ckaznocha/marathon-resource

package dates

import (
    "errors"
    "sort"
    "time"
)

//Dates is a sortable slice of times
type Dates []time.Time

func (d Dates) Len() int           { return len(d) }
func (d Dates) Less(i, j int) bool { return d[i].Before(d[j]) }
func (d Dates) Swap(i, j int)      { d[i], d[j] = d[j], d[i] }

//NewerTimestamps returns all timestamps in a list newer than a given timestamp
func NewerTimestamps(
    timestampStrings []string,
    currentTimestampString string,
) ([]string, error) {
    var (
        currentTimestampIndex int
        timestamps            = make(Dates, len(timestampStrings))
    )
    for i, v := range timestampStrings {
        t, err := time.Parse(time.RFC3339Nano, v)
        if err != nil {
            return nil, err
        }
        timestamps[i] = t
    }

    if len(currentTimestampString) == 0 {
        currentTimestampString = time.Unix(0, 0).Format(time.RFC3339Nano)
    }

    currentTimestamp, err := time.Parse(
        time.RFC3339Nano,
        currentTimestampString,
    )
    if err != nil {
        return nil, err
    }

    if !sort.IsSorted(timestamps) {
        sort.Sort(timestamps)
    }

    currentTimestampIndex = sort.Search(
        len(timestamps),
        func(i int) bool {
            return timestamps[i].After(currentTimestamp) ||
                timestamps[i].Equal(currentTimestamp)
        },
    )

    if currentTimestampIndex >= len(timestamps) {
        return nil, errors.New("Version not found")
    }

    var newerTimestamps []string
    for _, v := range timestamps[currentTimestampIndex:] {
        newerTimestamps = append(newerTimestamps, v.Format(time.RFC3339Nano))
    }

    return newerTimestamps, nil

}