parquet 1.0.1

// 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.

//! Contains column reader API.

use std::{
    cmp::{max, min},
    collections::HashMap,
};

use super::page::{Page, PageReader};
use crate::basic::*;
use crate::data_type::*;
use crate::encodings::{
    decoding::{get_decoder, Decoder, DictDecoder, PlainDecoder},
    levels::LevelDecoder,
};
use crate::errors::{ParquetError, Result};
use crate::schema::types::ColumnDescPtr;
use crate::util::memory::ByteBufferPtr;

/// Column reader for a Parquet type.
pub enum ColumnReader {
    BoolColumnReader(ColumnReaderImpl<BoolType>),
    Int32ColumnReader(ColumnReaderImpl<Int32Type>),
    Int64ColumnReader(ColumnReaderImpl<Int64Type>),
    Int96ColumnReader(ColumnReaderImpl<Int96Type>),
    FloatColumnReader(ColumnReaderImpl<FloatType>),
    DoubleColumnReader(ColumnReaderImpl<DoubleType>),
    ByteArrayColumnReader(ColumnReaderImpl<ByteArrayType>),
    FixedLenByteArrayColumnReader(ColumnReaderImpl<FixedLenByteArrayType>),
}

/// Gets a specific column reader corresponding to column descriptor `col_descr`. The
/// column reader will read from pages in `col_page_reader`.
pub fn get_column_reader(
    col_descr: ColumnDescPtr,
    col_page_reader: Box<PageReader>,
) -> ColumnReader {
    match col_descr.physical_type() {
        Type::BOOLEAN => ColumnReader::BoolColumnReader(ColumnReaderImpl::new(
            col_descr,
            col_page_reader,
        )),
        Type::INT32 => ColumnReader::Int32ColumnReader(ColumnReaderImpl::new(
            col_descr,
            col_page_reader,
        )),
        Type::INT64 => ColumnReader::Int64ColumnReader(ColumnReaderImpl::new(
            col_descr,
            col_page_reader,
        )),
        Type::INT96 => ColumnReader::Int96ColumnReader(ColumnReaderImpl::new(
            col_descr,
            col_page_reader,
        )),
        Type::FLOAT => ColumnReader::FloatColumnReader(ColumnReaderImpl::new(
            col_descr,
            col_page_reader,
        )),
        Type::DOUBLE => ColumnReader::DoubleColumnReader(ColumnReaderImpl::new(
            col_descr,
            col_page_reader,
        )),
        Type::BYTE_ARRAY => ColumnReader::ByteArrayColumnReader(ColumnReaderImpl::new(
            col_descr,
            col_page_reader,
        )),
        Type::FIXED_LEN_BYTE_ARRAY => ColumnReader::FixedLenByteArrayColumnReader(
            ColumnReaderImpl::new(col_descr, col_page_reader),
        ),
    }
}

/// Gets a typed column reader for the specific type `T`, by "up-casting" `col_reader` of
/// non-generic type to a generic column reader type `ColumnReaderImpl`.
///
/// Panics if actual enum value for `col_reader` does not match the type `T`.
pub fn get_typed_column_reader<T: DataType>(
    col_reader: ColumnReader,
) -> ColumnReaderImpl<T> {
    T::get_column_reader(col_reader).unwrap_or_else(|| {
        panic!(
            "Failed to convert column reader into a typed column reader for `{}` type",
            T::get_physical_type()
        )
    })
}

/// Typed value reader for a particular primitive column.
pub struct ColumnReaderImpl<T: DataType> {
    descr: ColumnDescPtr,
    def_level_decoder: Option<LevelDecoder>,
    rep_level_decoder: Option<LevelDecoder>,
    page_reader: Box<PageReader>,
    current_encoding: Option<Encoding>,

    // The total number of values stored in the data page.
    num_buffered_values: u32,

    // The number of values from the current data page that has been decoded into memory
    // so far.
    num_decoded_values: u32,

    // Cache of decoders for existing encodings
    decoders: HashMap<Encoding, Box<Decoder<T>>>,
}

impl<T: DataType> ColumnReaderImpl<T> {
    /// Creates new column reader based on column descriptor and page reader.
    pub fn new(descr: ColumnDescPtr, page_reader: Box<PageReader>) -> Self {
        Self {
            descr,
            def_level_decoder: None,
            rep_level_decoder: None,
            page_reader,
            current_encoding: None,
            num_buffered_values: 0,
            num_decoded_values: 0,
            decoders: HashMap::new(),
        }
    }

    /// Reads a batch of values of at most `batch_size`.
    ///
    /// This will try to read from the row group, and fills up at most `batch_size` values
    /// for `def_levels`, `rep_levels` and `values`. It will stop either when the row
    /// group is depleted or `batch_size` values has been read, or there is no space
    /// in the input slices (values/definition levels/repetition levels).
    ///
    /// Note that in case the field being read is not required, `values` could contain
    /// less values than `def_levels`. Also note that this will skip reading def / rep
    /// levels if the field is required / not repeated, respectively.
    ///
    /// If `def_levels` or `rep_levels` is `None`, this will also skip reading the
    /// respective levels. This is useful when the caller of this function knows in
    /// advance that the field is required and non-repeated, therefore can avoid
    /// allocating memory for the levels data. Note that if field has definition
    /// levels, but caller provides None, there might be inconsistency between
    /// levels/values (see comments below).
    ///
    /// Returns a tuple where the first element is the actual number of values read,
    /// and the second element is the actual number of levels read.
    #[inline]
    pub fn read_batch(
        &mut self,
        batch_size: usize,
        mut def_levels: Option<&mut [i16]>,
        mut rep_levels: Option<&mut [i16]>,
        values: &mut [T::T],
    ) -> Result<(usize, usize)> {
        let mut values_read = 0;
        let mut levels_read = 0;

        // Compute the smallest batch size we can read based on provided slices
        let mut batch_size = min(batch_size, values.len());
        if let Some(ref levels) = def_levels {
            batch_size = min(batch_size, levels.len());
        }
        if let Some(ref levels) = rep_levels {
            batch_size = min(batch_size, levels.len());
        }

        // Read exhaustively all pages until we read all batch_size values/levels
        // or there are no more values/levels to read.
        while max(values_read, levels_read) < batch_size {
            if !self.has_next()? {
                break;
            }

            // Batch size for the current iteration
            let iter_batch_size = {
                // Compute approximate value based on values decoded so far
                let mut adjusted_size = min(
                    batch_size,
                    (self.num_buffered_values - self.num_decoded_values) as usize,
                );

                // Adjust batch size by taking into account how much data there
                // to read. As batch_size is also smaller than value and level
                // slices (if available), this ensures that available space is not
                // exceeded.
                adjusted_size = min(adjusted_size, batch_size - values_read);
                adjusted_size = min(adjusted_size, batch_size - levels_read);

                adjusted_size
            };

            let mut values_to_read = 0;
            let mut num_def_levels = 0;
            let mut num_rep_levels = 0;

            // If the field is required and non-repeated, there are no definition levels
            if self.descr.max_def_level() > 0 && def_levels.as_ref().is_some() {
                if let Some(ref mut levels) = def_levels {
                    num_def_levels = self.read_def_levels(
                        &mut levels[levels_read..levels_read + iter_batch_size],
                    )?;
                    for i in levels_read..levels_read + num_def_levels {
                        if levels[i] == self.descr.max_def_level() {
                            values_to_read += 1;
                        }
                    }
                }
            } else {
                // If max definition level == 0, then it is REQUIRED field, read all
                // values. If definition levels are not provided, we still
                // read all values.
                values_to_read = iter_batch_size;
            }

            if self.descr.max_rep_level() > 0 && rep_levels.is_some() {
                if let Some(ref mut levels) = rep_levels {
                    num_rep_levels = self.read_rep_levels(
                        &mut levels[levels_read..levels_read + iter_batch_size],
                    )?;

                    // If definition levels are defined, check that rep levels == def
                    // levels
                    if def_levels.is_some() {
                        assert_eq!(
                            num_def_levels, num_rep_levels,
                            "Number of decoded rep / def levels did not match"
                        );
                    }
                }
            }

            // At this point we have read values, definition and repetition levels.
            // If both definition and repetition levels are defined, their counts
            // should be equal. Values count is always less or equal to definition levels.
            //
            // Note that if field is not required, but no definition levels are provided,
            // we would read values of batch size and (if provided, of course) repetition
            // levels of batch size - [!] they will not be synced, because only definition
            // levels enforce number of non-null values to read.

            let curr_values_read =
                self.read_values(&mut values[values_read..values_read + values_to_read])?;

            // Update all "return" counters and internal state.

            // This is to account for when def or rep levels are not provided
            let curr_levels_read = max(num_def_levels, num_rep_levels);
            self.num_decoded_values += max(curr_levels_read, curr_values_read) as u32;
            levels_read += curr_levels_read;
            values_read += curr_values_read;
        }

        Ok((values_read, levels_read))
    }

    /// Reads a new page and set up the decoders for levels, values or dictionary.
    /// Returns false if there's no page left.
    fn read_new_page(&mut self) -> Result<bool> {
        #[allow(while_true)]
        while true {
            match self.page_reader.get_next_page()? {
                // No more page to read
                None => return Ok(false),
                Some(current_page) => {
                    match current_page {
                        // 1. Dictionary page: configure dictionary for this page.
                        p @ Page::DictionaryPage { .. } => {
                            self.configure_dictionary(p)?;
                            continue;
                        }
                        // 2. Data page v1
                        Page::DataPage {
                            buf,
                            num_values,
                            encoding,
                            def_level_encoding,
                            rep_level_encoding,
                            statistics: _,
                        } => {
                            self.num_buffered_values = num_values;
                            self.num_decoded_values = 0;

                            let mut buffer_ptr = buf;

                            if self.descr.max_rep_level() > 0 {
                                let mut rep_decoder = LevelDecoder::v1(
                                    rep_level_encoding,
                                    self.descr.max_rep_level(),
                                );
                                let total_bytes = rep_decoder.set_data(
                                    self.num_buffered_values as usize,
                                    buffer_ptr.all(),
                                );
                                buffer_ptr = buffer_ptr.start_from(total_bytes);
                                self.rep_level_decoder = Some(rep_decoder);
                            }

                            if self.descr.max_def_level() > 0 {
                                let mut def_decoder = LevelDecoder::v1(
                                    def_level_encoding,
                                    self.descr.max_def_level(),
                                );
                                let total_bytes = def_decoder.set_data(
                                    self.num_buffered_values as usize,
                                    buffer_ptr.all(),
                                );
                                buffer_ptr = buffer_ptr.start_from(total_bytes);
                                self.def_level_decoder = Some(def_decoder);
                            }

                            // Data page v1 does not have offset, all content of buffer
                            // should be passed
                            self.set_current_page_encoding(
                                encoding,
                                &buffer_ptr,
                                0,
                                num_values as usize,
                            )?;
                            return Ok(true);
                        }
                        // 3. Data page v2
                        Page::DataPageV2 {
                            buf,
                            num_values,
                            encoding,
                            num_nulls: _,
                            num_rows: _,
                            def_levels_byte_len,
                            rep_levels_byte_len,
                            is_compressed: _,
                            statistics: _,
                        } => {
                            self.num_buffered_values = num_values;
                            self.num_decoded_values = 0;

                            let mut offset = 0;

                            // DataPage v2 only supports RLE encoding for repetition
                            // levels
                            if self.descr.max_rep_level() > 0 {
                                let mut rep_decoder =
                                    LevelDecoder::v2(self.descr.max_rep_level());
                                let bytes_read = rep_decoder.set_data_range(
                                    self.num_buffered_values as usize,
                                    &buf,
                                    offset,
                                    rep_levels_byte_len as usize,
                                );
                                offset += bytes_read;
                                self.rep_level_decoder = Some(rep_decoder);
                            }

                            // DataPage v2 only supports RLE encoding for definition
                            // levels
                            if self.descr.max_def_level() > 0 {
                                let mut def_decoder =
                                    LevelDecoder::v2(self.descr.max_def_level());
                                let bytes_read = def_decoder.set_data_range(
                                    self.num_buffered_values as usize,
                                    &buf,
                                    offset,
                                    def_levels_byte_len as usize,
                                );
                                offset += bytes_read;
                                self.def_level_decoder = Some(def_decoder);
                            }

                            self.set_current_page_encoding(
                                encoding,
                                &buf,
                                offset,
                                num_values as usize,
                            )?;
                            return Ok(true);
                        }
                    };
                }
            }
        }

        Ok(true)
    }

    /// Resolves and updates encoding and set decoder for the current page
    fn set_current_page_encoding(
        &mut self,
        mut encoding: Encoding,
        buffer_ptr: &ByteBufferPtr,
        offset: usize,
        len: usize,
    ) -> Result<()> {
        if encoding == Encoding::PLAIN_DICTIONARY {
            encoding = Encoding::RLE_DICTIONARY;
        }

        let decoder = if encoding == Encoding::RLE_DICTIONARY {
            self.decoders
                .get_mut(&encoding)
                .expect("Decoder for dict should have been set")
        } else {
            // Search cache for data page decoder
            if !self.decoders.contains_key(&encoding) {
                // Initialize decoder for this page
                let data_decoder = get_decoder::<T>(self.descr.clone(), encoding)?;
                self.decoders.insert(encoding, data_decoder);
            }
            self.decoders.get_mut(&encoding).unwrap()
        };

        decoder.set_data(buffer_ptr.start_from(offset), len as usize)?;
        self.current_encoding = Some(encoding);
        Ok(())
    }

    #[inline]
    fn has_next(&mut self) -> Result<bool> {
        if self.num_buffered_values == 0
            || self.num_buffered_values == self.num_decoded_values
        {
            // TODO: should we return false if read_new_page() = true and
            // num_buffered_values = 0?
            if !self.read_new_page()? {
                Ok(false)
            } else {
                Ok(self.num_buffered_values != 0)
            }
        } else {
            Ok(true)
        }
    }

    #[inline]
    fn read_rep_levels(&mut self, buffer: &mut [i16]) -> Result<usize> {
        let level_decoder = self
            .rep_level_decoder
            .as_mut()
            .expect("rep_level_decoder be set");
        level_decoder.get(buffer)
    }

    #[inline]
    fn read_def_levels(&mut self, buffer: &mut [i16]) -> Result<usize> {
        let level_decoder = self
            .def_level_decoder
            .as_mut()
            .expect("def_level_decoder be set");
        level_decoder.get(buffer)
    }

    #[inline]
    fn read_values(&mut self, buffer: &mut [T::T]) -> Result<usize> {
        let encoding = self
            .current_encoding
            .expect("current_encoding should be set");
        let current_decoder = self
            .decoders
            .get_mut(&encoding)
            .expect(format!("decoder for encoding {} should be set", encoding).as_str());
        current_decoder.get(buffer)
    }

    #[inline]
    fn configure_dictionary(&mut self, page: Page) -> Result<bool> {
        let mut encoding = page.encoding();
        if encoding == Encoding::PLAIN || encoding == Encoding::PLAIN_DICTIONARY {
            encoding = Encoding::RLE_DICTIONARY
        }

        if self.decoders.contains_key(&encoding) {
            return Err(general_err!("Column cannot have more than one dictionary"));
        }

        if encoding == Encoding::RLE_DICTIONARY {
            let mut dictionary = PlainDecoder::<T>::new(self.descr.type_length());
            let num_values = page.num_values();
            dictionary.set_data(page.buffer().clone(), num_values as usize)?;

            let mut decoder = DictDecoder::new();
            decoder.set_dict(Box::new(dictionary))?;
            self.decoders.insert(encoding, Box::new(decoder));
            Ok(true)
        } else {
            Err(nyi_err!(
                "Invalid/Unsupported encoding type for dictionary: {}",
                encoding
            ))
        }
    }
}

#[cfg(test)]
mod tests {
    use super::*;

    use rand::distributions::uniform::SampleUniform;
    use std::{collections::VecDeque, rc::Rc, vec::IntoIter};

    use crate::basic::Type as PhysicalType;
    use crate::column::page::Page;
    use crate::schema::types::{ColumnDescriptor, ColumnPath, Type as SchemaType};
    use crate::util::test_common::make_pages;

    const NUM_LEVELS: usize = 128;
    const NUM_PAGES: usize = 2;
    const MAX_DEF_LEVEL: i16 = 5;
    const MAX_REP_LEVEL: i16 = 5;

    // Macro to generate test cases
    macro_rules! test {
        // branch for generating i32 cases
        ($test_func:ident, i32, $func:ident, $def_level:expr, $rep_level:expr,
     $num_pages:expr, $num_levels:expr, $batch_size:expr, $min:expr, $max:expr) => {
            test_internal!(
                $test_func,
                Int32Type,
                get_test_int32_type,
                $func,
                $def_level,
                $rep_level,
                $num_pages,
                $num_levels,
                $batch_size,
                $min,
                $max
            );
        };
        // branch for generating i64 cases
        ($test_func:ident, i64, $func:ident, $def_level:expr, $rep_level:expr,
     $num_pages:expr, $num_levels:expr, $batch_size:expr, $min:expr, $max:expr) => {
            test_internal!(
                $test_func,
                Int64Type,
                get_test_int64_type,
                $func,
                $def_level,
                $rep_level,
                $num_pages,
                $num_levels,
                $batch_size,
                $min,
                $max
            );
        };
    }

    macro_rules! test_internal {
        ($test_func:ident, $ty:ident, $pty:ident, $func:ident, $def_level:expr,
     $rep_level:expr, $num_pages:expr, $num_levels:expr, $batch_size:expr,
     $min:expr, $max:expr) => {
            #[test]
            fn $test_func() {
                let desc = Rc::new(ColumnDescriptor::new(
                    Rc::new($pty()),
                    None,
                    $def_level,
                    $rep_level,
                    ColumnPath::new(Vec::new()),
                ));
                let mut tester = ColumnReaderTester::<$ty>::new();
                tester.$func(desc, $num_pages, $num_levels, $batch_size, $min, $max);
            }
        };
    }

    test!(
        test_read_plain_v1_int32,
        i32,
        plain_v1,
        MAX_DEF_LEVEL,
        MAX_REP_LEVEL,
        NUM_PAGES,
        NUM_LEVELS,
        16,
        std::i32::MIN,
        std::i32::MAX
    );
    test!(
        test_read_plain_v2_int32,
        i32,
        plain_v2,
        MAX_DEF_LEVEL,
        MAX_REP_LEVEL,
        NUM_PAGES,
        NUM_LEVELS,
        16,
        std::i32::MIN,
        std::i32::MAX
    );

    test!(
        test_read_plain_v1_int32_uneven,
        i32,
        plain_v1,
        MAX_DEF_LEVEL,
        MAX_REP_LEVEL,
        NUM_PAGES,
        NUM_LEVELS,
        17,
        std::i32::MIN,
        std::i32::MAX
    );
    test!(
        test_read_plain_v2_int32_uneven,
        i32,
        plain_v2,
        MAX_DEF_LEVEL,
        MAX_REP_LEVEL,
        NUM_PAGES,
        NUM_LEVELS,
        17,
        std::i32::MIN,
        std::i32::MAX
    );

    test!(
        test_read_plain_v1_int32_multi_page,
        i32,
        plain_v1,
        MAX_DEF_LEVEL,
        MAX_REP_LEVEL,
        NUM_PAGES,
        NUM_LEVELS,
        512,
        std::i32::MIN,
        std::i32::MAX
    );
    test!(
        test_read_plain_v2_int32_multi_page,
        i32,
        plain_v2,
        MAX_DEF_LEVEL,
        MAX_REP_LEVEL,
        NUM_PAGES,
        NUM_LEVELS,
        512,
        std::i32::MIN,
        std::i32::MAX
    );

    // test cases when column descriptor has MAX_DEF_LEVEL = 0 and MAX_REP_LEVEL = 0
    test!(
        test_read_plain_v1_int32_required_non_repeated,
        i32,
        plain_v1,
        0,
        0,
        NUM_PAGES,
        NUM_LEVELS,
        16,
        std::i32::MIN,
        std::i32::MAX
    );
    test!(
        test_read_plain_v2_int32_required_non_repeated,
        i32,
        plain_v2,
        0,
        0,
        NUM_PAGES,
        NUM_LEVELS,
        16,
        std::i32::MIN,
        std::i32::MAX
    );

    test!(
        test_read_plain_v1_int64,
        i64,
        plain_v1,
        1,
        1,
        NUM_PAGES,
        NUM_LEVELS,
        16,
        std::i64::MIN,
        std::i64::MAX
    );
    test!(
        test_read_plain_v2_int64,
        i64,
        plain_v2,
        1,
        1,
        NUM_PAGES,
        NUM_LEVELS,
        16,
        std::i64::MIN,
        std::i64::MAX
    );

    test!(
        test_read_plain_v1_int64_uneven,
        i64,
        plain_v1,
        1,
        1,
        NUM_PAGES,
        NUM_LEVELS,
        17,
        std::i64::MIN,
        std::i64::MAX
    );
    test!(
        test_read_plain_v2_int64_uneven,
        i64,
        plain_v2,
        1,
        1,
        NUM_PAGES,
        NUM_LEVELS,
        17,
        std::i64::MIN,
        std::i64::MAX
    );

    test!(
        test_read_plain_v1_int64_multi_page,
        i64,
        plain_v1,
        1,
        1,
        NUM_PAGES,
        NUM_LEVELS,
        512,
        std::i64::MIN,
        std::i64::MAX
    );
    test!(
        test_read_plain_v2_int64_multi_page,
        i64,
        plain_v2,
        1,
        1,
        NUM_PAGES,
        NUM_LEVELS,
        512,
        std::i64::MIN,
        std::i64::MAX
    );

    // test cases when column descriptor has MAX_DEF_LEVEL = 0 and MAX_REP_LEVEL = 0
    test!(
        test_read_plain_v1_int64_required_non_repeated,
        i64,
        plain_v1,
        0,
        0,
        NUM_PAGES,
        NUM_LEVELS,
        16,
        std::i64::MIN,
        std::i64::MAX
    );
    test!(
        test_read_plain_v2_int64_required_non_repeated,
        i64,
        plain_v2,
        0,
        0,
        NUM_PAGES,
        NUM_LEVELS,
        16,
        std::i64::MIN,
        std::i64::MAX
    );

    test!(
        test_read_dict_v1_int32_small,
        i32,
        dict_v1,
        MAX_DEF_LEVEL,
        MAX_REP_LEVEL,
        2,
        2,
        16,
        0,
        3
    );
    test!(
        test_read_dict_v2_int32_small,
        i32,
        dict_v2,
        MAX_DEF_LEVEL,
        MAX_REP_LEVEL,
        2,
        2,
        16,
        0,
        3
    );

    test!(
        test_read_dict_v1_int32,
        i32,
        dict_v1,
        MAX_DEF_LEVEL,
        MAX_REP_LEVEL,
        NUM_PAGES,
        NUM_LEVELS,
        16,
        0,
        3
    );
    test!(
        test_read_dict_v2_int32,
        i32,
        dict_v2,
        MAX_DEF_LEVEL,
        MAX_REP_LEVEL,
        NUM_PAGES,
        NUM_LEVELS,
        16,
        0,
        3
    );

    test!(
        test_read_dict_v1_int32_uneven,
        i32,
        dict_v1,
        MAX_DEF_LEVEL,
        MAX_REP_LEVEL,
        NUM_PAGES,
        NUM_LEVELS,
        17,
        0,
        3
    );
    test!(
        test_read_dict_v2_int32_uneven,
        i32,
        dict_v2,
        MAX_DEF_LEVEL,
        MAX_REP_LEVEL,
        NUM_PAGES,
        NUM_LEVELS,
        17,
        0,
        3
    );

    test!(
        test_read_dict_v1_int32_multi_page,
        i32,
        dict_v1,
        MAX_DEF_LEVEL,
        MAX_REP_LEVEL,
        NUM_PAGES,
        NUM_LEVELS,
        512,
        0,
        3
    );
    test!(
        test_read_dict_v2_int32_multi_page,
        i32,
        dict_v2,
        MAX_DEF_LEVEL,
        MAX_REP_LEVEL,
        NUM_PAGES,
        NUM_LEVELS,
        512,
        0,
        3
    );

    test!(
        test_read_dict_v1_int64,
        i64,
        dict_v1,
        MAX_DEF_LEVEL,
        MAX_REP_LEVEL,
        NUM_PAGES,
        NUM_LEVELS,
        16,
        0,
        3
    );
    test!(
        test_read_dict_v2_int64,
        i64,
        dict_v2,
        MAX_DEF_LEVEL,
        MAX_REP_LEVEL,
        NUM_PAGES,
        NUM_LEVELS,
        16,
        0,
        3
    );

    #[test]
    fn test_read_batch_values_only() {
        test_read_batch_int32(16, &mut vec![0; 10], None, None); // < batch_size
        test_read_batch_int32(16, &mut vec![0; 16], None, None); // == batch_size
        test_read_batch_int32(16, &mut vec![0; 51], None, None); // > batch_size
    }

    #[test]
    fn test_read_batch_values_def_levels() {
        test_read_batch_int32(16, &mut vec![0; 10], Some(&mut vec![0; 10]), None);
        test_read_batch_int32(16, &mut vec![0; 16], Some(&mut vec![0; 16]), None);
        test_read_batch_int32(16, &mut vec![0; 51], Some(&mut vec![0; 51]), None);
    }

    #[test]
    fn test_read_batch_values_rep_levels() {
        test_read_batch_int32(16, &mut vec![0; 10], None, Some(&mut vec![0; 10]));
        test_read_batch_int32(16, &mut vec![0; 16], None, Some(&mut vec![0; 16]));
        test_read_batch_int32(16, &mut vec![0; 51], None, Some(&mut vec![0; 51]));
    }

    #[test]
    fn test_read_batch_different_buf_sizes() {
        test_read_batch_int32(
            16,
            &mut vec![0; 8],
            Some(&mut vec![0; 9]),
            Some(&mut vec![0; 7]),
        );
        test_read_batch_int32(
            16,
            &mut vec![0; 1],
            Some(&mut vec![0; 9]),
            Some(&mut vec![0; 3]),
        );
    }

    #[test]
    fn test_read_batch_values_def_rep_levels() {
        test_read_batch_int32(
            128,
            &mut vec![0; 128],
            Some(&mut vec![0; 128]),
            Some(&mut vec![0; 128]),
        );
    }

    #[test]
    fn test_read_batch_adjust_after_buffering_page() {
        // This test covers scenario when buffering new page results in setting number
        // of decoded values to 0, resulting on reading `batch_size` of values, but it is
        // larger than we can insert into slice (affects values and levels).
        //
        // Note: values are chosen to reproduce the issue.
        //
        let primitive_type = get_test_int32_type();
        let desc = Rc::new(ColumnDescriptor::new(
            Rc::new(primitive_type),
            None,
            1,
            1,
            ColumnPath::new(Vec::new()),
        ));

        let num_pages = 2;
        let num_levels = 4;
        let batch_size = 5;
        let values = &mut vec![0; 7];
        let def_levels = &mut vec![0; 7];
        let rep_levels = &mut vec![0; 7];

        let mut tester = ColumnReaderTester::<Int32Type>::new();
        tester.test_read_batch(
            desc,
            Encoding::RLE_DICTIONARY,
            num_pages,
            num_levels,
            batch_size,
            std::i32::MIN,
            std::i32::MAX,
            values,
            Some(def_levels),
            Some(rep_levels),
            false,
        );
    }

    // ----------------------------------------------------------------------
    // Helper methods to make pages and test
    //
    // # Overview
    //
    // Most of the test functionality is implemented in `ColumnReaderTester`, which
    // provides some general data page test methods:
    // - `test_read_batch_general`
    // - `test_read_batch`
    //
    // There are also some high level wrappers that are part of `ColumnReaderTester`:
    // - `plain_v1` -> call `test_read_batch_general` with data page v1 and plain encoding
    // - `plain_v2` -> call `test_read_batch_general` with data page v2 and plain encoding
    // - `dict_v1` -> call `test_read_batch_general` with data page v1 + dictionary page
    // - `dict_v2` -> call `test_read_batch_general` with data page v2 + dictionary page
    //
    // And even higher level wrappers that simplify testing of almost the same test cases:
    // - `get_test_int32_type`, provides dummy schema type
    // - `get_test_int64_type`, provides dummy schema type
    // - `test_read_batch_int32`, wrapper for `read_batch` tests, since they are basically
    //   the same, just different def/rep levels and batch size.
    //
    // # Page assembly
    //
    // Page construction and generation of values, definition and repetition levels
    // happens in `make_pages` function.
    // All values are randomly generated based on provided min/max, levels are calculated
    // based on provided max level for column descriptor (which is basically either int32
    // or int64 type in tests) and `levels_per_page` variable.
    //
    // We use `DataPageBuilder` and its implementation `DataPageBuilderImpl` to actually
    // turn values, definition and repetition levels into data pages (either v1 or v2).
    //
    // Those data pages are then stored as part of `TestPageReader` (we just pass vector
    // of generated pages directly), which implements `PageReader` interface.
    //
    // # Comparison
    //
    // This allows us to pass test page reader into column reader, so we can test
    // functionality of column reader - see `test_read_batch`, where we create column
    // reader -> typed column reader, buffer values in `read_batch` method and compare
    // output with generated data.

    // Returns dummy Parquet `Type` for primitive field, because most of our tests use
    // INT32 physical type.
    fn get_test_int32_type() -> SchemaType {
        SchemaType::primitive_type_builder("a", PhysicalType::INT32)
            .with_repetition(Repetition::REQUIRED)
            .with_logical_type(LogicalType::INT_32)
            .with_length(-1)
            .build()
            .expect("build() should be OK")
    }

    // Returns dummy Parquet `Type` for INT64 physical type.
    fn get_test_int64_type() -> SchemaType {
        SchemaType::primitive_type_builder("a", PhysicalType::INT64)
            .with_repetition(Repetition::REQUIRED)
            .with_logical_type(LogicalType::INT_64)
            .with_length(-1)
            .build()
            .expect("build() should be OK")
    }

    // Tests `read_batch()` functionality for INT32.
    //
    // This is a high level wrapper on `ColumnReaderTester` that allows us to specify some
    // boilerplate code for setting up definition/repetition levels and column descriptor.
    fn test_read_batch_int32(
        batch_size: usize,
        values: &mut [i32],
        def_levels: Option<&mut [i16]>,
        rep_levels: Option<&mut [i16]>,
    ) {
        let primitive_type = get_test_int32_type();
        // make field is required based on provided slices of levels
        let max_def_level = if def_levels.is_some() {
            MAX_DEF_LEVEL
        } else {
            0
        };
        let max_rep_level = if def_levels.is_some() {
            MAX_REP_LEVEL
        } else {
            0
        };

        let desc = Rc::new(ColumnDescriptor::new(
            Rc::new(primitive_type),
            None,
            max_def_level,
            max_rep_level,
            ColumnPath::new(Vec::new()),
        ));
        let mut tester = ColumnReaderTester::<Int32Type>::new();
        tester.test_read_batch(
            desc,
            Encoding::RLE_DICTIONARY,
            NUM_PAGES,
            NUM_LEVELS,
            batch_size,
            std::i32::MIN,
            std::i32::MAX,
            values,
            def_levels,
            rep_levels,
            false,
        );
    }

    struct ColumnReaderTester<T: DataType>
    where
        T::T: PartialOrd + SampleUniform + Copy,
    {
        rep_levels: Vec<i16>,
        def_levels: Vec<i16>,
        values: Vec<T::T>,
    }

    impl<T: DataType> ColumnReaderTester<T>
    where
        T::T: PartialOrd + SampleUniform + Copy,
    {
        pub fn new() -> Self {
            Self {
                rep_levels: Vec::new(),
                def_levels: Vec::new(),
                values: Vec::new(),
            }
        }

        // Method to generate and test data pages v1
        fn plain_v1(
            &mut self,
            desc: ColumnDescPtr,
            num_pages: usize,
            num_levels: usize,
            batch_size: usize,
            min: T::T,
            max: T::T,
        ) {
            self.test_read_batch_general(
                desc,
                Encoding::PLAIN,
                num_pages,
                num_levels,
                batch_size,
                min,
                max,
                false,
            );
        }

        // Method to generate and test data pages v2
        fn plain_v2(
            &mut self,
            desc: ColumnDescPtr,
            num_pages: usize,
            num_levels: usize,
            batch_size: usize,
            min: T::T,
            max: T::T,
        ) {
            self.test_read_batch_general(
                desc,
                Encoding::PLAIN,
                num_pages,
                num_levels,
                batch_size,
                min,
                max,
                true,
            );
        }

        // Method to generate and test dictionary page + data pages v1
        fn dict_v1(
            &mut self,
            desc: ColumnDescPtr,
            num_pages: usize,
            num_levels: usize,
            batch_size: usize,
            min: T::T,
            max: T::T,
        ) {
            self.test_read_batch_general(
                desc,
                Encoding::RLE_DICTIONARY,
                num_pages,
                num_levels,
                batch_size,
                min,
                max,
                false,
            );
        }

        // Method to generate and test dictionary page + data pages v2
        fn dict_v2(
            &mut self,
            desc: ColumnDescPtr,
            num_pages: usize,
            num_levels: usize,
            batch_size: usize,
            min: T::T,
            max: T::T,
        ) {
            self.test_read_batch_general(
                desc,
                Encoding::RLE_DICTIONARY,
                num_pages,
                num_levels,
                batch_size,
                min,
                max,
                true,
            );
        }

        // Helper function for the general case of `read_batch()` where `values`,
        // `def_levels` and `rep_levels` are always provided with enough space.
        fn test_read_batch_general(
            &mut self,
            desc: ColumnDescPtr,
            encoding: Encoding,
            num_pages: usize,
            num_levels: usize,
            batch_size: usize,
            min: T::T,
            max: T::T,
            use_v2: bool,
        ) {
            let mut def_levels = vec![0; num_levels * num_pages];
            let mut rep_levels = vec![0; num_levels * num_pages];
            let mut values = vec![T::T::default(); num_levels * num_pages];
            self.test_read_batch(
                desc,
                encoding,
                num_pages,
                num_levels,
                batch_size,
                min,
                max,
                &mut values,
                Some(&mut def_levels),
                Some(&mut rep_levels),
                use_v2,
            );
        }

        // Helper function to test `read_batch()` method with custom buffers for values,
        // definition and repetition levels.
        fn test_read_batch(
            &mut self,
            desc: ColumnDescPtr,
            encoding: Encoding,
            num_pages: usize,
            num_levels: usize,
            batch_size: usize,
            min: T::T,
            max: T::T,
            values: &mut [T::T],
            mut def_levels: Option<&mut [i16]>,
            mut rep_levels: Option<&mut [i16]>,
            use_v2: bool,
        ) {
            let mut pages = VecDeque::new();
            make_pages::<T>(
                desc.clone(),
                encoding,
                num_pages,
                num_levels,
                min,
                max,
                &mut self.def_levels,
                &mut self.rep_levels,
                &mut self.values,
                &mut pages,
                use_v2,
            );
            let max_def_level = desc.max_def_level();
            let page_reader = TestPageReader::new(Vec::from(pages));
            let column_reader: ColumnReader =
                get_column_reader(desc, Box::new(page_reader));
            let mut typed_column_reader = get_typed_column_reader::<T>(column_reader);

            let mut curr_values_read = 0;
            let mut curr_levels_read = 0;
            let mut done = false;
            while !done {
                let actual_def_levels =
                    def_levels.as_mut().map(|vec| &mut vec[curr_levels_read..]);
                let actual_rep_levels =
                    rep_levels.as_mut().map(|vec| &mut vec[curr_levels_read..]);

                let (values_read, levels_read) = typed_column_reader
                    .read_batch(
                        batch_size,
                        actual_def_levels,
                        actual_rep_levels,
                        &mut values[curr_values_read..],
                    )
                    .expect("read_batch() should be OK");

                if values_read == 0 && levels_read == 0 {
                    done = true;
                }

                curr_values_read += values_read;
                curr_levels_read += levels_read;
            }

            assert!(
                values.len() >= curr_values_read,
                "values.len() >= values_read"
            );
            assert_eq!(
                &values[0..curr_values_read],
                &self.values[0..curr_values_read],
                "values content doesn't match"
            );

            if let Some(ref levels) = def_levels {
                assert!(
                    levels.len() >= curr_levels_read,
                    "def_levels.len() >= levels_read"
                );
                assert_eq!(
                    &levels[0..curr_levels_read],
                    &self.def_levels[0..curr_levels_read],
                    "definition levels content doesn't match"
                );
            }

            if let Some(ref levels) = rep_levels {
                assert!(
                    levels.len() >= curr_levels_read,
                    "rep_levels.len() >= levels_read"
                );
                assert_eq!(
                    &levels[0..curr_levels_read],
                    &self.rep_levels[0..curr_levels_read],
                    "repetition levels content doesn't match"
                );
            }

            if def_levels.is_none() && rep_levels.is_none() {
                assert!(
                    curr_levels_read == 0,
                    "expected to read 0 levels, found {}",
                    curr_levels_read
                );
            } else if def_levels.is_some() && max_def_level > 0 {
                assert!(
                    curr_levels_read >= curr_values_read,
                    "expected levels read to be greater than values read"
                );
            }
        }
    }

    struct TestPageReader {
        pages: IntoIter<Page>,
    }

    impl TestPageReader {
        pub fn new(pages: Vec<Page>) -> Self {
            Self {
                pages: pages.into_iter(),
            }
        }
    }

    impl PageReader for TestPageReader {
        fn get_next_page(&mut self) -> Result<Option<Page>> {
            Ok(self.pages.next())
        }
    }
}