package org.kohsuke.rngom.digested;

import org.w3c.dom.Attr;
import org.w3c.dom.CDATASection;
import org.w3c.dom.Comment;
import org.w3c.dom.Document;
import org.w3c.dom.DocumentFragment;
import org.w3c.dom.Element;
import org.w3c.dom.EntityReference;
import org.w3c.dom.NamedNodeMap;
import org.w3c.dom.Node;
import org.w3c.dom.NodeList;
import org.w3c.dom.ProcessingInstruction;
import org.w3c.dom.Text;

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

/**
 * Printer of DOM to XML using StAX {@link XMLStreamWriter}.
 * 
 * @author <A href="mailto:demakov@ispras.ru">Alexey Demakov</A>
 */
class DOMPrinter {
    protected XMLStreamWriter out;

    public DOMPrinter(XMLStreamWriter out) {
        this.out = out;
    }

    public void print(Node node) throws XMLStreamException {
        switch (node.getNodeType()) {
        case Node.DOCUMENT_NODE:
            visitDocument((Document) node);
            break;
        case Node.DOCUMENT_FRAGMENT_NODE:
            visitDocumentFragment((DocumentFragment) node);
            break;
        case Node.ELEMENT_NODE:
            visitElement((Element) node);
            break;
        case Node.TEXT_NODE:
            visitText((Text) node);
            break;
        case Node.CDATA_SECTION_NODE:
            visitCDATASection((CDATASection) node);
            break;
        case Node.PROCESSING_INSTRUCTION_NODE:
            visitProcessingInstruction((ProcessingInstruction) node);
            break;
        case Node.ENTITY_REFERENCE_NODE:
            visitReference((EntityReference) node);
            break;
        case Node.COMMENT_NODE:
            visitComment((Comment) node);
            break;
        case Node.DOCUMENT_TYPE_NODE:
            break;
        case Node.ATTRIBUTE_NODE:
        case Node.ENTITY_NODE:
        default:
            throw new XMLStreamException("Unexpected DOM Node Type "
                + node.getNodeType()
            );
        }
    }

    protected void visitChildren(Node node)
        throws XMLStreamException {
        NodeList nodeList = node.getChildNodes();
        if (nodeList != null) {
            for (int i = 0; i < nodeList.getLength(); i++) {
                print(nodeList.item(i));
            }
        }
    }

    protected void visitDocument(Document document)
        throws XMLStreamException {
        out.writeStartDocument();
        print(document.getDocumentElement());
        out.writeEndDocument();
    }

    protected void visitDocumentFragment(DocumentFragment documentFragment)
        throws XMLStreamException {
        visitChildren(documentFragment);
    }

    protected void visitElement(Element node)
        throws XMLStreamException {
        out.writeStartElement(node.getPrefix()
            , node.getLocalName()
            , node.getNamespaceURI()
        );
        NamedNodeMap attrs = node.getAttributes();
        for (int i = 0; i < attrs.getLength(); i++) {
            visitAttr((Attr) attrs.item(i));
        }
        visitChildren(node);
        out.writeEndElement();
    }

    protected void visitAttr(Attr node)
        throws XMLStreamException {
        String name = node.getLocalName();
        if (name.equals("xmlns")) {
            out.writeDefaultNamespace(node.getNamespaceURI());
        } else {
            String prefix = node.getPrefix();
            if (prefix != null && prefix.equals("xmlns")) {
                out.writeNamespace(prefix, node.getNamespaceURI());
            } else {
                out.writeAttribute(prefix
                    , node.getNamespaceURI()
                    , name
                    , node.getNodeValue()
                );
            }
        }
    }

    protected void visitComment(Comment comment) throws XMLStreamException {
        out.writeComment(comment.getData());
    }

    protected void visitText(Text node) throws XMLStreamException {
        out.writeCharacters(node.getNodeValue());
    }

    protected void visitCDATASection(CDATASection cdata) throws XMLStreamException {
        out.writeCData(cdata.getNodeValue());
    }

    protected void visitProcessingInstruction(ProcessingInstruction processingInstruction)
        throws XMLStreamException {
        out.writeProcessingInstruction(processingInstruction.getNodeName()
            , processingInstruction.getData()
        );
    }

    protected void visitReference(EntityReference entityReference)
        throws XMLStreamException {
        visitChildren(entityReference);
    }
}