#pragma once
#include <Core/SortDescription.h>


namespace DB
{

/// Compares fields in terms of sorting order, considering direction.
bool less(const Field & lhs, const Field & rhs, int direction);
bool equals(const Field & lhs, const Field & rhs);

/** Helps to implement modifier WITH FILL for ORDER BY clause.
 *  Stores row as array of fields and provides functions to generate next row for filling gaps and for comparing rows.
 *  Used in FillingTransform.
 */
class FillingRow
{
public:
    explicit FillingRow(const SortDescription & sort_description);

    /// Generates next row according to fill 'from', 'to' and 'step' values.
    /// Return pair of boolean
    /// apply - true if filling values should be inserted into result set
    /// value_changed - true if filling row value was changed
    std::pair<bool, bool> next(const FillingRow & to_row);

    void initFromDefaults(size_t from_pos = 0);

    Field & operator[](size_t index) { return row[index]; }
    const Field & operator[](size_t index) const { return row[index]; }
    size_t size() const { return row.size(); }
    bool operator<(const FillingRow & other) const;
    bool operator==(const FillingRow & other) const;
    bool operator>=(const FillingRow & other) const;
    bool isNull() const;

    int getDirection(size_t index) const { return sort_description[index].direction; }
    FillColumnDescription & getFillDescription(size_t index) { return sort_description[index].fill_description; }
    const FillColumnDescription & getFillDescription(size_t index) const { return sort_description[index].fill_description; }

    String dump() const;

private:
    Row row;
    SortDescription sort_description;
};

WriteBuffer & operator<<(WriteBuffer & out, const FillingRow & row);

}