periods.go

package logs

import (
	"time"
)

type Period struct {
	Start time.Time `json:"start_time"`
	End   time.Time `json:"end_time"`
}

func (p Period) Duration() time.Duration {
	return p.End.Sub(p.Start)
}

type Periods []Period

func NewPeriods(start time.Time, end time.Time) Periods {
	if end.Before(start) {
		return []Period{}
	}
	return []Period{{Start: start, End: end}}
}

func (ps Periods) Without(p Period) Periods {
	if len(ps) == 0 {
		return ps //nothing left to take from
	}
	if p.End.Before(ps[0].Start) {
		return ps //before first period
	}
	if p.Start.After(ps[len(ps)-1].End) {
		return ps //after last period
	}

	//logger.Debugf("Start: %+v", ps)
	nextIndex := 0
	for nextIndex < len(ps) && ps[nextIndex].End.Before(p.Start) {
		//logger.Debugf("skip[%d]: %s > %s", nextIndex, p.Start, ps[nextIndex].End)
		nextIndex++
	}
	toDelete := []int{}
	for nextIndex < len(ps) && ps[nextIndex].End.Before(p.End) {
		if ps[nextIndex].Start.Before(p.Start) {
			//trim tail
			//logger.Debugf("tail[%d] %s->%s", nextIndex, ps[nextIndex].End, p.Start)
			ps[nextIndex].End = p.Start
		} else {
			//delete this period completely and move to next
			toDelete = append(toDelete, nextIndex)
			//logger.Debugf("delete[%d] %s..%s", nextIndex, ps[nextIndex].Start, ps[nextIndex].End)
		}
		nextIndex++
	}
	if nextIndex < len(ps) && ps[nextIndex].End.After(p.End) {
		if ps[nextIndex].Start.Before(p.Start) {
			//remove part of this period
			ps = append(ps, Period{Start: p.End, End: ps[nextIndex].End})
			ps[nextIndex].End = p.Start
			//logger.Debugf("split[%d]", nextIndex)
		} else {
			if ps[nextIndex].Start.Before(p.End) {
				//trim head of period to start after removed peroid, then stop
				//logger.Debugf("head[%d] %s->%s", nextIndex, ps[nextIndex].Start, p.End)
				ps[nextIndex].Start = p.End
			}
		}
	}

	//delete selected periods completely