/**
 * Copyright (C) 2010-2017 Gordon Fraser, Andrea Arcuri and EvoSuite
 * contributors
 *
 * This file is part of EvoSuite.
 *
 * EvoSuite is free software: you can redistribute it and/or modify it
 * under the terms of the GNU Lesser General Public License as published
 * by the Free Software Foundation, either version 3.0 of the License, or
 * (at your option) any later version.
 *
 * EvoSuite 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
 * Lesser Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with EvoSuite. If not, see <http://www.gnu.org/licenses/>.
 */
package org.evosuite.instrumentation.error;

import static org.junit.Assert.assertEquals;
import static org.junit.Assert.assertTrue;

import java.math.BigDecimal;
import java.util.ArrayList;
import java.util.Collection;
import java.util.List;

import org.evosuite.instrumentation.error.ErrorConditionChecker;
import org.junit.Assume;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.junit.runners.Parameterized;
import org.junit.runners.Parameterized.Parameters;
import org.objectweb.asm.Opcodes;

@RunWith(Parameterized.class)
public class TestDoubleUnderflow {

	private double x;
	private double y;
	
	// Creates the test data
	@Parameters
	public static Collection<Object[]> data() {
		Object[] values = new Object[] { -Double.MAX_VALUE, -Double.MIN_VALUE/2.0, 0.0, Double.MAX_VALUE/ 2.0, Double.MAX_VALUE};
		List<Object[]> valuePairs = new ArrayList<Object[]>();
		for(Object val1 : values) {
			for(Object val2 : values) {
				valuePairs.add(new Object[] {val1, val2});
			}
		}
		return valuePairs;
	}
	
	public TestDoubleUnderflow(double x, double y) {
		this.x = x;
		this.y = y;
	}


	private void assertUnderflow(BigDecimal preciseResult, int distance, double doubleResult) {
		BigDecimal maxResult = new BigDecimal(-Double.MAX_VALUE);
		if(preciseResult.compareTo(maxResult) < 0) {
			assertTrue("Expected negative value for "+x+" and "+y+": "+distance, distance < 0);
			assertEquals(Double.NEGATIVE_INFINITY, doubleResult, 0.0);
		} else {
			assertTrue("Expected positive value for "+x+" and "+y+": "+distance, distance >= 0);
		}		
	}

	
	@Test
	public void testAddUnderflow() {
		int result = ErrorConditionChecker.underflowDistance(x, y, Opcodes.DADD);
		assertUnderflow(new BigDecimal(x).add(new BigDecimal(y)), result, x + y);
	}

	@Test
	public void testSubUnderflow() {
		int result = ErrorConditionChecker.underflowDistance(x, y, Opcodes.DSUB);
		assertUnderflow(new BigDecimal(x).subtract(new BigDecimal(y)), result, x - y);
	}

	@Test
	public void testMulUnderflow() {
		int result = ErrorConditionChecker.underflowDistance(x, y, Opcodes.DMUL);
		assertUnderflow(new BigDecimal(x).multiply(new BigDecimal(y)), result, x * y);
	}

	@Test
	public void testDivUnderflow() {
		Assume.assumeTrue(y != 0D);

		int result = ErrorConditionChecker.underflowDistance(x, y, Opcodes.DDIV);
		assertUnderflow(new BigDecimal(x).divide(new BigDecimal(y)), result, x / y);
	}
}