/**
*Class DomEcho
*@author Martin Carlsson
Internetprogrammering 4 Course
*/
import javax.xml.parsers.*;
import org.w3c.dom.*;
import java.io.*;
import org.xml.sax.*;

/**
*DOM Echo creates and writes a DOM-träd the output of choice by the use of XMLSerializer.
*@see XMLSerializer
*/
public class DomEcho {
    
    /**
    Parses the result and echos it back if it's well-formed.
    */
    void parseEcho(String xmlFilename, String outputSource) {
        
        try {    
            File xmlFile = new File(xmlFilename);
            Document document = null;
            DocumentBuilderFactory factory =
            DocumentBuilderFactory.newInstance();
            DocumentBuilder builder = factory.newDocumentBuilder();
            document = builder.parse(xmlFile);
            XMLSerializer xmlSerializer = new XMLSerializer();
            if(outputSource.trim().equals("System.out"))
                 xmlSerializer.serialize(document, System.out);
            else
                xmlSerializer.serialize(document, new File(outputSource));
        }
        catch (SAXException e) {
            System.err.println("\n" + xmlFilename + " is not wellformed!");
            System.exit(1);
        } 
        catch (IOException e) {
            System.err.println(e);
            System.exit(1);
        }
        catch(ParserConfigurationException e) {
            System.err.println(e);
            System.exit(1);
        }
    }
    /**
    *Main.
    */
    public static void main(String[] args)  throws Exception {
       
        String resultText = null;
        DomEcho dEcho = new DomEcho();
         
        if(args.length == 1 && args[0].trim().equals("help") || args.length == 0) {
            usage();
            return;
        }
        else if (args.length >= 2) {
            dEcho.parseEcho(args[0], args[1]);
            resultText = "\n\nThe file " + args[0] + " is wellformed\nEchoed content of " + args[0] + " can be found in " + args[1];    
        }
        else if(args.length == 1) {
            dEcho.parseEcho(args[0], "System.out");
            resultText ="\n\nThe file " + args[0] + " is wellformed\nFinished echoing content of " + args[0];
        }
        if(resultText != null)
            System.out.println(resultText);
    }
    /**
    Help information.
    */
    private static void usage() {
        System.out.println("\n**********DomEcho usage***************************");
        System.out.println("Usage: DomEcho <file.xml>");
        System.out.println("       or");
        System.out.println("       DomEcho <file.xml><outputFile.xxx>");
        System.out.println("About:");
        System.out.println("       DomEcho parses the content of a xml file");
        System.out.println("       and echos to stdout or to a file of choise");
        System.out.println("       if the parsed file is well-formed.");
        System.out.println("       Default output is stdout.");
        System.out.println("       DomEcho help = this message");
        System.out.println("****************************************************");
    }
} // End DomEcho