#include <memory>


class BufferedReader {
 public:
  explicit BufferedReader(PackageStream* stream) {
    stream_ = stream;
    buffer_ = new char[stream_->PackageLen()];
    pos_ = 0;
    buffer_size_ = 0;
  }
  int32_t Read(char* output_buffer, int32_t buffer_len) {
      int32_t buffer_len_ = buffer_len;
      int32_t current_strpos = 0;
      while (buffer_len > 0) {
          if (pos_ == buffer_size_) {
              buffer_size_ = stream_->ReadPackage(buffer_);
              pos_ = 0;
              if (buffer_size_ == 0) {
                  delete[] buffer_;
                  return buffer_len_ - buffer_len;
              }
          }
          if (buffer_size_ - pos_ < buffer_len) {
              memcpy(output_buffer + current_strpos, \
                     buffer_ + pos_, buffer_size_ - pos_);
              current_strpos += buffer_size_ - pos_;
              buffer_len -= buffer_size_ - pos_;
              pos_ = 0;
              buffer_size_ = stream_->ReadPackage(buffer_);
              if (buffer_size_ == 0) {
                  delete[] buffer_;
                  return buffer_len_ - buffer_len;
              } else {
                  memcpy(output_buffer + current_strpos, \
                         buffer_ + pos_, buffer_size_ - pos_);
                  pos_ += buffer_len;
                  buffer_len = 0;
              }
          }
      }
      return buffer_len_;
  }

 private:
  char* buffer_;
  PackageStream* stream_;
  int32_t pos_;
  int32_t buffer_size_;
};