go时间段分周

这段程序是受困于当初写数据统计时有个非常变态的周统计需求，所以做了一个关于ISO周划分的函数

package awesome

import "time"

type WeekDate struct {
	ISOYear   int
	ISOWeek   int
	StartTime time.Time
	EndTime   time.Time
}

func groupByWeekDate(startTime, endTime time.Time) []WeekDate {
	// Sunday -> Saturday  0,1,2,3,4,5,6
	startOffset := int(time.Monday - startTime.Weekday())
	// 只有Monday减去Sunday的时候是正数
	if startOffset > 0 {
		startOffset = -6
	}
	startMonday := startTime.AddDate(0, 0, startOffset)

	endOffset := int(7 - endTime.Weekday())
	if endOffset == 7 {
		endOffset = 0
	}
	endSunday := endTime.AddDate(0, 0, endOffset)

	var res = make([]WeekDate, 0)
	for i := startMonday; i.Before(endSunday) || i.Equal(endSunday); i = i.AddDate(0, 0, 7) {
		iISOYear, iISOWeek := i.ISOWeek()
		var tmp = WeekDate{
			ISOYear:   iISOYear,
			ISOWeek:   iISOWeek,
			StartTime: i,
			EndTime:   i.AddDate(0, 0, 6),
		}
		res = append(res, tmp)
	}

	return res
}