/*
 *  eXist Open Source Native XML Database
 *  Copyright (C) 2001-2014 The eXist Project
 *  http://exist-db.org
 *
 *  This program is free software; you can redistribute it and/or
 *  modify it under the terms of the GNU Lesser General Public License
 *  as published by the Free Software Foundation; either version 2
 *  of the License, or (at your option) any later version.
 *
 *  This program is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU Lesser General Public License for more details.
 *
 *  You should have received a copy of the GNU Lesser General Public License
 *  along with this program; if not, write to the Free Software
 *  Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 *
 *  $Id$
 */
package org.exist.dom.persistent;

import org.exist.numbering.NodeId;
import org.exist.storage.Signatures;
import org.exist.util.ByteConversion;
import org.exist.util.pool.NodePool;
import org.exist.xquery.XPathException;
import org.exist.xquery.value.StringValue;
import org.w3c.dom.Comment;
import org.w3c.dom.Node;

import javax.xml.XMLConstants;

import static java.nio.charset.StandardCharsets.UTF_8;

public class CommentImpl extends AbstractCharacterData implements Comment {

    public CommentImpl() {
        super(Node.COMMENT_NODE);
    }

    public CommentImpl(final String data) {
        super(Node.COMMENT_NODE, data);
    }

    public CommentImpl(final char[] data, final int start, final int howmany) {
        super(Node.COMMENT_NODE, data, start, howmany);
    }

    @Override
    public String getLocalName() {
        return "";
    }

    @Override
    public String getNamespaceURI() {
        return XMLConstants.NULL_NS_URI;
    }

    @Override
    public String toString() {
        return "<!-- " + cdata.toString() + " -->";
    }

    /**
     * Serializes a (persistent DOM) Comment to a byte array
     *
     * data = signature nodeIdUnitsLength nodeId cdata
     *
     * signature = [byte] 0x60
     *
     * nodeIdUnitsLength = [short] (2 bytes) The number of units of the comment's NodeId
     * nodeId = {@see org.exist.numbering.DLNBase#serialize(byte[], int)}
     *
     * cdata = jUtf8
     *
     * jUtf8 = {@see java.io.DataOutputStream#writeUTF(java.lang.String)}
     */
    @Override
    public byte[] serialize() {
        String s;
        try {
            s = StringValue.expand(cdata);
        } catch(final XPathException e) {
            LOG.warn(e);
            s = cdata.toString();
        }
        final byte[] cd = s.getBytes(UTF_8);

        final int nodeIdLen = nodeId.size();
        final byte[] data = new byte[StoredNode.LENGTH_SIGNATURE_LENGTH + NodeId.LENGTH_NODE_ID_UNITS +
            +nodeIdLen + cd.length];
        int pos = 0;
        data[pos] = (byte) (Signatures.Comm << 0x5);
        pos += StoredNode.LENGTH_SIGNATURE_LENGTH;
        ByteConversion.shortToByte((short) nodeId.units(), data, pos);
        pos += NodeId.LENGTH_NODE_ID_UNITS;
        nodeId.serialize(data, pos);
        pos += nodeIdLen;
        System.arraycopy(cd, 0, data, pos, cd.length);
        return data;
    }

    public static StoredNode deserialize(final byte[] data, final int start, final int len,
                                         final DocumentImpl doc, final boolean pooled) {
        int pos = start;
        pos += LENGTH_SIGNATURE_LENGTH;
        final int dlnLen = ByteConversion.byteToShort(data, pos);
        pos += NodeId.LENGTH_NODE_ID_UNITS;
        final NodeId dln = doc.getBrokerPool().getNodeFactory().createFromData(dlnLen, data, pos);
        int nodeIdLen = dln.size();
        pos += nodeIdLen;
        final String cdata = new String(data, pos, len - (pos - start), UTF_8);
        //OK : we have the necessary material to build the comment
        final CommentImpl comment;
        if(pooled) {
            comment = (CommentImpl) NodePool.getInstance().borrowNode(Node.COMMENT_NODE);
        } else {
            comment = new CommentImpl();
        }
        comment.setNodeId(dln);
        comment.appendData(cdata);
        return comment;
    }
}