#include <algorithm>
#include <cstring>
#include <iostream>
#include <string>

class BufferedWriter {
public:
  char buffer[16];
  std::size_t filled;

  BufferedWriter() {
    std::fill(this->buffer, this->buffer + sizeof(this->buffer), 0);

    this->filled = 0;
  }

  std::size_t write(const char* bytes, const size_t length) {
    if (length > sizeof(this->buffer) - filled) {
      std::size_t total = this->flush() + length;

      std::cout << std::string(bytes, length);

      return total;
    } else {
      std::strncpy(this->buffer + filled, bytes, length);

      this->filled += length;

      return 0;
    }
  }

  std::size_t flush() {
    if (this->filled == 0) {
      return 0;
    }

    std::cout << std::string(this->buffer, this->filled);

    std::size_t total = this->filled;

    this->filled = 0;

    std::fill(this->buffer, this->buffer + sizeof(this->buffer), 0);

    return total;
  }
};

int main(int argc, char** argv) {
  BufferedWriter writer;

  writer.write("hello\n", 6);

  writer.write("world\n", 6);

  writer.write("12345678\n", 9);

  writer.write("lol\n", 4);

  std::cout << "all writes made, flushing the buffer..." << std::endl;

  writer.flush();
}