package org.simantics.xml.sax.base;

import java.io.BufferedOutputStream;
import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.OutputStream;

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

import org.simantics.db.ReadGraph;
import org.simantics.db.Resource;
import org.simantics.db.Session;
import org.simantics.db.common.request.ReadRequest;
import org.simantics.db.exception.DatabaseException;
import org.simantics.message.ILogger;
import org.simantics.message.MessageService;

public class AbstractExporter {
	
	private static String ENCODING = "UTF-8";
	private static String XML_VERSION = "1.0";
	
	private Session session;
	private File file;
	private ILogger logger;
	private Resource root;
	private XMLWriter xmlWriter;
	private boolean indentOutput = true;
	
	public AbstractExporter(Session session, File file , Resource root, XMLWriter xmlWriter)  {
		this.session = session;
		this.file = file;
		this.root = root;
		this.xmlWriter = xmlWriter;
	}
	
	public AbstractExporter(Session session, File file , Resource root)  {
		this.session = session;
		this.file = file;
		this.root = root;
	}
	
	public void setXmlWriter(XMLWriter xmlWriter) {
		this.xmlWriter = xmlWriter;
	}
	
	public void setIndentOutput(boolean indentOutput) {
		this.indentOutput = indentOutput;
	}
	
	public void doExport() throws DatabaseException {
		doExport(MessageService.getDefault()); 	
	}
	
	public void doExport(ILogger logger) throws DatabaseException {
		ExportRequest req = new ExportRequest();
		session.syncRequest(req);
	}
	
	private static XMLStreamWriter createIdentXMLStreamWriter(OutputStream textWriter) throws XMLStreamException {
		XMLOutputFactory output = XMLOutputFactory.newInstance();
		return new IndentingXMLStreamWriter(output.createXMLStreamWriter(textWriter, ENCODING));
		//return new com.sun.xml.internal.txw2.output.IndentingXMLStreamWriter(output.createXMLStreamWriter(textWriter, "UTF-8"));
	}
	
	private static XMLStreamWriter createXMLStreamWriter(OutputStream textWriter) throws XMLStreamException {
		XMLOutputFactory output = XMLOutputFactory.newInstance();
		return output.createXMLStreamWriter(textWriter, ENCODING);
	}
	
	
	private class ExportRequest extends ReadRequest {
		@Override
		public void run(ReadGraph graph) throws DatabaseException {
			XMLStreamWriter writer = null;
			OutputStream os = null;
			try {
				os = new BufferedOutputStream(new FileOutputStream(file));
				if (indentOutput)
					writer =createIdentXMLStreamWriter(os);
				else
					writer =createXMLStreamWriter(os);
				writer.writeStartDocument(ENCODING, XML_VERSION);
				
				xmlWriter.write(root, writer);
				
				writer.writeEndDocument();
				writer.flush();
				writer.close();
				os.close();
			} catch (IOException|XMLStreamException e) {
				try {
					writer.close();
				} catch (XMLStreamException err) {
					
				}
				try {
					 os.close();
				}catch (IOException err) {
					
				}
				throw new DatabaseException(e);
			} 
			
			
		}
	}

}