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|
package main
import (
"fmt"
"os"
"strconv"
"strings"
"time"
)
const usage = `usage: when <time>
This program converts the given time into various formats (currently a local
timestamp, UTC timestamp, and UNIX epoch). It tries to guess what the input is.
Some valid queries:
2024-01-05
1715079241
tomorrow 5PM
-22h
-7h10m
Mar 15
Sep 3 18:00
For now a single timestamp and a single duration (which is added either to the
current time, or the given time) is supported.`
func printTime(t time.Time) {
fmt.Println("Local:", t.Format("Mon 02 January 2006 at 15:04:05 MST"))
fmt.Println("UTC: ", t.UTC().Format(time.RFC3339))
fmt.Println("UNIX: ", t.Unix())
}
type FieldSet uint8
const (
SetYear FieldSet = 1 << iota
SetDay
SetMonth
SetHour
SetMinute
SetSecond
SetLocation
)
const (
SetDate = SetYear | SetDay | SetMonth
SetClock = SetHour | SetMinute | SetSecond
)
// mergeTimes returns a new time.Time with all fields in this overridden with the
// specified fields from that.
func mergeTimes(this time.Time, that time.Time, set FieldSet) time.Time {
year, month, day := this.Date()
hour, min, sec := this.Clock()
loc := this.Location()
if set&SetYear == SetYear {
year = that.Year()
}
if set&SetMonth == SetMonth {
month = that.Month()
}
if set&SetDay == SetDay {
day = that.Day()
}
if set&SetHour == SetHour {
hour = that.Hour()
}
if set&SetMinute == SetMinute {
min = that.Minute()
}
if set&SetSecond == SetSecond {
sec = that.Second()
}
if set&SetLocation == SetLocation {
loc = that.Location()
}
return time.Date(year, month, day, hour, min, sec, 0, loc)
}
func parseTime(input string) (time.Time, error) {
// try unix times
if i, err := strconv.ParseInt(input, 10, 64); err == nil {
if i < 9999999999 {
return time.Unix(i, 0), nil
}
if i < 9999999999999 {
return time.UnixMilli(i), nil
}
}
// try simple date/time formats
if t, err := time.Parse(time.DateOnly, input); err == nil {
return t, nil
}
if t, err := time.Parse(time.Kitchen, input); err == nil {
now := time.Now()
return mergeTimes(now, t, SetClock), nil
}
if t, err := time.Parse(time.TimeOnly, input); err == nil {
now := time.Now()
return mergeTimes(now, t, SetClock), nil
}
if t, err := time.Parse("15:04", input); err == nil {
now := time.Now()
return mergeTimes(now, t, SetClock), nil
}
if t, err := time.Parse("3PM", input); err == nil {
now := time.Now()
return mergeTimes(now, t, SetClock), nil
}
if t, err := time.Parse(time.DateTime, input); err == nil {
return t, nil
}
if t, err := time.Parse(time.Stamp, input); err == nil {
now := time.Now()
return mergeTimes(t, now, SetYear|SetLocation), nil
}
if t, err := time.Parse("Jan _2 15:04", input); err == nil {
now := time.Now()
return mergeTimes(t, now, SetYear|SetLocation), nil
}
if t, err := time.Parse("Jan _2", input); err == nil {
now := time.Now()
return mergeTimes(t, now, SetYear|SetLocation), nil
}
return time.Time{}, fmt.Errorf("could not parse time: %q", input)
}
func parseDuration(input string) (time.Duration, error) {
// some simple rewriting
switch input {
case "yesterday":
input = "-24h"
case "tomorrow":
input = "24h"
case "today", "now":
return time.Duration(0), nil
}
// TODO: days, months, weeks, ...
return time.ParseDuration(input)
}
func main() {
if len(os.Args) < 2 {
fmt.Fprintln(os.Stderr, usage)
os.Exit(1)
}
var d time.Duration
var t time.Time
var err error
var haveTime, haveDuration bool
// Try to parse entire input as one full thing, before getting more
// clever.
if t, err = parseTime(strings.Join(os.Args[1:], " ")); err == nil {
printTime(t)
return
}
for _, arg := range os.Args[1:] {
if !haveTime {
if t, err = parseTime(arg); err == nil {
haveTime = true
continue
}
}
if !haveDuration {
if d, err = parseDuration(arg); err == nil {
haveDuration = true
continue
}
}
}
if err != nil {
fmt.Fprintln(os.Stderr, "Not sure what you want, try another time.")
os.Exit(1)
}
if haveTime && haveDuration {
printTime(t.Add(d))
} else if haveTime {
printTime(t)
} else if haveDuration {
printTime(time.Now().Add(d))
} else {
fmt.Fprintln(os.Stderr, "Not sure what you want, try another time.")
os.Exit(1)
}
}
|
