/*
 * ============LICENSE_START=======================================================
 * Integrity Monitor
 * ================================================================================
 * Copyright (C) 2018 AT&T Intellectual Property. All rights reserved.
 * ================================================================================
 * Licensed 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.
 * ============LICENSE_END=========================================================
 */

package org.onap.policy.common.utils.test;

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

import java.lang.reflect.Constructor;

/**
 * Used to test various Exception subclasses. Uses reflection to identify the
 * constructors that the subclass supports.
 */
public class ExceptionsTester extends ThrowablesTester {

	/**
	 * Runs tests, on an Exception subclass, for all of the standard
	 * constructors. If the Exception subclass does not support a given type of
	 * constructor, then it skips that test.
	 * 
	 * @param claz
	 *            subclass to be tested
	 * @return the number of constructors that were found/tested
	 * @throws ConstructionError
	 *             if the Exception subclass cannot be constructed
	 * @throws AssertionError
	 *             if the constructed objects fail to pass various tests
	 */
	public <T extends Exception> int test(Class<T> claz) {
		int ncons = testException(claz);

		assertTrue(ncons > 0);

		return ncons;
	}

	/**
	 * Runs tests, on an Exception subclass, for all of the standard
	 * constructors. If the Exception subclass does not support a given type of
	 * constructor, then it skips that test. Does <i>not</i> throw an exception
	 * if no standard constructors are found.
	 * 
	 * @param claz
	 *            subclass to be tested
	 * @return the number of constructors that were found/tested
	 * @throws ConstructionError
	 *             if the Exception subclass cannot be constructed
	 * @throws AssertionError
	 *             if the constructed objects fail to pass various tests
	 */
	public <T extends Exception> int testException(Class<T> claz) {
		int ncons = 0;

		ncons += testThrowable(claz);
		ncons += testException_Exception(claz);
		ncons += testException_StringException(claz);
		ncons += testException_StringExceptionBooleanBoolean(claz);

		return ncons;
	}

	/**
	 * Tests exceptions created via the constructor that takes just an
	 * Exception. Verifies that:
	 * <ul>
	 * <li><i>toString()</i> returns a non-null value</li>
	 * <li><i>getMessage()</i> returns the cause's message</li>
	 * <li><i>getCause()</i> returns the original cause passed to the
	 * constructor</li>
	 * </ul>
	 * 
	 * If the Exception subclass does not support this type of constructor, then
	 * this method simply returns.
	 * 
	 * @param claz
	 *            subclass to be tested
	 * @return {@code 1}, if the subclass supports this type of constructor,
	 *         {@code 0} otherwise
	 * @throws ConstructionError
	 *             if the Exception subclass cannot be constructed
	 * @throws AssertionError
	 *             if the constructed objects fail to pass various tests
	 */
	public <T extends Exception> int testException_Exception(Class<T> claz) {
		Constructor<T> cons = getConstructor(claz, "exception", Exception.class);
		if (cons == null) {
			return 0;
		}

		Exception cause = new Exception(EXPECTED_EXCEPTION_MSG);
		T ex = newInstance(cons, cause);

		assertNotNull(ex.toString());
		assertEquals(ex.getMessage(), ex.getMessage());
		assertEquals(cause, ex.getCause());

		return 1;
	}

	/**
	 * Tests exceptions created via the constructor that takes a String and an
	 * Exception. Verifies that:
	 * <ul>
	 * <li><i>toString()</i> returns a non-null value</li>
	 * <li><i>getMessage()</i> returns the original message passed to the
	 * constructor</li>
	 * <li><i>getCause()</i> returns the original cause passed to the
	 * constructor</li>
	 * </ul>
	 * 
	 * If the Exception subclass does not support this type of constructor, then
	 * this method simply returns.
	 * 
	 * @param claz
	 *            subclass to be tested
	 * @return {@code 1}, if the subclass supports this type of constructor,
	 *         {@code 0} otherwise
	 * @throws ConstructionError
	 *             if the Exception subclass cannot be constructed
	 */
	public <T extends Exception> int testException_StringException(Class<T> claz) {
		Constructor<T> cons = getConstructor(claz, "string-exception", String.class, Exception.class);
		if (cons == null) {
			return 0;
		}

		Exception cause = new Exception(EXPECTED_EXCEPTION_MSG);
		T ex = newInstance(cons, "world", cause);

		assertNotNull(ex.toString());
		assertEquals("world", ex.getMessage());
		assertEquals(cause, ex.getCause());

		return 1;
	}

	/**
	 * Tests exceptions created via the constructor that takes a String, an
	 * Exception, and two booleans. Verifies that:
	 * <ul>
	 * <li><i>toString()</i> returns a non-null value</li>
	 * <li><i>getMessage()</i> returns the original message passed to the
	 * constructor</li>
	 * <li><i>getCause()</i> returns the original cause passed to the
	 * constructor</li>
	 * <li>suppressed exceptions can be added, if enabled</li>
	 * <li>the stack trace can be added, if enabled</li>
	 * </ul>
	 * 
	 * If the Exception subclass does not support this type of constructor, then
	 * this method simply returns.
	 * 
	 * @param claz
	 *            subclass to be tested
	 * @return {@code 1}, if the subclass supports this type of constructor,
	 *         {@code 0} otherwise
	 * @throws ConstructionError
	 *             if the Exception subclass cannot be constructed
	 */
	public <T extends Exception> int testException_StringExceptionBooleanBoolean(Class<T> claz) {
		Constructor<T> cons = getConstructor(claz, "string-exception-flags", String.class, Exception.class,
				Boolean.TYPE, Boolean.TYPE);
		if (cons == null) {
			return 0;
		}

		// test each combination of "message" and "cause"
		testThrowable_MessageCauseCombos(cons);

		// test each combination of the boolean flags
		testThrowable_FlagCombos(cons);

		return 1;
	}
}