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package org.kie.dmn.backend.marshalling;

import javax.xml.stream.XMLStreamException;
import javax.xml.stream.XMLStreamWriter;

import com.thoughtworks.xstream.io.StreamException;
import com.thoughtworks.xstream.io.naming.NameCoder;
import com.thoughtworks.xstream.io.xml.QNameMap;
import com.thoughtworks.xstream.io.xml.StaxWriter;


public class CustomStaxWriter extends StaxWriter implements AutoCloseable {
    /** 
     * ATTENTION this is intercepted during XStream StaxDriver creation as there is no proper API to inherit.
     * Do not mutate reference - mutating this reference would not sort any effect on the actual underlying StaxWriter
     */
    private XMLStreamWriter out;
    private int tagDepth = 0;
    private static enum Op {
        START_NODE, END_NODE, VALUE;
    }
    private Op lastOp = null;
    
    public CustomStaxWriter(QNameMap qnameMap, XMLStreamWriter out, boolean writeStartEndDocument, boolean repairingNamespace, NameCoder nameCoder) throws XMLStreamException {
        super(qnameMap, out, writeStartEndDocument, repairingNamespace, nameCoder);
        this.out = out;
    }

    public void writeNamespace(String prefix, String uri) throws XMLStreamException {
        if (prefix.equals(out.getPrefix(uri))) {
            // Do nothing: XStream internals actually already provided this mapping.
        } else {
            out.writeNamespace(prefix, uri);
        }
    }

    public void setDefaultNamespace(String uri) throws XMLStreamException {
        out.setDefaultNamespace(uri);
    }

    @Override
    public void endNode() {
        if ( this.lastOp == Op.END_NODE ) {
            try {
                out.writeCharacters( System.lineSeparator() );
                for ( int i = 0; i < (tagDepth-1); i++ ) { out.writeCharacters("  "); }
            } catch (XMLStreamException e) {
                throw new StreamException(e);
            }
        }
        super.endNode();
        --this.tagDepth;
        
        this.lastOp = Op.END_NODE;
        
        if ( this.tagDepth == 0 ) {
            if ( out.getClass().getPackage().getName().startsWith("com.ctc.wstx") ) {
                // DROOLS-1630: problem with Woodstox trying to insert trailing newline before EOF
                // java.lang.NullPointerException
                //   at java.lang.System.arraycopy(Native Method)
                //   at java.lang.String.getChars(String.java:826)
                //   at com.ctc.wstx.sw.BufferingXmlWriter.writeRaw(BufferingXmlWriter.java:314)
                //   at com.ctc.wstx.sw.BaseStreamWriter.writeCharacters(BaseStreamWriter.java:436)
                //   at org.kie.dmn.backend.marshalling.CustomStaxWriter.endNode(CustomStaxWriter.java:55)
                // where CustomStaxWriter.java:55 was inserting of trailing newline before EOF, but Woodstox seems to close early it internal write buffer
                // before having the opportunity to append the trailing line.
                // Therefore, in case of WoodStx, do not insert trailing newline before EOF.
            } else {
                // closed last element before EOF
                try {
                    out.writeCharacters( System.lineSeparator() );
                } catch (XMLStreamException e) {
                    throw new StreamException(e);
                }
            }
        }
    }

    @Override
    public void startNode(String arg0) {
        try {
            out.writeCharacters( System.lineSeparator() );
            for ( int i = 0; i < tagDepth; i++ ) { out.writeCharacters("  "); }
        } catch (XMLStreamException e) {
            throw new StreamException(e);
        }
        super.startNode(arg0);
        ++this.tagDepth;
        
        this.lastOp = Op.START_NODE;
    }

    @Override
    public void setValue(String text) {
        super.setValue(text);
        
        this.lastOp = Op.VALUE;
    }

    public QNameMap getQNameMap() {
        return super.getQNameMap();
    }
    
}