package libyear

import (
	"fmt"
	"time"
)

// Info defines a version and a commit time for that version
type Info struct {
	Version string    // version string
	Time    time.Time // commit time
}

// Pair is a set of versions for a dependency (current and newest possible)
type Pair struct {
	Name    string
	Latest  Info
	Current Info
}

// Calc returns the summed time distance (as a time.Duration) between a set of Pairs of modules.
// TODO: sum can only represent ~290 years before overflowing, but we don't actually need nanosecond precision!
// Probably worth switching to hour-based summing here.
func Calc(p ...Pair) time.Duration {
	sum := time.Duration(0)
	for i := range p {
		sum = sum + p[i].Latest.Time.Sub(p[i].Current.Time)
	}
	return sum
}

// DecimalYear conversts a time.Duration (which is in nsec) to a two-decimal-place count of years.
func DecimalYear(d time.Duration) string {
	return fmt.Sprintf("%.2f", float64(d.Truncate(time.Hour)/time.Hour)/float64(8760))
}