/*
 * Copyright 2001-2004 The Apache Software Foundation.
 * 
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 * 
 *      http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */ 


package org.apache.commons.digester.rss;


import java.io.File;
import java.io.IOException;
import java.io.InputStream;
import java.net.URL;

import org.apache.commons.digester.Digester;
import org.apache.commons.logging.LogFactory;
import org.xml.sax.InputSource;
import org.xml.sax.SAXException;


/**
 * <p>Implementation of <strong>org.apache.commons.digester.Digester</strong>
 * designed to process input streams that conform to the <em>Rich Site
 * Summary</em> DTD, version 0.91.  For more information about this format,
 * see the <a href="http://my.netscape.com/publish/">My Netscape</a> site.</p>
 *
 * <p>The default implementation object returned by calling
 * <code>parse()</code> (an instance of
 * <code>org.apache.commons.digester.rss.Channel</code>)
 * knows how to render itself in XML format via the <code>render()</code>
 * method.  See the test <code>main()</code> method below for an
 * example of using these classes.</p>
 */

public class RSSDigester extends Digester {


    // ----------------------------------------------------------- Constructors


    // ----------------------------------------------------- Instance Variables


    /**
     * Have we been configured yet?
     */
    protected boolean configured = false;


    /**
     * The set of public identifiers, and corresponding resource names,
     * for the versions of the DTDs that we know about.
     */
    protected static final String registrations[] = {
        "-//Netscape Communications//DTD RSS 0.9//EN",
        "/org/apache/commons/digester/rss/rss-0.9.dtd",
        "-//Netscape Communications//DTD RSS 0.91//EN",
        "/org/apache/commons/digester/rss/rss-0.91.dtd",
    };


    // ------------------------------------------------------------- Properties


    /**
     * The fully qualified class name of the <code>Channel</code>
     * implementation class.
     */
    protected String channelClass = "org.apache.commons.digester.rss.Channel";

    public String getChannelClass() {
        return (this.channelClass);
    }

    public void setChannelClass(String channelClass) {
        this.channelClass = channelClass;
    }


    /**
     * The fully qualified class name of the <code>Image</code>
     * implementation class.
     */
    protected String imageClass = "org.apache.commons.digester.rss.Image";

    public String getImageClass() {
        return (this.imageClass);
    }

    public void setImageClass(String imageClass) {
        this.imageClass = imageClass;
    }


    /**
     * The fully qualified class name of the <code>Item</code>
     * implementation class.
     */
    protected String itemClass = "org.apache.commons.digester.rss.Item";

    public String getItemClass() {
        return (this.itemClass);
    }

    public void setItemClass(String itemClass) {
        this.itemClass = itemClass;
    }


    /**
     * The fully qualified class name of the <code>TextInput</code>
     * implementation class.
     */
    protected String textInputClass =
            "org.apache.commons.digester.rss.TextInput";

    public String getTextInputClass() {
        return (this.textInputClass);
    }

    public void setTextInputClass(String textInputClass) {
        this.textInputClass = textInputClass;
    }


    // --------------------------------------------------------- Public Methods


    /**
     * Parse the content of the specified file using this Digester.  Returns
     * the root element from the object stack (which will be the Channel).
     *
     * @param file File containing the XML data to be parsed
     *
     * @exception IOException if an input/output error occurs
     * @exception SAXException if a parsing exception occurs
     */
    public Object parse(File file) throws IOException, SAXException {

        configure();
        return (super.parse(file));

    }


    /**
     * Parse the content of the specified input source using this Digester.
     * Returns the root element from the object stack (which will be the
     * Channel).
     *
     * @param input Input source containing the XML data to be parsed
     *
     * @exception IOException if an input/output error occurs
     * @exception SAXException if a parsing exception occurs
     */
    public Object parse(InputSource input) throws IOException, SAXException {

        configure();
        return (super.parse(input));

    }


    /**
     * Parse the content of the specified input stream using this Digester.
     * Returns the root element from the object stack (which will be
     * the Channel).
     *
     * @param input Input stream containing the XML data to be parsed
     *
     * @exception IOException if an input/output error occurs
     * @exception SAXException if a parsing exception occurs
     */
    public Object parse(InputStream input) throws IOException, SAXException {

        configure();
        return (super.parse(input));

    }


    /**
     * Parse the content of the specified URI using this Digester.
     * Returns the root element from the object stack (which will be
     * the Channel).
     *
     * @param uri URI containing the XML data to be parsed
     *
     * @exception IOException if an input/output error occurs
     * @exception SAXException if a parsing exception occurs
     */
    public Object parse(String uri) throws IOException, SAXException {

        configure();
        return (super.parse(uri));

    }


    // -------------------------------------------------------- Package Methods


    // ------------------------------------------------------ Protected Methods


    /**
     * Configure the parsing rules that will be used to process RSS input.
     */
    protected void configure() {

        if (configured) {
            return;
        }

        // Register local copies of the DTDs we understand
        for (int i = 0; i < registrations.length; i += 2) {
            URL url = this.getClass().getResource(registrations[i + 1]);
            if (url != null) {
                register(registrations[i], url.toString());
            }
        }

        // FIXME - validate the "version" attribute of the rss element?

        // Add the rules for the Channel object
        addObjectCreate("rss/channel", channelClass);
        addCallMethod("rss/channel/copyright", "setCopyright", 0);
        addCallMethod("rss/channel/description", "setDescription", 0);
        addCallMethod("rss/channel/docs", "setDocs", 0);
        addCallMethod("rss/channel/language", "setLanguage", 0);
        addCallMethod("rss/channel/lastBuildDate", "setLastBuildDate", 0);
        addCallMethod("rss/channel/link", "setLink", 0);
        addCallMethod("rss/channel/managingEditor", "setManagingEditor", 0);
        addCallMethod("rss/channel/pubDate", "setPubDate", 0);
        addCallMethod("rss/channel/rating", "setRating", 0);
        addCallMethod("rss/channel/skipDays/day", "addSkipDay", 0);
        addCallMethod("rss/channel/skipHours/hour", "addSkipHour", 0);
        addCallMethod("rss/channel/title", "setTitle", 0);
        addCallMethod("rss/channel/webMaster", "setWebMaster", 0);

        // Add the rules for the Image object
        addObjectCreate("rss/channel/image", imageClass);
        addSetNext("rss/channel/image", "setImage",
                "org.apache.commons.digester.rss.Image");
        addCallMethod("rss/channel/image/description", "setDescription", 0);
        addCallMethod("rss/channel/image/height", "setHeight", 0,
                new Class[]{ Integer.TYPE });
        addCallMethod("rss/channel/image/link", "setLink", 0);
        addCallMethod("rss/channel/image/title", "setTitle", 0);
        addCallMethod("rss/channel/image/url", "setURL", 0);
        addCallMethod("rss/channel/image/width", "setWidth", 0,
                new Class[]{ Integer.TYPE });

        // Add the rules for the Item object
        addObjectCreate("rss/channel/item", itemClass);
        addSetNext("rss/channel/item", "addItem",
                "org.apache.commons.digester.rss.Item");
        addCallMethod("rss/channel/item/description", "setDescription", 0);
        addCallMethod("rss/channel/item/link", "setLink", 0);
        addCallMethod("rss/channel/item/title", "setTitle", 0);

        // Add the rules for the TextInput object
        addObjectCreate("rss/channel/textinput", textInputClass);
        addSetNext("rss/channel/textinput", "setTextInput",
                "org.apache.commons.digester.rss.TextInput");
        addCallMethod("rss/channel/textinput/description",
                "setDescription", 0);
        addCallMethod("rss/channel/textinput/link", "setLink", 0);
        addCallMethod("rss/channel/textinput/name", "setName", 0);
        addCallMethod("rss/channel/textinput/title", "setTitle", 0);

        // Mark this digester as having been configured
        configured = true;

    }


    // ------------------------------------------------------ Test Main Program


    /**
     * Test main program that parses the channel description included in this
     * package as a static resource.
     *
     * @param args The command line arguments (ignored)
     */
    public static void main(String args[]) {

        try {
            System.out.println("RSSDigester Test Program");
            System.out.println("Opening input stream ...");
            InputStream is = RSSDigester.class.getResourceAsStream
                    ("/org/apache/commons/digester/rss/rss-example.xml");
            System.out.println("Creating new digester ...");
            RSSDigester digester = new RSSDigester();
            if ((args.length > 0) && (args[0].equals("-debug"))) {
                digester.setLogger(LogFactory.getLog("RSSDigester"));
            }
            System.out.println("Parsing input stream ...");
            Channel channel = (Channel) digester.parse(is);
            System.out.println("Closing input stream ...");
            is.close();
            System.out.println("Dumping channel info ...");
            channel.render(System.out);
        } catch (Exception e) {
            System.out.println("-->Exception");
            e.printStackTrace(System.out);
        }

    }


}