// SitemapParser.java
// ------------------------
// part of YaCy
// (C) by Michael Peter Christen; mc@anomic.de
// first published on http://www.anomic.de
// Frankfurt, Germany, 2007
//
// this file is contributed by Martin Thelian
// last major change: $LastChangedDate$ by $LastChangedBy$
// Revision: $LastChangedRevision$
//
// 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
//
// Using this software in any meaning (reading, learning, copying, compiling,
// running) means that you agree that the Author(s) is (are) not responsible
// for cost, loss of data or any harm that may be caused directly or indirectly
// by usage of this softare or this documentation. The usage of this software
// is on your own risk. The installation and usage (starting/running) of this
// software may allow other people or application to access your computer and
// any attached devices and is highly dependent on the configuration of the
// software which must be done by the user of the software; the author(s) is
// (are) also not responsible for proper configuration and usage of the
// software, even if provoked by documentation provided together with
// the software.
//
// Any changes to this file according to the GPL as documented in the file
// gpl.txt aside this file in the shipment you received can be done to the
// lines that follows this copyright notice here, but changes must not be
// done inside the copyright notive above. A re-distribution must contain
// the intact and unchanged copyright notice.
// Contributions and changes to the program code must be marked as such.

package de.anomic.data;

import java.io.InputStream;
import java.net.MalformedURLException;
import java.text.ParseException;
import java.util.Date;
import java.util.zip.GZIPInputStream;

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

import org.apache.commons.httpclient.protocol.Protocol;
import org.xml.sax.Attributes;
import org.xml.sax.SAXException;
import org.xml.sax.helpers.DefaultHandler;

import de.anomic.crawler.CrawlEntry;
import de.anomic.crawler.CrawlProfile;
import de.anomic.crawler.ZURL;
import de.anomic.http.JakartaCommonsHttpClient;
import de.anomic.http.JakartaCommonsHttpResponse;
import de.anomic.http.httpdByteCountInputStream;
import de.anomic.index.indexURLReference;
import de.anomic.plasma.plasmaSwitchboard;
import de.anomic.server.serverDate;
import de.anomic.server.logging.serverLog;
import de.anomic.yacy.yacyURL;

/**
 * Class to parse a sitemap file.<br>
 * An example sitemap file is depicted below:<br>
 * 
 * <pre>
 * &lt;?xml version=&quot;1.0&quot; encoding=&quot;UTF-8&quot;?&gt;
 * &lt;urlset xmlns=&quot;http://www.sitemaps.org/schemas/sitemap/0.9&quot;&gt;
 *    &lt;url&gt;
 *       &lt;loc&gt;http://www.example.com/&lt;/loc&gt;
 *       &lt;lastmod&gt;2005-01-01&lt;/lastmod&gt;
 *       &lt;changefreq&gt;monthly&lt;/changefreq&gt;
 *       &lt;priority&gt;0.8&lt;/priority&gt;
 *    &lt;/url&gt;
 * &lt;/urlset&gt; 
 * </pre>
 * 
 * A real example can be found here: http://www.xt-service.de/sitemap.xml An example robots.txt containing a sitemap
 * URL: http://notepad.emaillink.de/robots.txt
 * 
 * @see Protocol at sitemaps.org <a href="http://www.sitemaps.org/protocol.php">http://www.sitemaps.org/protocol.php</a>
 * @see Protocol at google.com <a
 *      href="https://www.google.com/webmasters/tools/docs/en/protocol.html">https://www.google.com/webmasters/tools/docs/en/protocol.html</a>
 */
public class SitemapParser extends DefaultHandler {
    public static final String XMLNS_SITEMAPS_ORG = "http://www.sitemaps.org/schemas/sitemap/0.9";
    public static final String XMLNS_SITEMAPS_GOOGLE = "http://www.google.com/schemas/sitemap/0.84";

    public static final String SITEMAP_XMLNS = "xmlns";
    public static final String SITEMAP_URLSET = "urlset";
    public static final String SITEMAP_URL = "url";
    public static final String SITEMAP_URL_LOC = "loc";
    public static final String SITEMAP_URL_LASTMOD = "lastmod";
    public static final String SITEMAP_URL_CHANGEFREQ = "changefreq";
    public static final String SITEMAP_URL_PRIORITY = "priority";

    /**
     * The crawling profile used to parse the URLs contained in the sitemap file
     */
    private CrawlProfile.entry crawlingProfile = null;

    /**
     * Reference to the plasmaswitchboard.
     */
    private plasmaSwitchboard switchboard = null;

    /**
     * Name of the current XML element
     */
    private String currentElement = null;

    /**
     * A special stream to count how many bytes were processed so far
     */
    private int streamCounter = 0;

    /**
     * The total length of the sitemap file
     */
    private long contentLength;

    /**
     * The amount of urls processes so far
     */
    private int urlCounter = 0;

    /**
     * the logger
     */
    private serverLog logger = new serverLog("SITEMAP");

    /**
     * The location of the sitemap file
     */
    private yacyURL siteMapURL = null;

    /**
     * The next URL to enqueue
     */
    private String nextURL = null;

    /**
     * last modification date of the {@link #nextURL}
     */
    private Date lastMod = null;

    public SitemapParser(plasmaSwitchboard sb, yacyURL sitemap, CrawlProfile.entry theCrawlingProfile) {
        if (sb == null)
            throw new NullPointerException("The switchboard must not be null");
        if (sitemap == null)
            throw new NullPointerException("The sitemap URL must not be null");
        this.switchboard = sb;
        this.siteMapURL = sitemap;

        if (theCrawlingProfile == null) {
            // create a new profile
            this.crawlingProfile = createProfile(this.siteMapURL.getHost(), this.siteMapURL);
        } else {
            // use an existing profile
            this.crawlingProfile = theCrawlingProfile;
        }
    }

    /**
     * Function to download and parse the sitemap file
     */
    public void parse() {
        // download document
        JakartaCommonsHttpClient client = new JakartaCommonsHttpClient(5000, null, null);
        JakartaCommonsHttpResponse res = null;
        try {
            res = client.GET(siteMapURL.toString());
            if (res.getStatusCode() != 200) {
                this.logger.logWarning("Unable to download the sitemap file " + this.siteMapURL +
                        "\nServer returned status: " + res.getStatusLine());
                return;
            }

            // getting some metadata
            String contentMimeType = res.getResponseHeader().mime();
            this.contentLength = res.getResponseHeader().contentLength();

            try {
                InputStream contentStream = res.getDataAsStream();
                if ((contentMimeType != null) &&
                        (contentMimeType.equals("application/x-gzip") || contentMimeType.equals("application/gzip"))) {
                    this.logger.logFine("Sitemap file has mimetype " + contentMimeType);
                    contentStream = new GZIPInputStream(contentStream);
                }

                httpdByteCountInputStream counterStream = new httpdByteCountInputStream(contentStream, null);
                // parse it
                this.logger.logInfo("Start parsing sitemap file " + this.siteMapURL + "\n\tMimeType: " + contentMimeType +
                        "\n\tLength:   " + this.contentLength);
                SAXParser saxParser = SAXParserFactory.newInstance().newSAXParser();
                saxParser.parse(counterStream, this);
                streamCounter += counterStream.getCount();
            } finally {
                res.closeStream();
            }
        } catch (Exception e) {
            this.logger.logWarning("Unable to parse sitemap file " + this.siteMapURL, e);
        } finally {
            if (res != null) {
                // release connection
                res.closeStream();
            }
        }
    }

    /**
     * @return the total length of the sitemap file in bytes or <code>-1</code> if the length is unknown
     */
    public long getTotalLength() {
        return this.contentLength;
    }

    /**
     * @return the amount of bytes of the sitemap file that were downloaded so far
     */
    public long getProcessedLength() {
        return streamCounter;
    }

    /**
     * @return the amount of URLs that were successfully enqueued so far
     */
    public long getUrlcount() {
        return this.urlCounter;
    }

    /**
     * @param localName local name
     * @param qName qualified name
     * @see DefaultHandler#startElement(java.lang.String, java.lang.String, java.lang.String, org.xml.sax.Attributes)
     */
    public void startElement(String namespaceURI, String localName, String qName, Attributes attrs) throws SAXException {
        this.currentElement = qName;

        // testing if the namespace is known
        if (qName.equalsIgnoreCase(SITEMAP_URLSET)) {
            String namespace = attrs.getValue(SITEMAP_XMLNS);
            if ((namespace == null) ||
                    ((!namespace.equals(XMLNS_SITEMAPS_ORG)) && (!namespace.equals(XMLNS_SITEMAPS_GOOGLE))))
                throw new SAXException("Unknown sitemap namespace: " + namespace);
        }
    }

    /**
     * @param localName local name
     * @param qName qualified name
     * @throws SAXException
     * @see DefaultHandler#endElement(java.lang.String, java.lang.String, java.lang.String)
     */
    public void endElement(String namespaceURI, String localName, String qName) throws SAXException {
        this.currentElement = "";

        if (qName.equalsIgnoreCase(SITEMAP_URL)) {
            if (this.nextURL == null)
                return;

            // get the url hash
            String nexturlhash = null;
            yacyURL url = null;
            try {
                url = new yacyURL(this.nextURL, null);
                nexturlhash = url.hash();
            } catch (MalformedURLException e1) {
            }

            // check if the url is known and needs to be recrawled
            if (this.lastMod != null) {
                String dbocc = this.switchboard.urlExists(nexturlhash);
                if ((dbocc != null) && (dbocc.equalsIgnoreCase("loaded"))) {
                    // the url was already loaded. we need to check the date
                    indexURLReference oldEntry = switchboard.wordIndex.getURL(nexturlhash, null, 0);
                    if (oldEntry != null) {
                        Date modDate = oldEntry.moddate();
                        // check if modDate is null
                        if (modDate.after(this.lastMod))
                            return;
                    }
                }
            }

            // URL needs to crawled
            String error = null;
            error = this.switchboard.crawlStacker.stackCrawl(url,
                                                             null, // this.siteMapURL.toString(),
                                                             this.switchboard.wordIndex.seedDB.mySeed().hash, this.nextURL, new Date(),
                                                             0, this.crawlingProfile);

            if (error != null) {
                try {
                    this.logger.logInfo("The URL '" + this.nextURL + "' can not be crawled. Reason: " + error);

                    // insert URL into the error DB
                    ZURL.Entry ee = this.switchboard.crawlQueues.errorURL.newEntry(
                            new CrawlEntry(
                                    switchboard.wordIndex.seedDB.mySeed().hash, 
                                    new yacyURL(this.nextURL, null), 
                                    "", 
                                    "", 
                                    new Date(),
                                    null,
                                    0, 
                                    0, 
                                    0),
                            this.switchboard.wordIndex.seedDB.mySeed().hash,
                            new Date(),
                            1,
                            error);
                    ee.store();
                    this.switchboard.crawlQueues.errorURL.push(ee);
                } catch (MalformedURLException e) {/* ignore this */
                }
            } else {
                this.logger.logInfo("New URL '" + this.nextURL + "' added for crawling.");

                // count successfully added URLs
                this.urlCounter++;
            }
        }
    }

    public void characters(char[] buf, int offset, int len) throws SAXException {
        if (this.currentElement.equalsIgnoreCase(SITEMAP_URL_LOC)) {
            // TODO: we need to decode the URL here
            this.nextURL = (new String(buf, offset, len)).trim();
            if (!this.nextURL.startsWith("http") && !this.nextURL.startsWith("https")) {
                this.logger.logInfo("The url '" + this.nextURL + "' has a wrong format. Ignore it.");
                this.nextURL = null;
            }
        } else if (this.currentElement.equalsIgnoreCase(SITEMAP_URL_LASTMOD)) {
            String dateStr = new String(buf, offset, len);
            try {
                this.lastMod = serverDate.parseISO8601(dateStr);
            } catch (ParseException e) {
                this.logger.logInfo("Unable to parse datestring '" + dateStr + "'");
            }
        }
    }

    private CrawlProfile.entry createProfile(String domainName, yacyURL sitemapURL) {
        return this.switchboard.profilesActiveCrawls.newEntry(domainName, sitemapURL,
        // crawlingFilter
                                                              ".*", ".*",
                                                              // Depth
                                                              0, 0,
                                                              // force recrawling
                                                              0,
                                                              // disable Auto-Dom-Filter
                                                              -1, -1,
                                                              // allow crawling of dynamic URLs
                                                              true,
                                                              // index text + media
                                                              true, true,
                                                              // don't store downloaded pages to Web Cache
                                                              false,
                                                              // store to TX cache
                                                              true,
                                                              // remote Indexing disabled
                                                              false,
                                                              // exclude stop-words
                                                              true, true, true);
    }
}