#pragma once

#include <DataTypes/IDataType.h>

namespace DB

{

/// A nullable data type is an ordinary data type provided with a tag

/// indicating that it also contains the NULL value. The following class

/// embodies this concept.

class DataTypeNullable final : public IDataType

{

public:

static constexpr bool is_parametric = true;

explicit DataTypeNullable(const DataTypePtr & nested_data_type_);

std::string doGetName() const override { return "Nullable(" + nested_data_type->getName() + ")"; }

const char * getFamilyName() const override { return "Nullable"; }

TypeIndex getTypeId() const override { return TypeIndex::Nullable; }

void updateHashImpl(SipHash & hash) const override;

MutableColumnPtr createColumn() const override;

MutableColumnPtr createUninitializedColumnWithSize(size_t size) const override;

Field getDefault() const override;

bool equals(const IDataType & rhs) const override;

bool isParametric() const override { return true; }

bool haveSubtypes() const override { return true; }

bool cannotBeStoredInTables() const override { return nested_data_type->cannotBeStoredInTables(); }

bool shouldAlignRightInPrettyFormats() const override { return nested_data_type->shouldAlignRightInPrettyFormats(); }

bool textCanContainOnlyValidUTF8() const override { return nested_data_type->textCanContainOnlyValidUTF8(); }

bool isComparable() const override { return nested_data_type->isComparable(); }

bool canBeComparedWithCollation() const override { return nested_data_type->canBeComparedWithCollation(); }

bool canBeUsedAsVersion() const override { return false; }

bool isSummable() const override { return nested_data_type->isSummable(); }

bool canBeUsedInBooleanContext() const override { return nested_data_type->canBeUsedInBooleanContext() || onlyNull(); }

bool haveMaximumSizeOfValue() const override { return nested_data_type->haveMaximumSizeOfValue(); }

size_t getMaximumSizeOfValueInMemory() const override { return 1 + nested_data_type->getMaximumSizeOfValueInMemory(); }

bool isNullable() const override { return true; }

size_t getSizeOfValueInMemory() const override;

bool onlyNull() const override;

bool canBeInsideLowCardinality() const override { return nested_data_type->canBeInsideLowCardinality(); }

bool canBePromoted() const override { return nested_data_type->canBePromoted(); }

MutableColumnConstPtr createColumnConst(size_t size, const Field & field) const override;

bool hasDynamicSubcolumnsData() const override { return nested_data_type->hasDynamicSubcolumns(); }

bool hasDynamicStructure() const override { return nested_data_type->hasDynamicStructure(); }

std::unique_ptr<SubstreamData>

getDynamicSubcolumnData(std::string_view subcolumn_name, const SubstreamData & data, size_t initial_array_level, bool throw_if_null) const override;

bool supportsSparseSerialization() const override { return nested_data_type->supportsSparseSerialization(); }

bool canBeInsideSparseColumns() const override { return nested_data_type->canBeInsideSparseColumns(); }

const DataTypePtr & getNestedType() const { return nested_data_type; }

void forEachChild(const ChildCallback & callback) const override;

private:

SerializationPtr doGetSerialization(const SerializationInfoSettings & settings) const override;

DataTypePtr nested_data_type;

};

DataTypePtr makeNullable(const DataTypePtr & type);

DataTypePtr makeNullableSafe(const DataTypePtr & type);

DataTypePtr removeNullable(const DataTypePtr & type);

DataTypePtr makeNullableOrLowCardinalityNullable(const DataTypePtr & type);

DataTypePtr makeNullableOrLowCardinalityNullableSafe(const DataTypePtr & type);

/// Nullable(T) -> T, LowCardinality(Nullable(T)) -> T

DataTypePtr removeNullableOrLowCardinalityNullable(const DataTypePtr & type);

bool canContainNull(const IDataType & type);

}