// kelondroBytesLongMap.java
// (C) 2008 by Michael Peter Christen; mc@yacy.net, Frankfurt a. M., Germany
// first published 08.04.2008 on http://yacy.net
//
// $LastChangedDate: 2006-04-02 22:40:07 +0200 (So, 02 Apr 2006) $
// $LastChangedRevision: 1986 $
// $LastChangedBy: orbiter $
//
// 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 de.anomic.kelondro.index;

import java.io.BufferedInputStream;
import java.io.BufferedOutputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.util.ArrayList;
import java.util.Iterator;
import java.util.concurrent.ArrayBlockingQueue;
import java.util.concurrent.BlockingQueue;
import java.util.concurrent.Callable;
import java.util.concurrent.ExecutionException;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.Future;

import de.anomic.kelondro.order.ByteOrder;
import de.anomic.kelondro.order.CloneableIterator;

public class BytesLongMap {
    
    private final Row rowdef;
    private RAMIndex index;
    
    /**
     * initialize a BytesLongMap
     * This may store a key and a long value for each key.
     * The class is used as index for database files
     * @param keylength
     * @param objectOrder
     * @param space
     */
    public BytesLongMap(final int keylength, final ByteOrder objectOrder, final int space) {
        this.rowdef = new Row(new Column[]{new Column("key", Column.celltype_binary, Column.encoder_bytes, keylength, "key"), new Column("long c-8 {b256}")}, objectOrder, 0);
        this.index = new RAMIndex(rowdef, space);
    }

    /**
     * initialize a BytesLongMap with the content of a dumped index
     * @param keylength
     * @param objectOrder
     * @param file
     * @throws IOException 
     */
    public BytesLongMap(final int keylength, final ByteOrder objectOrder, final File file) throws IOException {
        this(keylength, objectOrder, (int) (file.length() / (keylength + 8)));
        // read the index dump and fill the index
        InputStream is = new BufferedInputStream(new FileInputStream(file), 1024 * 1024);
        byte[] a = new byte[keylength + 8];
        int c;
        while (true) {
            c = is.read(a);
            if (c <= 0) break;
            this.index.addUnique(this.rowdef.newEntry(a));
        }
        is.close();
        assert this.index.size() == file.length() / (keylength + 8);
    }

    /**
     * write a dump of the index to a file. All entries are written in order
     * which makes it possible to read them again in a fast way
     * @param file
     * @return the number of written entries
     * @throws IOException
     */
    public int dump(File file) throws IOException {
        // we must use an iterator from the combined index, because we need the entries sorted
        // otherwise we could just write the byte[] from the in kelondroRowSet which would make
        // everything much faster, but this is not an option here.
        Iterator<Row.Entry> i = this.index.rows(true, null);
        OutputStream os = new BufferedOutputStream(new FileOutputStream(file), 1024 * 1024);
        int c = 0;
        while (i.hasNext()) {
            os.write(i.next().bytes());
            c++;
        }
        os.flush();
        os.close();
        return c;
    }

    public Row row() {
        return index.row();
    }
    
    public void clear() throws IOException {
        index.clear();
    }
    
    public synchronized long getl(final byte[] key) throws IOException {
        assert (key != null);
        final Row.Entry indexentry = index.get(key);
        if (indexentry == null) return -1;
        return indexentry.getColLong(1);
    }
    
    public synchronized long putl(final byte[] key, final long l) throws IOException {
        assert l >= 0 : "l = " + l;
        assert (key != null);
        final Row.Entry newentry = index.row().newEntry();
        newentry.setCol(0, key);
        newentry.setCol(1, l);
        final Row.Entry oldentry = index.put(newentry);
        if (oldentry == null) return -1;
        return oldentry.getColLong(1);
    }
    
    public synchronized void addl(final byte[] key, final long l) throws IOException {
        assert l >= 0 : "l = " + l;
        assert (key != null);
        final Row.Entry newentry = this.rowdef.newEntry();
        newentry.setCol(0, key);
        newentry.setCol(1, l);
        index.addUnique(newentry);
    }
    
    public synchronized ArrayList<Long[]> removeDoubles() throws IOException {
        final ArrayList<RowCollection> indexreport = index.removeDoubles();
        final ArrayList<Long[]> report = new ArrayList<Long[]>();
        Long[] is;
        int c;
        for (final RowCollection rowset: indexreport) {
            is = new Long[rowset.size()];
            c = 0;
            for (Row.Entry e: rowset) {
                is[c++] = Long.valueOf(e.getColLong(1));
            }
            report.add(is);
        }
        return report;
    }
    
    public synchronized long removel(final byte[] key) throws IOException {
        assert (key != null);
        final Row.Entry indexentry = index.remove(key);
        if (indexentry == null) return -1;
        return indexentry.getColLong(1);
    }

    public synchronized long removeonel() throws IOException {
        final Row.Entry indexentry = index.removeOne();
        if (indexentry == null) return -1;
        return indexentry.getColLong(1);
    }
    
    public synchronized int size() {
        return index.size();
    }
    
    public synchronized CloneableIterator<byte[]> keys(final boolean up, final byte[] firstKey) throws IOException {
        return index.keys(up, firstKey);
    }

    public synchronized CloneableIterator<Row.Entry> rows(final boolean up, final byte[] firstKey) throws IOException {
        return index.rows(up, firstKey);
    }
    
    public synchronized void close() {
        index.close();
        index = null;
    }
    
    /**
     * this method creates a concurrent thread that can take entries that are used to initialize the map
     * it should be used when a bytesLongMap is initialized when a file is read. Concurrency of FileIO and
     * map creation will speed up the initialization process.
     * @param keylength
     * @param objectOrder
     * @param space
     * @param bufferSize
     * @return
     */
    public static initDataConsumer asynchronusInitializer(final int keylength, final ByteOrder objectOrder, final int space, int bufferSize) {
        initDataConsumer initializer = new initDataConsumer(new BytesLongMap(keylength, objectOrder, space), bufferSize);
        ExecutorService service = Executors.newSingleThreadExecutor();
        initializer.setResult(service.submit(initializer));
        service.shutdown();
        return initializer;
    }

    private static class entry {
        public byte[] key;
        public long l;
        public entry(final byte[] key, final long l) {
            this.key = key;
            this.l = l;
        }
    }
    private static final entry poisonEntry = new entry(new byte[0], 0);
    
    public static class initDataConsumer implements Callable<BytesLongMap> {

        private BlockingQueue<entry> cache;
        private BytesLongMap map;
        private Future<BytesLongMap> result;
        
        public initDataConsumer(BytesLongMap map, int bufferCount) {
            this.map = map;
            cache = new ArrayBlockingQueue<entry>(bufferCount);
        }
        
        protected void setResult(Future<BytesLongMap> result) {
            this.result = result;
        }
        
        /**
         * hand over another entry that shall be inserted into the BytesLongMap with an addl method
         * @param key
         * @param l
         */
        public void consume(final byte[] key, final long l) {
            try {
                cache.put(new entry(key, l));
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
        }
        
        /**
         * to signal the initialization thread that no more entries will be sublitted with consumer()
         * this method must be called. The process will not terminate if this is not called before.
         */
        public void finish() {
            try {
                cache.put(poisonEntry);
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
        }
        
        /**
         * this must be called after a finish() was called. this method blocks until all entries
         * had been processed, and the content was sorted. It returns the kelondroBytesLongMap
         * that the user wanted to initialize
         * @return
         * @throws InterruptedException
         * @throws ExecutionException
         */
        public BytesLongMap result() throws InterruptedException, ExecutionException {
            return this.result.get();
        }
        
        public BytesLongMap call() throws IOException {
            try {
                entry c;
                while ((c = cache.take()) != poisonEntry) {
                    map.addl(c.key, c.l);
                }
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
            map.index.finishInitialization();
            return map;
        }
        
    }
}