cmd/tai64nlocal/main.go

   1 /*
   2 go.cypherpunks.ru/tai64n -- Pure Go TAI64/TAI64N implementation
   3 Copyright (C) 2020-2022 Sergey Matveev <stargrave@stargrave.org>
   4
   5 This program is free software: you can redistribute it and/or modify
   6 it under the terms of the GNU General Public License as published by
   7 the Free Software Foundation, version 3 of the License.
   8
   9 This program is distributed in the hope that it will be useful,
  10 but WITHOUT ANY WARRANTY; without even the implied warranty of
  11 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12 GNU General Public License for more details.
  13
  14 You should have received a copy of the GNU General Public License
  15 along with this program.  If not, see <http://www.gnu.org/licenses/>.
  16 */
  17
  18 package main
  19
  20 import (
  21         "bufio"
  22         "flag"
  23         "fmt"
  24         "log"
  25         "os"
  26         "strings"
  27         "time"
  28
  29         "go.cypherpunks.ru/tai64n/v2"
  30 )
  31
  32 func main() {
  33         log.SetFlags(0)
  34         flag.Usage = func() {
  35                 fmt.Fprintf(
  36                         flag.CommandLine.Output(),
  37                         "Replace \"@HEX(TAI64)\"-prefixed line with human readable UTC.\n",
  38                 )
  39                 flag.PrintDefaults()
  40         }
  41         leapsecs := flag.Bool("leapsecs", false, "Take leap seconds into account: honest TAI->UTC")
  42         db := flag.String("leapsecsdb", "", "Use that leapsecs.dat leap seconds database")
  43         flag.Parse()
  44
  45         if *db != "" {
  46                 buf, err := os.ReadFile(*db)
  47                 if err != nil {
  48                         log.Fatalln(err)
  49                 }
  50                 tai64n.LeapsecsDBLoad(buf)
  51         }
  52
  53         scanner := bufio.NewScanner(os.Stdin)
  54         var err error
  55         var s string
  56         var sep int
  57         var t time.Time
  58         for {
  59                 if !scanner.Scan() {
  60                         if err = scanner.Err(); err != nil {
  61                                 log.Fatalln(err)
  62                         }
  63                         break
  64                 }
  65                 s = scanner.Text()
  66                 if s[0] != '@' {
  67                         os.Stdout.WriteString(s + "\n")
  68                         continue
  69                 }
  70                 sep = strings.IndexByte(s, byte(' '))
  71                 if sep == -1 {
  72                         os.Stdout.WriteString(s + "\n")
  73                         continue
  74                 }
  75                 t, err = tai64n.Decode(s[1:sep])
  76                 if err != nil {
  77                         log.Fatalln(err)
  78                 }
  79                 if *leapsecs {
  80                         t = tai64n.LeapsecsSub(t)
  81                 }
  82                 os.Stdout.WriteString(t.Format(tai64n.LocalFmt) + s[sep:] + "\n")
  83         }
  84 }