// Copyright (c) 2015-2021 MinIO, Inc.//// This file is part of MinIO Object Storage stack//// This program is free software: you can redistribute it and/or modify// it under the terms of the GNU Affero General Public License as published by// the Free Software Foundation, either version 3 of the License, or// (at your option) any later version.//// This program is distributed in the hope that it will be useful// but WITHOUT ANY WARRANTY; without even the implied warranty of// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the// GNU Affero General Public License for more details.//// You should have received a copy of the GNU Affero General Public License// along with this program.  If not, see <http://www.gnu.org/licenses/>. package sql import (	"time") const (	layoutYear       = "2006T"	layoutMonth      = "2006-01T"	layoutDay        = "2006-01-02T"	layoutMinute     = "2006-01-02T15:04Z07:00"	layoutSecond     = "2006-01-02T15:04:05Z07:00"	layoutNanosecond = "2006-01-02T15:04:05.999999999Z07:00") var tformats = []string{	layoutYear,	layoutMonth,	layoutDay,	layoutMinute,	layoutSecond,	layoutNanosecond,} func parseSQLTimestamp(s string) (t time.Time, err error) {	for _, f := range tformats {		t, err = time.Parse(f, s)		if err == nil {			break		}	}	return} // FormatSQLTimestamp - returns the a string representation of the// timestamp as used in S3 Selectfunc FormatSQLTimestamp(t time.Time) string {	_, zoneOffset := t.Zone()	hasZone := zoneOffset != 0	hasFracSecond := t.Nanosecond() != 0	hasSecond := t.Second() != 0	hasTime := t.Hour() != 0 || t.Minute() != 0	hasDay := t.Day() != 1	hasMonth := t.Month() != 1 	switch {	case hasFracSecond:		return t.Format(layoutNanosecond)	case hasSecond:		return t.Format(layoutSecond)	case hasTime || hasZone:		return t.Format(layoutMinute)	case hasDay:		return t.Format(layoutDay)	case hasMonth:		return t.Format(layoutMonth)	default:		return t.Format(layoutYear)	}} const (	timePartYear           = "YEAR"	timePartMonth          = "MONTH"	timePartDay            = "DAY"	timePartHour           = "HOUR"	timePartMinute         = "MINUTE"	timePartSecond         = "SECOND"	timePartTimezoneHour   = "TIMEZONE_HOUR"	timePartTimezoneMinute = "TIMEZONE_MINUTE") func extract(what string, t time.Time) (v *Value, err error) {	switch what {	case timePartYear:		return FromInt(int64(t.Year())), nil	case timePartMonth:		return FromInt(int64(t.Month())), nil	case timePartDay:		return FromInt(int64(t.Day())), nil	case timePartHour:		return FromInt(int64(t.Hour())), nil	case timePartMinute:		return FromInt(int64(t.Minute())), nil	case timePartSecond:		return FromInt(int64(t.Second())), nil	case timePartTimezoneHour:		_, zoneOffset := t.Zone()		return FromInt(int64(zoneOffset / 3600)), nil	case timePartTimezoneMinute:		_, zoneOffset := t.Zone()		return FromInt(int64((zoneOffset % 3600) / 60)), nil	default:		// This does not happen		return nil, errNotImplemented	}} func dateAdd(timePart string, qty float64, t time.Time) (*Value, error) {	var duration time.Duration	switch timePart {	case timePartYear:		return FromTimestamp(t.AddDate(int(qty), 0, 0)), nil	case timePartMonth:		return FromTimestamp(t.AddDate(0, int(qty), 0)), nil	case timePartDay:		return FromTimestamp(t.AddDate(0, 0, int(qty))), nil	case timePartHour:		duration = time.Duration(qty) * time.Hour	case timePartMinute:		duration = time.Duration(qty) * time.Minute	case timePartSecond:		duration = time.Duration(qty) * time.Second	default:		return nil, errNotImplemented	}	return FromTimestamp(t.Add(duration)), nil} // dateDiff computes the difference between two times in terms of the// `timePart` which can be years, months, days, hours, minutes or// seconds. For difference in years, months or days, the time part,// including timezone is ignored.func dateDiff(timePart string, ts1, ts2 time.Time) (*Value, error) {	if ts2.Before(ts1) {		v, err := dateDiff(timePart, ts2, ts1)		if err == nil {			v.negate()		}		return v, err	} 	duration := ts2.Sub(ts1)	y1, m1, d1 := ts1.Date()	y2, m2, d2 := ts2.Date() 	switch timePart {	case timePartYear:		dy := int64(y2 - y1)		if m2 > m1 || (m2 == m1 && d2 >= d1) {			return FromInt(dy), nil		}		return FromInt(dy - 1), nil	case timePartMonth:		m1 += time.Month(12 * y1)		m2 += time.Month(12 * y2) 		return FromInt(int64(m2 - m1)), nil	case timePartDay:		return FromInt(int64(duration / (24 * time.Hour))), nil	case timePartHour:		hours := duration / time.Hour		return FromInt(int64(hours)), nil	case timePartMinute:		minutes := duration / time.Minute		return FromInt(int64(minutes)), nil	case timePartSecond:		seconds := duration / time.Second		return FromInt(int64(seconds)), nil	default: 	}	return nil, errNotImplemented}