// kelondroSplitTable.java
// (C) 2006 by Michael Peter Christen; mc@yacy.net, Frankfurt a. M., Germany
// first published 12.10.2006 on http://www.anomic.de
//
// This is a part of YaCy, a peer-to-peer based web search engine
//
// $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.table;

import java.io.File;
import java.io.IOException;
import java.util.ArrayList;
import java.util.Calendar;
import java.util.Date;
import java.util.HashMap;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
import java.util.concurrent.Callable;
import java.util.concurrent.CompletionService;
import java.util.concurrent.ExecutionException;
import java.util.concurrent.ExecutorCompletionService;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Future;
import java.util.concurrent.LinkedBlockingQueue;
import java.util.concurrent.RejectedExecutionException;
import java.util.concurrent.ThreadPoolExecutor;
import java.util.concurrent.TimeUnit;

import de.anomic.kelondro.blob.Cache;
import de.anomic.kelondro.index.Column;
import de.anomic.kelondro.index.RAMIndex;
import de.anomic.kelondro.index.Row;
import de.anomic.kelondro.index.RowCollection;
import de.anomic.kelondro.index.ObjectIndex;
import de.anomic.kelondro.order.CloneableIterator;
import de.anomic.kelondro.order.NaturalOrder;
import de.anomic.kelondro.order.MergeIterator;
import de.anomic.kelondro.order.Order;
import de.anomic.kelondro.order.StackIterator;
import de.anomic.kelondro.util.Log;
import de.anomic.kelondro.util.NamePrefixThreadFactory;

public class SplitTable implements ObjectIndex {

    // this is a set of kelondro tables
    // the set is divided into tables with different entry date
    // the table type can be either kelondroFlex or kelondroEco

    private static final int EcoFSBufferSize = 20;
    static final ObjectIndex dummyIndex = new RAMIndex(new Row(new Column[]{new Column("key", Column.celltype_binary, Column.encoder_bytes, 2, "key")}, NaturalOrder.naturalOrder, 0), 0);

    // the thread pool for the keeperOf executor service
    private ExecutorService executor;
    
    private HashMap<String, ObjectIndex> tables; // a map from a date string to a kelondroIndex object
    private final Row rowdef;
    private final File path;
    private final String tablename;
    private final Order<Row.Entry> entryOrder;
    
    public SplitTable(final File path, final String tablename, final Row rowdef, final boolean resetOnFail) {
        this.path = path;
        this.tablename = tablename;
        this.rowdef = rowdef;
        this.entryOrder = new Row.EntryComparator(rowdef.objectOrder);
        init(resetOnFail);
    }
    
    public void init(final boolean resetOnFail) {

        // init the thread pool for the keeperOf executor service
        this.executor = new ThreadPoolExecutor(
        		Runtime.getRuntime().availableProcessors() + 1, 
        		Runtime.getRuntime().availableProcessors() + 1, 10, 
        		TimeUnit.SECONDS, 
        		new LinkedBlockingQueue<Runnable>(), 
        		new NamePrefixThreadFactory(tablename));
        
        // initialized tables map
        this.tables = new HashMap<String, ObjectIndex>();
        if (!(path.exists())) path.mkdirs();
        final String[] tablefile = path.list();
        String date;
        
        // first pass: find tables
        final HashMap<String, Long> t = new HashMap<String, Long>();
        long ram, sum = 0;
        File f;
        for (int i = 0; i < tablefile.length; i++) {
            if ((tablefile[i].startsWith(tablename)) &&
                (tablefile[i].charAt(tablename.length()) == '.') &&
                (tablefile[i].length() == tablename.length() + 7)) {
                f = new File(path, tablefile[i]);
                if (f.isDirectory()) {
                    ram = FlexTable.staticRAMIndexNeed(path, tablefile[i], rowdef);
                } else {
                    ram = EcoTable.staticRAMIndexNeed(f, rowdef);
                }
                if (ram > 0) {
                    t.put(tablefile[i], Long.valueOf(ram));
                    sum += ram;
                }
            }
        }
        
        // second pass: open tables
        Iterator<Map.Entry<String, Long>> i;
        Map.Entry<String, Long> entry;
        String maxf;
        long maxram;
        ObjectIndex table;
        while (t.size() > 0) {
            // find maximum table
            maxram = 0;
            maxf = null;
            i = t.entrySet().iterator();
            while (i.hasNext()) {
                entry = i.next();
                ram = entry.getValue().longValue();
                if (ram > maxram) {
                    maxf = entry.getKey();
                    maxram = ram;
                }
            }
            
            // open next biggest table
            t.remove(maxf);
            if(maxf != null) {
                date = maxf.substring(tablename.length() + 1);
                f = new File(path, maxf);
                if (f.isDirectory()) {
                    // this is a kelonodroFlex table
                    FlexTable.delete(path, maxf);
                    Log.logInfo("kelondroSplitTable", "replaced partial flex table " + f + " by new eco table");
                }
                Log.logInfo("kelondroSplitTable", "opening partial eco table " + f);
                table = new EcoTable(f, rowdef, EcoTable.tailCacheUsageAuto, EcoFSBufferSize, 0);
                tables.put(date, table);
            }
        }
    }
    
    public void clear() throws IOException {
    	this.close();
    	final String[] l = path.list();
    	for (int i = 0; i < l.length; i++) {
    		if (l[i].startsWith(tablename)) {
    		    final File f = new File(path, l[i]);
    		    if (f.isDirectory()) FlexWidthArray.delete(path, l[i]); else f.delete();
    		}
    	}
    	init(true);
    }
    
    public String filename() {
        return new File(path, tablename).toString();
    }
    
    private static final Calendar thisCalendar = Calendar.getInstance();
    public static final String dateSuffix(final Date date) {
        int month, year;
        final StringBuilder suffix = new StringBuilder(6);
        synchronized (thisCalendar) {
            thisCalendar.setTime(date);
            month = thisCalendar.get(Calendar.MONTH) + 1;
            year = thisCalendar.get(Calendar.YEAR);
        }
        if ((year < 1970) && (year >= 70)) suffix.append("19").append(Integer.toString(year));
        else if (year < 1970) suffix.append("20").append(Integer.toString(year));
        else if (year > 3000) return null;
        else suffix.append(Integer.toString(year));
        if (month < 10) suffix.append("0").append(Integer.toString(month)); else suffix.append(Integer.toString(month));
        return new String(suffix);    
    }
    
    public int size() {
        final Iterator<ObjectIndex> i = tables.values().iterator();
        int s = 0;
        while (i.hasNext()) s += i.next().size();
        return s;
    }
    
    public int writeBufferSize() {
        int s = 0;
        for (final ObjectIndex index : tables.values()) {
            if (index instanceof Cache) s += ((Cache) index).writeBufferSize();
        }
        return s;
    }
    
    public Row row() {
        return this.rowdef;
    }
    
    public boolean has(final byte[] key) {
        return keeperOf(key) != null;
    }
    
    public synchronized Row.Entry get(final byte[] key) throws IOException {
        final ObjectIndex keeper = keeperOf(key);
        if (keeper == null) return null;
        return keeper.get(key);
    }
    
    public synchronized void putMultiple(final List<Row.Entry> rows) throws IOException {
        throw new UnsupportedOperationException("not yet implemented");
    }
    
    public synchronized Row.Entry put(final Row.Entry row) throws IOException {
        return put(row, null); // entry for current date
    }
    
    public synchronized Row.Entry put(final Row.Entry row, Date entryDate) throws IOException {
        assert row.objectsize() <= this.rowdef.objectsize;
        final ObjectIndex keeper = keeperOf(row.getColBytes(0));
        if (keeper != null) return keeper.put(row);
        if ((entryDate == null) || (entryDate.after(new Date()))) entryDate = new Date(); // fix date
        final String suffix = dateSuffix(entryDate);
        if (suffix == null) return null;
        ObjectIndex table = tables.get(suffix);
        if (table == null) {
            // open table
            final File f = new File(path, tablename + "." + suffix);
            if (f.exists()) {
                if (f.isDirectory()) {
                    FlexTable.delete(path, tablename + "." + suffix);
                }
                // open a eco table
                table = new EcoTable(f, rowdef, EcoTable.tailCacheDenyUsage, EcoFSBufferSize, 0);
            } else {
                // make new table
                table = new EcoTable(f, rowdef, EcoTable.tailCacheDenyUsage, EcoFSBufferSize, 0);
            }
            tables.put(suffix, table);
        }
        table.put(row);
        return null;
    }
    
    public synchronized ObjectIndex keeperOf(final byte[] key) {
        // because the index is stored only in one table,
        // and the index is completely in RAM, a concurrency will create
        // not concurrent File accesses
        //long start = System.currentTimeMillis();
        
        // start a concurrent query to database tables
        final CompletionService<ObjectIndex> cs = new ExecutorCompletionService<ObjectIndex>(executor);
        final int s = tables.size();
        int rejected = 0;
        for (final ObjectIndex table : tables.values()) {
            try {
                cs.submit(new Callable<ObjectIndex>() {
                    public ObjectIndex call() {
                        if (table.has(key)) return table;
                        return dummyIndex;
                    }
                });
            } catch (final RejectedExecutionException e) {
                // the executor is either shutting down or the blocking queue is full
                // execute the search direct here without concurrency
                if (table.has(key)) return table;
                rejected++;
            }
        }

        // read the result
        try {
            for (int i = 0, n = s - rejected; i < n; i++) {
                final Future<ObjectIndex> f = cs.take();
                final ObjectIndex index = f.get();
                if (index != dummyIndex) {
                    //System.out.println("*DEBUG SplitTable success.time = " + (System.currentTimeMillis() - start) + " ms");
                    return index;
                }
            }
            //System.out.println("*DEBUG SplitTable fail.time = " + (System.currentTimeMillis() - start) + " ms");
            return null;
        } catch (final InterruptedException e) {
            Thread.currentThread().interrupt();
        } catch (final ExecutionException e) {
            throw new RuntimeException(e.getCause());
        }
        //System.out.println("*DEBUG SplitTable fail.time = " + (System.currentTimeMillis() - start) + " ms");
        return null;
    }
    
    public synchronized void addUnique(final Row.Entry row) throws IOException {
        addUnique(row, null);
    }
    
    public synchronized void addUnique(final Row.Entry row, Date entryDate) throws IOException {
        assert row.objectsize() <= this.rowdef.objectsize;
        if ((entryDate == null) || (entryDate.after(new Date()))) entryDate = new Date(); // fix date
        final String suffix = dateSuffix(entryDate);
        if (suffix == null) return;
        ObjectIndex table = tables.get(suffix);
        if (table == null) {
            // make new table
            table = new EcoTable(new File(path, tablename + "." + suffix), rowdef, EcoTable.tailCacheDenyUsage, EcoFSBufferSize, 0);
            tables.put(suffix, table);
        }
        table.addUnique(row);
    }
    
    public synchronized void addUniqueMultiple(final List<Row.Entry> rows) throws IOException {
        final Iterator<Row.Entry> i = rows.iterator();
        while (i.hasNext()) addUnique(i.next());
    }
    
    public synchronized void addUniqueMultiple(final List<Row.Entry> rows, final Date entryDate) throws IOException {
        final Iterator<Row.Entry> i = rows.iterator();
        while (i.hasNext()) addUnique(i.next(), entryDate);
    }
    
    public ArrayList<RowCollection> removeDoubles() throws IOException {
        final Iterator<ObjectIndex> i = tables.values().iterator();
        final ArrayList<RowCollection> report = new ArrayList<RowCollection>();
        while (i.hasNext()) {
            report.addAll(i.next().removeDoubles());
        }
        return report;
    }
    
    public synchronized Row.Entry remove(final byte[] key) throws IOException {
        final ObjectIndex table = keeperOf(key);
        if (table == null) return null;
        return table.remove(key);
    }
    
    public synchronized Row.Entry removeOne() throws IOException {
        final Iterator<ObjectIndex> i = tables.values().iterator();
        ObjectIndex table, maxtable = null;
        int maxcount = -1;
        while (i.hasNext()) {
            table = i.next();
            if (table.size() > maxcount) {
                maxtable = table;
                maxcount = table.size();
            }
        }
        if (maxtable == null) {
            return null;
        }
        return maxtable.removeOne();
    }
    
    public synchronized CloneableIterator<byte[]> keys(final boolean up, final byte[] firstKey) throws IOException {
        final List<CloneableIterator<byte[]>> c = new ArrayList<CloneableIterator<byte[]>>(tables.size());
        final Iterator<ObjectIndex> i = tables.values().iterator();
        while (i.hasNext()) {
            c.add(i.next().keys(up, firstKey));
        }
        return MergeIterator.cascade(c, rowdef.objectOrder, MergeIterator.simpleMerge, up);
    }
    
    public synchronized CloneableIterator<Row.Entry> rows(final boolean up, final byte[] firstKey) throws IOException {
        final List<CloneableIterator<Row.Entry>> c = new ArrayList<CloneableIterator<Row.Entry>>(tables.size());
        final Iterator<ObjectIndex> i = tables.values().iterator();
        while (i.hasNext()) {
            c.add(i.next().rows(up, firstKey));
        }
        return MergeIterator.cascade(c, entryOrder, MergeIterator.simpleMerge, up);
    }
    
    public synchronized CloneableIterator<Row.Entry> rows() throws IOException {
        final List<CloneableIterator<Row.Entry>> c = new ArrayList<CloneableIterator<Row.Entry>>(tables.size());
        final Iterator<ObjectIndex> i = tables.values().iterator();
        while (i.hasNext()) {
            c.add(i.next().rows());
        }
        return StackIterator.stack(c);
    }

    public final int cacheObjectChunkSize() {
        // dummy method
        return -1;
    }
    
    public long[] cacheObjectStatus() {
        // dummy method
        return null;
    }
    
    public final int cacheNodeChunkSize() {
        // returns the size that the node cache uses for a single entry
        return -1;
    }
    
    public final int[] cacheNodeStatus() {
        // a collection of different node cache status values
        return new int[]{0,0,0,0,0,0,0,0,0,0};
    }
    
    public synchronized void close() {
        if (tables == null) return;
        this.executor.shutdown();
        try {
            this.executor.awaitTermination(3, TimeUnit.SECONDS);
        } catch (final InterruptedException e) {
        }
        this.executor = null;
        final Iterator<ObjectIndex> i = tables.values().iterator();
        while (i.hasNext()) {
            i.next().close();
        }
        this.tables = null;
    }
    
    public static void main(final String[] args) {
        System.out.println(dateSuffix(new Date()));
    }

    public void deleteOnExit() {
        for (ObjectIndex i: this.tables.values()) i.deleteOnExit();
    }
    
}