/*******************************************************************************
 * Copyright (c) 2004-2008 Andras Schmidt, Andras Balogh, Istvan Rath and Daniel Varro
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/epl-v10.html
 *
 * Contributors:
 *    Gabor Bergmann, Istvan Rath - initial API and implementation
 *******************************************************************************/

package org.eclipse.viatra2.natives;

import java.util.Random;

import org.eclipse.viatra2.core.IModelSpace;
import org.eclipse.viatra2.errors.VPMRuntimeException;
import org.eclipse.viatra2.natives.NativeFunctionParameter.ParameterType;

/**
 * Native function to generate a fresh random number.
 * 
 * @author Gabor Bergmann
 * 
 */
@VIATRANativeFunction(
		name = "randomInteger", 
		remark = "Returns a fresh random non-negative integer less than the argument, or a random integer without range restriction if no argument is provided.", 
		params = {
				@NativeFunctionParameter(
						type = ParameterType.INTEGER, 
						name="range", 
						description="the upper limit of the random integers, omit if full range is required")}, 
		returns = { ParameterType.INTEGER })
public class RandomIntegerFunction implements ASMNativeFunction {

	Random random = new Random();

	public Object evaluate(IModelSpace msp, Object[] params) throws VPMRuntimeException {
		if (params.length > 0 && params[0] !=null && params[0] instanceof Integer)
			return random.nextInt((Integer)params[0]);
		else return random.nextInt();
	}

	public String getDescription() {
		return "Returns a fresh random non-negative integer less than the range argument, or a random integer without range restriction if no argument is provided.";
	}

	public String getID() {
		return this.getClass().getCanonicalName();
	}

	public String getName() {
		return "randomInteger"; // ez megy a VTCLbe
	}

}