/*
    * DavMail POP/IMAP/SMTP/CalDav/LDAP Exchange Gateway
    * Copyright (C) 2009  Mickael Guessant
    *
    * This program is free software; you can redistribute it and/or
    * modify it under the terms of the GNU General Public License
    * as published by the Free Software Foundation; either version 2
    * of the License, or (at your option) any later version.
    *
   * This program is distributed in the hope that it will be useful,
   * but WITHOUT ANY WARRANTY; without even the implied warranty of
   * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   * GNU General Public License for more details.
   *
   * You should have received a copy of the GNU General Public License
   * along with this program; if not, write to the Free Software
   * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
   */
  package davmail.http;
  
  import java.io.ByteArrayInputStream;
  import java.io.InputStream;
  import java.lang.reflect.Constructor;
  import java.lang.reflect.Method;
  import java.nio.charset.StandardCharsets;
  import java.security.AuthProvider;
  import java.security.Provider;
  import java.security.Security;
  
  /**
   * Add the SunPKCS11 Provider.
   */
  public final class SunPKCS11ProviderHandler {
  
      private SunPKCS11ProviderHandler() {
      }
  
      /**
       * Register PKCS11 provider.
       *
       * @param pkcs11Config PKCS11 config string
       */
      public static void registerProvider(String pkcs11Config) {
          Provider p;
  
          try {
              @SuppressWarnings("unchecked") Class<AuthProvider> sunPkcs11Class = (Class<AuthProvider>) Class.forName("sun.security.pkcs11.SunPKCS11");
              Constructor<AuthProvider> sunPkcs11Constructor = sunPkcs11Class.getDeclaredConstructor(InputStream.class);
              p = sunPkcs11Constructor.newInstance(new ByteArrayInputStream(pkcs11Config.getBytes(StandardCharsets.UTF_8)));
          } catch (NoSuchMethodException e) {
              // try java 9 configuration
              p = configurePkcs11Provider(pkcs11Config);
          } catch (Exception e) {
              throw new PKCS11ProviderException(buildErrorMessage(e));
          }
  
          Security.addProvider(p);
      }
  
      private static Provider configurePkcs11Provider(String pkcs11Config) {
          Provider p;
          try {
              p = Security.getProvider("SunPKCS11");
              // new Java 9 configure method
              Method configureMethod = Provider.class.getDeclaredMethod("configure", String.class);
              configureMethod.invoke(p, "--"+pkcs11Config);
          } catch (Exception e) {
              throw new PKCS11ProviderException(buildErrorMessage(e));
          }
          return p;
      }
  
      private static String buildErrorMessage(Exception e) {
          StringBuilder errorMessage = new StringBuilder("Unable to configure SunPKCS11 provider");
          Throwable cause = e.getCause();
          while (cause != null) {
              errorMessage.append(" ").append(cause.getMessage());
              cause = cause.getCause();
          }
          return errorMessage.toString();
      }
  
      static final class PKCS11ProviderException extends RuntimeException {
          public PKCS11ProviderException(String message) {
              super(message);
          }
      }
  
  }