// plasmaSnippetCache.java
// -----------------------
// part of YaCy
// (C) by Michael Peter Christen; mc@anomic.de
// first published on http://www.anomic.de
// Frankfurt, Germany, 2005
// last major change: 07.06.2005
//
// 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.plasma;

import java.util.*;
import java.io.File;
import java.io.IOException;
import java.net.URL;
import de.anomic.htmlFilter.htmlFilterContentScraper;
import de.anomic.kelondro.kelondroMScoreCluster;
import de.anomic.server.serverFileUtils;
import de.anomic.server.logging.serverLog;
import de.anomic.http.httpHeader;
import de.anomic.yacy.yacySearch;

public class plasmaSnippetCache {

    private static final int maxCache = 500;
    
    public static final int SOURCE_CACHE = 0;
    public static final int SOURCE_FILE = 1;
    public static final int SOURCE_WEB = 2;
    
    public static final int ERROR_NO_HASH_GIVEN = 11;
    public static final int ERROR_SOURCE_LOADING = 12;
    public static final int ERROR_RESOURCE_LOADING = 13;
    public static final int ERROR_PARSER_FAILED = 14;
    public static final int ERROR_PARSER_NO_LINES = 15;
    public static final int ERROR_NO_MATCH = 16;
    
    private int                   snippetsScoreCounter;
    private kelondroMScoreCluster snippetsScore;
    private HashMap               snippetsCache;
    private plasmaHTCache         cacheManager;
    private plasmaParser          parser;
    private serverLog             log;
    private String                remoteProxyHost;
    private int                   remoteProxyPort;
    private boolean               remoteProxyUse;
    
    public plasmaSnippetCache(plasmaHTCache cacheManager, plasmaParser parser,
                              String remoteProxyHost, int remoteProxyPort, boolean remoteProxyUse,
                              serverLog log) {
        this.cacheManager = cacheManager;
        this.parser = parser;
        this.log = log;
        this.remoteProxyHost = remoteProxyHost;
        this.remoteProxyPort = remoteProxyPort;
        this.remoteProxyUse = remoteProxyUse;
        this.snippetsScoreCounter = 0;
        this.snippetsScore = new kelondroMScoreCluster();
        this.snippetsCache = new HashMap();        
    }
    
    public class result {
        public String line;
        public String error;
        public int source;
        public result(String line, int source, String errortext) {
            this.line = line;
            this.source = source;
            this.error = errortext;
        }
        public String toString() {
            return line;
        }
    }
    
    public boolean existsInCache(URL url, Set queryhashes) {
        return retrieveFromCache(yacySearch.set2string(queryhashes), plasmaURL.urlHash(url)) != null;
    }
    
    public result retrieve(URL url, Set queryhashes, boolean fetchOnline) {
        // heise = "0OQUNU3JSs05"
        if (queryhashes.size() == 0) {
            //System.out.println("found no queryhashes for url retrieve " + url);
            return new result(null, ERROR_NO_HASH_GIVEN, "no query hashes given");
        }
        String urlhash = plasmaURL.urlHash(url);
        
        // try to get snippet from snippetCache
        int source = SOURCE_CACHE;
        String wordhashes = yacySearch.set2string(queryhashes);
        String line = retrieveFromCache(wordhashes, urlhash);
        if (line != null) {
            //System.out.println("found snippet for url " + url + " in cache: " + line);
            return new result(line, source, null);
        }
        
        // if the snippet is not in the cache, we can try to get it from the htcache
        byte[] resource = null;
        try {
            resource = cacheManager.loadResource(url);
            if ((fetchOnline) && (resource == null)) {
                loadResourceFromWeb(url, 5000);
                resource = cacheManager.loadResource(url);
                source = SOURCE_WEB;
            }
        } catch (IOException e) {
            return new result(null, ERROR_SOURCE_LOADING, "error loading resource from web: " + e.getMessage());
        }
        if (resource == null) {
            //System.out.println("cannot load document for url " + url);
            return new result(null, ERROR_RESOURCE_LOADING, "error loading resource from web, cacheManager returned NULL");
        }
        plasmaParserDocument document = parseDocument(url, resource);
        
        if (document == null) return new result(null, ERROR_PARSER_FAILED, "parser error/failed"); // cannot be parsed
        //System.out.println("loaded document for url " + url);
        String[] sentences = document.getSentences();
        //System.out.println("----" + url.toString()); for (int l = 0; l < sentences.length; l++) System.out.println(sentences[l]);
        if ((sentences == null) || (sentences.length == 0)) {
            //System.out.println("found no sentences in url " + url);
            return new result(null, ERROR_PARSER_NO_LINES, "parser returned no sentences");
        }

        // we have found a parseable non-empty file: use the lines
        line = computeSnippet(sentences, queryhashes, 12 * queryhashes.size(), 120);
        //System.out.println("loaded snippet for url " + url + ": " + line);
        if (line == null) return new result(null, ERROR_NO_MATCH, "no matching snippet found");
        if (line.length() > 120) line = line.substring(0, 120);

        // finally store this snippet in our own cache
        storeToCache(wordhashes, urlhash, line);
        return new result(line, source, null);
    }
    
    public synchronized void storeToCache(String wordhashes, String urlhash, String snippet) {
        // generate key
        String key = urlhash + wordhashes;

        // do nothing if snippet is known
        if (snippetsCache.containsKey(key)) return;

        // learn new snippet
        snippetsScore.addScore(key, snippetsScoreCounter++);
        snippetsCache.put(key, snippet);

        // care for counter
        if (snippetsScoreCounter == java.lang.Integer.MAX_VALUE) {
            snippetsScoreCounter = 0;
            snippetsScore = new kelondroMScoreCluster();
            snippetsCache = new HashMap();
        }
        
        // flush cache if cache is full
        while (snippetsCache.size() > maxCache) {
            key = (String) snippetsScore.getMinObject();
            snippetsScore.deleteScore(key);
            snippetsCache.remove(key);
        }
    }
    
    private String retrieveFromCache(String wordhashes, String urlhash) {
        // generate key
        String key = urlhash + wordhashes;
        return (String) snippetsCache.get(key);
    }
    
    private String computeSnippet(String[] sentences, Set queryhashes, int minLength, int maxLength) {
        if ((sentences == null) || (sentences.length == 0)) return null;
        if ((queryhashes == null) || (queryhashes.size() == 0)) return null;
        kelondroMScoreCluster hitTable = new kelondroMScoreCluster();
        Iterator j;
        HashSet hs;
        for (int i = 0; i < sentences.length; i++) {
            if ((sentences[i].length() > minLength) && (sentences[i].length() < maxLength)) {
                hs = hashSentence(sentences[i]);
                j = queryhashes.iterator();
                while (j.hasNext()) {
                    if (hs.contains((String) j.next())) hitTable.incScore(new Integer(i));
                }
            }
        }
        int score = hitTable.getMaxScore(); // best number of hits
        if (score <= 0) return null;
        // we found (a) line(s) that have <score> hits.
        // now find the shortest line of these hits
        int shortLineIndex = -1;
        int shortLineLength = Integer.MAX_VALUE;
        for (int i = 0; i < sentences.length; i++) {
            if ((hitTable.getScore(new Integer(i)) == score) &&
                (sentences[i].length() < shortLineLength)) {
                shortLineIndex = i;
                shortLineLength = sentences[i].length();
            }
        }
        // find a first result
        String result = sentences[shortLineIndex];
        if (score == queryhashes.size()) return result;
        // the result has not all words in it.
        // find another sentence that represents the missing other words
        // first remove all words that appear in the result from the queryhashes
        hs = hashSentence(result);
        j = queryhashes.iterator();
        while (j.hasNext()) {
            if (hs.contains((String) j.next())) j.remove();
        }
        if (queryhashes.size() == 0) return result;
        // now find recursively more sentences
        String nextSnippet = computeSnippet(sentences, queryhashes, minLength, maxLength);
        return result + ((nextSnippet == null) ? "" : (" ... " + nextSnippet));
    }
    
    private HashSet hashSentence(String sentence) {
        HashSet set = new HashSet();
        Enumeration words = plasmaCondenser.wordTokenizer(sentence);
        while (words.hasMoreElements()) set.add(plasmaWordIndexEntry.word2hash((String) words.nextElement()));
        return set;
    }
     
    public plasmaParserDocument parseDocument(URL url, byte[] resource) {
        if (resource == null) return null;
        httpHeader header = null;
        try {
            header = cacheManager.getCachedResponse(plasmaURL.urlHash(url));
        } catch (IOException e) {}
        
        if (header == null) {
            String filename = cacheManager.getCachePath(url).getName();
            int p = filename.lastIndexOf('.');
            if ((p < 0) ||
                ((p >= 0) && (plasmaParser.supportedFileExtContains(filename.substring(p + 1))))) {
                return parser.parseSource(url, "text/html", resource);
            } else {
                return null;
            }
        } else {
            if (plasmaParser.supportedMimeTypesContains(header.mime())) {
                return parser.parseSource(url, header.mime(), resource);
            } else {
                return null;
            }
        }
    }
    
    public byte[] getResource(URL url, boolean fetchOnline) {
        // load the url as resource from the web
        try {
            //return httpc.singleGET(url, 5000, null, null, remoteProxyHost, remoteProxyPort);
            byte[] resource = cacheManager.loadResource(url);
            if ((fetchOnline) && (resource == null)) {
                loadResourceFromWeb(url, 5000);
                resource = cacheManager.loadResource(url);
            }
            return resource;
        } catch (IOException e) {
            return null;
        }
    }
    
    private void loadResourceFromWeb(URL url, int socketTimeout) throws IOException {
        plasmaCrawlWorker.load(
            url, 
            null, 
            null, 
            0, 
            null,
            socketTimeout,
            remoteProxyHost,
            remoteProxyPort,
            remoteProxyUse,
            cacheManager,
            log);
    }
    
}