/* test card reader: call this program at the same time with 2 different readers */

package main

import (

  "fmt"
  "flag"
  "os"
  "strings"
  "encoding/hex"
  "github.com/ebfe/scard"
)


/* ----------------------------------------------------------------------------------------------- */
func H2b (h string)  ([]byte) {
  decoded, err := hex.DecodeString (h)
  if err != nil {fmt.Printf ("Error: H2b: not a hex string <%s>\n", h); os.Exit (-1)}
  return decoded
}


/* ----------------------------------------------------------------------------------------------- */
func B2h (b []byte)  (string) { 
  s := hex.EncodeToString(b)
  return  strings.ToUpper (s)
}


/* ----------------------------------------------------------------------------------------------- */
func send (card *scard.Card, apdu string) (string) {
  
  // remove dots
  apdu = strings.Replace(apdu, ".", "", -1)
  
  Bcmd := H2b (apdu) 
  fmt.Println (">: ", apdu)
  Brsp, err := card.Transmit (Bcmd)
  if err != nil {fmt.Println ("Error: Transmit: ", err); os.Exit (-1)}
  rsp := B2h (Brsp)
  fmt.Println ("<: ", rsp)
  return rsp
}


/* ------------------------------------------------------------------------------------------------ */
func main() {

  var readerno        int           // selected number of reader

  flag.IntVar     (&readerno,     "cardreader",  0,                     "Card Reader No")
  flag.Parse() 

  context, err1 := scard.EstablishContext()
  if err1 != nil {fmt.Println ("Error: EstablishContext: ", err1); os.Exit (-1)}

  reader_list, err2 := context.ListReaders()
  if err2 != nil {fmt.Println ("Error: ListReaders: ", err2); os.Exit (-1)}
  
  fmt.Println ("Available Readers:")
  for i, r := range reader_list { fmt.Println ("- ", i, ": ", r) }
    
  reader := reader_list[readerno]
  card, err3 := context.Connect (reader, scard.ShareShared, scard.ProtocolAny)
  if err3 != nil { fmt.Println ("Error: Connect failed"); os.Exit (-1)}
       
  status, err4 := card.Status()
  if err4 != nil { fmt.Println ("Error: Status failed"); os.Exit (-1)}
  
  fmt.Println ("ATR: ", status.Atr)
 

  apdu := "A020.0001.08.30303030FFFFFFFF"        // Verify PIN (0000)
  send (card, apdu)
  send (card, "A0A40000023F0000")                // select Root
  send (card, "A0C0000022")                      // GET RESPONSE
  
  
  
  // Finish
  err5 := card.Disconnect (scard.ResetCard)
  if err5 != nil { fmt.Println ("Error: Disconnect failed"); os.Exit (-1)}
  context.Release()  

}