/*******************************************************************************
 * Copyright (c) 2006, 2015 Wind River Systems and others.
 *
 * This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License 2.0
 * which accompanies this distribution, and is available at
 * https://www.eclipse.org/legal/epl-2.0/
 *
 * SPDX-License-Identifier: EPL-2.0
 *
 * Contributors:
 *     Wind River Systems - initial API and implementation
 *******************************************************************************/
package org.eclipse.cdt.tests.dsf.concurrent;

import static org.junit.Assert.assertEquals;

import java.util.Arrays;
import java.util.concurrent.ExecutionException;

import org.eclipse.cdt.dsf.concurrent.DataRequestMonitor;
import org.eclipse.cdt.dsf.concurrent.DsfRunnable;
import org.eclipse.cdt.dsf.concurrent.ImmediateInDsfExecutor;
import org.eclipse.cdt.dsf.concurrent.Query;
import org.eclipse.cdt.dsf.concurrent.RequestCache;
import org.eclipse.cdt.dsf.concurrent.Transaction;
import org.eclipse.cdt.tests.dsf.TestDsfExecutor;
import org.eclipse.core.runtime.CoreException;
import org.junit.After;
import org.junit.Before;
import org.junit.Test;

/**
 * Tests that exercise the Transaction object.
 */
public class TransactionTests {
	final static private int NUM_CACHES = 5;

	TestDsfExecutor fExecutor;
	TestCache[] fTestCaches = new TestCache[NUM_CACHES];
	DataRequestMonitor<?>[] fRetrieveRms = new DataRequestMonitor<?>[NUM_CACHES];

	class TestCache extends RequestCache<Integer> {

		final private int fIndex;

		public TestCache(int index) {
			super(new ImmediateInDsfExecutor(fExecutor));
			fIndex = index;
		}

		@Override
		protected void retrieve(DataRequestMonitor<Integer> rm) {
			synchronized (TransactionTests.this) {
				fRetrieveRms[fIndex] = rm;
				TransactionTests.this.notifyAll();
			}
		}

	}

	class TestSingleTransaction extends Transaction<Integer> {

		@Override
		protected Integer process() throws InvalidCacheException, CoreException {
			validate(fTestCaches[0]);
			return fTestCaches[0].getData();
		}
	}

	class TestSumTransaction extends Transaction<Integer> {
		@Override
		protected Integer process() throws InvalidCacheException, CoreException {
			validate(fTestCaches);

			int sum = 0;
			for (RequestCache<Integer> cache : fTestCaches) {
				sum += cache.getData();
			}
			return sum;
		}
	}

	/**
	 * There's no rule on how quickly the cache has to start data retrieval
	 * after it has been requested.  It could do it immediately, or it could
	 * wait a dispatch cycle, etc..
	 */
	private void waitForRetrieveRm(boolean all) {
		synchronized (this) {
			if (all) {
				while (Arrays.asList(fRetrieveRms).contains(null)) {
					try {
						wait();
					} catch (InterruptedException e) {
						return;
					}
				}
			} else {
				while (fRetrieveRms[0] == null) {
					try {
						wait();
					} catch (InterruptedException e) {
						return;
					}
				}
			}
		}
	}

	@Before
	public void startExecutor() throws ExecutionException, InterruptedException {
		fExecutor = new TestDsfExecutor();
		for (int i = 0; i < fTestCaches.length; i++) {
			fTestCaches[i] = new TestCache(i);
		}
	}

	@After
	public void shutdownExecutor() throws ExecutionException, InterruptedException {
		fExecutor.submit(new DsfRunnable() {
			@Override
			public void run() {
				fExecutor.shutdown();
			}
		}).get();
		if (fExecutor.exceptionsCaught()) {
			Throwable[] exceptions = fExecutor.getExceptions();
			throw new ExecutionException(exceptions[0]);
		}
		fRetrieveRms = new DataRequestMonitor<?>[NUM_CACHES];
		fTestCaches = new TestCache[NUM_CACHES];
		fExecutor = null;
	}

	@Test
	public void singleTransactionTest() throws InterruptedException, ExecutionException {
		final TestSingleTransaction testTransaction = new TestSingleTransaction();
		// Request data from cache
		Query<Integer> q = new Query<Integer>() {
			@Override
			protected void execute(DataRequestMonitor<Integer> rm) {
				testTransaction.request(rm);
			}
		};
		fExecutor.execute(q);

		// Wait until the cache starts data retrieval.
		waitForRetrieveRm(false);

		// Set the data without using an executor.
		((DataRequestMonitor<Integer>) fRetrieveRms[0]).setData(1);
		fRetrieveRms[0].done();

		assertEquals(1, (int) q.get());
	}

	@Test
	public void sumTransactionTest() throws InterruptedException, ExecutionException {

		final TestSumTransaction testTransaction = new TestSumTransaction();
		// Request data from cache
		Query<Integer> q = new Query<Integer>() {
			@Override
			protected void execute(DataRequestMonitor<Integer> rm) {
				testTransaction.request(rm);
			}
		};
		fExecutor.execute(q);

		// Wait until the cache starts data retrieval.
		waitForRetrieveRm(true);

		// Set the data without using an executor.
		for (DataRequestMonitor<?> rm : fRetrieveRms) {
			((DataRequestMonitor<Integer>) rm).setData(1);
			rm.done();
		}

		fExecutor.execute(q);
		assertEquals(NUM_CACHES, (int) q.get());
	}

}
