/*
 * Copyright (C) 1999 Norman Walsh, <ndw@nwalsh.com>
 * This program is free software; you can redistribute it and/or modify
 * it to your hearts content. If you change this file, please remove
 * my name from it.
 *
 * WARRANTY
 * 
 * THIS PACKAGE IS PROVIDED "AS IS" AND WITHOUT ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
 * WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE.
 */

import java.io.*;
import java.net.URL;
import java.net.MalformedURLException;

import org.xml.sax.Parser;
import org.xml.sax.SAXException;
import org.xml.sax.InputSource;
import org.xml.sax.helpers.ParserFactory;
import com.ibm.xml.parsers.DOMParser;
import org.w3c.dom.*;

public class cfgFile {

    static String defaultParserClass = "com.ibm.xml.parsers.DOMParser";
    static Document doc = null;

    public cfgFile(String cfgDoc) throws Exception {
	// Construct a new cfgFile using the default parser class
	loadDoc(cfgDoc, defaultParserClass);
    }

    public cfgFile(String cfgDoc, String parserClass) throws Exception {
	// Construct a new cfgFile using the specified parser class
	loadDoc(cfgDoc, parserClass);
    }

    public String getProfileString(String sectname,
				   String varname,
				   String defval) {
	// Find varname in sectname and return its 'value', or return defval

	if (doc == null) {
	    // This should never happen...
	    return defval;
	}

	// Find the section
	Element section = getSection(sectname);
	if (section == null) {
	    return defval;
	}

	// Find the entry
	Element entry = getEntry(section, varname);
	if (entry == null) {
	    return defval;
	} else {
	    return entry.getAttribute("value");
	}
    }

    public void setProfileString(String sectname,
				 String varname,
				 String value) {
	// Set varname to value in sectname

	if (doc == null) {
	    // This should never happen...
	    return;
	}

	Element root = doc.getDocumentElement();
	Element section = getSection(sectname);

	if (section == null) {
	    // Create one
	    section = doc.createElement("section");
	    section.setAttribute("name", sectname);
	    root.appendChild(section);
	}

	Element entry = getEntry(section, varname);

	if (entry == null) {
	    // Create one
	    entry = doc.createElement("entry");
	    entry.setAttribute("name", varname);
	    section.appendChild(entry);
	}

	entry.setAttribute("value", value);
    }

    public void write(PrintStream out) {
	// Write out the configuration file
	Element root = doc.getDocumentElement();
	out.println("<?xml version='1.0'?>");
	writeElement(out, root, "");
    }

    private void loadDoc(String cfgDoc, String parserClass) throws Exception {
	// Parse the cfgDoc, or construct an empty document if cfgDoc is null.

	// Create the underlying parser
	Parser parser = ParserFactory.makeParser(parserClass);

	if (cfgDoc == null) {
	    // There's no document, so manufacture one with a simple
	    // ByteInputStream...
	    String cfgText = "<cfgfile></cfgfile>";
	    ByteArrayInputStream cfgStream 
		= new ByteArrayInputStream(cfgText.getBytes());
	    InputSource cfgSource = new InputSource(cfgStream);

	    // Parse the "document"
	    parser.parse(cfgSource);
	} else {
	    // Create a URL for the cfgDoc
	    URL cfgURL = createURL(cfgDoc);

	    // Parse the document
	    parser.parse(cfgURL.toString());
	}

	// Initialize doc to the DOM document built by the parser
	doc = ((DOMParser) parser).getDocument();
    }

    static void writeElement(PrintStream out, Element e, String indent) {
	// Write the XML for an element to the specified stream.
	// This function calls itself recursively to process chilren
	// of the starting element.  Only element children are written;
	// comments, PIs, and other nodes are ignored.
	Node node = e.getFirstChild();
	NamedNodeMap attrs = e.getAttributes();
	Node attr;
	int count;

	out.print(indent + "<" + e.getTagName());
	for (count = 0; count < attrs.getLength(); count++) {
	    attr = attrs.item(count);
	    out.print(" ");
	    out.print(attr.getNodeName() + "=\"" + attr.getNodeValue() + "\"");
	}

	if (node == null) {
	    out.println("/>");
	} else {
	    out.println(">");

	    while (node != null) {
		if (node.getNodeType() == Node.ELEMENT_NODE) {
		    writeElement(out, (Element) node, indent+"  ");
		} 
		node = node.getNextSibling();
	    }
	    out.println(indent + "</" + e.getTagName() + ">");
	}
    }

    private Element getSection(String name) {
	// Find the section named 'name' and return it
	return findChild(doc.getDocumentElement(), "section", name);
    }

    private Element getEntry(Element section, String name) {
	// Find the entry named 'name' in 'section' and return it,
	return findChild(section, "entry", name);
    }

    private Element findChild(Element parent, String elemname, String name) {
	// Find the 'elemname' child of parent named 'name' and return it;
	// return null if no such child exists.
	Node node = parent.getFirstChild();
	Element child;
	
	while (node != null) {
	    if (node.getNodeType() == Node.ELEMENT_NODE) {
		child = (Element) node;
		if (child.getTagName().equals(elemname)
		    && child.getAttribute("name").equals(name)) { 
		    return child;
		}
	    }
	    node = node.getNextSibling();
	}

	return null;
    }

    private URL createURL(String name) throws Exception {
	// Turn a URL-string or filename into a URL object
	URL url = null;
	File file = null;

        try {
	    url = new URL(name);
	    // if this doesn't cause an exception, return the URL
            return url;
        } catch (MalformedURLException ex) {
	    // ignore the exception
        }
	
	// If it wasn't a URL, it must be a file...
	file = new File(name);
	url  = new URL("file:" + file.getAbsolutePath());

	return url;
    };
}