/*
 * call-seq:
 *   list_cache([cache_name]) -> array
 *
 * Call krb5_cc_next_cred to fetch credentials from a cachefile.  With no parameters, it fetches the credentials in the default cachefile.  With one parameter, it fetches the credentials in the named cachefile.  Returns a list of Krb5Auth::Krb5::Cred objects on success, raises Krb5Auth::Krb5::Exception on failure.
 */
static VALUE Krb5_list_cache_creds(int argc, VALUE *argv, VALUE self)
{
  struct ruby_krb5 *kerb;
  krb5_error_code krbret;
  char *cache_name;
  krb5_ccache cc;
  krb5_cc_cursor cur;
  krb5_creds creds;
  char *name;
  char *sname;
  krb5_ticket *tkt;
  VALUE result;
  VALUE line;
    
  if (argc == 0) {
    cache_name = NULL;
  }
  else if (argc == 1) {
    Check_Type(argv[0], T_STRING);
    cache_name = STR2CSTR(argv[0]);
  }
  else {
    rb_raise(rb_eRuntimeError, "Invalid arguments");
  }

  Data_Get_Struct(self, struct ruby_krb5, kerb);
  if (!kerb) {
    NOSTRUCT_EXCEPT();
    return Qfalse;
  }

  if (cache_name == NULL) {
    krbret = krb5_cc_default(kerb->ctx, &cc);
  }
  else {
    krbret = krb5_cc_resolve(kerb->ctx, cache_name, &cc);
  }

  if (krbret) {
    goto cache_fail_raise;
  }

  krbret = krb5_cc_start_seq_get(kerb->ctx, cc, &cur);
  if (krbret) {
    goto cache_fail_close;
  }

  result = rb_ary_new();
  while (!(krbret = krb5_cc_next_cred(kerb->ctx, cc, &cur, &creds))) {
    krbret = krb5_unparse_name(kerb->ctx, creds.client, &name);
    if (krbret) {
      krb5_free_cred_contents(kerb->ctx, &creds);
      break;
    }
    krbret = krb5_unparse_name(kerb->ctx, creds.server, &sname);
    if (krbret) {
      free(name);
      krb5_free_cred_contents(kerb->ctx, &creds);
      break;
    }
    krbret = krb5_decode_ticket(&creds.ticket, &tkt);
    if (krbret) {
      free(sname);
      free(name);
      krb5_free_cred_contents(kerb->ctx, &creds);
      break;
    }
    line = rb_class_new_instance(0, NULL, cCred);
    rb_iv_set(line, "@client", rb_str_new2(name));
    rb_iv_set(line, "@server", rb_str_new2(sname));
    rb_iv_set(line, "@starttime", INT2NUM(creds.times.starttime));
    rb_iv_set(line, "@authtime", INT2NUM(creds.times.authtime));
    rb_iv_set(line, "@endtime", INT2NUM(creds.times.endtime));
    rb_iv_set(line, "@ticket_flags", INT2NUM(creds.ticket_flags));
    rb_iv_set(line, "@cred_enctype", INT2NUM(creds.keyblock.enctype));
    rb_iv_set(line, "@ticket_enctype", INT2NUM(tkt->enc_part.enctype));
    rb_ary_push(result, line);
    krb5_free_ticket(kerb->ctx, tkt);
    free(sname);
    free(name);
    krb5_free_cred_contents(kerb->ctx, &creds);
  }

  if (krbret != KRB5_CC_END) {
    // FIXME: do we need to free up "result" here?  There will be no
    // references to it, so I think the garbage collector will pick it up,
    // but I'm not sure.

    goto cache_fail_close;
  }

  krbret = krb5_cc_end_seq_get(kerb->ctx, cc, &cur);

  krb5_cc_close(kerb->ctx, cc);

  return result;

 cache_fail_close:
  krb5_cc_close(kerb->ctx, cc);

 cache_fail_raise:
  Krb5_register_error(krbret);

  return Qfalse;
}