/*
 *  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 Vladimir N. Molotkov, Stepan M. Mishura
 */

package org.apache.harmony.security.asn1;

import java.io.IOException;
import java.math.BigInteger;

/**
 * This class represents ASN.1 Integer type.
 * 
 * @see http://asn1.elibel.tm.fr/en/standards/index.htm
 */

public class ASN1Integer extends ASN1Primitive {

	// default implementation
	private static final ASN1Integer ASN1 = new ASN1Integer();

	/**
	 * Converts primitive int value to a form most suitable for encoding.
	 * 
	 * @param value
	 *            primitive value to be encoded
	 * @return object suitable for encoding
	 */
	public static Object fromIntValue(int value) {
		// FIXME optimize
		return BigInteger.valueOf(value).toByteArray();
	}

	/**
	 * Returns ASN.1 Integer type default implementation
	 * 
	 * The default implementation works with encoding that is represented as
	 * byte array in two's-complement notation.
	 * 
	 * @return ASN.1 Integer type default implementation
	 */
	public static ASN1Integer getInstance() {
		return ASN1;
	}

	//
	//
	// Decode
	//
	//

	/**
	 * Converts decoded ASN.1 Integer to int value.
	 * 
	 * @param decoded
	 *            a decoded object corresponding to {@link #asn1 this type}
	 * @return decoded int value.
	 */
	public static int toIntValue(Object decoded) {
		return new BigInteger((byte[]) decoded).intValue();// FIXME optimize
	}

	/**
	 * Constructs ASN.1 Integer type
	 * 
	 * The constructor is provided for inheritance purposes when there is a need
	 * to create a custom ASN.1 Integer type. To get a default implementation it
	 * is recommended to use getInstance() method.
	 */
	public ASN1Integer() {
		super(TAG_INTEGER);
	}

	//
	//
	// Encode
	//
	//

	@Override
	public Object decode(BerInputStream in) throws IOException {
		in.readInteger();

		if (in.isVerify) {
			return null;
		}
		return getDecodedObject(in);
	}

	@Override
	public void encodeContent(BerOutputStream out) {
		out.encodeInteger();
	}

	/**
	 * Extracts array of bytes from BER input stream.
	 * 
	 * @param in
	 *            - BER input stream
	 * @return array of bytes
	 */
	@Override
	public Object getDecodedObject(BerInputStream in) throws IOException {
		final byte[] bytesEncoded = new byte[in.length];
		System.arraycopy(in.buffer, in.contentOffset, bytesEncoded, 0,
				in.length);
		return bytesEncoded;
	}

	@Override
	public void setEncodingContent(BerOutputStream out) {
		out.length = ((byte[]) out.content).length;
	}
}