interval.go

package vttime

import (
	"fmt"
	"time"
)

// Interval describes a time interval
type Interval struct {
	earliest time.Time
	latest   time.Time
}

// NewInterval creates a new Interval from the provided times.
// earliest has to be smaller or equal to latest, or an error is returned.
func NewInterval(earliest, latest time.Time) (Interval, error) {
	if latest.Sub(earliest) < 0 {
		return Interval{}, fmt.Errorf("NewInterval: earliest has to be smaller or equal to latest, but got: earliest=%v latest=%v", earliest, latest)
	}
	return Interval{
		earliest: earliest,
		latest:   latest,
	}, nil
}

// Earliest returns the earliest time in the interval. If Interval was
// from calling Now(), it is guaranteed the real time was greater or
// equal than Earliest().
func (i Interval) Earliest() time.Time {
	return i.earliest
}

// Latest returns the latest time in the interval. If Interval was
// from calling Now(), it is guaranteed the real time was lesser or
// equal than Latest().
func (i Interval) Latest() time.Time {
	return i.latest
}

// Less returns true if the provided interval is earlier than the parameter.
// Since both intervals are inclusive, comparison has to be strict.
func (i Interval) Less(other Interval) bool {
	return i.latest.Sub(other.earliest) < 0
}

// IsValid returns true iff latest >= earliest, meaning the interval
// is actually a real valid interval.
func (i Interval) IsValid() bool {
	return i.latest.Sub(i.earliest) >= 0
}