/* Copyright (C) 2008 Casper Bang (casper.bang@gmail.com)
 *
 * This library 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 2.1 of the License, or 
 * (at your option) any later version.
 *
 * This library 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 library; if not, write to the Free Software Foundation, 
 * Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA 
 */

package com.brunata.webbill.backend.reporting;

import java.io.BufferedInputStream;
import java.io.ByteArrayInputStream;
import java.io.FilterInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.StringWriter;
import java.io.UnsupportedEncodingException;
import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;
import javax.xml.parsers.ParserConfigurationException;
import javax.xml.transform.OutputKeys;
import javax.xml.transform.Transformer;
import javax.xml.transform.TransformerConfigurationException;
import javax.xml.transform.TransformerException;
import javax.xml.transform.TransformerFactory;
import javax.xml.transform.dom.DOMSource;
import javax.xml.transform.stream.StreamResult;
// import org.slf4j.LoggerFactory;
import org.w3c.dom.Document;
import org.w3c.dom.Node;
import org.w3c.dom.Element;
import org.w3c.dom.Attr;

import org.xml.sax.SAXException;

import org.apache.log4j.Logger;

/**
 * This is a decorator around an InputStream, which will convert a modern XSD based Jasper design into the legacy DTD
 * version. This is desirable since modern tools i.e. the iReport plugin for NetBeans 6.5 generates designs based on the
 * modern XSD schema, whereas the Jasper engine itself that we use apparently can not handle XSD but instead require DTD's.
 * 
 * All you have to do to use this converting decorator, is to pipe your Jasper design InputStream through this one, and
 * it will automatically take care of adding a DTD docType and remove attributes which will typically cause a legacy
 * Jasper version to choke.
 *
 * @author Casper Bang
 */
public class LegacyJasperInputStream extends FilterInputStream
{

  static Logger log4j = Logger.getLogger(LegacyJasperInputStream.class);

    /**
     * @param is        The InputStream with the modern XSD based Jasper design
     */
    public LegacyJasperInputStream(final InputStream is){
        super( convertToLegacyFormat(is) );
    }

    private static InputStream convertToLegacyFormat(final InputStream is){
        Document document = convertInputStreamToDOM( is );
        document.getDocumentElement().removeAttribute("xmlns");
        document.getDocumentElement().removeAttribute("xmlns:xsi");
        document.getDocumentElement().removeAttribute("xsi:schemaLocation");

        Element reportFont = document.createElement("reportFont");

        Attr name = document.createAttribute("name");
        Attr isDefault = document.createAttribute("isDefault");
        Attr pdfEncoding = document.createAttribute("pdfEncoding");
        Attr pdfFontName = document.createAttribute("pdfFontName");
        Attr isPdfEmbedded = document.createAttribute("isPdfEmbedded");

        name.setNodeValue("Helvetica");
        isDefault.setNodeValue("true");
        pdfEncoding.setNodeValue("Cp1251");
        pdfFontName.setNodeValue("LiberationSans-Regular.ttf");
        isPdfEmbedded.setNodeValue("true");

        reportFont.setAttributeNode(name);
        reportFont.setAttributeNode(isDefault);
        reportFont.setAttributeNode(pdfEncoding);
        reportFont.setAttributeNode(pdfFontName);
        reportFont.setAttributeNode(isPdfEmbedded);
        document.getDocumentElement().insertBefore(reportFont, document.getDocumentElement().getFirstChild());

        return convertStringToInputStream( addDocTypeAndConvertDOMToString(document) );
    }


    private static Document convertInputStreamToDOM(final InputStream is){
        Document document = null;
        BufferedInputStream bis = new BufferedInputStream(is);
        DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
        DocumentBuilder builder = null;

        try {
            builder = factory.newDocumentBuilder();
        }
        catch (ParserConfigurationException ex) {
//            LoggerFactory.getLogger(LegacyJasperInputStream.class).error(ex.getMessage(), ex);
        }

        try {
            document = builder.parse(bis);
        } catch (SAXException ex) {
//            LoggerFactory.getLogger(LegacyJasperInputStream.class).error(ex.getMessage(), ex);
        } catch (IOException ex) {
//            LoggerFactory.getLogger(LegacyJasperInputStream.class).error(ex.getMessage(), ex);
        }

        return document;
    }

    private static String addDocTypeAndConvertDOMToString(final Document document){

        TransformerFactory transfac = TransformerFactory.newInstance();
        Transformer trans = null;
        try {
            trans = transfac.newTransformer();
        } catch (TransformerConfigurationException ex) {
//            LoggerFactory.getLogger(LegacyJasperInputStream.class).error(ex.getMessage(), ex);
        }

        trans.setOutputProperty(OutputKeys.OMIT_XML_DECLARATION, "yes");
        trans.setOutputProperty(OutputKeys.DOCTYPE_PUBLIC, "//JasperReports//DTD Report Design//EN");
        trans.setOutputProperty(OutputKeys.DOCTYPE_SYSTEM, "http://jasperreports.sourceforge.net/dtds/jasperreport.dtd");

        StringWriter sw = new StringWriter();
        StreamResult result = new StreamResult(sw);
        DOMSource source = new DOMSource(document);
        try {
            trans.transform(source, result);
        } catch (TransformerException ex) {
//            LoggerFactory.getLogger(LegacyJasperInputStream.class).error(ex.getMessage(), ex);
        }

        return sw.toString();
    }

    private static InputStream convertStringToInputStream(final String template){
        InputStream is = null;
        try {
            is = new ByteArrayInputStream(template.getBytes("UTF-8"));
        } catch (UnsupportedEncodingException ex) {
//           LoggerFactory.getLogger(LegacyJasperInputStream.class).debug(ex.getMessage(), ex);
        }
        return is;
    }
}