/**
 * Copyright (c) 2002-2011 "Neo Technology,"
 * Network Engine for Objects in Lund AB [http://neotechnology.com]
 *
 * This file is part of Neo4j.
 *
 * Neo4j is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Affero General Public License as
 * published by the Free Software Foundation, either version 3 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 Affero General Public License for more details.
 *
 * You should have received a copy of the GNU Affero General Public License
 * along with this program. If not, see <http://www.gnu.org/licenses/>.
 */
package org.neo4j.index.timeline;

import static java.lang.Long.MAX_VALUE;
import static org.apache.lucene.search.NumericRangeQuery.newLongRange;
import static org.neo4j.index.impl.lucene.ValueContext.numeric;

import java.util.Map;

import org.apache.lucene.search.Sort;
import org.apache.lucene.search.SortField;
import org.neo4j.graphdb.GraphDatabaseService;
import org.neo4j.graphdb.PropertyContainer;
import org.neo4j.graphdb.index.Index;
import org.neo4j.graphdb.index.IndexHits;
import org.neo4j.index.impl.lucene.QueryContext;

public class LuceneTimeline<T extends PropertyContainer> implements TimelineIndex<T>
{
    private static final String FIELD = "timestamp";
    private final Index<T> index;

    public LuceneTimeline( GraphDatabaseService db, Index<T> index )
    {
        assertIsLuceneIndex( db, index );
        this.index = index;
    }
    
    private void assertIsLuceneIndex( GraphDatabaseService db, Index<T> index )
    {
        Map<String, String> config = db.index().getConfiguration( index );
        if ( !config.get( "provider" ).equals( "lucene" ) ) // Not so hard coded please
        {
            throw new IllegalArgumentException( index + " isn't a Lucene index" );
        }
    }

    private T getSingle( boolean reversed )
    {
        IndexHits<T> hits = index.query( sort( everythingQuery().topDocs( 1 ), reversed ) );
        return hits.getSingle();
    }
    
    private QueryContext everythingQuery()
    {
        return new QueryContext( newLongRange( FIELD, 0L, MAX_VALUE, true, true ) );
    }

    private QueryContext rangeQuery( Long startTimestampOrNull, Long endTimestampOrNull )
    {
        long start = startTimestampOrNull != null ? startTimestampOrNull : 0L;
        long end = endTimestampOrNull != null ? endTimestampOrNull : MAX_VALUE;
        return new QueryContext( newLongRange( FIELD, start, end, false, false ) );
    }
    
    private QueryContext sort( QueryContext query, boolean reversed )
    {
        return query.sort( new Sort( new SortField( FIELD, SortField.LONG, reversed ) ) );
    }
    
    @Override
    public T getLast()
    {
        return getSingle( true );
    }

    @Override
    public T getFirst()
    {
        return getSingle( false );
    }

    @Override
    public void remove( T entity, long timestamp )
    {
        index.remove( entity, FIELD, timestamp );
    }

    @Override
    public void add( T entity, long timestamp )
    {
        index.add( entity, FIELD, numeric( timestamp ) );
    }
    
    @Override
    public IndexHits<T> getBetween( Long startTimestampOrNull, Long endTimestampOrNull )
    {
        return getBetween( startTimestampOrNull, endTimestampOrNull, false );
    }
    
    @Override
    public IndexHits<T> getBetween( Long startTimestampOrNull, Long endTimestampOrNull, boolean reversed )
    {
        return index.query( sort( rangeQuery( startTimestampOrNull, endTimestampOrNull ), reversed ) );
    }
}