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