#// Usage: jjs -scripting gutenberg.js

/*

 * Copyright (c) 2014, Oracle and/or its affiliates. All rights reserved.

 * 

 * Redistribution and use in source and binary forms, with or without

 * modification, are permitted provided that the following conditions

 * are met:

 * 

 *   - Redistributions of source code must retain the above copyright

 *     notice, this list of conditions and the following disclaimer.

 * 

 *   - Redistributions in binary form must reproduce the above copyright

 *     notice, this list of conditions and the following disclaimer in the

 *     documentation and/or other materials provided with the distribution.

 * 

 *   - Neither the name of Oracle nor the names of its

 *     contributors may be used to endorse or promote products derived

 *     from this software without specific prior written permission.

 * 

 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS

 * IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,

 * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR

 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE COPYRIGHT OWNER OR

 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,

 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,

 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR

 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF

 * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING

 * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS

 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

 */

// Simple example that demonstrates reading XML Rss feed

// to generate a HTML file from script and show it by browser

// Java classes used

var Characters = Java.type("javax.xml.stream.events.Characters");

var Factory = Java.type("javax.xml.stream.XMLInputFactory");

var File = Java.type("java.io.File");

var FileWriter = Java.type("java.io.FileWriter");

var PrintWriter = Java.type("java.io.PrintWriter");

var URL = Java.type("java.net.URL");

// read Rss feed from a URL. Returns an array

// of objects having only title and link properties

function readRssFeed(url) {

    var fac = Factory.newInstance();

    var reader = fac.createXMLEventReader(url.openStream());

    // get text content from next event

    function getChars() {

        var result = "";

        var e = reader.nextEvent();

        if (e instanceof Characters) {

            result = e.getData();

        }

        return result;

    }

    var items = [];

    var title, link;

    var inItem = false;

    while (reader.hasNext()) {

        var evt = reader.nextEvent();

        if (evt.isStartElement()) {

            var local = evt.name.localPart;

            if (local == "item") {

               // capture title, description now

               inItem = true;

            }

            if (inItem) {

                switch (local) {

                    case 'title':

                        title = getChars();

                        break;

                    case 'link':

                        link = getChars();

                        break;

                }

            }

        } else if (evt.isEndElement()) {

            var local = evt.name.localPart;

            if (local == "item") {

                // one item done, save it in result array

                items.push({ title: title, link: link });

                inItem = false;

            }

        }

    }

    return items;

}

// generate simple HTML for an RSS feed

function getBooksHtml() {

    var url = new URL("http://www.gutenberg.org/cache/epub/feeds/today.rss");

    var items = readRssFeed(url);

    var str = "<ul>";

    // Nashorn's string interpolation and heredoc

    // support is very handy in generating text content

    // that is filled with elements from runtime objects.

    // We insert title and link in <li> elements here.

    for each (i in items) {

        str += <<EOF

<li>

    <a href="${i.link}">${i.title}</a>

</li>

EOF

    }

    str += "</ul>";

    return str;

}

// write the string to the given file

function writeTo(file, str) {

    var w = new PrintWriter(new FileWriter(file));

    try {

        w.print(str);

    } finally {

        w.close();

    }

}

// generate books HTML

var str = getBooksHtml();

// write to file. __DIR__ is directory where

// this script is stored.

var file = new File(__DIR__ + "books.html");

writeTo(file, str);

// show it by desktop browser

try {

    var Desktop = Java.type("java.awt.Desktop");

    Desktop.desktop.browse(file.toURI());

} catch (e) {

    print(e);

}