ntfy/util/time.go
2023-01-26 22:57:18 -05:00

110 lines
2.8 KiB
Go

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
}