package main

import (
	"flag"
	"fmt"
	"time"

	"github.com/lestrrat-go/strftime"
)

func main() {
	in := flag.String("in", "2006-01-02T15:04:05", "input layout")
	out := flag.String("out", "%s", "output layout (or strftime)")
	flag.Parse()

	formatter := func(t time.Time) string {
		return t.Format(*out)
	}
	if pattern, err := strftime.New(
		*out,
		strftime.WithUnixSeconds('s'),
		strftime.WithMilliseconds('L'),
	); err == nil {
		formatter = func(t time.Time) string {
			return pattern.FormatString(t)
		}
	}
	for _, flag := range flag.Args() {
		t, err := time.ParseInLocation(*in, flag, time.Local)
		if err != nil {
			panic(err)
		}
		fmt.Println(formatter(t))
	}
}