#include <DB/Core/Defines.h>

#include <DB/IO/ReadHelpers.h>
#include <DB/IO/VarInt.h>
#include <DB/IO/CompressedReadBufferFromFile.h>

#include <DB/Columns/ColumnArray.h>
#include <DB/DataTypes/DataTypeArray.h>
#include <DB/DataTypes/DataTypeFactory.h>

#include <DB/DataStreams/NativeBlockInputStream.h>


namespace DB
{


NativeBlockInputStream::NativeBlockInputStream(
	ReadBuffer & istr_, UInt64 server_revision_,
	const IndexForNativeFormat * index_)
	: istr(istr_), server_revision(server_revision_), index(index_)
{
	if (index)
	{
		istr_concrete = typeid_cast<CompressedReadBufferFromFile *>(&istr);
		if (!istr_concrete)
			throw Exception("When need to use index for NativeBlockInputStream, istr must be CompressedReadBufferFromFile.", ErrorCodes::LOGICAL_ERROR);

		index_block_it = index->blocks.begin();
		index_column_it = index_block_it->columns.begin();
	}
}


void NativeBlockInputStream::readData(const IDataType & type, IColumn & column, ReadBuffer & istr, size_t rows)
{
	/** Для массивов требуется сначала десериализовать смещения, а потом значения.
	  */
	if (const DataTypeArray * type_arr = typeid_cast<const DataTypeArray *>(&type))
	{
		IColumn & offsets_column = *typeid_cast<ColumnArray &>(column).getOffsetsColumn();
		type_arr->getOffsetsType()->deserializeBinary(offsets_column, istr, rows, 0);

		if (offsets_column.size() != rows)
			throw Exception("Cannot read all data in NativeBlockInputStream.", ErrorCodes::CANNOT_READ_ALL_DATA);

		if (rows)
			readData(
				*type_arr->getNestedType(),
				typeid_cast<ColumnArray &>(column).getData(),
				istr,
				typeid_cast<const ColumnArray &>(column).getOffsets()[rows - 1]);
	}
	else
		type.deserializeBinary(column, istr, rows, 0);	/// TODO Использовать avg_value_size_hint.

	if (column.size() != rows)
		throw Exception("Cannot read all data in NativeBlockInputStream.", ErrorCodes::CANNOT_READ_ALL_DATA);
}


Block NativeBlockInputStream::readImpl()
{
	Block res;

	const DataTypeFactory & data_type_factory = DataTypeFactory::instance();

	if (index && index_block_it == index->blocks.end())
		return res;

	if (istr.eof())
	{
		if (index)
			throw Exception("Input doesn't contain all data for index.", ErrorCodes::CANNOT_READ_ALL_DATA);

		return res;
	}

	/// Дополнительная информация о блоке.
	if (server_revision >= DBMS_MIN_REVISION_WITH_BLOCK_INFO)
		res.info.read(istr);

	/// Размеры
	size_t columns = 0;
	size_t rows = 0;

	if (!index)
	{
		readVarUInt(columns, istr);
		readVarUInt(rows, istr);
	}
	else
	{
		columns = index_block_it->num_columns;
		rows = index_block_it->num_rows;
	}

	for (size_t i = 0; i < columns; ++i)
	{
		if (index)	/// Если текущая позиция какая требуется, то реального seek-а не происходит.
			istr_concrete->seek(index_column_it->location.offset_in_compressed_file, index_column_it->location.offset_in_decompressed_block);

		ColumnWithTypeAndName column;

		/// Имя
		readBinary(column.name, istr);

		/// Тип
		String type_name;
		readBinary(type_name, istr);
		column.type = data_type_factory.get(type_name);

		if (index)
		{
			/// Индекс позволяет сделать проверки.
			if (index_column_it->name != column.name)
				throw Exception("Index points to column with wrong name: corrupted index or data", ErrorCodes::INCORRECT_INDEX);
			if (index_column_it->type != type_name)
				throw Exception("Index points to column with wrong type: corrupted index or data", ErrorCodes::INCORRECT_INDEX);
		}

		/// Данные
		column.column = column.type->createColumn();
		readData(*column.type, *column.column, istr, rows);

		res.insert(column);

		if (index)
			++index_column_it;
	}

	if (index)
	{
		if (index_column_it != index_block_it->columns.end())
			throw Exception("Inconsistent index: not all columns were read", ErrorCodes::INCORRECT_INDEX);

		++index_block_it;
	}

	return res;
}


void IndexForNativeFormat::read(ReadBuffer & istr, const NameSet & required_columns)
{
	while (!istr.eof())
	{
		blocks.emplace_back();
		IndexOfBlockForNativeFormat & block = blocks.back();

		readVarUInt(block.num_columns, istr);
		readVarUInt(block.num_rows, istr);

		if (block.num_columns < required_columns.size())
			throw Exception("Index contain less than required columns", ErrorCodes::INCORRECT_INDEX);

		for (size_t i = 0; i < block.num_columns; ++i)
		{
			IndexOfOneColumnForNativeFormat column_index;

			readBinary(column_index.name, istr);
			readBinary(column_index.type, istr);
			readBinary(column_index.location.offset_in_compressed_file, istr);
			readBinary(column_index.location.offset_in_decompressed_block, istr);

			if (required_columns.count(column_index.name))
				block.columns.push_back(std::move(column_index));
		}

		if (block.columns.size() < required_columns.size())
			throw Exception("Index contain less than required columns", ErrorCodes::INCORRECT_INDEX);
		if (block.columns.size() > required_columns.size())
			throw Exception("Index contain duplicate columns", ErrorCodes::INCORRECT_INDEX);

		block.num_columns = block.columns.size();
	}
}


}