/*
 * Copyright (c) 2000, 2018 Oracle and/or its affiliates. All rights reserved.
 *
 * This program and the accompanying materials are made available under the
 * terms of the Eclipse Public License v. 2.0, which is available at
 * http://www.eclipse.org/legal/epl-2.0.
 *
 * This Source Code may also be made available under the following Secondary
 * Licenses when the conditions for such availability set forth in the
 * Eclipse Public License v. 2.0 are satisfied: GNU General Public License,
 * version 2 with the GNU Classpath Exception, which is available at
 * https://www.gnu.org/software/classpath/license.html.
 *
 * SPDX-License-Identifier: EPL-2.0 OR GPL-2.0 WITH Classpath-exception-2.0
 */

package com.sun.jndi.ldap.ctl;

import java.io.IOException;
import javax.naming.ldap.BasicControl;
import com.sun.jndi.ldap.Ber;
import com.sun.jndi.ldap.BerEncoder;

/**
 * This class implements the LDAPv3 Request Control for server-side sorting
 * of search results as defined in
 * <a href="http://www.ietf.org/rfc/rfc2891.txt">RFC-2891</a>.
 *
 * The control's value has the following ASN.1 definition:
 * <pre>
 *
 *     SortKeyList ::= SEQUENCE OF SEQUENCE {
 *         attributeType     AttributeDescription,
 *         orderingRule  [0] MatchingRuleId OPTIONAL,
 *         reverseOrder  [1] BOOLEAN DEFAULT FALSE }
 *
 * </pre>
 *
 * @see SortResponseControl
 * @author Vincent Ryan
 */
final public class SortControl extends BasicControl {

    /**
     * The server-side sort control's assigned object identifier
     * is 1.2.840.113556.1.4.473.
     */
    public static final String OID = "1.2.840.113556.1.4.473";

    private static final long serialVersionUID = 8931633399436504556L;

    /**
     * Constructs a server-side sort control.
     *
     * @param    sortBy        The keys to sort by.
     * @param    criticality The control's criticality setting.
     * @exception IOException If a BER encoding error occurs.
     */
    public SortControl(SortKey[] sortBy, boolean criticality)
        throws IOException {

        super(OID, criticality, null);
        super.value = setEncodedValue(sortBy);
    }

    /**
     * Constructs a server-side sort control.
     *
     * @param    sortBy    The attribute IDs to sort by.
     * @param    criticality The control's criticality setting.
     * @exception IOException If a BER encoding error occurs.
     */
    public SortControl(String[] sortBy, boolean criticality)
        throws IOException {

        super(OID, criticality, null);

        if (sortBy == null || (sortBy.length == 0)) {
            return;
        }

        SortKey[] sortKeys = new SortKey[sortBy.length];
        for (int i = 0; i < sortBy.length; i++) {
            sortKeys[i] = new SortKey(sortBy[i]);
        }
        super.value = setEncodedValue(sortKeys);
    }

    /**
     * Sets the ASN.1 BER encoded value of the sort control.
     * The result is the raw BER bytes including the tag and length of
     * the control's value. It does not include the controls OID or criticality.
     *
     * @param    sortKeys    The keys to sort by.
     * @return A possibly null byte array representing the ASN.1 BER encoded
     *         value of the LDAP sort control.
     * @exception IOException If a BER encoding error occurs.
     */
    private byte[] setEncodedValue(SortKey[] sortKeys) throws IOException {

        // build the ASN.1 encoding
        BerEncoder ber = new BerEncoder(32);
        String matchingRule;

        ber.beginSeq(Ber.ASN_SEQUENCE | Ber.ASN_CONSTRUCTOR);

        for (int i = 0; i < sortKeys.length; i++) {
            ber.beginSeq(Ber.ASN_SEQUENCE | Ber.ASN_CONSTRUCTOR);
            ber.encodeString(sortKeys[i].getAttributeID(), true); // v3

            if ((matchingRule = sortKeys[i].getMatchingRuleID()) != null) {
                ber.encodeString(matchingRule, (Ber.ASN_CONTEXT | 0), true);
            }
            if (! sortKeys[i].isAscending()) {
                ber.encodeBoolean(true, (Ber.ASN_CONTEXT | 1));
            }
            ber.endSeq();
        }
        ber.endSeq();

        return ber.getTrimmedBuf();
    }
}