package main

import (
	"flag"
	"fmt"
	"os"
	"strconv"
	"time"
)

var nflag = flag.Bool("n", false, "print as number of seconds since epoch")
var uflag = flag.Bool("u", false, "print utc")

func usage() {
        fmt.Fprintf(os.Stderr, "usage: date [-un] [seconds]\n")
        os.Exit(2)
}

func error(s string) {
	fmt.Fprint(os.Stderr, s, "\n")
	os.Exit(1)
}

func main() {
	flag.Usage = usage
	flag.Parse()
	args := flag.Args()
	var now time.Time
	if len(args) == 0 {
		now = time.Now()
	} else if len(args) != 1 {
		usage()
	} else {
		s, err := strconv.ParseInt(args[0], 0, 64)
		if err != nil {
			error(fmt.Sprint("bad number: ", err))
		}
		now = time.Unix(s, 0)
	}
	if *nflag {
		fmt.Printf("%d\n", now.Unix())
	} else if *uflag {
		fmt.Printf("%s\n", now.UTC().Format("Mon Jan 2 15:04:05 MST 2006"))
	} else {
		fmt.Printf("%s\n", now.Format("Mon Jan 2 15:04:05 MST 2006"))
	}
}