void ParquetFilePrinter::DebugPrint()

in src/parquet/printer.cc [35:155]
100 lines of code
17 McCabe index (conditional complexity)

void ParquetFilePrinter::DebugPrint(std::ostream& stream, std::list<int> selected_columns,
                                    bool print_values, bool print_key_value_metadata,
                                    const char* filename) {
  const FileMetaData* file_metadata = fileReader->metadata().get();

  stream << "File Name: " << filename << "\n";
  stream << "Version: " << file_metadata->version() << "\n";
  stream << "Created By: " << file_metadata->created_by() << "\n";
  stream << "Total rows: " << file_metadata->num_rows() << "\n";

  if (print_key_value_metadata) {
    auto key_value_metadata = file_metadata->key_value_metadata();
    int64_t size_of_key_value_metadata = key_value_metadata->size();
    stream << "Key Value File Metadata: " << size_of_key_value_metadata << " entries\n";
    for (int64_t i = 0; i < size_of_key_value_metadata; i++) {
      stream << " Key nr " << i << " " << key_value_metadata->key(i) << ": "
             << key_value_metadata->value(i) << "\n";
    }
  }

  stream << "Number of RowGroups: " << file_metadata->num_row_groups() << "\n";
  stream << "Number of Real Columns: "
         << file_metadata->schema()->group_node()->field_count() << "\n";

  if (selected_columns.size() == 0) {
    for (int i = 0; i < file_metadata->num_columns(); i++) {
      selected_columns.push_back(i);
    }
  } else {
    for (auto i : selected_columns) {
      if (i < 0 || i >= file_metadata->num_columns()) {
        throw ParquetException("Selected column is out of range");
      }
    }
  }

  stream << "Number of Columns: " << file_metadata->num_columns() << "\n";
  stream << "Number of Selected Columns: " << selected_columns.size() << "\n";
  for (auto i : selected_columns) {
    const ColumnDescriptor* descr = file_metadata->schema()->Column(i);
    stream << "Column " << i << ": " << descr->name() << " ("
           << TypeToString(descr->physical_type()) << ")" << std::endl;
  }

  for (int r = 0; r < file_metadata->num_row_groups(); ++r) {
    stream << "--- Row Group " << r << " ---\n";

    auto group_reader = fileReader->RowGroup(r);
    std::unique_ptr<RowGroupMetaData> group_metadata = file_metadata->RowGroup(r);

    stream << "--- Total Bytes " << group_metadata->total_byte_size() << " ---\n";
    stream << "  Rows: " << group_metadata->num_rows() << "---\n";

    // Print column metadata
    for (auto i : selected_columns) {
      auto column_chunk = group_metadata->ColumnChunk(i);
      std::shared_ptr<RowGroupStatistics> stats = column_chunk->statistics();

      const ColumnDescriptor* descr = file_metadata->schema()->Column(i);
      stream << "Column " << i << std::endl << ", Values: " << column_chunk->num_values();
      if (column_chunk->is_stats_set()) {
        std::string min = stats->EncodeMin(), max = stats->EncodeMax();
        stream << ", Null Values: " << stats->null_count()
               << ", Distinct Values: " << stats->distinct_count() << std::endl
               << "  Max: " << FormatStatValue(descr->physical_type(), max)
               << ", Min: " << FormatStatValue(descr->physical_type(), min);
      } else {
        stream << "  Statistics Not Set";
      }
      stream << std::endl
             << "  Compression: " << CompressionToString(column_chunk->compression())
             << ", Encodings: ";
      for (auto encoding : column_chunk->encodings()) {
        stream << EncodingToString(encoding) << " ";
      }
      stream << std::endl
             << "  Uncompressed Size: " << column_chunk->total_uncompressed_size()
             << ", Compressed Size: " << column_chunk->total_compressed_size()
             << std::endl;
    }

    if (!print_values) {
      continue;
    }

    static constexpr int bufsize = 25;
    char buffer[bufsize];

    // Create readers for selected columns and print contents
    vector<std::shared_ptr<Scanner>> scanners(selected_columns.size(), nullptr);
    int j = 0;
    for (auto i : selected_columns) {
      std::shared_ptr<ColumnReader> col_reader = group_reader->Column(i);

      std::stringstream ss;
      ss << "%-" << COL_WIDTH << "s";
      std::string fmt = ss.str();

      snprintf(buffer, bufsize, fmt.c_str(),
               file_metadata->schema()->Column(i)->name().c_str());
      stream << buffer;

      // This is OK in this method as long as the RowGroupReader does not get
      // deleted
      scanners[j++] = Scanner::Make(col_reader);
    }
    stream << "\n";

    bool hasRow;
    do {
      hasRow = false;
      for (auto scanner : scanners) {
        if (scanner->HasNext()) {
          hasRow = true;
          scanner->PrintNext(stream, 27);
        }
      }
      stream << "\n";
    } while (hasRow);
  }
}