cmd/tai64nlocal/main.go

   1 // go.cypherpunks.ru/tai64n -- Pure Go TAI64/TAI64N implementation
   2 // Copyright (C) 2020-2024 Sergey Matveev <stargrave@stargrave.org>
   3 //
   4 // This program is free software: you can redistribute it and/or modify
   5 // it under the terms of the GNU General Public License as published by
   6 // the Free Software Foundation, version 3 of the License.
   7 //
   8 // This program is distributed in the hope that it will be useful,
   9 // but WITHOUT ANY WARRANTY; without even the implied warranty of
  10 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  11 // GNU General Public License for more details.
  12 //
  13 // You should have received a copy of the GNU General Public License
  14 // along with this program.  If not, see <http://www.gnu.org/licenses/>.
  15
  16 package main
  17
  18 import (
  19         "bufio"
  20         "flag"
  21         "fmt"
  22         "log"
  23         "os"
  24         "strings"
  25         "time"
  26
  27         "go.cypherpunks.ru/tai64n/v2"
  28 )
  29
  30 func main() {
  31         log.SetFlags(0)
  32         flag.Usage = func() {
  33                 fmt.Fprintf(
  34                         flag.CommandLine.Output(),
  35                         "Replace \"@HEX(TAI64)\"-prefixed line with human readable UTC.\n",
  36                 )
  37                 flag.PrintDefaults()
  38         }
  39         leapsecs := flag.Bool("leapsecs", false, "Take leap seconds into account: honest TAI->UTC")
  40         db := flag.String("leapsecsdb", "", "Use that leapsecs.dat leap seconds database")
  41         flag.Parse()
  42
  43         if *db != "" {
  44                 buf, err := os.ReadFile(*db)
  45                 if err != nil {
  46                         log.Fatalln(err)
  47                 }
  48                 tai64n.LeapsecsDBLoad(buf)
  49         }
  50
  51         scanner := bufio.NewScanner(os.Stdin)
  52         var err error
  53         var s string
  54         var sep int
  55         var t time.Time
  56         for {
  57                 if !scanner.Scan() {
  58                         if err = scanner.Err(); err != nil {
  59                                 log.Fatalln(err)
  60                         }
  61                         break
  62                 }
  63                 s = scanner.Text()
  64                 if s[0] != '@' {
  65                         os.Stdout.WriteString(s + "\n")
  66                         continue
  67                 }
  68                 sep = strings.IndexByte(s, byte(' '))
  69                 if sep == -1 {
  70                         os.Stdout.WriteString(s + "\n")
  71                         continue
  72                 }
  73                 t, err = tai64n.Decode(s[1:sep])
  74                 if err != nil {
  75                         log.Fatalln(err)
  76                 }
  77                 if *leapsecs {
  78                         t = tai64n.LeapsecsSub(t)
  79                 }
  80                 os.Stdout.WriteString(t.Format(tai64n.LocalFmt) + s[sep:] + "\n")
  81         }
  82 }