package util import ( "errors" "github.com/olebedev/when" "regexp" "strconv" "strings" "time" ) var ( errUnparsableTime = errors.New("unable to parse time") durationStrRegex = regexp.MustCompile(`(?i)^(\d+)\s*(d|days?|h|hours?|m|mins?|minutes?|s|secs?|seconds?)$`) ) // NextOccurrenceUTC takes a time of day (e.g. 9:00am), and returns the next occurrence // of that time from the current time (in UTC). func NextOccurrenceUTC(timeOfDay, base time.Time) time.Time { hour, minute, seconds := timeOfDay.UTC().Clock() now := base.UTC() next := time.Date(now.Year(), now.Month(), now.Day(), hour, minute, seconds, 0, time.UTC) if next.Before(now) { next = next.AddDate(0, 0, 1) } return next } // ParseFutureTime parses a date/time string to a time.Time. It supports unix timestamps, durations // and natural language dates func ParseFutureTime(s string, now time.Time) (time.Time, error) { s = strings.TrimSpace(s) t, err := parseUnixTime(s, now) if err == nil { return t, nil } t, err = parseFromDuration(s, now) if err == nil { return t, nil } t, err = parseNaturalTime(s, now) if err == nil { return t, nil } return time.Time{}, errUnparsableTime } func parseFromDuration(s string, now time.Time) (time.Time, error) { d, err := parseDuration(s) if err == nil { return now.Add(d), nil } return time.Time{}, errUnparsableTime } func parseDuration(s string) (time.Duration, error) { d, err := time.ParseDuration(s) if err == nil { return d, nil } matches := durationStrRegex.FindStringSubmatch(s) if matches != nil { number, err := strconv.Atoi(matches[1]) if err != nil { return 0, errUnparsableTime } switch unit := matches[2][0:1]; unit { case "d": return time.Duration(number) * 24 * time.Hour, nil case "h": return time.Duration(number) * time.Hour, nil case "m": return time.Duration(number) * time.Minute, nil case "s": return time.Duration(number) * time.Second, nil default: return 0, errUnparsableTime } } return 0, errUnparsableTime } func parseUnixTime(s string, now time.Time) (time.Time, error) { t, err := strconv.Atoi(s) if err != nil { return time.Time{}, err } else if int64(t) < now.Unix() { return time.Time{}, errUnparsableTime } return time.Unix(int64(t), 0).UTC(), nil } func parseNaturalTime(s string, now time.Time) (time.Time, error) { r, err := when.EN.Parse(s, now) // returns "nil, nil" if no matches! if err != nil || r == nil { return time.Time{}, errUnparsableTime } else if r.Time.After(now) { return r.Time, nil } // Hack: If the time is parsable, but not in the future, // simply append "tomorrow, " to it. r, err = when.EN.Parse("tomorrow, "+s, now) // returns "nil, nil" if no matches! if err != nil || r == nil { return time.Time{}, errUnparsableTime } else if r.Time.After(now) { return r.Time, nil } return time.Time{}, errUnparsableTime }