package lab.art;

import java.util.Random;

/**
 * This utility class provides methods to create expressions.
 * 
 * @author Franck van Breugel
 */
public class Expressions 
{
    private Expressions() {}
    
    /**
     * Returns a random expression.
     * 
     * @param random a Random object.
     * @pre. random != null
     * @return a random expression.
     */
    public static Expression getRandom(Random random)
    {
	final int TYPES = 6;
	final int PRODUCT = 0;
	final int AVERAGE = 1;
	final int SINE = 2;
	final int COSINE = 3;
	final int VARIABLE_X = 4;
	final int VARIABLE_Y = 5;
	
	Expression expression;
	
	switch (random.nextInt(TYPES))
	{
	    case PRODUCT : 
		expression = new Product(Expressions.getRandom(random), Expressions.getRandom(random));
		break;
	    case AVERAGE : 
		expression = new Average(Expressions.getRandom(random), Expressions.getRandom(random));
		break;
	    case SINE : 
		expression = new Sine(Expressions.getRandom(random));
		break;
	    case COSINE : 
		expression = new Cosine(Expressions.getRandom(random));
		break;
	    case VARIABLE_X :
		expression = new VariableX();
		break;
	    case VARIABLE_Y :
		expression = new VariableY();
		break;
	    default :
		expression = null;
	}
	
	return expression;
    }
}