// SurrogateReader.java
// (C) 2009 by Michael Peter Christen; mc@yacy.net, Frankfurt a. M., Germany
// first published 15.04.2009 on http://yacy.net
//
// $LastChangedDate: 2006-04-02 22:40:07 +0200 (So, 02 Apr 2006) $
// $LastChangedRevision: 1986 $
// $LastChangedBy: orbiter $
//
// LICENSE
// 
// This program is free software; you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation; either version 2 of the License, or
// (at your option) any later version.
//
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with this program; if not, write to the Free Software
// Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA

package de.anomic.xml;

import java.io.BufferedInputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.util.Iterator;
import java.util.concurrent.LinkedBlockingQueue;

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

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

import de.anomic.crawler.Surrogate;

public class SurrogateReader extends DefaultHandler implements Runnable, Iterator<Surrogate> {

    // class variables
    private final StringBuilder buffer;
    private boolean parsingValue;
    private Surrogate surrogate;
    private String elementName;
    private LinkedBlockingQueue<Surrogate> surrogates;
    private SAXParser saxParser;
    private InputStream stream;
    private boolean isrunning;
    
    public SurrogateReader(final InputStream stream) throws IOException {
        this.buffer = new StringBuilder();
        this.parsingValue = false;
        this.surrogate = null;
        this.elementName = null;
        this.surrogates = new LinkedBlockingQueue<Surrogate>();
        this.stream = stream;
        final SAXParserFactory factory = SAXParserFactory.newInstance();
        try {
            this.saxParser = factory.newSAXParser();
        } catch (ParserConfigurationException e) {
            e.printStackTrace();
            throw new IOException(e.getMessage());
        } catch (SAXException e) {
            e.printStackTrace();
            throw new IOException(e.getMessage());
        }
        this.isrunning = false;
    }
    
    public void run() {
        this.isrunning = true;
        try {
            this.saxParser.parse(this.stream, this);
        } catch (SAXException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        } finally {
            this.isrunning = false;
        }
    }
    
    public void startElement(final String uri, final String name, final String tag, final Attributes atts) throws SAXException {
        if ("document".equals(tag)) {
            this.surrogate = new Surrogate();
        } else if ("element".equals(tag)) {
            this.elementName = atts.getValue("name");
        } else if ("value".equals(tag)) {
            this.buffer.setLength(0);
            this.parsingValue = true;
        }
    }

    public void endElement(final String uri, final String name, final String tag) {
        if (tag == null) return;
        if ("document".equals(tag)) {
            this.surrogates.add(this.surrogate);
            this.surrogate = null;
            this.buffer.setLength(0);
            this.parsingValue = false;
        } else if ("element".equals(tag)) {
            this.buffer.setLength(0);
            this.parsingValue = false;
        } else if ("value".equals(tag)) {
            final String value = buffer.toString().trim();
            if (this.elementName != null) {
                this.surrogate.put(this.elementName, value);
            }
            this.buffer.setLength(0);
            this.parsingValue = false;
        }
    }

    public void characters(final char ch[], final int start, final int length) {
        if (parsingValue) {
            buffer.append(ch, start, length);
        }
    }

    public boolean hasNext() {
        return this.isrunning || this.surrogates.size() > 0;
    }

    public Surrogate next() {
        try {
            return this.surrogates.take();
        } catch (InterruptedException e) {
            e.printStackTrace();
            return null;
        }
    }

    public void remove() {
        throw new UnsupportedOperationException("cannot remove here");
    }
    
    public static void main(String[] args) {
        File f = new File(args[0]);
        SurrogateReader sr;
        try {
            sr = new SurrogateReader(new BufferedInputStream(new FileInputStream(f)));

            Thread t = new Thread(sr);
            t.start();
            Surrogate s;
            while (sr.hasNext()) {
                s = sr.next();
                System.out.println("Title: " + s.title());
                System.out.println("Date: " + s.date());
                System.out.println("URL: " + s.url());
                System.out.println("Language: " + s.language());
                System.out.println("Body: " + s.body());
                System.out.println("Categories: " + s.categories());
            }
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}
    /*
Example surrogate

<?xml version="1.0" encoding="utf-8"?>
<documents>
  <document id="1">
    <element name="docdatetime">
    <value>2009-03-02T11:12:36Z</value>
    </element>
    <element name="url">
    <value>http://de.wikipedia.org/wiki/Alan_Smithee</value>
    </element>
    <element name="language">
    <value>de</value>
    </element>
    <element name="title">
    <value><![CDATA[Alan Smithee]]></value>
    </element>
    <element name="body">
    <value><![CDATA[Der als Filmregisseur oft genannte '''Alan Smithee''' ist ein Anagramm]]></value>
    </element>
    <element name="categories">
    <value><![CDATA[Fiktive Person;Pseudonym]]></value>
    </element>
   </document>
</documents>

docdatetime is in ISO 8601
     */