is

  // done for the key if `persisted_user_defined_timestamps_` is false and

  // `ts_sz_` is non-zero.

  // The timestamp stripping only applies to the keys added to the block. If the

  // value contains user defined timestamp that needed to be stripped too, such

  // as the `first_internal_key` in an `IndexValue` for an index block, the

  // value part for a range deletion entry, their timestamp should be stripped

  // before calling `BlockBuilder::Add`.

  // Timestamp stripping only applies to data block and index blocks including

  // index block for data blocks, index block for partitioned filter blocks,

  // index block for partitioned index blocks. In summary, this only applies to

  // block whose key are real user keys or internal keys created from user keys.

  const bool is_user_key_;

  std::string buffer_;              // Destination buffer

  std::vector<uint32_t> restarts_;  // Restart points

  size_t estimate_;

  int counter_;    // Number of entries emitted since restart

  bool finished_;  // Has Finish() been called?

  std::string last_key_;

  DataBlockHashIndexBuilder data_block_hash_index_builder_;

#ifndef NDEBUG

  bool add_with_last_key_called_ = false;

#endif

};

}  // namespace ROCKSDB_NAMESPACE