// Parser.java
// (C) 2009 by Michael Peter Christen; mc@yacy.net, Frankfurt a. M., Germany
// first published 09.07.2009 on http://yacy.net
//
// This is a part of YaCy, a peer-to-peer based web search engine
//
// $LastChangedDate: 2009-03-20 16:44:59 +0100 (Fr, 20 Mrz 2009) $
// $LastChangedRevision: 5736 $
// $LastChangedBy: borg-0300 $
//
// 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 net.yacy.document;

import java.io.BufferedInputStream;
import java.io.ByteArrayInputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStream;
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 java.util.concurrent.ConcurrentHashMap;

import net.yacy.document.parser.bzipParser;
import net.yacy.document.parser.csvParser;
import net.yacy.document.parser.docParser;
import net.yacy.document.parser.gzipParser;
import net.yacy.document.parser.htmlParser;
import net.yacy.document.parser.odtParser;
import net.yacy.document.parser.ooxmlParser;
import net.yacy.document.parser.pdfParser;
import net.yacy.document.parser.pptParser;
import net.yacy.document.parser.psParser;
import net.yacy.document.parser.rssParser;
import net.yacy.document.parser.rtfParser;
import net.yacy.document.parser.sevenzipParser;
import net.yacy.document.parser.swfParser;
import net.yacy.document.parser.tarParser;
import net.yacy.document.parser.torrentParser;
import net.yacy.document.parser.vcfParser;
import net.yacy.document.parser.vsdParser;
import net.yacy.document.parser.xlsParser;
import net.yacy.document.parser.zipParser;
import net.yacy.document.parser.images.genericImageParser;
import net.yacy.kelondro.data.meta.DigestURI;
import net.yacy.kelondro.logging.Log;
import net.yacy.kelondro.util.FileUtils;


public final class TextParser {

    private static final Log log = new Log("PARSER");
    private static final Object v = new Object();

    private static final Map<String, Idiom> mime2parser = new ConcurrentHashMap<String, Idiom>();
    private static final Map<String, Idiom> ext2parser = new ConcurrentHashMap<String, Idiom>();
    private static final Map<String, String> ext2mime = new ConcurrentHashMap<String, String>();
    private static final Map<String, Object> denyMime = new ConcurrentHashMap<String, Object>();
    private static final Map<String, Object> denyExtensionx = new ConcurrentHashMap<String, Object>();
    
    static {
        initParser(new bzipParser());
        initParser(new csvParser());
        initParser(new docParser());
        initParser(new gzipParser());
        initParser(new htmlParser());
        initParser(new genericImageParser());
        initParser(new odtParser());
        initParser(new ooxmlParser());
        initParser(new pdfParser());
        initParser(new pptParser());
        initParser(new psParser());
        initParser(new rssParser());
        initParser(new rtfParser());
        initParser(new sevenzipParser());
        initParser(new swfParser());
        initParser(new tarParser());
        initParser(new torrentParser());
        initParser(new vcfParser());
        initParser(new vsdParser());
        initParser(new xlsParser());
        initParser(new zipParser());
    }
    
    public static Set<Idiom> idioms() {
        Set<Idiom> c = new HashSet<Idiom>();
        c.addAll(ext2parser.values());
        c.addAll(mime2parser.values());
        return c;
    }

    private static void initParser(Idiom parser) {
        String prototypeMime = null;
        for (String mime: parser.supportedMimeTypes()) {
            // process the mime types
            final String mimeType = normalizeMimeType(mime);
            if (prototypeMime == null) prototypeMime = mimeType;
            Idiom p0 = mime2parser.get(mimeType);
            if (p0 != null) log.logSevere("parser for mime '" + mimeType + "' was set to '" + p0.getName() + "', overwriting with new parser '" + parser.getName() + "'.");
            mime2parser.put(mimeType, parser);
            Log.logInfo("PARSER", "Parser for mime type '" + mimeType + "': " + parser.getName());
        }
        
        if (prototypeMime != null) for (String ext: parser.supportedExtensions()) {
            ext = ext.toLowerCase();
            String s = ext2mime.get(ext);
            if (s != null) log.logSevere("parser for extension '" + ext + "' was set to mime '" + s + "', overwriting with new mime '" + prototypeMime + "'.");
            ext2mime.put(ext, prototypeMime);
        }
        
        for (String ext: parser.supportedExtensions()) {
            // process the extensions
            ext = ext.toLowerCase();
            Idiom p0 = ext2parser.get(ext);
            if (p0 != null) log.logSevere("parser for extension '" + ext + "' was set to '" + p0.getName() + "', overwriting with new parser '" + parser.getName() + "'.");
            ext2parser.put(ext, parser);
            Log.logInfo("PARSER", "Parser for extension '" + ext + "': " + parser.getName());
        }
    }
    
    public static Document parseSource(
            final DigestURI location,
            final String mimeType,
            final String charset,
            final File sourceFile
        ) throws InterruptedException, ParserException {

        BufferedInputStream sourceStream = null;
        try {
            if (log.isFine()) log.logFine("Parsing '" + location + "' from file");
            if (!sourceFile.exists() || !sourceFile.canRead() || sourceFile.length() == 0) {
                final String errorMsg = sourceFile.exists() ? "Empty resource file." : "No resource content available (2).";
                log.logInfo("Unable to parse '" + location + "'. " + errorMsg);
                throw new ParserException(errorMsg, location);
            }
            sourceStream = new BufferedInputStream(new FileInputStream(sourceFile));
            return parseSource(location, mimeType, charset, sourceFile.length(), sourceStream);
        } catch (final Exception e) {
            if (e instanceof InterruptedException) throw (InterruptedException) e;
            if (e instanceof ParserException) throw (ParserException) e;
            log.logSevere("Unexpected exception in parseSource from File: " + e.getMessage(), e);
            throw new ParserException("Unexpected exception: " + e.getMessage(), location);
        } finally {
            if (sourceStream != null)try {
                sourceStream.close();
            } catch (final Exception ex) {}
        }
    }
    
    public static Document parseSource(
            final DigestURI location,
            String mimeType,
            final String charset,
            final byte[] content
        ) throws InterruptedException, ParserException {
        return parseSource(location, mimeType, charset, content.length, new ByteArrayInputStream(content));
    }
    
    public static Document parseSource(
            final DigestURI location,
            String mimeType,
            final String charset,
            final long contentLength,
            final InputStream sourceStream
        ) throws InterruptedException, ParserException {
        if (log.isFine()) log.logFine("Parsing '" + location + "' from stream");
        mimeType = normalizeMimeType(mimeType);
        List<Idiom> idioms = null;
        try {
            idioms = idiomParser(location, mimeType);
        } catch (ParserException e) {
            final String errorMsg = "Parser Failure for extension '" + location.getFileExtension() + "' or mimetype '" + mimeType + "': " + e.getMessage();
            log.logWarning(errorMsg);
            throw new ParserException(errorMsg, location);
        }
        assert !idioms.isEmpty();
        
        // if we do not have more than one parser or the content size is over MaxInt
        // then we use only one stream-oriented parser.
        if (idioms.size() == 1 || contentLength > Integer.MAX_VALUE) {
            // use a specific stream-oriented parser
            return parseSource(location, mimeType, idioms.get(0), charset, contentLength, sourceStream);
        }
        
        // in case that we know more parsers we first transform the content into a byte[] and use that as base
        // for a number of different parse attempts.
        try {
            return parseSource(location, mimeType, idioms, charset, FileUtils.read(sourceStream, (int) contentLength));
        } catch (IOException e) {
            throw new ParserException(e.getMessage(), location);
        }
    }

    private static Document parseSource(
            final DigestURI location,
            String mimeType,
            Idiom idiom,
            final String charset,
            final long contentLength,
            final InputStream sourceStream
        ) throws InterruptedException, ParserException {
        if (log.isFine()) log.logFine("Parsing '" + location + "' from stream");
        final String fileExt = location.getFileExtension();
        final String documentCharset = htmlParser.patchCharsetEncoding(charset);
        assert idiom != null;

        if (log.isFine()) log.logInfo("Parsing " + location + " with mimeType '" + mimeType + "' and file extension '" + fileExt + "'.");
        idiom.setContentLength(contentLength);
        try {
            return idiom.parse(location, mimeType, documentCharset, sourceStream);
        } catch (ParserException e) {
            throw new ParserException("parser failed: " + idiom.getName(), location);
        }
    }

    private static Document parseSource(
            final DigestURI location,
            String mimeType,
            List<Idiom> idioms,
            final String charset,
            final byte[] sourceArray
        ) throws InterruptedException, ParserException {
        final String fileExt = location.getFileExtension();
        if (log.isFine()) log.logInfo("Parsing " + location + " with mimeType '" + mimeType + "' and file extension '" + fileExt + "' from byte[]");
        final String documentCharset = htmlParser.patchCharsetEncoding(charset);
        assert !idioms.isEmpty();

        Document doc = null;
        HashMap<Idiom, ParserException> failedParser = new HashMap<Idiom, ParserException>();
        for (Idiom parser: idioms) {
            parser.setContentLength(sourceArray.length);
            try {
                doc = parser.parse(location, mimeType, documentCharset, new ByteArrayInputStream(sourceArray));
            } catch (ParserException e) {
                failedParser.put(parser, e);
                //log.logWarning("tried parser '" + parser.getName() + "' to parse " + location.toNormalform(true, false) + " but failed: " + e.getMessage(), e);
            }
            if (doc != null) break;
        }
        
        if (doc == null) {
            if (failedParser.size() == 0) {
                final String errorMsg = "Parsing content with file extension '" + location.getFileExtension() + "' and mimetype '" + mimeType + "' failed.";
                //log.logWarning("Unable to parse '" + location + "'. " + errorMsg);
                throw new ParserException(errorMsg, location);
            } else {
                String failedParsers = "";
                for (Map.Entry<Idiom, ParserException> error: failedParser.entrySet()) {
                    log.logWarning("tried parser '" + error.getKey().getName() + "' to parse " + location.toNormalform(true, false) + " but failed: " + error.getValue().getMessage(), error.getValue());
                    failedParsers += error.getKey().getName() + " ";
                }
                throw new ParserException("All parser failed: " + failedParsers, location);
            }
        }
        return doc;
    }
    
    /**
     * check if the parser supports the given content.
     * @param url
     * @param mimeType
     * @return returns null if the content is supported. If the content is not supported, return a error string.
     */
    public static String supports(final DigestURI url, String mimeType) {
        try {
            // try to get a parser. If this works, we don't need the parser itself, we just return null to show that everything is ok.
            List<Idiom> idioms = idiomParser(url, mimeType);
            return (idioms == null || idioms.isEmpty()) ? "no parser found" : null;
        } catch (ParserException e) {
            // in case that a parser is not available, return a error string describing the problem.
            return e.getMessage();
        }
    }
    
    /**
     * find a parser for a given url and mime type
     * because mime types returned by web severs are sometimes wrong, we also compute the mime type again
     * from the extension that can be extracted from the url path. That means that there are 3 criteria
     * that can be used to select a parser:
     * - the given extension
     * - the given mime type
     * - the mime type computed from the extension
     * @param url the given url
     * @param mimeType the given mime type
     * @return a list of Idiom parsers that may be appropriate for the given criteria
     * @throws ParserException
     */
    private static List<Idiom> idiomParser(final DigestURI url, String mimeType1) throws ParserException {
        List<Idiom> idioms = new ArrayList<Idiom>(2);
        
        // check extension
        String ext = url.getFileExtension();
        Idiom idiom;
        if (ext != null && ext.length() > 0) {
            ext = ext.toLowerCase();
            if (denyExtensionx.containsKey(ext)) throw new ParserException("file extension '" + ext + "' is denied (1)", url);
            idiom = ext2parser.get(ext);
            if (idiom != null) idioms.add(idiom);
        }
        
        // check given mime type
        if (mimeType1 != null) {
            mimeType1 = normalizeMimeType(mimeType1);
            if (denyMime.containsKey(mimeType1)) throw new ParserException("mime type '" + mimeType1 + "' is denied (1)", url);
            idiom = mime2parser.get(mimeType1);
            if (idiom != null && !idioms.contains(idiom)) idioms.add(idiom);
        }
        
        // check mime type computed from extension
        String mimeType2 = ext2mime.get(ext);
        if (mimeType2 == null || denyMime.containsKey(mimeType2)) return idioms; // in this case we are a bit more lazy
        idiom = mime2parser.get(mimeType2);
        if (idiom != null && !idioms.contains(idiom)) idioms.add(idiom);
        
        // finall check if we found any parser
        if (idioms.isEmpty()) throw new ParserException("no parser found for extension '" + ext + "' and mime type '" + mimeType1 + "'", url);
        
        return idioms;
    }
    
    public static String supportsMime(String mimeType) {
        if (mimeType == null) return null;
        mimeType = normalizeMimeType(mimeType);
        if (denyMime.containsKey(mimeType)) return "mime type '" + mimeType + "' is denied (2)";
        if (mime2parser.get(mimeType) == null) return "no parser for mime '" + mimeType + "' available";
        return null;
    }
    
    public static String supportsExtension(final DigestURI url) {
        String ext = url.getFileExtension().toLowerCase();
        if (ext == null || ext.length() == 0) return null;
        if (denyExtensionx.containsKey(ext)) return "file extension '" + ext + "' is denied (2)";
        String mimeType = ext2mime.get(ext);
        if (mimeType == null) return "no parser available";
        Idiom idiom = mime2parser.get(mimeType);
        assert idiom != null;
        if (idiom == null) return "no parser available (internal error!)";
        return null;
    }
    
    public static String mimeOf(DigestURI url) {
        return mimeOf(url.getFileExtension());
    }
    
    public static String mimeOf(String ext) {
        return ext2mime.get(ext.toLowerCase());
    }
    
    private static String normalizeMimeType(String mimeType) {
        if (mimeType == null) return "application/octet-stream";
        mimeType = mimeType.toLowerCase();
        final int pos = mimeType.indexOf(';');
        return ((pos < 0) ? mimeType.trim() : mimeType.substring(0, pos).trim());
    }
    
    public static void setDenyMime(String denyList) {
        denyMime.clear();
        String n;
        for (String s: denyList.split(",")) {
            n = normalizeMimeType(s);
            if (n != null && n.length() > 0) denyMime.put(n, v);
        }
    }
    
    public static String getDenyMime() {
        String s = "";
        for (String d: denyMime.keySet()) s += d + ",";
        if (s.length() > 0) s = s.substring(0, s.length() - 1);
        return s;
    }
    
    public static void grantMime(String mime, boolean grant) {
        String n = normalizeMimeType(mime);
        if (n == null || n.length() == 0) return;
        if (grant) denyMime.remove(n); else denyMime.put(n, v);
    }
    
    public static void setDenyExtension(String denyList) {
        denyExtensionx.clear();
        for (String s: denyList.split(",")) denyExtensionx.put(s, v);
    }
    
    public static String getDenyExtension() {
        String s = "";
        for (String d: denyExtensionx.keySet()) s += d + ",";
        s = s.substring(0, s.length() - 1);
        return s;
    }
    
    public static void grantExtension(String ext, boolean grant) {
        if (grant) denyExtensionx.remove(ext); else denyExtensionx.put(ext, v);
    }
}