// Licensed to the Apache Software Foundation (ASF) under one
// or more contributor license agreements.  See the NOTICE file
// distributed with this work for additional information
// regarding copyright ownership.  The ASF licenses this file
// to you under the Apache License, Version 2.0 (the
// "License"); you may not use this file except in compliance
// with the License.  You may obtain a copy of the License at
//
//   http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing,
// software distributed under the License is distributed on an
// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
// KIND, either express or implied.  See the License for the
// specific language governing permissions and limitations
// under the License.

#include "parquet/column_reader.h"

#include <algorithm>
#include <cstdint>
#include <memory>

#include <arrow/buffer.h>
#include <arrow/memory_pool.h>
#include <arrow/util/bit-util.h>
#include <arrow/util/compression.h>
#include <arrow/util/rle-encoding.h>

#include "parquet/column_page.h"
#include "parquet/encoding-internal.h"
#include "parquet/parquet_types.h"
#include "parquet/properties.h"
#include "parquet/thrift.h"

using arrow::MemoryPool;

namespace parquet {

LevelDecoder::LevelDecoder() : num_values_remaining_(0) {}

LevelDecoder::~LevelDecoder() {}

int LevelDecoder::SetData(Encoding::type encoding, int16_t max_level,
                          int num_buffered_values, const uint8_t* data) {
  int32_t num_bytes = 0;
  encoding_ = encoding;
  num_values_remaining_ = num_buffered_values;
  bit_width_ = BitUtil::Log2(max_level + 1);
  switch (encoding) {
    case Encoding::RLE: {
      num_bytes = *reinterpret_cast<const int32_t*>(data);
      const uint8_t* decoder_data = data + sizeof(int32_t);
      if (!rle_decoder_) {
        rle_decoder_.reset(new ::arrow::RleDecoder(decoder_data, num_bytes, bit_width_));
      } else {
        rle_decoder_->Reset(decoder_data, num_bytes, bit_width_);
      }
      return static_cast<int>(sizeof(int32_t)) + num_bytes;
    }
    case Encoding::BIT_PACKED: {
      num_bytes =
          static_cast<int32_t>(BitUtil::BytesForBits(num_buffered_values * bit_width_));
      if (!bit_packed_decoder_) {
        bit_packed_decoder_.reset(new ::arrow::BitReader(data, num_bytes));
      } else {
        bit_packed_decoder_->Reset(data, num_bytes);
      }
      return num_bytes;
    }
    default:
      throw ParquetException("Unknown encoding type for levels.");
  }
  return -1;
}

int LevelDecoder::Decode(int batch_size, int16_t* levels) {
  int num_decoded = 0;

  int num_values = std::min(num_values_remaining_, batch_size);
  if (encoding_ == Encoding::RLE) {
    num_decoded = rle_decoder_->GetBatch(levels, num_values);
  } else {
    num_decoded = bit_packed_decoder_->GetBatch(bit_width_, levels, num_values);
  }
  num_values_remaining_ -= num_decoded;
  return num_decoded;
}

ReaderProperties default_reader_properties() {
  static ReaderProperties default_reader_properties;
  return default_reader_properties;
}

// ----------------------------------------------------------------------
// SerializedPageReader deserializes Thrift metadata and pages that have been
// assembled in a serialized stream for storing in a Parquet files

// This subclass delimits pages appearing in a serialized stream, each preceded
// by a serialized Thrift format::PageHeader indicating the type of each page
// and the page metadata.
class SerializedPageReader : public PageReader {
 public:
  SerializedPageReader(std::unique_ptr<InputStream> stream, int64_t total_num_rows,
                       Compression::type codec, ::arrow::MemoryPool* pool)
      : stream_(std::move(stream)),
        decompression_buffer_(AllocateBuffer(pool, 0)),
        seen_num_rows_(0),
        total_num_rows_(total_num_rows) {
    max_page_header_size_ = kDefaultMaxPageHeaderSize;
    decompressor_ = GetCodecFromArrow(codec);
  }

  // Implement the PageReader interface
  std::shared_ptr<Page> NextPage() override;

  void set_max_page_header_size(uint32_t size) override { max_page_header_size_ = size; }

 private:
  std::unique_ptr<InputStream> stream_;

  format::PageHeader current_page_header_;
  std::shared_ptr<Page> current_page_;

  // Compression codec to use.
  std::unique_ptr<::arrow::Codec> decompressor_;
  std::shared_ptr<ResizableBuffer> decompression_buffer_;

  // Maximum allowed page size
  uint32_t max_page_header_size_;

  // Number of rows read in data pages so far
  int64_t seen_num_rows_;

  // Number of rows in all the data pages
  int64_t total_num_rows_;
};

std::shared_ptr<Page> SerializedPageReader::NextPage() {
  // Loop here because there may be unhandled page types that we skip until
  // finding a page that we do know what to do with
  while (seen_num_rows_ < total_num_rows_) {
    int64_t bytes_read = 0;
    int64_t bytes_available = 0;
    uint32_t header_size = 0;
    const uint8_t* buffer;
    uint32_t allowed_page_size = kDefaultPageHeaderSize;

    // Page headers can be very large because of page statistics
    // We try to deserialize a larger buffer progressively
    // until a maximum allowed header limit
    while (true) {
      buffer = stream_->Peek(allowed_page_size, &bytes_available);
      if (bytes_available == 0) {
        return std::shared_ptr<Page>(nullptr);
      }

      // This gets used, then set by DeserializeThriftMsg
      header_size = static_cast<uint32_t>(bytes_available);
      try {
        DeserializeThriftMsg(buffer, &header_size, &current_page_header_);
        break;
      } catch (std::exception& e) {
        // Failed to deserialize. Double the allowed page header size and try again
        std::stringstream ss;
        ss << e.what();
        allowed_page_size *= 2;
        if (allowed_page_size > max_page_header_size_) {
          ss << "Deserializing page header failed.\n";
          throw ParquetException(ss.str());
        }
      }
    }
    // Advance the stream offset
    stream_->Advance(header_size);

    int compressed_len = current_page_header_.compressed_page_size;
    int uncompressed_len = current_page_header_.uncompressed_page_size;

    // Read the compressed data page.
    buffer = stream_->Read(compressed_len, &bytes_read);
    if (bytes_read != compressed_len) {
      std::stringstream ss;
      ss << "Page was smaller (" << bytes_read << ") than expected (" << compressed_len
         << ")";
      ParquetException::EofException(ss.str());
    }

    // Uncompress it if we need to
    if (decompressor_ != nullptr) {
      // Grow the uncompressed buffer if we need to.
      if (uncompressed_len > static_cast<int>(decompression_buffer_->size())) {
        PARQUET_THROW_NOT_OK(decompression_buffer_->Resize(uncompressed_len, false));
      }
      PARQUET_THROW_NOT_OK(
          decompressor_->Decompress(compressed_len, buffer, uncompressed_len,
                                    decompression_buffer_->mutable_data()));
      buffer = decompression_buffer_->data();
    }

    auto page_buffer = std::make_shared<Buffer>(buffer, uncompressed_len);

    if (current_page_header_.type == format::PageType::DICTIONARY_PAGE) {
      const format::DictionaryPageHeader& dict_header =
          current_page_header_.dictionary_page_header;

      bool is_sorted = dict_header.__isset.is_sorted ? dict_header.is_sorted : false;

      return std::make_shared<DictionaryPage>(page_buffer, dict_header.num_values,
                                              FromThrift(dict_header.encoding),
                                              is_sorted);
    } else if (current_page_header_.type == format::PageType::DATA_PAGE) {
      const format::DataPageHeader& header = current_page_header_.data_page_header;

      EncodedStatistics page_statistics;
      if (header.__isset.statistics) {
        const format::Statistics& stats = header.statistics;
        if (stats.__isset.max) {
          page_statistics.set_max(stats.max);
        }
        if (stats.__isset.min) {
          page_statistics.set_min(stats.min);
        }
        if (stats.__isset.null_count) {
          page_statistics.set_null_count(stats.null_count);
        }
        if (stats.__isset.distinct_count) {
          page_statistics.set_distinct_count(stats.distinct_count);
        }
      }

      seen_num_rows_ += header.num_values;

      return std::make_shared<DataPage>(
          page_buffer, header.num_values, FromThrift(header.encoding),
          FromThrift(header.definition_level_encoding),
          FromThrift(header.repetition_level_encoding), page_statistics);
    } else if (current_page_header_.type == format::PageType::DATA_PAGE_V2) {
      const format::DataPageHeaderV2& header = current_page_header_.data_page_header_v2;
      bool is_compressed = header.__isset.is_compressed ? header.is_compressed : false;

      seen_num_rows_ += header.num_values;

      return std::make_shared<DataPageV2>(
          page_buffer, header.num_values, header.num_nulls, header.num_rows,
          FromThrift(header.encoding), header.definition_levels_byte_length,
          header.repetition_levels_byte_length, is_compressed);
    } else {
      // We don't know what this page type is. We're allowed to skip non-data
      // pages.
      continue;
    }
  }
  return std::shared_ptr<Page>(nullptr);
}

std::unique_ptr<PageReader> PageReader::Open(std::unique_ptr<InputStream> stream,
                                             int64_t total_num_rows,
                                             Compression::type codec,
                                             ::arrow::MemoryPool* pool) {
  return std::unique_ptr<PageReader>(
      new SerializedPageReader(std::move(stream), total_num_rows, codec, pool));
}

// ----------------------------------------------------------------------

ColumnReader::ColumnReader(const ColumnDescriptor* descr,
                           std::unique_ptr<PageReader> pager, MemoryPool* pool)
    : descr_(descr),
      pager_(std::move(pager)),
      num_buffered_values_(0),
      num_decoded_values_(0),
      pool_(pool) {}

ColumnReader::~ColumnReader() {}

template <typename DType>
void TypedColumnReader<DType>::ConfigureDictionary(const DictionaryPage* page) {
  int encoding = static_cast<int>(page->encoding());
  if (page->encoding() == Encoding::PLAIN_DICTIONARY ||
      page->encoding() == Encoding::PLAIN) {
    encoding = static_cast<int>(Encoding::RLE_DICTIONARY);
  }

  auto it = decoders_.find(encoding);
  if (it != decoders_.end()) {
    throw ParquetException("Column cannot have more than one dictionary.");
  }

  if (page->encoding() == Encoding::PLAIN_DICTIONARY ||
      page->encoding() == Encoding::PLAIN) {
    PlainDecoder<DType> dictionary(descr_);
    dictionary.SetData(page->num_values(), page->data(), page->size());

    // The dictionary is fully decoded during DictionaryDecoder::Init, so the
    // DictionaryPage buffer is no longer required after this step
    //
    // TODO(wesm): investigate whether this all-or-nothing decoding of the
    // dictionary makes sense and whether performance can be improved

    auto decoder = std::make_shared<DictionaryDecoder<DType>>(descr_, pool_);
    decoder->SetDict(&dictionary);
    decoders_[encoding] = decoder;
  } else {
    ParquetException::NYI("only plain dictionary encoding has been implemented");
  }

  current_decoder_ = decoders_[encoding].get();
}

// PLAIN_DICTIONARY is deprecated but used to be used as a dictionary index
// encoding.
static bool IsDictionaryIndexEncoding(const Encoding::type& e) {
  return e == Encoding::RLE_DICTIONARY || e == Encoding::PLAIN_DICTIONARY;
}

template <typename DType>
bool TypedColumnReader<DType>::ReadNewPage() {
  // Loop until we find the next data page.
  const uint8_t* buffer;

  while (true) {
    current_page_ = pager_->NextPage();
    if (!current_page_) {
      // EOS
      return false;
    }

    if (current_page_->type() == PageType::DICTIONARY_PAGE) {
      ConfigureDictionary(static_cast<const DictionaryPage*>(current_page_.get()));
      continue;
    } else if (current_page_->type() == PageType::DATA_PAGE) {
      const DataPage* page = static_cast<const DataPage*>(current_page_.get());

      // Read a data page.
      num_buffered_values_ = page->num_values();

      // Have not decoded any values from the data page yet
      num_decoded_values_ = 0;

      buffer = page->data();

      // If the data page includes repetition and definition levels, we
      // initialize the level decoder and subtract the encoded level bytes from
      // the page size to determine the number of bytes in the encoded data.
      int64_t data_size = page->size();

      // Data page Layout: Repetition Levels - Definition Levels - encoded values.
      // Levels are encoded as rle or bit-packed.
      // Init repetition levels
      if (descr_->max_repetition_level() > 0) {
        int64_t rep_levels_bytes = repetition_level_decoder_.SetData(
            page->repetition_level_encoding(), descr_->max_repetition_level(),
            static_cast<int>(num_buffered_values_), buffer);
        buffer += rep_levels_bytes;
        data_size -= rep_levels_bytes;
      }
      // TODO figure a way to set max_definition_level_ to 0
      // if the initial value is invalid

      // Init definition levels
      if (descr_->max_definition_level() > 0) {
        int64_t def_levels_bytes = definition_level_decoder_.SetData(
            page->definition_level_encoding(), descr_->max_definition_level(),
            static_cast<int>(num_buffered_values_), buffer);
        buffer += def_levels_bytes;
        data_size -= def_levels_bytes;
      }

      // Get a decoder object for this page or create a new decoder if this is the
      // first page with this encoding.
      Encoding::type encoding = page->encoding();

      if (IsDictionaryIndexEncoding(encoding)) {
        encoding = Encoding::RLE_DICTIONARY;
      }

      auto it = decoders_.find(static_cast<int>(encoding));
      if (it != decoders_.end()) {
        if (encoding == Encoding::RLE_DICTIONARY) {
          DCHECK(current_decoder_->encoding() == Encoding::RLE_DICTIONARY);
        }
        current_decoder_ = it->second.get();
      } else {
        switch (encoding) {
          case Encoding::PLAIN: {
            std::shared_ptr<DecoderType> decoder(new PlainDecoder<DType>(descr_));
            decoders_[static_cast<int>(encoding)] = decoder;
            current_decoder_ = decoder.get();
            break;
          }
          case Encoding::RLE_DICTIONARY:
            throw ParquetException("Dictionary page must be before data page.");

          case Encoding::DELTA_BINARY_PACKED:
          case Encoding::DELTA_LENGTH_BYTE_ARRAY:
          case Encoding::DELTA_BYTE_ARRAY:
            ParquetException::NYI("Unsupported encoding");

          default:
            throw ParquetException("Unknown encoding type.");
        }
      }
      current_decoder_->SetData(static_cast<int>(num_buffered_values_), buffer,
                                static_cast<int>(data_size));
      return true;
    } else {
      // We don't know what this page type is. We're allowed to skip non-data
      // pages.
      continue;
    }
  }
  return true;
}

// ----------------------------------------------------------------------
// Batch read APIs

int64_t ColumnReader::ReadDefinitionLevels(int64_t batch_size, int16_t* levels) {
  if (descr_->max_definition_level() == 0) {
    return 0;
  }
  return definition_level_decoder_.Decode(static_cast<int>(batch_size), levels);
}

int64_t ColumnReader::ReadRepetitionLevels(int64_t batch_size, int16_t* levels) {
  if (descr_->max_repetition_level() == 0) {
    return 0;
  }
  return repetition_level_decoder_.Decode(static_cast<int>(batch_size), levels);
}

// ----------------------------------------------------------------------
// Dynamic column reader constructor

std::shared_ptr<ColumnReader> ColumnReader::Make(const ColumnDescriptor* descr,
                                                 std::unique_ptr<PageReader> pager,
                                                 MemoryPool* pool) {
  switch (descr->physical_type()) {
    case Type::BOOLEAN:
      return std::make_shared<BoolReader>(descr, std::move(pager), pool);
    case Type::INT32:
      return std::make_shared<Int32Reader>(descr, std::move(pager), pool);
    case Type::INT64:
      return std::make_shared<Int64Reader>(descr, std::move(pager), pool);
    case Type::INT96:
      return std::make_shared<Int96Reader>(descr, std::move(pager), pool);
    case Type::FLOAT:
      return std::make_shared<FloatReader>(descr, std::move(pager), pool);
    case Type::DOUBLE:
      return std::make_shared<DoubleReader>(descr, std::move(pager), pool);
    case Type::BYTE_ARRAY:
      return std::make_shared<ByteArrayReader>(descr, std::move(pager), pool);
    case Type::FIXED_LEN_BYTE_ARRAY:
      return std::make_shared<FixedLenByteArrayReader>(descr, std::move(pager), pool);
    default:
      ParquetException::NYI("type reader not implemented");
  }
  // Unreachable code, but supress compiler warning
  return std::shared_ptr<ColumnReader>(nullptr);
}

// ----------------------------------------------------------------------
// Instantiate templated classes

template class PARQUET_TEMPLATE_EXPORT TypedColumnReader<BooleanType>;
template class PARQUET_TEMPLATE_EXPORT TypedColumnReader<Int32Type>;
template class PARQUET_TEMPLATE_EXPORT TypedColumnReader<Int64Type>;
template class PARQUET_TEMPLATE_EXPORT TypedColumnReader<Int96Type>;
template class PARQUET_TEMPLATE_EXPORT TypedColumnReader<FloatType>;
template class PARQUET_TEMPLATE_EXPORT TypedColumnReader<DoubleType>;
template class PARQUET_TEMPLATE_EXPORT TypedColumnReader<ByteArrayType>;
template class PARQUET_TEMPLATE_EXPORT TypedColumnReader<FLBAType>;

}  // namespace parquet