// plasmaNURL.java 
// -----------------------
// part of YaCy
// (C) by Michael Peter Christen; mc@anomic.de
// first published on http://www.anomic.de
// Frankfurt, Germany, 2004
// last major change: 09.08.2004
//
// 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.

// NURL - noticed (known but not loaded) URL's

package de.anomic.crawler;

import java.io.File;
import java.io.IOException;
import java.util.ArrayList;
import java.util.HashSet;
import java.util.Iterator;

import de.anomic.crawler.Balancer;
import de.anomic.crawler.CrawlEntry;
import de.anomic.server.logging.serverLog;

public class NoticedURL {
    
    public static final int STACK_TYPE_NULL     =  0; // do not stack
    public static final int STACK_TYPE_CORE     =  1; // put on local stack
    public static final int STACK_TYPE_LIMIT    =  2; // put on global stack
    public static final int STACK_TYPE_OVERHANG =  3; // put on overhang stack; links that are known but not crawled
    public static final int STACK_TYPE_REMOTE   =  4; // put on remote-triggered stack
    public static final int STACK_TYPE_IMAGE    = 11; // put on image stack
    public static final int STACK_TYPE_MOVIE    = 12; // put on movie stack
    public static final int STACK_TYPE_MUSIC    = 13; // put on music stack

    private static final long minimumLocalDelta  =   0; // the minimum time difference between access of the same local domain
    private static final long minimumGlobalDelta = 333; // the minimum time difference between access of the same global domain
    private static final long maximumDomAge   =  60000; // the maximum age of a domain until it is used for another crawl attempt
    
    private Balancer coreStack;      // links found by crawling to depth-1
    private Balancer limitStack;     // links found by crawling at target depth
    private Balancer remoteStack;    // links from remote crawl orders
    //private final plasmaCrawlBalancer overhangStack;  // links found by crawling at depth+1
    //private kelondroStack imageStack;     // links pointing to image resources
    //private kelondroStack movieStack;     // links pointing to movie resources
    //private kelondroStack musicStack;     // links pointing to music resources

    public NoticedURL(File cachePath) {
        super();
        coreStack = new Balancer(cachePath, "urlNoticeCoreStack", false);
        limitStack = new Balancer(cachePath, "urlNoticeLimitStack", false);
        //overhangStack = new plasmaCrawlBalancer(overhangStackFile);
        remoteStack = new Balancer(cachePath, "urlNoticeRemoteStack", false);
    }

    public void close() {
        if (coreStack != null) {
            coreStack.close();
            coreStack = null;
        }
        if (limitStack != null) {
            limitStack.close();
            limitStack = null;
        }
        //overhangStack.close();
        if (remoteStack != null) {
            remoteStack.close();
            remoteStack = null;
        }
    }
    
    public void finalize() {
        if ((coreStack != null) || (limitStack != null) || (remoteStack != null)) {
            serverLog.logWarning("plasmaCrawlNURL", "NURL stack closed by finalizer");
            close();
        }
    }
    
    public boolean notEmpty() {
        return coreStack.notEmpty() || limitStack.notEmpty() || remoteStack.notEmpty();
    }
    
    public int size() {
        // this does not count the overhang stack size
        return ((coreStack == null) ? 0 : coreStack.size()) + ((limitStack == null) ? 0 : limitStack.size()) + ((remoteStack == null) ? 0 : remoteStack.size());
    }

    public int stackSize(int stackType) {
        switch (stackType) {
            case STACK_TYPE_CORE:     return (coreStack == null) ? 0 : coreStack.size();
            case STACK_TYPE_LIMIT:    return (limitStack == null) ? 0 : limitStack.size();
            case STACK_TYPE_OVERHANG: return 0;
            case STACK_TYPE_REMOTE:   return (remoteStack == null) ? 0 : remoteStack.size();
            default: return -1;
        }
    }

    public boolean existsInStack(String urlhash) {
        return
            coreStack.has(urlhash) ||
            limitStack.has(urlhash) ||
            //overhangStack.has(urlhash) || 
            remoteStack.has(urlhash);
    }
    
    public void push(int stackType, CrawlEntry entry) {
        try {
            switch (stackType) {
                case STACK_TYPE_CORE:
                    coreStack.push(entry);
                    break;
                case STACK_TYPE_LIMIT:
                    limitStack.push(entry);
                    break;
                case STACK_TYPE_REMOTE:
                    remoteStack.push(entry);
                    break;
                default: break;
            }
        } catch (IOException er) {}
    }

    public CrawlEntry get(String urlhash) {
        CrawlEntry entry = null;
        try {if ((entry = coreStack.get(urlhash)) != null) return entry;} catch (IOException e) {}
        try {if ((entry = limitStack.get(urlhash)) != null) return entry;} catch (IOException e) {}
        try {if ((entry = remoteStack.get(urlhash)) != null) return entry;} catch (IOException e) {}
        return null;
    }
    
    /**
     * remove a CrawlEntry by a given hash. Usage of this method is not encouraged,
     * because the underlying data structure (crawl stacks) cannot handle removals very good.
     * @param urlhash
     * @return true, if the entry was removed; false if not
     */
    public boolean removeByURLHash(String urlhash) {
        HashSet<String> urlHashes = new HashSet<String>();
        urlHashes.add(urlhash);
        try {return coreStack.remove(urlHashes) > 0;} catch (IOException e) {}
        try {return limitStack.remove(urlHashes) > 0;} catch (IOException e) {}
        try {return remoteStack.remove(urlHashes) > 0;} catch (IOException e) {}
        return false;
    }
    
    public int removeByProfileHandle(String handle) {
        int removed = 0;
        try {removed += coreStack.removeAllByProfileHandle(handle);} catch (IOException e) {}
        try {removed += limitStack.removeAllByProfileHandle(handle);} catch (IOException e) {}
        try {removed += remoteStack.removeAllByProfileHandle(handle);} catch (IOException e) {}
        return removed;
    }
    
    public CrawlEntry[] top(int stackType, int count) {
        switch (stackType) {
            case STACK_TYPE_CORE:     return top(coreStack, count);
            case STACK_TYPE_LIMIT:    return top(limitStack, count);
            case STACK_TYPE_REMOTE:   return top(remoteStack, count);
            default: return null;
        }
    }
    
    public CrawlEntry pop(int stackType, boolean delay) throws IOException {
        switch (stackType) {
            case STACK_TYPE_CORE:     return pop(coreStack, delay);
            case STACK_TYPE_LIMIT:    return pop(limitStack, delay);
            case STACK_TYPE_REMOTE:   return pop(remoteStack, delay);
            default: return null;
        }
    }

    public void shift(int fromStack, int toStack) {
        try {
            CrawlEntry entry = pop(fromStack, false);
            if (entry != null) push(toStack, entry);
        } catch (IOException e) {
            return;
        }
    }

    public void clear(int stackType) {
        switch (stackType) {
                case STACK_TYPE_CORE:     coreStack.clear(); break;
                case STACK_TYPE_LIMIT:    limitStack.clear(); break;
                case STACK_TYPE_REMOTE:   remoteStack.clear(); break;
                default: return;
            }
    }
    
    private CrawlEntry pop(Balancer balancer, boolean delay) throws IOException {
        // this is a filo - pop
        int s;
        CrawlEntry entry;
        synchronized (balancer) {
        while ((s = balancer.size()) > 0) {
            entry = balancer.pop((delay) ? minimumLocalDelta : 0, (delay) ? minimumGlobalDelta : 0, maximumDomAge);
            if (entry == null) {
                if (s > balancer.size()) continue;
                int aftersize = balancer.size();
                balancer.clear(); // the balancer is broken and cannot shrink
                throw new IOException("entry is null, balancer cannot shrink (bevore pop = " + s + ", after pop = " + aftersize + "); reset of balancer");
            }
            return entry;
        }
        }
        throw new IOException("balancer stack is empty");
    }
    
    private CrawlEntry[] top(Balancer balancer, int count) {
        // this is a filo - top
        if (count > balancer.size()) count = balancer.size();
        ArrayList<CrawlEntry> list = new ArrayList<CrawlEntry>(count);
        for (int i = 0; i < count; i++) {
            try {
                CrawlEntry entry = balancer.top(i);
                if (entry == null) break;
                list.add(entry);
            } catch (IOException e) {
                break;
            }
        }
        return (CrawlEntry[]) list.toArray(new CrawlEntry[list.size()]);
    }
    
    public Iterator<CrawlEntry> iterator(int stackType) {
        // returns an iterator of plasmaCrawlBalancerEntry Objects
        try {switch (stackType) {
            case STACK_TYPE_CORE:     return coreStack.iterator();
            case STACK_TYPE_LIMIT:    return limitStack.iterator();
            case STACK_TYPE_REMOTE:   return remoteStack.iterator();
            default: return null;
        }} catch (IOException e) {
            return new HashSet<CrawlEntry>().iterator();
        }
    }
    
}