/**
 * Copyright (c) 2011, The University of Southampton and the individual contributors.
 * 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 the University of Southampton 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.
 */
package org.openimaj.tools.web;

import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.HashSet;
import java.util.List;
import java.util.Map;
import java.util.Set;

import javax.xml.parsers.ParserConfigurationException;
import javax.xml.parsers.SAXParserFactory;

import org.xml.sax.Attributes;
import org.xml.sax.InputSource;
import org.xml.sax.SAXException;
import org.xml.sax.XMLReader;
import org.xml.sax.helpers.DefaultHandler;

/**
 * A script for reading the RDF dump from DMOZ and flattening it to
 * CSV format
 *
 * @author Jonathon Hare (jsh2@ecs.soton.ac.uk)
 *
 */
public class Dmoz2CSV {
        static class Topic {
                String name;
                List<String> link = new ArrayList<String>();
                List<String> link1 = new ArrayList<String>();
        }

        static class ExternalPage {
                String about;
                String title;
                String description;
        }

        static class RecordsHandler extends DefaultHandler {
                Set<Topic> topics = new HashSet<Topic>();
                Map<String, ExternalPage> resources = new HashMap<String, ExternalPage>();
                Topic currentTopic = null;
                ExternalPage currentResource = null;
                boolean isTitle = false;
                boolean isDescription = false;

                @Override
                public void startElement(String ns, String localName, String qName, Attributes atts) {
                        if (qName.equals("Topic")) {
                                currentTopic = new Topic();
                                currentTopic.name = atts.getValue("r:id");
                        } else if (qName.equals("link")) {
                                currentTopic.link.add(atts.getValue("r:resource"));
                        } else if (qName.equals("link1")) {
                                currentTopic.link1.add(atts.getValue("r:resource"));
                        } else if (qName.equals("ExternalPage")) {
                                currentResource = new ExternalPage();
                                currentResource.about = atts.getValue("about");
                        } else if (qName.equals("d:Title")) {
                                isTitle = true;
                        } else if (qName.equals("d:Description")) {
                                isDescription = true;
                        }
                }

                @Override
                public void characters(char[] chars, int offset, int length) {
                        if (isDescription)
                                currentResource.description = new String(chars, offset, length);
                        if (isTitle)
                                currentResource.title = new String(chars, offset, length);

                        isTitle = false;
                        isDescription = false;
                }

                @Override
                public void endElement(String ns, String localName, String qName) {
                        if (qName.equals("Topic")) {
                                if (currentTopic.link.size() > 0 && currentTopic.link1.size() > 0)
                                        topics.add(currentTopic);
                        } else if (qName.equals("ExternalPage")) {
                                resources.put(currentResource.about, currentResource);
                        }
                }
        }

        /**
         * Returns a field value escaped for special characters
         * @param input A String to be evaluated
         * @return A properly formatted String
         */
        static String escape(String input) {
                input = input.replaceAll("\n", " ");
                input = input.replaceAll("\r", " ");

                if (input.contains(",") || input.contains("\"") || (!input.trim().equals(input))) { 
                        return '"' + input.replaceAll("\"", "\"\"") + '"';
                } else {
                        return input;
                }
        }

        /**
         * Appends a row of values to the output
         * @param values A list of values
         * @return this CsvBuffer instance
         */
        static String toCSV(Object... values) {
                List<String> escapedValues = new ArrayList<String>();
                for (Object o : values) escapedValues.add(escape(o.toString()));

                StringBuilder content = new StringBuilder();
                for (int i=0; i<escapedValues.size(); i++) { 
                        content.append(escapedValues.get(i));
                        if (i < escapedValues.size()-1) content.append(",");
                }
                content.append("\r\n");
                return content.toString();
        }

        /**
         * Main method. 
         * @param args
         * @throws SAXException
         * @throws ParserConfigurationException
         * @throws IOException
         */
        public static void main(String[] args) throws SAXException, ParserConfigurationException, IOException {
                RecordsHandler handler = new RecordsHandler();
                XMLReader reader = SAXParserFactory.newInstance().newSAXParser().getXMLReader();
                reader.setContentHandler(handler);

                for (String file : args) {
                        InputSource is = new InputSource(new InputStreamReader(new FileInputStream(file), "UTF-8"));

                        is.setEncoding("UTF-8");
                        reader.parse(is);

                        for (Topic top : handler.topics) {
                                for (String it : top.link1) {
                                        System.out.println(toCSV(top.name, "LINK1", it, handler.resources.get(it).title, handler.resources.get(it).description));
                                }

                                for (String it : top.link) {
                                        System.out.println(toCSV(top.name, "LINK", it, handler.resources.get(it).title, handler.resources.get(it).description));
                                }
                        }
                }
        }
}