/* ***** BEGIN LICENSE BLOCK *****
 * Version: MPL 1.1/GPL 2.0/LGPL 2.1
 *
 * The contents of this file are subject to the Mozilla Public License Version
 * 1.1 (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.mozilla.org/MPL/
 *
 * Software distributed under the License is distributed on an "AS IS" basis,
 * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
 * for the specific language governing rights and limitations under the
 * License.
 *
 * The Original Code is the Netscape Security Services for Java.
 *
 * The Initial Developer of the Original Code is
 * Netscape Communications Corporation.
 * Portions created by the Initial Developer are Copyright (C) 1998-2000
 * the Initial Developer. All Rights Reserved.
 *
 * Contributor(s):
 *
 * Alternatively, the contents of this file may be used under the terms of
 * either the GNU General Public License Version 2 or later (the "GPL"), or
 * the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
 * in which case the provisions of the GPL or the LGPL are applicable instead
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 * ***** END LICENSE BLOCK ***** */
package org.mozilla.jss.pkix.primitive;

import org.mozilla.jss.asn1.*;
import org.mozilla.jss.util.Assert;
import java.io.InputStream;
import java.io.OutputStream;
import java.io.IOException;

public class AlgorithmIdentifier implements ASN1Value {

    private OBJECT_IDENTIFIER oid;
    private ASN1Value parameters=null;
    private SEQUENCE sequence = new SEQUENCE();

    public static final Tag TAG = SEQUENCE.TAG;
    public Tag getTag() {
        return TAG;
    }

    /**
     * Creates an <i>AlgorithmIdentifier</i> with no parameter.
     */
    public AlgorithmIdentifier(OBJECT_IDENTIFIER oid) {
        this.oid = oid;
        sequence.addElement( oid );
    }

    /**
     * Creates an <i>AlgorithmIdentifier</i>.
     * 
     * @param parameters The algorithm parameters. A value of <code>null</code>
     *      will be encoded with an ASN.1 <code>NULL</code>.
     */
    public AlgorithmIdentifier(OBJECT_IDENTIFIER oid, ASN1Value parameters) {
        this.oid = oid;
        sequence.addElement( oid );
        this.parameters = parameters;
        if( parameters != null ) {
            sequence.addElement(parameters);
        } else {
            sequence.addElement(new NULL());
        }
    }

    public OBJECT_IDENTIFIER getOID() {
        return oid;
    }

    /**
     * If this instance was constructed, returns the
     * parameter passed in to the constructer.  If this instance was
     * decoded from a template, returns an ANY that was read from the
     * BER stream. In either case, it will return null if no parameters
     * were supplied.
     */
    public ASN1Value getParameters() {
        return parameters;
    }

    private static final AlgorithmIdentifier.Template templateInstance =
                                new AlgorithmIdentifier.Template();
    public static AlgorithmIdentifier.Template getTemplate() {
        return templateInstance;
    }

    public void encode(OutputStream ostream) throws IOException {
        encode(TAG, ostream);
    }

    public void encode(Tag implicit, OutputStream ostream)
        throws IOException
    {
        sequence.encode(implicit, ostream);
    }

public static class Template implements ASN1Template {

    public boolean tagMatch(Tag tag) {
        return TAG.equals(tag);
    }

    public ASN1Value decode(InputStream istream)
        throws IOException, InvalidBERException
    {
        return decode(TAG, istream);
    }

    public ASN1Value decode(Tag implicit, InputStream istream)
        throws IOException, InvalidBERException
    {
        SEQUENCE.Template seqt = new SEQUENCE.Template();
        seqt.addElement( new OBJECT_IDENTIFIER.Template() );
        seqt.addOptionalElement( new ANY.Template() );

        SEQUENCE seq = (SEQUENCE) seqt.decode(implicit, istream);

        // the template should have enforced this
        Assert._assert( seq.size() == 2 );

        return new AlgorithmIdentifier(
            (OBJECT_IDENTIFIER)seq.elementAt(0),  // OID
            seq.elementAt(1)                      // parameters
        );
    }
} // end of Template

}
