/* CertificateFactory.java -- Certificate Factory Class
   Copyright (C) 1999, 2002, 2003 Free Software Foundation, Inc.

This file is part of GNU Classpath.

GNU Classpath 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, or (at your option)
any later version.
 
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General Public License for more details.

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02111-1307 USA.

Linking this library statically or dynamically with other modules is
making a combined work based on this library.  Thus, the terms and
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As a special exception, the copyright holders of this library give you
permission to link this library with independent modules to produce an
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package java.security.cert;

import java.security.NoSuchAlgorithmException;
import java.security.NoSuchProviderException;
import java.security.Provider;
import java.security.Security;

import java.io.InputStream;

import java.util.Collection;
import java.util.Iterator;
import java.util.List;

import gnu.java.security.Engine;

/**
 * This class implements the CertificateFactory class interface used to
 * generate certificates, certificate revocation lists (CRLs), and certificate
 * paths objects from their encoded forms.
 *
 * @author Mark Benvenuto
 * @author Casey Marshall
 * @since JDK 1.2
 * @status Fully compatible with JDK 1.4.
 */
public class CertificateFactory
{

  /** The service name for certificate factories. */
  private static final String CERTIFICATE_FACTORY = "CertificateFactory";

  private CertificateFactorySpi certFacSpi;
  private Provider provider;
  private String type;

  /**
   * Creates an instance of CertificateFactory.
   *
   * @param certFacSpi The underlying CertificateFactory engine.
   * @param provider   The provider of this implementation.
   * @param type       The type of Certificate this factory creates.
   */
  protected CertificateFactory(CertificateFactorySpi certFacSpi,
                               Provider provider, String type)
  {
    this.certFacSpi = certFacSpi;
    this.provider = provider;
    this.type = type;
  }

// Class methods.
  // ------------------------------------------------------------------------

  /** 
   * Gets an instance of the CertificateFactory class representing
   * the specified certificate factory. If the type is not 
   * found then, it throws CertificateException.
   *
   * @param type     The type of certificate factory to create.
   * @return a CertificateFactory repesenting the desired type
   * @throws CertificateException If the type of certificate is not
   *    implemented by any installed provider.
   */
  public static final CertificateFactory getInstance(String type)
    throws CertificateException
  {
    Provider[] p = Security.getProviders();

    for (int i = 0; i < p.length; i++)
      {
        try
          {
            return getInstance(type, p[i]);
          }
        catch (CertificateException ignored)
          {
          }
      }

    throw new CertificateException(type);
  }

  /** 
   * Gets an instance of the CertificateFactory class representing
   * the specified certificate factory from the specified provider. 
   * If the type is not found then, it throws {@link CertificateException}. 
   * If the provider is not found, then it throws 
   * {@link java.security.NoSuchProviderException}.
   *
   * @param type     The type of certificate factory to create.
   * @param provider The name of the provider from which to get the
   *        implementation.
   * @return A CertificateFactory for the desired type.
   * @throws CertificateException If the type of certificate is not
   *         implemented by the named provider.
   * @throws NoSuchProviderException If the named provider is not installed.
   */
  public static final CertificateFactory getInstance(String type,
                                                     String provider) 
    throws CertificateException, NoSuchProviderException
  {
    Provider p = Security.getProvider(provider);
    if( p == null)
      throw new NoSuchProviderException();

    return getInstance(type, p);
  }

  /**
   * Get a certificate factory for the given certificate type from the
   * given provider.
   *
   * @param type     The type of certificate factory to create.
   * @param provider The provider from which to get the implementation.
   * @return A CertificateFactory for the desired type.
   * @throws CertificateException If the type of certificate is not
   *         implemented by the provider.
   * @throws IllegalArgumentException If the provider is null.
   */
  public static final CertificateFactory getInstance(String type,
                                                     Provider provider)
    throws CertificateException
  {
    if (provider == null)
      throw new IllegalArgumentException("null provider");

    try
      {
        return new CertificateFactory((CertificateFactorySpi)
          Engine.getInstance(CERTIFICATE_FACTORY, type, provider),
          provider, type);
      }
    catch (ClassCastException cce)
      {
        throw new CertificateException(type);
      }
    catch (java.lang.reflect.InvocationTargetException ite)
      {
        throw new CertificateException(type);
      }
    catch (NoSuchAlgorithmException nsae)
      {
        throw new CertificateException(nsae.getMessage());
      }
  }

// Instance methods.
  // ------------------------------------------------------------------------

  /**
   * Gets the provider of this implementation.
   *
   * @return The provider of this implementation.
   */
  public final Provider getProvider()
  {
    return provider;
  }

  /**
   * Returns the type of the certificate this factory creates.
   *
   * @return A string with the type of certificate
   */
  public final String getType()
  {
    return type;
  }

  /**
   * Generates a Certificate from the encoded data read
   * from an InputStream.
   *
   * <p>The input stream must contain only one certificate.
   *
   * <p>If there exists a specialized certificate class for the
   * certificate format handled by the certificate factory
   * then the return Ceritificate should be a typecast of it.
   * Ex: A X.509 CertificateFactory should return X509Certificate.
   *
   * <p>For X.509 certificates, the certificate in inStream must be
   * DER encoded and supplied in binary or printable (Base64) 
   * encoding. If the certificate is in Base64 encoding, it must be 
   * bounded by -----BEGINCERTIFICATE-----, and 
   * -----END CERTIFICATE-----. 
   *
   * @param inStream An input stream containing the certificate data.
   * @return A certificate initialized from the decoded InputStream data.
   * @throws CertificateException If an error occurs decoding the
   *   certificate.
   */
  public final Certificate generateCertificate(InputStream inStream)
    throws CertificateException
  {
    return certFacSpi.engineGenerateCertificate(inStream);
  }

  /**
   * Returns a collection of certificates that were read from the 
   * input stream. It may be empty, have only one, or have 
   * multiple certificates.
   *
   * For a X.509 certificate factory, the stream may contain a
   * single DER encoded certificate or a PKCS#7 certificate 
   * chain. This is a PKCS#7 <I>SignedData</I> object with the 
   * most significant field being <I>certificates</I>. If no 
   * CRLs are present, then an empty collection is returned.
	 *
   * @param inStream An input stream containing the certificate data.
   * @return A collection of certificates initialized from the decoded
   *   InputStream data.
   * @throws CertificateException If an error occurs decoding the
   *   certificates.
   */
  public final Collection generateCertificates(InputStream inStream)
    throws CertificateException
  {
    return certFacSpi.engineGenerateCertificates(inStream);
  }

  /**
   * Generates a CRL based on the encoded data read
   * from the InputStream.
   *
   * <p>The input stream must contain only one CRL.
   *
   * <p>If there exists a specialized CRL class for the
   * CRL format handled by the certificate factory
   * then the return CRL should be a typecast of it.
   * Ex: A X.509 CertificateFactory should return X509CRL.
   *
   * @param inStream An input stream containing the CRL data.
   * @return A CRL initialized from the decoded InputStream data.
   * @throws CRLException If an error occurs decoding the CRL.
   */
  public final CRL generateCRL(InputStream inStream)
    throws CRLException
  {
    return certFacSpi.engineGenerateCRL(inStream);
  }

  /**
   * <p>Generates CRLs based on the encoded data read
   * from the InputStream.
   *
   * <p>For a X.509 certificate factory, the stream may contain a
   * single DER encoded CRL or a PKCS#7 CRL set. This is a 
   * PKCS#7 <I>SignedData</I> object with the most significant 
   * field being <I>crls</I>. If no CRLs are present, then an
   * empty collection is returned.
   *
   * @param inStream an input stream containing the CRLs.
   * @return a collection of CRLs initialized from the decoded
   *    InputStream data.
   * @throws CRLException If an error occurs decoding the CRLs.
   */
  public final Collection generateCRLs(InputStream inStream)
    throws CRLException
  {
    return certFacSpi.engineGenerateCRLs( inStream );
  }

  /**
   * Generate a {@link CertPath} and initialize it with data parsed from
   * the input stream. The default encoding of this factory is used.
   *
   * @param inStream The InputStream containing the CertPath data.
   * @return A CertPath initialized from the input stream data.
   * @throws CertificateException If an error occurs decoding the
   * CertPath.
   */
  public final CertPath generateCertPath(InputStream inStream)
    throws CertificateException
  {
    return certFacSpi.engineGenerateCertPath(inStream);
  }

  /**
   * Generate a {@link CertPath} and initialize it with data parsed from
   * the input stream, using the specified encoding.
   *
   * @param inStream The InputStream containing the CertPath data.
   * @param encoding The encoding of the InputStream data.
   * @return A CertPath initialized from the input stream data.
   * @throws CertificateException If an error occurs decoding the
   *   CertPath.
   */
  public final CertPath generateCertPath(InputStream inStream, String encoding)
    throws CertificateException
  {
    return certFacSpi.engineGenerateCertPath(inStream, encoding);
  }

  /**
   * Generate a {@link CertPath} and initialize it with the certificates
   * in the {@link java.util.List} argument.
   *
   * @param certificates The list of certificates with which to create
   *   the CertPath.
   * @return A CertPath initialized from the certificates.
   * @throws CertificateException If an error occurs generating the
   *   CertPath.
   */
  public final CertPath generateCertPath(List certificates)
    throws CertificateException
  {
    return certFacSpi.engineGenerateCertPath(certificates);
  }

  /**
   * Returns an Iterator of CertPath encodings supported by this
   * factory, with the default encoding first. The returned Iterator
   * cannot be modified.
   *
   * @return The Iterator of supported encodings.
   */
  public final Iterator getCertPathEncodings()
  {
    return certFacSpi.engineGetCertPathEncodings();
  }
} // class CertificateFactory