#ifndef LOCKFREE_READ_HELPER_H
#define LOCKFREE_READ_HELPER_H

#include <cassert>
#include <cstdio>
#include <random>
#include <vector>
#ifndef P_EFF
#ifndef NDEBUG
#define P_ERR(...) fprintf(stderr, __VA_ARGS__)
#else
#define P_ERR(...)
#endif
#endif

class ReadHelper {
  unsigned long long max_value = 0, min_value = 0x7fffffffff;

  char const *filename;

public:
  ReadHelper(char const *filename) : filename(filename) {}
  unsigned long long maxValue() const { return max_value; }
  unsigned long long minValue() const { return min_value; }

  std::vector<unsigned long long> population_vector;
  inline void store_into_vector(unsigned long long value) {
    if (max_value < value) {
      max_value = value;
    }
    if (min_value > value) {
      min_value = value;
    }
    population_vector.push_back(value);
  }

  static unsigned long randomRow(unsigned long max_value_) {
    std::random_device randomDevice;
    std::mt19937 mt19937(randomDevice());
    std::uniform_int_distribution<std::mt19937::result_type> dst(0, max_value_);
    return dst(mt19937);
  }

  void readFile(long sample_length, unsigned long &total_row,
                unsigned long max_number) {
    auto read_number = 0UL;
    FILE *file = fopen(filename, "r");
    assert(file);
    P_ERR("Reading sample");
    for (long long i;
         read_number < max_number && fscanf(file, "%lld ", &i) != EOF;
         store_into_vector(i))
      read_number++;

    if (total_row > 0) {
      P_ERR("\rReading skip");
      read_number = randomRow(total_row - sample_length - max_number - 256);
      total_row = read_number;
      // fprintf(stderr, "Skip %lu\n", read_number);
      for (long long i; read_number > 0 && fscanf(file, "%lld ", &i) != EOF;)
        read_number--;
    }

    P_ERR("\rReading population");
    read_number = 0;

    auto remain = sample_length + 256;
    for (long long i; read_number < remain && fscanf(file, "%lld ", &i) != EOF;
         store_into_vector(i))
      read_number++;
    fclose(file);
    P_ERR("\r");
  }
};
#endif