/*
 *  Licensed to the Apache Software Foundation (ASF) under one or more
 *  contributor license agreements.  See the NOTICE file distributed with
 *  this work for additional information regarding copyright ownership.
 *  The ASF licenses this file to You under the Apache License, Version 2.0
 *  (the "License"); you may not use this file except in compliance with
 *  the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 *  Unless required by applicable law or agreed to in writing, software
 *  distributed under the License is distributed on an "AS IS" BASIS,
 *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *  See the License for the specific language governing permissions and
 *  limitations under the License.
 */

/**
 * @author Alexander Y. Kleymenov
 */

package org.apache.harmony.security.x509;

import java.security.KeyFactory;
import java.security.NoSuchAlgorithmException;
import java.security.PublicKey;
import java.security.spec.InvalidKeySpecException;
import java.security.spec.X509EncodedKeySpec;

import org.apache.harmony.security.asn1.ASN1BitString;
import org.apache.harmony.security.asn1.ASN1Sequence;
import org.apache.harmony.security.asn1.ASN1Type;
import org.apache.harmony.security.asn1.BerInputStream;
import org.apache.harmony.security.asn1.BitString;
import org.apache.harmony.security.utils.AlgNameMapper;

/**
 * The class encapsulates the ASN.1 DER encoding/decoding work with the
 * following structure which is a part of X.509 certificate (as specified in RFC
 * 3280 - Internet X.509 Public Key Infrastructure. Certificate and Certificate
 * Revocation List (CRL) Profile. http://www.ietf.org/rfc/rfc3280.txt):
 * 
 * <pre>
 *  SubjectPublicKeyInfo  ::=  SEQUENCE  {
 *      algorithm            AlgorithmIdentifier,
 *      subjectPublicKey     BIT STRING  
 *  }
 * </pre>
 */
public class SubjectPublicKeyInfo {

	// the value of algorithmID field of the structure
	private final AlgorithmIdentifier algorithmID;
	// the value of subjectPublicKey field of the structure
	private final byte[] subjectPublicKey;
	// the public key corresponding to this SubjectPublicKeyInfo
	private PublicKey publicKey;
	// the value of unusedBits field of the structure
	private final int unusedBits;
	// the ASN.1 encoded form of SubjectPublicKeyInfo
	private byte[] encoding;

	public static final ASN1Sequence ASN1 = new ASN1Sequence(new ASN1Type[] {
			AlgorithmIdentifier.ASN1, ASN1BitString.getInstance() }) {

		@Override
		protected Object getDecodedObject(BerInputStream in) {
			final Object[] values = (Object[]) in.content;
			return new SubjectPublicKeyInfo((AlgorithmIdentifier) values[0],
					((BitString) values[1]).bytes,
					((BitString) values[1]).unusedBits, in.getEncoded());
		}

		@Override
		protected void getValues(Object object, Object[] values) {

			final SubjectPublicKeyInfo spki = (SubjectPublicKeyInfo) object;

			values[0] = spki.algorithmID;
			values[1] = new BitString(spki.subjectPublicKey, spki.unusedBits);
		}
	};

	/**
	 * TODO
	 * 
	 * @param algID
	 *            : AlgorithmIdentifier
	 * @param subjectPublicKey
	 *            : byte[]
	 */
	public SubjectPublicKeyInfo(AlgorithmIdentifier algID,
			byte[] subjectPublicKey) {
		this(algID, subjectPublicKey, 0);
	}

	/**
	 * TODO
	 * 
	 * @param algID
	 *            : AlgorithmIdentifier
	 * @param subjectPublicKey
	 *            : byte[]
	 * @param unused
	 *            : int
	 */
	public SubjectPublicKeyInfo(AlgorithmIdentifier algID,
			byte[] subjectPublicKey, int unused) {
		this(algID, subjectPublicKey, 0, null);
	}

	//
	// TODO
	// @param algID: AlgorithmIdentifier
	// @param subjectPublicKey: byte[]
	// @param unused: int
	// @param encoding: byte[]
	//
	private SubjectPublicKeyInfo(AlgorithmIdentifier algID,
			byte[] subjectPublicKey, int unused, byte[] encoding) {
		algorithmID = algID;
		this.subjectPublicKey = subjectPublicKey;
		unusedBits = unused;
		this.encoding = encoding;
	}

	/**
	 * Returns the value of algorithmIdentifier field of the structure.
	 * 
	 * @return algorithmIdentifier
	 */
	public AlgorithmIdentifier getAlgorithmIdentifier() {
		return algorithmID;
	}

	/**
	 * Returns ASN.1 encoded form of this X.509 SubjectPublicKeyInfo value.
	 * 
	 * @return a byte array containing ASN.1 encode form.
	 */
	public byte[] getEncoded() {
		if (encoding == null) {
			encoding = ASN1.encode(this);
		}
		return encoding;
	}

	/**
	 * Returns The PublicKey corresponding to this SubjectPublicKeyInfo
	 * instance.
	 * 
	 * @return public key corresponding to this SubjectPublicKeyInfo.
	 */
	public PublicKey getPublicKey() {
		if (publicKey == null) {
			final String alg_oid = algorithmID.getAlgorithm();
			try {
				String alg = AlgNameMapper.map2AlgName(alg_oid);

				if (alg == null) {
					alg = alg_oid;
				}
				publicKey = KeyFactory.getInstance(alg).generatePublic(
						new X509EncodedKeySpec(getEncoded()));
			} catch (final InvalidKeySpecException e) {
			} catch (final NoSuchAlgorithmException e) {
			}
			if (publicKey == null) {
				publicKey = new X509PublicKey(alg_oid, getEncoded(),
						subjectPublicKey);
			}
		}
		return publicKey;
	}

	/**
	 * Returns the value of subjectPublicKey field of the structure.
	 * 
	 * @return subjectPublicKey
	 */
	public byte[] getSubjectPublicKey() {
		return subjectPublicKey;
	}

	/**
	 * Returns the value of unusedBits field of the structure.
	 * 
	 * @return unusedBits
	 */
	public int getUnusedBits() {
		return unusedBits;
	}
}