// 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 <memory>
#include <stdint.h>

#include "rocksdb/options.h"
#include "rocksdb/table.h"

namespace rocksdb {

struct Options;
struct EnvOptions;

using std::unique_ptr;
class Status;
class RandomAccessFile;
class WritableFile;
class Table;
class TableBuilder;

// IndexedTable requires fixed length key, configured as a constructor
// parameter of the factory class. Output file format:
// +-------------+-----------------+
// | version     | user_key_length |
// +------------++------------------------------+  <= key1 offset
// | [key_size] |  key1       | value_size  |   |
// +------------+-------------+-------------+   |
// | value1                                     |
// |                                            |
// +----------------------------------------+---+  <= key2 offset
// | [key_size] |  key2       | value_size  |   |
// +------------+-------------+-------------+   |
// | value2                                     |
// |                                            |
// |        ......                              |
// +-----------------+--------------------------+
// If user_key_length = kVariableLength, it means the key is variable length,
// there will be an extra field for key size encoded before every key.
class PlainTableFactory: public TableFactory {
public:
  ~PlainTableFactory() {
  }
  // user_key_size is the length of the user key. If it is set to be
  // kVariableLength, then it means variable length. Otherwise, all the
  // keys need to have the fix length of this value. bloom_num_bits is
  // number of bits used for bloom filer per key. hash_table_ratio is
  // the desired utilization of the hash table used for prefix hashing.
  // hash_table_ratio = number of prefixes / #buckets in the hash table
  explicit PlainTableFactory(uint32_t user_key_len = kVariableLength,
                             int bloom_num_bits = 0,
                             double hash_table_ratio = 0.75) :
      user_key_len_(user_key_len), bloom_num_bits_(bloom_num_bits),
      hash_table_ratio_(hash_table_ratio) {
  }
  const char* Name() const override {
    return "PlainTable";
  }
  Status GetTableReader(const Options& options, const EnvOptions& soptions,
                        unique_ptr<RandomAccessFile> && file,
                        uint64_t file_size,
                        unique_ptr<TableReader>* table) const override;

  TableBuilder* GetTableBuilder(const Options& options, WritableFile* file,
                                CompressionType compression_type) const
                                    override;

  static const uint32_t kVariableLength = 0;
private:
  uint32_t user_key_len_;
  int bloom_num_bits_;
  double hash_table_ratio_;
};

}  // namespace rocksdb