/*
 * ============LICENSE_START=======================================================
 * Integrity Audit
 * ================================================================================
 * Copyright (C) 2017-2018 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.ia;

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

import java.io.FileOutputStream;
import java.io.IOException;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Iterator;
import java.util.LinkedList;
import java.util.List;
import java.util.Properties;
import java.util.concurrent.BlockingQueue;
import java.util.concurrent.CountDownLatch;
import java.util.concurrent.LinkedBlockingQueue;
import java.util.concurrent.TimeUnit;

import javax.persistence.EntityManager;
import javax.persistence.EntityManagerFactory;
import javax.persistence.EntityTransaction;
import javax.persistence.Persistence;

import org.onap.policy.common.utils.jpa.EntityMgrCloser;
import org.onap.policy.common.utils.jpa.EntityMgrFactoryCloser;
import org.onap.policy.common.utils.jpa.EntityTransCloser;
import org.onap.policy.common.utils.test.log.logback.ExtractAppender;
import org.slf4j.LoggerFactory;

import ch.qos.logback.classic.Level;
import ch.qos.logback.classic.Logger;

/**
 * All JUnits are designed to run in the local development environment where
 * they have write privileges and can execute time-sensitive tasks.
 * <p/>
 * Many of the test verification steps are performed by scanning for items
 * written to the log file. Rather than actually scan the log file, an
 * {@link ExtractAppender} is used to monitor events that are logged and extract
 * relevant items. In order to attach the appender to the debug log, it assumes
 * that the debug log is a <i>logback</i> Logger configured per EELF.
 * <p/>
 * These tests use a temporary, in-memory DB, which is dropped once the tests
 * complete.
 */
public class IntegrityAuditTestBase {

	/**
	 * Root of the debug logger, as defined in the logback-test.xml.
	 */
	protected static final Logger debugLogger = (Logger) LoggerFactory.getLogger("com.att.eelf.debug");

	/**
	 * Root of the error logger, as defined in the logback-test.xml.
	 */
	protected static final Logger errorLogger = (Logger) LoggerFactory.getLogger("com.att.eelf.error");

	/**
	 * Directory containing the log files.
	 */
	private static final String LOG_DIR = "testingLogs/common-modules/integrity-audit";

	/**
	 * Max time, in milliseconds, to wait for a latch to be triggered.
	 */
	protected static final long WAIT_MS = 5000l;

	/**
	 * Milliseconds that auditor should sleep between audit steps.
	 */
	protected static final long SLEEP_INTERVAL_MS = 2l;

	/**
	 * Milliseconds that auditor should sleep when an audit completes.
	 */
	protected static final long COMPLETION_INTERVAL_MS = 5l;

	/**
	 * Milliseconds that an entire audit-simulation cycles takes.
	 */
	protected static final long AUDIT_SIMULATION_MS = SLEEP_INTERVAL_MS * AuditThread.AUDIT_SIMULATION_ITERATIONS;

	/**
	 * Milliseconds that it takes for an auditor's last update to become stale.
	 * Includes a 1ms fudge factor.
	 */
	protected static final long STALE_MS = 1 + 2 * Math.max(COMPLETION_INTERVAL_MS, AUDIT_SIMULATION_MS);

	/**
	 * Milliseconds that the db-audit should wait between makings updates.
	 */
	private static final long DB_AUDIT_UPDATE_MS = 10l;

	/**
	 * Milliseconds that the db-audit should sleep between cycles.
	 */
	private static final long DB_AUDIT_SLEEP_MS = 3l;

	public static final String DEFAULT_DB_URL_PREFIX = "jdbc:h2:mem:";

	protected static final String dbDriver = "org.h2.Driver";
	protected static final String dbUser = "testu";
	protected static final String dbPwd = "testp";
	protected static final String siteName = "SiteA";
	protected static final String nodeType = "pdp_xacml";

	// will be defined by the test *Classes*
	protected static String dbUrl;

	/**
	 * Persistence unit for PDP sequence A.
	 */
	protected static final String A_SEQ_PU = "testPU";

	/**
	 * Persistence unit for PDP sequence B.
	 */
	protected static final String B_SEQ_PU = "integrityAuditPU";

	/**
	 * Matches the start of an audit for arbitrary PDPs in the debug log.
	 */
	protected static final String START_AUDIT_RE = "Starting audit simulation for resourceName=([^,]*)";

	/**
	 * Properties to be used in all tests.
	 */
	protected static Properties properties;

	/**
	 * Entity manager factory pointing to the in-memory DB for A_SEQ_PU.
	 */
	protected static EntityManagerFactory emf;

	/**
	 * Entity manager factory pointing to the in-memory DB associated with emf.
	 */
	protected static EntityManager em;

	/**
	 * Saved debug logger level, to be restored once all tests complete.
	 */
	private static Level savedDebugLevel;

	/**
	 * Saved error logger level, to be restored once all tests complete.
	 */
	private static Level savedErrorLevel;

	/**
	 * Saved audit sleep interval, to be restored once all tests complete.
	 */
	private static long savedSleepIntervalMs;

	/**
	 * Saved audit completion interval, to be restored once all tests complete.
	 */
	private static long savedCompletionIntervalMs;

	/**
	 * Saved db audit update time, to be restored once all tests complete.
	 */
	private static long savedDbAuditUpdateMs;

	/**
	 * Saved db audit sleep time, to be restored once all tests complete.
	 */
	private static long savedDbAuditSleepMs;

	/**
	 * List of auditors whose threads must be stopped when a given test case
	 * ends.
	 */
	private List<MyIntegrityAudit> auditors;

	/**
	 * List of appenders that must be removed from loggers when a given test
	 * case ends.
	 */
	private List<LogApp> appenders;

	/**
	 * Saves current configuration information and then sets new values.
	 * 
	 * @param dbDriver
	 *            the name of the DB Driver class
	 * @param dbUrl
	 *            the URL to the DB
	 * @throws IOException
	 * @throws Exception
	 */
	protected static void setUpBeforeClass(String dbUrl) throws IOException {

		// truncate the logs
		new FileOutputStream(LOG_DIR + "/audit.log").close();
		new FileOutputStream(LOG_DIR + "/debug.log").close();
		new FileOutputStream(LOG_DIR + "/error.log").close();
		new FileOutputStream(LOG_DIR + "/metrics.log").close();

		IntegrityAuditTestBase.dbUrl = dbUrl;

		// save data that we have to restore at the end of the test
		savedDebugLevel = debugLogger.getLevel();
		savedErrorLevel = errorLogger.getLevel();
		savedSleepIntervalMs = AuditThread.getAuditThreadSleepIntervalMillis();
		savedCompletionIntervalMs = AuditThread.getAuditCompletionIntervalMillis();
		savedDbAuditUpdateMs = DbAudit.getDbAuditUpdateMillis();
		savedDbAuditSleepMs = DbAudit.getDbAuditSleepMillis();

		AuditThread.setAuditThreadSleepIntervalMillis(SLEEP_INTERVAL_MS);
		AuditThread.setAuditCompletionIntervalMillis(COMPLETION_INTERVAL_MS);

		DbAudit.setDbAuditUpdateMillis(DB_AUDIT_UPDATE_MS);
		DbAudit.setDbAuditSleepMillis(DB_AUDIT_SLEEP_MS);

		IntegrityAudit.setUnitTesting(true);

		properties = new Properties();
		properties.put(IntegrityAuditProperties.DB_DRIVER, dbDriver);
		properties.put(IntegrityAuditProperties.DB_URL, dbUrl);
		properties.put(IntegrityAuditProperties.DB_USER, dbUser);
		properties.put(IntegrityAuditProperties.DB_PWD, dbPwd);
		properties.put(IntegrityAuditProperties.SITE_NAME, siteName);
		properties.put(IntegrityAuditProperties.NODE_TYPE, nodeType);

		emf = Persistence.createEntityManagerFactory(A_SEQ_PU, makeProperties());

		// keep this open so the in-memory DB stays around until all tests are
		// done
		em = emf.createEntityManager();

		debugLogger.setLevel(Level.DEBUG);
		errorLogger.setLevel(Level.ERROR);
	}

	/**
	 * Restores the configuration to what it was before the test.
	 */
	protected static void tearDownAfterClass() {
		AuditThread.setAuditThreadSleepIntervalMillis(savedSleepIntervalMs);
		AuditThread.setAuditCompletionIntervalMillis(savedCompletionIntervalMs);

		DbAudit.setDbAuditUpdateMillis(savedDbAuditUpdateMs);
		DbAudit.setDbAuditSleepMillis(savedDbAuditSleepMs);

		IntegrityAudit.setUnitTesting(false);

		debugLogger.setLevel(savedDebugLevel);
		errorLogger.setLevel(savedErrorLevel);

		// this should result in the in-memory DB being deleted
		em.close();
		emf.close();
	}

	/**
	 * Sets up for a test, which includes deleting all records from the
	 * IntegrityAuditEntity table.
	 */
	protected void setUp() {
		auditors = new LinkedList<>();
		appenders = new LinkedList<>();

		properties.put(IntegrityAuditProperties.AUDIT_PERIOD_MILLISECONDS, String.valueOf(SLEEP_INTERVAL_MS));

		// Clean up the DB
		try (EntityTransCloser etc = new EntityTransCloser(em.getTransaction())) {
			EntityTransaction et = etc.getTransation();

			em.createQuery("Delete from IntegrityAuditEntity").executeUpdate();

			// commit transaction
			et.commit();
		}
	}

	/**
	 * Cleans up after a test, removing any ExtractAppenders from the logger and
	 * stopping any AuditThreads.
	 */
	protected void tearDown() {
		for (LogApp p : appenders) {
			p.detach();
		}

		for (MyIntegrityAudit p : auditors) {
			p.stopAuditThread();
		}
	}

	/**
	 * 
	 * @param properties
	 * @param persistenceUnit
	 * @param tableName
	 */
	public void truncateTable(Properties properties, String persistenceUnit, String tableName) {

		try (EntityMgrFactoryCloser emfc = new EntityMgrFactoryCloser(
				Persistence.createEntityManagerFactory(persistenceUnit, properties));
				EntityMgrCloser emc = new EntityMgrCloser(emfc.getFactory().createEntityManager());
				EntityTransCloser etc = new EntityTransCloser(emc.getManager().getTransaction())) {

			EntityManager em = emc.getManager();
			EntityTransaction et = etc.getTransation();

			// Clean up the DB
			em.createQuery("Delete from " + tableName).executeUpdate();

			// commit transaction
			et.commit();
		}
	}

	/**
	 * Verifies that items appear within the log, in order. A given item may
	 * appear more than once. In addition, the log may contain extra items;
	 * those are ignored.
	 * 
	 * @param textre
	 *            regular expression used to extract an item from a line in the
	 *            log. The first "capture" group of the regular expression is
	 *            assumed to contain the extracted item
	 * @param items
	 *            items that should be matched by the items extracted from the
	 *            log, in order
	 * @throws IOException
	 * @throws AssertionError
	 *             if the desired items were not all found
	 */
	protected void verifyItemsInLog(ExtractAppender app, String... items) throws IOException {

		Iterator<String> it = new ArrayList<>(Arrays.asList(items)).iterator();
		if (!it.hasNext()) {
			return;
		}

		String expected = it.next();
		String last = null;

		for (String rName : app.getExtracted()) {
			if (rName.equals(expected)) {
				if (!it.hasNext()) {
					// matched all of the items
					return;
				}

				last = expected;
				expected = it.next();

			} else if (!rName.equals(last)) {
				List<String> remaining = getRemaining(expected, it);
				fail("missing items " + remaining + ", but was: " + rName);
			}
		}

		List<String> remaining = getRemaining(expected, it);
		assertTrue("missing items " + remaining, remaining.isEmpty());
	}

	/**
	 * Gets the remaining items from an iterator
	 * 
	 * @param current
	 *            the current item, to be included within the list
	 * @param it
	 *            iterator from which to get the remaining items
	 * @return a list of the remaining items
	 */
	private LinkedList<String> getRemaining(String current, Iterator<String> it) {
		LinkedList<String> remaining = new LinkedList<>();
		remaining.add(current);

		while (it.hasNext()) {
			remaining.add(it.next());
		}
		return remaining;
	}

	/**
	 * Waits for a thread to stop. If the thread doesn't complete in the
	 * allotted time, then it interrupts it and waits again.
	 * 
	 * @param auditor
	 *            the thread for which to wait
	 * @return {@code true} if the thread stopped, {@code false} otherwise
	 */
	public boolean waitThread(MyIntegrityAudit auditor) {
		if (auditor != null) {
			try {
				auditor.interrupt();

				if (!auditor.joinAuditThread(WAIT_MS)) {
					System.out.println("failed to stop audit thread");
					return false;
				}

			} catch (InterruptedException e) {
				Thread.currentThread().interrupt();
			}
		}

		return true;
	}

	/**
	 * Makes a new auditor.
	 * 
	 * @param resourceName2
	 * @param persistenceUnit2
	 * @return a new auditor
	 * @throws Exception
	 */
	protected MyIntegrityAudit makeAuditor(String resourceName2, String persistenceUnit2) throws Exception {
		return new MyIntegrityAudit(resourceName2, persistenceUnit2, makeProperties());
	}

	/**
	 * Watches for patterns in a logger by attaching a ExtractAppender to it.
	 * 
	 * @param logger
	 *            the logger to watch
	 * @param regex
	 *            regular expression used to extract relevant text
	 * @return a new appender
	 */
	protected ExtractAppender watch(Logger logger, String regex) {
		ExtractAppender app = new ExtractAppender(regex);
		appenders.add(new LogApp(logger, app));

		return app;
	}

	/**
	 * Makes a new Property set that's a clone of {@link #properties}.
	 * 
	 * @return a new Property set containing all of a copy of all of the
	 *         {@link #properties}
	 */
	protected static Properties makeProperties() {
		Properties props = new Properties();
		props.putAll(properties);
		return props;
	}

	/**
	 * Waits for data to become stale and then runs an audit on several auditors
	 * in parallel.
	 * 
	 * @param auditors
	 * @throws InterruptedException
	 */
	protected void waitStaleAndRun(MyIntegrityAudit... auditors) throws InterruptedException {
		waitStale();
		runAudit(auditors);
	}

	/**
	 * Runs an audit on several auditors in parallel.
	 * 
	 * @param auditors
	 * @throws InterruptedException
	 */
	protected void runAudit(MyIntegrityAudit... auditors) throws InterruptedException {

		// start an audit cycle on each auditor
		List<CountDownLatch> latches = new ArrayList<>(auditors.length);
		for (MyIntegrityAudit p : auditors) {
			latches.add(p.startAudit());
		}

		// wait for each auditor to complete its cycle
		for (CountDownLatch latch : latches) {
			waitLatch(latch);
		}
	}

	/**
	 * Waits for a latch to reach zero.
	 * 
	 * @param latch
	 * @throws InterruptedException
	 * @throws AssertionError
	 *             if the latch did not reach zero in the allotted time
	 */
	protected void waitLatch(CountDownLatch latch) throws InterruptedException {
		assertTrue(latch.await(WAIT_MS, TimeUnit.SECONDS));
	}

	/**
	 * Sleep a bit so that the currently designated pdp becomes stale.
	 * 
	 * @throws InterruptedException
	 */
	protected void waitStale() throws InterruptedException {
		Thread.sleep(STALE_MS);
	}

	/**
	 * Tracks which appender has been added to a logger.
	 */
	private static class LogApp {
		private final Logger logger;
		private final ExtractAppender appender;

		public LogApp(Logger logger, ExtractAppender appender) {
			this.logger = logger;
			this.appender = appender;

			logger.addAppender(appender);

			appender.start();
		}

		public void detach() {
			logger.detachAppender(appender);
		}
	}

	/**
	 * Manages audits by inserting latches into a queue for the AuditThread to
	 * count.
	 */
	protected class MyIntegrityAudit extends IntegrityAudit {

		/**
		 * Queue from which the AuditThread will take latches.
		 */
		private BlockingQueue<CountDownLatch> queue = null;

		/**
		 * Constructs an auditor and starts the AuditThread.
		 * 
		 * @param resourceName
		 * @param persistenceUnit
		 * @param properties
		 * @throws Exception
		 */
		public MyIntegrityAudit(String resourceName, String persistenceUnit, Properties properties) throws Exception {
			super(resourceName, persistenceUnit, properties);

			auditors.add(this);

			startAuditThread();
		}

		/**
		 * Interrupts the AuditThread.
		 */
		public void interrupt() {
			super.stopAuditThread();
		}

		/**
		 * Triggers an audit by adding a latch to the queue.
		 * 
		 * @return the latch that was added
		 * @throws InterruptedException
		 */
		public CountDownLatch startAudit() throws InterruptedException {
			CountDownLatch latch = new CountDownLatch(1);
			queue.add(latch);

			return latch;
		}

		/**
		 * Starts a new AuditThread. Creates a new latch queue and associates it
		 * with the thread.
		 */
		@Override
		public final void startAuditThread() throws IntegrityAuditException {
			if (queue != null) {
				// queue up a bogus latch, in case a thread is still running
				queue.add(new CountDownLatch(1) {
					@Override
					public void countDown() {
						throw new RuntimeException("auditor has multiple threads");
					}
				});
			}

			queue = new LinkedBlockingQueue<>();

			if (super.startAuditThread(queue)) {
				// wait for the thread to start
				CountDownLatch latch = new CountDownLatch(1);
				queue.add(latch);
				
				try {
					waitLatch(latch);
					
				} catch (InterruptedException e) {
					Thread.currentThread().interrupt();
					throw new IntegrityAuditException(e);
				}
			}
		}

		/**
		 * Stops the AuditThread and waits for it to stop.
		 * 
		 * @throws AssertionError
		 *             if the thread is still running
		 */
		@Override
		public void stopAuditThread() {
			super.stopAuditThread();

			assertTrue(waitThread(this));
		}
	}
}