/*
 * (c) Copyright 2007-2011 by Volker Bergmann. All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, is permitted under the terms of the
 * GNU General Public License.
 *
 * For redistributing this software or a derivative work under a license other
 * than the GPL-compatible Free Software License as defined by the Free
 * Software Foundation or approved by OSI, you must first obtain a commercial
 * license to this software product from Volker Bergmann.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * WITHOUT A WARRANTY OF ANY KIND. ALL EXPRESS OR IMPLIED CONDITIONS,
 * REPRESENTATIONS AND WARRANTIES, INCLUDING ANY IMPLIED WARRANTY OF
 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE OR NON-INFRINGEMENT, ARE
 * HEREBY EXCLUDED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 */

package org.databene.benerator.primitive;

import java.util.concurrent.atomic.AtomicLong;

import org.databene.benerator.util.ThreadSafeNonNullGenerator;
import org.databene.commons.ConfigurationError;

/**
 * Generates long values by continuously incrementing a base (min) value.
 * @author Volker Bergmann
 * @since 0.3.04
 */
public class IncrementGenerator extends ThreadSafeNonNullGenerator<Long> {

    private static final long DEFAULT_MIN = 1;
    private static final long DEFAULT_MAX = Long.MAX_VALUE - 1;
    
    // attributes ------------------------------------------------------------------------------------------------------
    
    private long min;
    private long max;
    private long increment;
    
    volatile AtomicLong cursor = new AtomicLong();
    
    // constructors ----------------------------------------------------------------------------------------------------
    
    public IncrementGenerator() {
        this(DEFAULT_MIN);
    }
    
    public IncrementGenerator(long min) {
        this(min, 1);
    }
    
    public IncrementGenerator(long min, long increment) {
        this(min, increment, DEFAULT_MAX);
    }
    
    public IncrementGenerator(long min, long increment, long max) {
        setMin(min);
        setIncrement(increment);
        setMax(max);
    }
    
    // properties ------------------------------------------------------------------------------------------------------

    public Long getMin() {
        return min;
    }
    
    public void setMin(Long min) {
        this.min = min;
        this.cursor.set(min);
    }
    
    public long getMax() {
        return max;
    }

    public void setMax(long max) {
        this.max = max;
    }
    
    public long getIncrement() {
    	return increment;
    }

	public void setIncrement(long increment) {
		if (increment < 1)
			throw new ConfigurationError("increment must be a positive number, but was " + increment);
    	this.increment = increment;
    }

    // Generator interface ---------------------------------------------------------------------------------------------

	public Class<Long> getGeneratedType() {
	    return Long.class;
    }

	@Override
	public Long generate() {
    	if (cursor.get() <= max)
    		return cursor.getAndAdd(increment);
    	else
    		return null;
    }
    
    @Override
    public void reset() {
        this.cursor.set(min);
    }

    // java.lang.Object overrides --------------------------------------------------------------------------------------
    
    @Override
    public String toString() {
        return getClass().getSimpleName() + '[' + cursor + ']';
    }

}