/*
 * Copyright (c) 2008-2017, Hazelcast, Inc. 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.
 */

package com.hazelcast.spi;

import com.hazelcast.test.HazelcastParallelClassRunner;
import com.hazelcast.test.annotation.ParallelTest;
import com.hazelcast.test.annotation.QuickTest;
import junit.framework.AssertionFailedError;
import org.junit.Rule;
import org.junit.Test;
import org.junit.experimental.categories.Category;
import org.junit.rules.ExpectedException;
import org.junit.runner.RunWith;

import java.util.concurrent.locks.LockSupport;

import static java.util.concurrent.TimeUnit.MILLISECONDS;
import static java.util.concurrent.TimeUnit.SECONDS;
import static org.junit.Assert.assertEquals;
import static org.junit.Assert.assertFalse;
import static org.junit.Assert.assertTrue;

@RunWith(HazelcastParallelClassRunner.class)
@Category({QuickTest.class, ParallelTest.class})
public class OperationCallIdTest {

    @Rule
    public final ExpectedException exceptionRule = ExpectedException.none();

    final Operation op = new MockOperation();

    @Test
    public void when_callIdNotSet_thenIsZero() {
        assertEquals(0, op.getCallId());
    }

    @Test
    public void when_setCallIdInitial_thenActive() throws Exception {
        op.setCallId(1);
        assertEquals(1, op.getCallId());
        assertTrue(op.isActive());
    }

    @Test(expected = IllegalArgumentException.class)
    public void when_setZeroCallId_thenFail() throws Exception {
        op.setCallId(0);
    }

    @Test(expected = IllegalArgumentException.class)
    public void when_setNegativeCallId_thenFail() {
        op.setCallId(-1);
    }

    @Test
    public void when_setCallIdOnActiveOp_thenFail() {
        // Given
        op.setCallId(1);
        assertTrue(op.isActive());

        // Then
        exceptionRule.expect(IllegalStateException.class);

        // When
        op.setCallId(1);
    }

    @Test
    public void when_deactivateActiveOp_thenInactive() {
        // Given
        op.setCallId(1);
        assertTrue(op.isActive());

        // When
        op.deactivate();

        // Then
        assertFalse(op.isActive());
    }

    @Test
    public void when_deactivateInitialStateOp_thenNothingHappens() {
        // Given
        assertFalse(op.isActive());

        // When
        op.deactivate();

        // Then
        assertFalse(op.isActive());
    }

    @Test
    public void when_deactivateDeactivatedOp_thenNothingHappens() {
        // Given
        op.setCallId(1);
        op.deactivate();
        assertFalse(op.isActive());

        // When
        op.deactivate();

        // Then
        assertFalse(op.isActive());
    }

    @Test
    public void when_getCallIdOnDeactivatedOp_thenCallIdPreserved() {
        // Given
        final int mockCallId = 1;
        op.setCallId(mockCallId);
        op.deactivate();

        // When
        long callId = op.getCallId();

        // Then
        assertEquals(callId, mockCallId);
    }

    @Test
    public void when_setCallIdOnDeactivatedOp_thenReactivated() {
        // Given
        op.setCallId(1);
        op.deactivate();

        // When
        int newCallId = 2;
        op.setCallId(newCallId);

        // Then
        assertTrue(op.isActive());
        assertEquals(newCallId, op.getCallId());
    }

    @Test
    public void when_concurrentlySetCallId_thenOnlyOneSucceeds() {
        new ConcurrentExcerciser().run();
    }
}

class MockOperation extends Operation {

    @Override
    public void run() throws Exception {
    }
}

class ConcurrentExcerciser {
    final Operation op = new MockOperation();
    volatile AssertionFailedError testFailure;
    volatile int activationCount;

    void run() {
        final Thread reader = new Thread() {
            @Override
            public void run() {
                try {
                    long previousCallId = 0;
                    while (!interrupted()) {
                        long callId;
                        while ((callId = op.getCallId()) == previousCallId) {
                            // Wait until a writer thread sets a call ID
                        }
                        activationCount++;
                        long deadline = System.currentTimeMillis() + SECONDS.toMillis(1);
                        while (System.currentTimeMillis() < deadline) {
                            assertEquals(callId, op.getCallId());
                        }
                        op.deactivate();
                        previousCallId = callId;
                    }
                } catch (AssertionFailedError e) {
                    testFailure = e;
                }
            }
        };
        final int writerCount = 4;
        final Thread[] writers = new Thread[writerCount];
        for (int i = 0; i < writers.length; i++) {
            final int initialCallId = i + 1;
            writers[i] = new Thread() {
                @Override
                public void run() {
                    long nextCallId = initialCallId;
                    while (!interrupted()) {
                        try {
                            op.setCallId(nextCallId);
                            nextCallId += writerCount;
                        } catch (IllegalStateException e) {
                            // Things are working as expected
                        }
                    }
                }
            };
        }
        try {
            reader.start();
            for (Thread t : writers) {
                t.start();
            }
            final long deadline = System.currentTimeMillis() + SECONDS.toMillis(5);
            while (System.currentTimeMillis() < deadline) {
                if (testFailure != null) {
                    throw testFailure;
                }
                LockSupport.parkNanos(MILLISECONDS.toNanos(1));
            }
        } finally {
            reader.interrupt();
            for (Thread t : writers) {
                t.interrupt();
            }
        }
        assertTrue("Failed to activate the operation at least twice", activationCount >= 2);
    }
}