#include <Columns/IColumn.h>

#include <Functions/IFunction.h>

#include <Functions/FunctionFactory.h>

#include <DataTypes/DataTypeString.h>

#include <base/getFQDNOrHostName.h>

#include <Core/Field.h>

namespace DB

{

class FunctionFQDN : public IFunction

{

public:

static constexpr auto name = "FQDN";

static FunctionPtr create(ContextPtr)

{

return std::make_shared<FunctionFQDN>();

}

String getName() const override

{

return name;

}

bool isDeterministic() const override { return false; }

bool isSuitableForShortCircuitArgumentsExecution(const DataTypesWithConstInfo & /*arguments*/) const override { return false; }

size_t getNumberOfArguments() const override

{

return 0;

}

DataTypePtr getReturnTypeImpl(const DataTypes & /*arguments*/) const override

{

return std::make_shared<DataTypeString>();

}

ColumnPtr executeImpl(const ColumnsWithTypeAndName &, const DataTypePtr & result_type, size_t input_rows_count) const override

{

return result_type->createColumnConst(

input_rows_count, getFQDNOrHostName())->convertToFullColumnIfConst();

}

};

REGISTER_FUNCTION(FQDN)

{

factory.registerFunction<FunctionFQDN>({}, FunctionFactory::Case::Insensitive);

factory.registerAlias("fullHostName", "FQDN");

}

}