package main

import (
  "fmt"
  "flag"
  "os"
  "log"
  "crypto/sha512"
)

type Opts struct {
  Inputs []string
}

func ParseOpts() Opts {
  var opts Opts

  flag.Parse()
  opts.Inputs = flag.Args()

  return opts
}

func ToHex(hash [sha512.Size]byte) string {
  result := ""

  for _, b := range hash {
    result += fmt.Sprintf("%x", b)
  }

  return result
}

func main() {
  opts := ParseOpts()

  for _, fname := range opts.Inputs {
    in_data, err := os.ReadFile(fname)
    if err != nil { log.Fatal(err) }

    hash := sha512.Sum512(in_data)

    fmt.Println(ToHex(hash), fname)
  }
}