#pragma once
#include "file_reader.hpp"
#include "file_writer.hpp"
#include "record.hpp"
#include <vector>

class MergeSorter {
private:
  std::vector<Record> buffer_;
  const std::string &tmp_dir_;
  size_t buffer_rows_ = 0;
  size_t disk_reads_ = 0;
  size_t disk_writes_ = 0;
  size_t phases_ = 0;

  std::span<Record> get_chunk_span(size_t chunk_index);
  size_t create_initial_runs(const std::string &input_file,
                             const std::string &next_dir);
  size_t merge_pass(const std::string &current_dir, const std::string &next_dir,
                    size_t run_count);
  void perform_k_way_merge(std::vector<std::unique_ptr<FileReader>> &readers,
                           FileWriter &writer);

public:
  MergeSorter(size_t buffer_rows, size_t buffer_cols,
              const std::string &tmp_dir);
  void sort_file(const std::string &input_file, const std::string &output_file);

  size_t disk_reads();
  size_t disk_writes();
  size_t phases();
};