#// Usage: jjs -scripting jsadapter_dom.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

// Uses XML DOM parser and DOM element wrapped by script 

// "proxy" (JSAdapter constructor)

// Java classes used

var DocBuilderFac = Java.type("javax.xml.parsers.DocumentBuilderFactory");

var Node = Java.type("org.w3c.dom.Node");

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

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

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

// constants from Node class

var ELEMENT_NODE = Node.ELEMENT_NODE;

var TEXT_NODE = Node.TEXT_NODE;

// parse XML from uri and return Document

function parseXML(uri) {

    var docBuilder = DocBuilderFac.newInstance().newDocumentBuilder();

    return docBuilder["parse(java.lang.String)"](uri);

}

// get child Elements of given name of the parent element given

function getChildElements(elem, name) {

    var nodeList = elem.childNodes;

    var childElems = [];

    var len = nodeList.length;

    for (var i = 0; i < len; i++) {

        var node = nodeList.item(i);

        if (node.nodeType == ELEMENT_NODE &&

            node.tagName == name) {

            childElems.push(wrapElement(node));

        }

    }

    return childElems;

}

// get concatenated child text content of an Element

function getElemText(elem) {

    var nodeList = elem.childNodes;

    var len = nodeList.length;

    var text = '';

    for (var i = 0; i < len; i++) {

        var node = nodeList.item(i);

        if (node.nodeType == TEXT_NODE) {

            text += node.nodeValue;

        } 

    }

    return text;

}

// Wrap DOM Element object as a convenient script object

// using JSAdapter. JSAdapter is like java.lang.reflect.Proxy

// in that it allows property access, method calls be trapped

// by 'magic' methods like __get__, __call__.

function wrapElement(elem) {

    if (! elem) {

        return elem;

    }

    return new JSAdapter() {

        // getter to expose child elements and attributes by name

        __get__: function(name) {

            if (typeof name == 'string') {

                if (name.startsWith('@')) {

                    var attr = elem.getAttributeNode(name.substring(1));

                    return !attr? undefined : attr.value;

                }

                var arr = getChildElements(elem, name);

                if (arr.length == 1) {

                    // single child element, expose as single element

                    return arr[0];

                } else {

                    // multiple children of given name, expose as array

                    return arr;

                }

            }

            return undefined;

        },

        __call__: function(name) {

            // toString override to get text content of this Element

            if (name == 'toString' || name == 'valueOf') {

                return getElemText(elem);

            }

            return undefined;

        }

    }

}

// generate HTML using here-doc and string interpolation

function getBooksHtml() {

    var doc = parseXML("http://www.gutenberg.org/cache/epub/feeds/today.rss");

    // wrap document root Element as script convenient object

    var rss = wrapElement(doc.documentElement);

    print("rss file version " + rss['@version']);

    var str = <<HEAD

<html>

<title>${rss.channel.title}</title>

<body>

<h1>${rss.channel.description}</h1>

<p>

Published on ${rss.channel.pubDate}

</p>

HEAD

    var items = rss.channel.item;

    for each (var i in items) {

        str += <<LIST

<dl>

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

<dd>${i.description}</dd>

</dl>

LIST

    }

    str += <<END

</body>

</html>

END

    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);

}