/**
 *  tarParser
 *  Copyright 2010 by Michael Peter Christen, mc@yacy.net, Frankfurt am Main, Germany
 *  First released 29.6.2010 at http://yacy.net
 *
 * $LastChangedDate$
 * $LastChangedRevision$
 * $LastChangedBy$
 *
 *  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.parser;

import java.io.File;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.InputStream;
import java.io.RandomAccessFile;
import java.net.MalformedURLException;
import java.util.Date;
import java.util.Set;
import java.util.zip.GZIPInputStream;

import org.apache.commons.compress.archivers.tar.TarArchiveEntry;
import org.apache.commons.compress.archivers.tar.TarArchiveInputStream;

import net.yacy.cora.document.encoding.UTF8;
import net.yacy.cora.document.id.DigestURL;
import net.yacy.cora.document.id.MultiProtocolURL;
import net.yacy.document.AbstractParser;
import net.yacy.document.Document;
import net.yacy.document.Parser;
import net.yacy.document.TextParser;
import net.yacy.document.VocabularyScraper;
import net.yacy.kelondro.util.FileUtils;

// this is a new implementation of this parser idiom using multiple documents as result set
/**
 * Parses the tar file and each contained file,
 * returns one document with combined content.
 */
public class tarParser extends AbstractParser implements Parser {

    private final static String MAGIC = "ustar"; // A magic for a tar archive, may appear at #101h-#105

    public tarParser() {
        super("Tape Archive File Parser");
        this.SUPPORTED_EXTENSIONS.add("tar");
        this.SUPPORTED_MIME_TYPES.add("application/x-tar");
        this.SUPPORTED_MIME_TYPES.add("application/tar");
        this.SUPPORTED_MIME_TYPES.add("applicaton/x-gtar");
        this.SUPPORTED_MIME_TYPES.add("multipart/x-tar");
    }

    @Override
    public Document[] parse(
            final DigestURL location,
            final String mimeType,
            final String charset,
            final Set<String> ignore_class_name,
            final VocabularyScraper scraper, 
            final int timezoneOffset,
            InputStream source) throws Parser.Failure, InterruptedException {

        final String filename = location.getFileName();
        final String ext = MultiProtocolURL.getFileExtension(filename);
        final DigestURL parentTarURL = createParentTarURL(location);
        // TODO is this hack really useful ? These extensions are already handled by the gzipParser
        if (ext.equals("gz") || ext.equals("tgz")) {
            try {
                source = new GZIPInputStream(source);
            } catch (final IOException e) {
                throw new Parser.Failure("tar parser: " + e.getMessage(), location);
            }
        }
        TarArchiveEntry entry;
        final TarArchiveInputStream tis = new TarArchiveInputStream(source);
        
        // create maindoc for this tar container
        final Document maindoc = createMainDocument(location, mimeType, charset, this);
        // loop through the elements in the tar file and parse every single file inside
        while (true) {
            try {
                File tmp = null;
                entry = tis.getNextTarEntry();
                if (entry == null) break;
                if (entry.isDirectory() || entry.getSize() <= 0) continue;
                final String name = entry.getName();
                final int idx = name.lastIndexOf('.');
                final String mime = TextParser.mimeOf((idx > -1) ? name.substring(idx+1) : "");
                try {
                    tmp = FileUtils.createTempFile(this.getClass(), name);
                    FileUtils.copy(tis, tmp, entry.getSize());
					/*
					 * Create an appropriate sub location to prevent unwanted fallback to the tarparser on resources included in the archive. 
					 * We use the tar file name as the parent sub path. Example : http://host/archive.tar/name.
					 * Indeed if we create a sub location with a '#' separator such as http://host/archive.tar#name, the
					 * extension of the URL is still ".tar", thus incorrectly making the tar parser
					 * as a possible parser for the sub resource.
					 */
                    final DigestURL subLocation = new DigestURL(parentTarURL, name);
                    final Document[] subDocs = TextParser.parseSource(subLocation, mime, null, ignore_class_name, scraper, timezoneOffset,	999, tmp);
                    if (subDocs == null) {
                    	continue;
                    }
                    maindoc.addSubDocuments(subDocs);
                } catch (final Parser.Failure e) {
                    AbstractParser.log.warn("tar parser entry " + name + ": " + e.getMessage());
                } finally {
                    if (tmp != null) FileUtils.deletedelete(tmp);
                }
            } catch (final IOException e) {
                AbstractParser.log.warn("tar parser:" + e.getMessage());
                break;
            }
        }
        return new Document[]{maindoc};
    }

	@Override
	public boolean isParseWithLimitsSupported() {
		return true;
	}

	@Override
	public Document[] parseWithLimits(final DigestURL location, final String mimeType, final String charset,
			final VocabularyScraper scraper, final int timezoneOffset, final InputStream source, final int maxLinks,
			final long maxBytes) throws Failure, InterruptedException, UnsupportedOperationException {

		final DigestURL parentTarURL = createParentTarURL(location);

		final TarArchiveInputStream tis = new TarArchiveInputStream(source);

		// create maindoc for this tar container
		final Document maindoc = createMainDocument(location, mimeType, charset, this);

		// loop through the elements in the tar file and parse every single file inside
		TarArchiveEntry entry;
		int totalProcessedLinks = 0;
		while (true) {
			try {
				entry = tis.getNextTarEntry();
				if (entry == null) {
					break;
				}

				/*
				 * We are here sure at least one entry has still to be processed : let's check
				 * now the bytes limit as sub parsers applied on eventual previous entries may
				 * not support partial parsing and would have thrown a Parser.Failure instead of
				 * marking the document as partially parsed.
				 */
				if (tis.getBytesRead() >= maxBytes) {
					maindoc.setPartiallyParsed(true);
					break;
				}

				if (entry.isDirectory() || entry.getSize() <= 0) {
					continue;
				}
				final String name = entry.getName();
				final int idx = name.lastIndexOf('.');
				final String mime = TextParser.mimeOf((idx > -1) ? name.substring(idx + 1) : "");
				try {
					/*
					 * Rely on the supporting parsers to respect the maxLinks and maxBytes limits on
					 * compressed content
					 */

					/*
					 * Create an appropriate sub location to prevent unwanted fallback to the
					 * tarparser on resources included in the archive. We use the tar file name as
					 * the parent sub path. Example : http://host/archive.tar/name. Indeed if we
					 * create a sub location with a '#' separator such as
					 * http://host/archive.tar#name, the extension of the URL is still ".tar", thus
					 * incorrectly making the tar parser as a possible parser for the sub resource.
					 */
					final DigestURL subLocation = new DigestURL(parentTarURL, name);
					final Document[] subDocs = TextParser.parseWithLimits(subLocation, mime, null, timezoneOffset, 999,
							entry.getSize(), tis, maxLinks - totalProcessedLinks, maxBytes - tis.getBytesRead());

					/*
					 * If the parser(s) did not consume all bytes in the entry, these ones will be
					 * skipped by the next call to getNextTarEntry()
					 */
					if (subDocs == null) {
						continue;
					}
					maindoc.addSubDocuments(subDocs);
					for (Document subDoc : subDocs) {
						if (subDoc.getAnchors() != null) {
							totalProcessedLinks += subDoc.getAnchors().size();
						}
					}
					/*
					 * Check if a limit has been exceeded (we are sure to pass here when maxLinks
					 * has been exceeded as this limit require parser support for partial parsing to
					 * be detected)
					 */
					if (subDocs[0].isPartiallyParsed()) {
						maindoc.setPartiallyParsed(true);
						break;
					}
				} catch (final Parser.Failure e) {
					AbstractParser.log.warn("tar parser entry " + name + ": " + e.getMessage());
				}
			} catch (final IOException e) {
				AbstractParser.log.warn("tar parser:" + e.getMessage());
				break;
			}
		}
		return new Document[] { maindoc };
	}

	/**
	 * Generate a parent URL to use for generating sub URLs on tar archive entries.
	 * 
	 * @param tarURL
	 *            the URL of the tar archive
	 * @return an URL ending with a "/" suitable as a base URL for archive entries
	 */
	private DigestURL createParentTarURL(final DigestURL tarURL) {
		String locationStr = tarURL.toNormalform(false);
		if (!locationStr.endsWith("/")) {
			locationStr += "/";
		}
		DigestURL parentTarURL;
		try {
			parentTarURL = new DigestURL(locationStr);
		} catch (MalformedURLException e1) {
			/* This should not happen */
			parentTarURL = tarURL;
		}
		return parentTarURL;
	}

	/**
	 * Create the main resulting parsed document for a tar container
	 * 
	 * @param location
	 *            the parsed resource URL
	 * @param mimeType
	 *            the media type of the resource
	 * @param charset
	 *            the charset name if known
	 * @param an
	 *            instance of tarParser that is registered as the parser origin of
	 *            the document
	 * @return a Document instance
	 */
	public static Document createMainDocument(final DigestURL location, final String mimeType, final String charset,
			final tarParser parser) {
		final String filename = location.getFileName();
		final Document maindoc = new Document(location, mimeType, charset, parser, null, null,
				AbstractParser
						.singleList(filename.isEmpty() ? location.toTokens() : MultiProtocolURL.unescape(filename)), // title
				null, null, null, null, 0.0d, 0.0d, (Object) null, null, null, null, false, new Date());
		return maindoc;
	}

    public final static boolean isTar(File f) {
        if (!f.exists() || f.length() < 0x105) return false;
        RandomAccessFile raf = null;
        try {
            raf = new RandomAccessFile(f, "r");
            raf.seek(0x101);
            byte[] b = new byte[5];
            raf.read(b);
            return MAGIC.equals(UTF8.String(b));
        } catch (final FileNotFoundException e) {
            return false;
        } catch (final IOException e) {
            return false;
        } finally {
            if (raf != null) try {raf.close();} catch (final IOException e) {}
        }
    }
}