/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.apache.commons.math.ode.sampling;

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

import java.io.ByteArrayOutputStream;
import java.io.ByteArrayInputStream;
import java.io.ObjectOutputStream;
import java.io.ObjectInputStream;
import java.io.IOException;

import org.apache.commons.math.ode.DerivativeException;
import org.apache.commons.math.ode.sampling.AbstractStepInterpolator;
import org.apache.commons.math.ode.sampling.DummyStepInterpolator;
import org.junit.Test;

public class DummyStepInterpolatorTest {

	@Test
	public void testNoReset() throws DerivativeException {

		double[] y = { 0.0, 1.0, -2.0 };
		DummyStepInterpolator interpolator = new DummyStepInterpolator(y, true);
		interpolator.storeTime(0);
		interpolator.shift();
		interpolator.storeTime(1);

		double[] result = interpolator.getInterpolatedState();
		for (int i = 0; i < result.length; ++i) {
			assertTrue(Math.abs(result[i] - y[i]) < 1.0e-10);
		}

	}

	@Test
	public void testFixedState() throws DerivativeException {

		double[] y = { 1.0, 3.0, -4.0 };
		DummyStepInterpolator interpolator = new DummyStepInterpolator(y, true);
		interpolator.storeTime(0);
		interpolator.shift();
		interpolator.storeTime(1);

		interpolator.setInterpolatedTime(0.1);
		double[] result = interpolator.getInterpolatedState();
		for (int i = 0; i < result.length; ++i) {
			assertTrue(Math.abs(result[i] - y[i]) < 1.0e-10);
		}

		interpolator.setInterpolatedTime(0.5);
		result = interpolator.getInterpolatedState();
		for (int i = 0; i < result.length; ++i) {
			assertTrue(Math.abs(result[i] - y[i]) < 1.0e-10);
		}

	}

	@Test
	public void testSerialization() throws DerivativeException, IOException, ClassNotFoundException {

		double[] y = { 0.0, 1.0, -2.0 };
		DummyStepInterpolator interpolator = new DummyStepInterpolator(y, true);
		interpolator.storeTime(0);
		interpolator.shift();
		interpolator.storeTime(1);

		ByteArrayOutputStream bos = new ByteArrayOutputStream();
		ObjectOutputStream oos = new ObjectOutputStream(bos);
		oos.writeObject(interpolator);

		assertTrue(bos.size() > 150);
		assertTrue(bos.size() < 250);

		ByteArrayInputStream bis = new ByteArrayInputStream(bos.toByteArray());
		ObjectInputStream ois = new ObjectInputStream(bis);
		DummyStepInterpolator dsi = (DummyStepInterpolator) ois.readObject();

		dsi.setInterpolatedTime(0.5);
		double[] result = dsi.getInterpolatedState();
		for (int i = 0; i < result.length; ++i) {
			assertTrue(Math.abs(result[i] - y[i]) < 1.0e-10);
		}

	}

	@Test
	public void testImpossibleSerialization() throws IOException {

		double[] y = { 0.0, 1.0, -2.0 };
		AbstractStepInterpolator interpolator = new BadStepInterpolator(y, true);
		interpolator.storeTime(0);
		interpolator.shift();
		interpolator.storeTime(1);

		ByteArrayOutputStream bos = new ByteArrayOutputStream();
		ObjectOutputStream oos = new ObjectOutputStream(bos);
		try {
			oos.writeObject(interpolator);
			fail("an exception should have been thrown");
		} catch (IOException ioe) {
			// expected behavior
			assertEquals(0, ioe.getMessage().length());
		} catch (Exception e) {
			fail("wrong exception caught");
		}

	}

	private static class BadStepInterpolator extends DummyStepInterpolator {
		@SuppressWarnings("unused")
		public BadStepInterpolator() {
		}

		public BadStepInterpolator(double[] y, boolean forward) {
			super(y, forward);
		}

		@Override
		protected void doFinalize() throws DerivativeException {
			throw new DerivativeException(null);
		}
	}

}
