package lab.art;

import static org.junit.Assert.*;

import java.util.Random;

import org.junit.Test;

public class BinaryExpressionTester 
{
    private static class MinimumOperator extends BinaryOperator
    {
	public double operation(double a, double b)
	{
	    return Math.min(a,  b);
	}
    }
    
    private static class Minimum extends BinaryExpression
    {
	public Minimum(Expression first, Expression second)
	{
	    super(first, second);
	}

	public double evaluate(double x, double y) 
	{
	    return super.evaluate(x, y, new MinimumOperator());
	}
    }
    
    @Test
    public void testConstructor() 
    {
	Expression first = new VariableX();
	Expression second = new VariableY();
	new Minimum(first, second);
    }
    
    @Test
    public void testEquals() 
    {
	Expression x = new VariableX();
	Expression y = new VariableY();
	Expression first = new Minimum(x, y);
	assertEquals("equals method failed", false, first.equals(null));
	assertEquals("equals method failed", false, first.equals(new Object()));
	assertEquals("equals method failed", true, first.equals(first));
	Expression second = new Minimum(y, x);
	assertEquals("equals method failed", true, first.equals(second));
    }
    
    @Test
    public void testHashCode() 
    {
	Expression first = new VariableX();
	Expression second = new VariableY();
	Expression expression = new Minimum(first, second);
	assertEquals("hashCode method failed", first.hashCode() + second.hashCode(), expression.hashCode());
    }
    
    @Test
    public void testEvaluate() 
    {
	Expression first = new VariableX();
	Expression second = new VariableY();
	BinaryExpression expression = new Minimum(first, second);
	
	Random random = new Random(System.currentTimeMillis());
	
	int NUMBER = 1000;
	double DELTA = 0.0001;
	for (int n = 0; n < NUMBER; n++)
	{
	    double x = random.nextDouble();
	    if (random.nextBoolean())
	    {
		x = -x;
	    }
	    double y = random.nextDouble();
	    if (random.nextBoolean())
	    {
		y = -y;
	    }
	    
	    assertEquals("evaluate failed", Math.min(x,  y), expression.evaluate(x, y), DELTA);
	}
    }
    
    @Test
    public void testToString() 
    {
	Expression first = new VariableX();
	Expression second = new VariableY();
	BinaryExpression expression = new Minimum(first, second);
	String pattern = "minimum of %s and %s";
	assertEquals("toString failed", "minimum of x and y", expression.toString(pattern));
    }
}