/**
 *  OAIPMHLoader
 *  Copyright 2009 by Michael Peter Christen
 *  First released 30.09.2009 at http://yacy.net
 *
 *  This is a part of YaCy, a peer-to-peer based web search engine
 *
 *  This library is free software; you can redistribute it and/or
 *  modify it under the terms of the GNU Lesser General Public
 *  License as published by the Free Software Foundation; either
 *  version 2.1 of the License, or (at your option) any later version.
 *
 *  This library 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
 *  Lesser General Public License for more details.
 *
 *  You should have received a copy of the GNU Lesser General Public License
 *  along with this program in the file lgpl21.txt
 *  If not, see <http://www.gnu.org/licenses/>.
 */

package net.yacy.document.importer;

import java.io.File;
import java.io.IOException;

import net.yacy.cora.federate.yacy.CacheStrategy;
import net.yacy.crawler.retrieval.Response;
import net.yacy.kelondro.data.meta.DigestURI;
import net.yacy.kelondro.logging.Log;
import net.yacy.kelondro.util.FileUtils;
import net.yacy.repository.LoaderDispatcher;
import net.yacy.search.snippet.TextSnippet;


// get one server with
// http://roar.eprints.org/index.php?action=csv
// list records from oai-pmh like
// http://opus.bsz-bw.de/fhhv/oai2/oai2.php?verb=ListRecords&metadataPrefix=oai_dc


public class OAIPMHLoader {

    private final DigestURI source;
    private final ResumptionToken resumptionToken;

    public OAIPMHLoader(final LoaderDispatcher loader, final DigestURI source, final File targetDir) throws IOException {
        this.source = source;

        // load the file from the net
        Log.logInfo("OAIPMHLoader", "loading record from " + source.toNormalform(true));
        Response response = null;
        IOException ee = null;
        for (int i = 0; i < 5; i++) {
            // make some retries if first attempt fails
            try {
                response = loader.load(loader.request(source, false, true), CacheStrategy.NOCACHE, Integer.MAX_VALUE, null, TextSnippet.snippetMinLoadDelay);
                break;
            } catch (IOException e) {
                Log.logWarning("OAIPMHLoader", "loading failed at attempt " + (i + 1) + ": " + source.toNormalform(true));
                ee = e;
                continue;
            }
        }
        if (response == null) throw ee;
        final byte[] b = response.getContent();
        this.resumptionToken = new ResumptionToken(source, b);
        //System.out.println("*** ResumptionToken = " + this.resumptionToken.toString());
        final File f1 = new File(targetDir, OAIPMHImporter.filename4Source(source));
        final File f0 = new File(targetDir, f1.getName() + ".tmp");

        // transaction-safe writing
        FileUtils.copy(b, f0);
        f0.renameTo(f1);
    }

    public ResumptionToken getResumptionToken() {
        return this.resumptionToken;
    }

    public String source() {
        return this.source.toNormalform(true);
    }

    public static StringBuilder escape(final String s) {
        final int len = s.length();
        final StringBuilder sbuf = new StringBuilder(len + 10);
        for (int i = 0; i < len; i++) {
            final int ch = s.charAt(i);
            if ('A' <= ch && ch <= 'Z') {           // 'A'..'Z'
                sbuf.append((char)ch);
            } else if ('a' <= ch && ch <= 'z') {    // 'a'..'z'
                sbuf.append((char)ch);
            } else if ('0' <= ch && ch <= '9') {    // '0'..'9'
                sbuf.append((char)ch);
            } else if (ch == ' ') {                 // space
                sbuf.append("%20");
            } else if (ch == '&' || ch == ':'       // unreserved
                    || ch == '-' || ch == '_'
                    || ch == '.' || ch == '!'
                    || ch == '~' || ch == '*'
                    || ch == '\'' || ch == '('
                    || ch == ')' || ch == ';') {
                sbuf.append((char)ch);
            }
        }
        return sbuf;
    }

    public static String unescape(final String s) {
        final int l  = s.length();
        final StringBuilder sbuf = new StringBuilder(l);
        int ch = -1;
        int b;
        for (int i = 0; i < l; i++) {
            /* Get next byte b from URL segment s */
            switch (ch = s.charAt(i)) {
                case '%':
                    if (i + 2 < l) {
                        ch = s.charAt(++i);
                        final int hb = (Character.isDigit ((char) ch) ? ch - '0' : 10 + Character.toLowerCase((char) ch) - 'a') & 0xF;
                        ch = s.charAt(++i);
                        final int lb = (Character.isDigit ((char) ch) ? ch - '0' : 10 + Character.toLowerCase ((char) ch) - 'a') & 0xF;
                        b = (hb << 4) | lb;
                    } else {
                        b = ch;
                    }
                    break;
                case '+':
                    b = ' ';
                    break;
                default:
                    b = ch;
            }
            sbuf.append(b);
        }
        return sbuf.toString();
    }
}
/*

http://an.oa.org/OAI-script?verb=GetRecord&identifier=oai:arXiv.org:hep-th/9901001&metadataPrefix=oai_dc

special characters in URIs must be encoded, the correct form of the above GET request URL is:

http://an.oa.org/OAI-script?verb=GetRecord&identifier=oai%3AarXiv.org%3Ahep-th%2F9901001&metadataPrefix=oai_dc

"/","%2F"
"?","%3F"
"#","%23"
"=","%3D"
"&","%26"
":","%3A"
";","%3B"
" ","%20"
"%","%25"
"+","%2B"

GetRecord
http://arXiv.org/oai2?verb=GetRecord&identifier=oai:arXiv.org:cs/0112017&metadataPrefix=oai_dc
http://opus.bsz-bw.de/fhhv/oai2/oai2.php?verb=GetRecord&identifier=oai:opus.bsz-bw.de-fhhv:6&metadataPrefix=oai_dc

Identify
http://memory.loc.gov/cgi-bin/oai?verb=Identify

ListIdentifiers
http://an.oa.org/OAI-script?verb=ListIdentifiers&from=1998-01-15&metadataPrefix=oldArXiv&set=physics:hep
http://an.oa.org/OAI-script?verb=ListIdentifiers&resumptionToken=xxx45abttyz
http://www.perseus.tufts.edu/cgi-bin/pdataprov?verb=ListIdentifiers&metadataPrefix=olac&from=2001-01-01&until=2001-01-01&set=Perseus:collection:PersInfo

ListMetadataFormats
http://www.perseus.tufts.edu/cgi-bin/pdataprov?verb=ListMetadataFormats&identifier=oai:perseus.tufts.edu:Perseus:text:1999.02.0119
http://memory.loc.gov/cgi-bin/oai?verb=ListMetadataFormats
http://memory.loc.gov/cgi-bin/oai?verb=ListMetadataFormats&identifier=oai:lcoa1.loc.gov:loc.rbc/rbpe.00000111
http://opus.bsz-bw.de/fhhv/oai2/oai2.php?verb=ListMetadataFormats

ListRecords
http://opus.bsz-bw.de/fhhv/oai2/oai2.php?verb=ListRecords&metadataPrefix=oai_dc
http://opus.bsz-bw.de/fhhv/oai2/oai2.php?verb=ListRecords&resumptionToken=455
http://opus.bsz-bw.de/fhhv/oai2/oai2.php?verb=ListRecords&resumptionToken=890
http://an.oa.org/OAI-script?verb=ListRecords&from=1998-01-15&set=physics:hep&metadataPrefix=oai_rfc1807
http://www.perseus.tufts.edu/cgi-b:in/pdataprov?verb=ListRecords&from=2002-05-01T14:15:00Z&until=2002-05-01T14:20:00Z&metadataPrefix=oai_dc
http://memory.loc.gov/cgi-bin/oai?verb=ListRecords&from=2002-06-01T02:00:00Z&until=2002-06-01T03:00:00Z&metadataPrefix=oai_marc

ListSets
http://an.oa.org/OAI-script?verb=ListSets
http://purl.org/alcme/etdcat/servlet/OAIHandler?verb=ListSets

urn identifier koennen ueber den resolver der d-nb aufgeloest werden:
http://nbn-resolving.de/urn:nbn:de:bsz:960-opus-1860

<?xml version="1.0" encoding="UTF-8"?>
<OAI-PMH xmlns="http://www.openarchives.org/OAI/2.0/"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://www.openarchives.org/OAI/2.0/
         http://www.openarchives.org/OAI/2.0/OAI-PMH.xsd">
 <responseDate>2009-10-01T22:20:04Z</responseDate>
 <request verb="ListRecords" metadataPrefix="oai_dc">http://opus.bsz-bw.de/fhhv/oai2/oai2.php</request>
 <ListRecords>
  <record>
   <header>
    <identifier>oai:opus.bsz-bw.de-fhhv:1</identifier>
    <datestamp>2008-03-04T12:17:33Z</datestamp>
    <setSpec>ddc:020</setSpec>
    <setSpec>pub-type:2</setSpec>
    <setSpec>has-source-swb:false</setSpec>
   </header>
   <metadata>
     <oai_dc:dc
       xmlns:oai_dc="http://www.openarchives.org/OAI/2.0/oai_dc/"
       xmlns:dc="http://purl.org/dc/elements/1.1/"
       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xsi:schemaLocation="http://www.openarchives.org/OAI/2.0/oai_dc/
       http://www.openarchives.org/OAI/2.0/oai_dc.xsd">
      <dc:title>Teaching Information Literacy with the Lerninformationssystem</dc:title>
      <dc:creator>Hauschke, Christian</dc:creator>
      <dc:creator>Ullmann, Nadine</dc:creator>
      <dc:subject>Informationskompetenz</dc:subject>
      <dc:subject>E-Learning</dc:subject>
      <dc:subject>Bibliothek</dc:subject>
      <dc:subject>Informationsvermittlung</dc:subject>
      <dc:subject>Wissenschaftliches Arbeiten</dc:subject>
      <dc:subject>information literacy</dc:subject>
      <dc:subject>e-learning</dc:subject>
      <dc:subject>library</dc:subject>
      <dc:subject>information dissemination</dc:subject>
      <dc:subject>Library and information sciences</dc:subject>
      <dc:description>A German university has developed a learning information system to improve information literacy among German students. An online tutorial based on this Lerninformationssystem has been developed. The structure of this learning information system is described, an online tutorial based on it is illustrated, and the different learning styles that it supports are indicated.</dc:description>
      <dc:publisher>Fachhochschule Hannover</dc:publisher>
      <dc:publisher>Sonstige Einrichtungen. Sonstige Einrichtungen</dc:publisher>
      <dc:date>2006</dc:date>
      <dc:type>Article</dc:type>
      <dc:format>application/pdf</dc:format>
      <dc:identifier>urn:nbn:de:bsz:960-opus-10</dc:identifier>
      <dc:identifier>http://opus.bsz-bw.de/fhhv/volltexte/2008/1/</dc:identifier>
      <dc:source>Australian Academic &amp; Research Libraries, 37 (1), S. 55-60</dc:source>
      <dc:language>eng</dc:language>
      <dc:rights>http://creativecommons.org/licenses/by/2.0/de/deed.de</dc:rights>
     </oai_dc:dc>
   </metadata>
  </record>
  <resumptionToken
     expirationDate="2009-10-02T20:20:04Z"
     completeListSize="226"
     cursor="0">119</resumptionToken>
 </ListRecords>
</OAI-PMH>

*/