// From Apache Harmony tests:
// https://github.com/apache/harmony/blob/trunk/classlib/modules/concurrent/src/test/java/JSR166TestCase.java
using Lucene.Net.Util;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Runtime.CompilerServices;
using System.Threading;
using System.Threading.Tasks;
using ThreadInterruptedException = System.Threading.ThreadInterruptedException;

#nullable enable

namespace Lucene.Net.Support.Threading
{
    /*
     * 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.
     */

    /// <summary>
    /// LUCENENET NOTE: This class has been adapted from the Apache Harmony
    /// tests. The original javadoc is included below, and adapted where necessary.
    /// <para />
    ///
    /// Base class for JSR166 Junit TCK tests.  Defines some constants,
    /// utility methods and classes, as well as a simple framework for
    /// helping to make sure that assertions failing in generated threads
    /// cause the associated test that generated them to itself fail (which
    /// JUnit does not otherwise arrange).  The rules for creating such
    /// tests are:
    ///
    /// <list type="bullets">
    ///
    /// <item> All assertions in code running in generated threads must use
    /// the forms <see cref="threadFail"/>, <see cref="threadAssertTrue"/>,
    /// <see cref="threadAssertEquals(long,long)"/>, <see cref="threadAssertEquals(object,object)"/>
    /// or <see cref="threadAssertNull"/>, (not
    /// <c>fail</c>, <c>assertTrue</c>, etc.) It is OK (but not
    /// particularly recommended) for other code to use these forms too.
    /// Only the most typically used JUnit assertion methods are defined
    /// this way, but enough to live with.</item>
    ///
    /// <item> If you override <see cref="SetUp"/> or <see cref="TearDown"/>, make sure
    /// to invoke <c>base.SetUp</c> and <c>base.TearDown</c> within
    /// them. These methods are used to clear and check for thread
    /// assertion failures.</item>
    ///
    /// <item>All delays and timeouts must use one of the constants
    /// <see cref="SHORT_DELAY_MS"/>, <see cref="SMALL_DELAY_MS"/>, <see cref="MEDIUM_DELAY_MS"/>,
    /// <see cref="LONG_DELAY_MS"/>. The idea here is that a SHORT is always
    /// discriminable from zero time, and always allows enough time for the
    /// small amounts of computation (creating a thread, calling a few
    /// methods, etc) needed to reach a timeout point. Similarly, a SMALL
    /// is always discriminable as larger than SHORT and smaller than
    /// MEDIUM.  And so on. These constants are set to conservative values,
    /// but even so, if there is ever any doubt, they can all be increased
    /// in one spot to rerun tests on slower platforms.</item>
    ///
    /// <item> All threads generated must be joined inside each test case
    /// method (or <c>fail</c> to do so) before returning from the
    /// method. The <see cref="joinPool"/> method can be used to do this when
    /// using Executors.</item>
    ///
    /// </list>
    ///
    /// <para />
    /// <b>Other notes</b>
    /// <list type="bullet">
    ///
    /// <item> Usually, there is one testcase method per JSR166 method
    /// covering "normal" operation, and then as many exception-testing
    /// methods as there are exceptions the method can throw. Sometimes
    /// there are multiple tests per JSR166 method when the different
    /// "normal" behaviors differ significantly. And sometimes testcases
    /// cover multiple methods when they cannot be tested in
    /// isolation.</item>
    ///
    /// <item> The documentation style for testcases is to provide as javadoc
    /// a simple sentence or two describing the property that the testcase
    /// method purports to test. The javadocs do not say anything about how
    /// the property is tested. To find out, read the code.</item>
    ///
    /// <item> These tests are "conformance tests", and do not attempt to
    /// test throughput, latency, scalability or other performance factors
    /// (see the separate "jtreg" tests for a set intended to check these
    /// for the most central aspects of functionality.) So, most tests use
    /// the smallest sensible numbers of threads, collection sizes, etc
    /// needed to check basic conformance.</item>
    ///
    /// <item>The test classes currently do not declare inclusion in
    /// any particular package to simplify things for people integrating
    /// them in TCK test suites.</item>
    ///
    /// <!-- LUCENENET: not implemented
    /// <item> As a convenience, the <c>main</c> of this class (JSR166TestCase)
    /// runs all JSR166 unit tests.</item>
    /// -->
    ///
    /// </list>
    /// </summary>
    public class JSR166TestCase : LuceneTestCase
    {
        // /**
        // * Runs all JSR166 unit tests using junit.textui.TestRunner
        // */
        //public static void main(String[] args)
        //{
        //    int iters = 1;
        //    if (args.length > 0)
        //        iters = Integer.parseInt(args[0]);
        //    Test s = suite();
        //    for (int i = 0; i < iters; ++i)
        //    {
        //        junit.textui.TestRunner.run(s);
        //        System.gc();
        //        System.runFinalization();
        //    }
        //    System.exit(0);
        //}

        ///**
        // * Collects all JSR166 unit tests as one suite
        // */
        //public static Test suite()
        //{
        //    TestSuite suite = new TestSuite("JSR166 Unit Tests");

        //    suite.addTest(new TestSuite(AbstractExecutorServiceTest.class));
        //    suite.addTest(new TestSuite(AbstractQueueTest.class));
        //    suite.addTest(new TestSuite(AbstractQueuedSynchronizerTest.class));
        //    suite.addTest(new TestSuite(ArrayBlockingQueueTest.class));
        //    suite.addTest(new TestSuite(AtomicBooleanTest.class));
        //    suite.addTest(new TestSuite(AtomicIntegerArrayTest.class));
        //    suite.addTest(new TestSuite(AtomicIntegerFieldUpdaterTest.class));
        //    suite.addTest(new TestSuite(AtomicIntegerTest.class));
        //    suite.addTest(new TestSuite(AtomicLongArrayTest.class));
        //    suite.addTest(new TestSuite(AtomicLongFieldUpdaterTest.class));
        //    suite.addTest(new TestSuite(AtomicLongTest.class));
        //    suite.addTest(new TestSuite(AtomicMarkableReferenceTest.class));
        //    suite.addTest(new TestSuite(AtomicReferenceArrayTest.class));
        //    suite.addTest(new TestSuite(AtomicReferenceFieldUpdaterTest.class));
        //    suite.addTest(new TestSuite(AtomicReferenceTest.class));
        //    suite.addTest(new TestSuite(AtomicStampedReferenceTest.class));
        //    suite.addTest(new TestSuite(ConcurrentHashMapTest.class));
        //    suite.addTest(new TestSuite(ConcurrentLinkedQueueTest.class));
        //    suite.addTest(new TestSuite(CopyOnWriteArrayListTest.class));
        //    suite.addTest(new TestSuite(CopyOnWriteArraySetTest.class));
        //    suite.addTest(new TestSuite(CountDownLatchTest.class));
        //    suite.addTest(new TestSuite(CyclicBarrierTest.class));
        //    suite.addTest(new TestSuite(DelayQueueTest.class));
        //    suite.addTest(new TestSuite(ExchangerTest.class));
        //    suite.addTest(new TestSuite(ExecutorsTest.class));
        //    suite.addTest(new TestSuite(ExecutorCompletionServiceTest.class));
        //    suite.addTest(new TestSuite(FutureTaskTest.class));
        //    suite.addTest(new TestSuite(LinkedBlockingQueueTest.class));
        //    suite.addTest(new TestSuite(LinkedListTest.class));
        //    suite.addTest(new TestSuite(LockSupportTest.class));
        //    suite.addTest(new TestSuite(PriorityBlockingQueueTest.class));
        //    suite.addTest(new TestSuite(PriorityQueueTest.class));
        //    suite.addTest(new TestSuite(ReentrantLockTest.class));
        //    suite.addTest(new TestSuite(ReentrantReadWriteLockTest.class));
        //    suite.addTest(new TestSuite(ScheduledExecutorTest.class));
        //    suite.addTest(new TestSuite(SemaphoreTest.class));
        //    suite.addTest(new TestSuite(SynchronousQueueTest.class));
        //    suite.addTest(new TestSuite(SystemTest.class));
        //    suite.addTest(new TestSuite(ThreadLocalTest.class));
        //    suite.addTest(new TestSuite(ThreadPoolExecutorTest.class));
        //    suite.addTest(new TestSuite(ThreadTest.class));
        //    suite.addTest(new TestSuite(TimeUnitTest.class));

        //    return suite;
        //}

        public static int SHORT_DELAY_MS;
        public static int SMALL_DELAY_MS;
        public static int MEDIUM_DELAY_MS;
        public static int LONG_DELAY_MS;

        /**
         * Returns the shortest timed delay. This could
         * be reimplemented to use for example a Property.
         */
        protected int getShortDelay()
        {
            return 50;
        }


        /**
         * Sets delays as multiples of SHORT_DELAY.
         */
        protected void setDelays()
        {
            SHORT_DELAY_MS = getShortDelay();
            SMALL_DELAY_MS = SHORT_DELAY_MS * 5;
            MEDIUM_DELAY_MS = SHORT_DELAY_MS * 10;
            LONG_DELAY_MS = SHORT_DELAY_MS * 50;
        }

        /**
         * Flag set true if any threadAssert methods fail
         */
        internal volatile bool threadFailed;

        /**
         * Initializes test to indicate that no thread assertions have failed
         */
        public override void SetUp()
        {
            base.SetUp();
            setDelays();
            threadFailed = false;
        }

        /**
         * Triggers test case failure if any thread assertions have failed
         */
        public override void TearDown()
        {
            assertFalse(threadFailed);
            base.TearDown();
        }

        /**
         * Fail, also setting status to indicate current testcase should fail
         */
        public void threadFail(string reason)
        {
            threadFailed = true;
            fail(reason);
        }

        /**
         * If expression not true, set status to indicate current testcase
         * should fail
         */
        public void threadAssertTrue(bool b)
        {
            if (!b)
            {
                threadFailed = true;
                assertTrue(b);
            }
        }

        /**
         * If expression not false, set status to indicate current testcase
         * should fail
         */
        public void threadAssertFalse(bool b)
        {
            if (b)
            {
                threadFailed = true;
                assertFalse(b);
            }
        }

        /**
         * If argument not null, set status to indicate current testcase
         * should fail
         */
        public void threadAssertNull(object? x)
        {
            if (x != null)
            {
                threadFailed = true;
                assertNull(x);
            }
        }

        /**
         * If arguments not equal, set status to indicate current testcase
         * should fail
         */
        public void threadAssertEquals(long x, long y)
        {
            if (x != y)
            {
                threadFailed = true;
                assertEquals(x, y);
            }
        }

        /**
         * If arguments not equal, set status to indicate current testcase
         * should fail
         */
        public void threadAssertEquals(object? x, object? y)
        {
            if (x != y && (x == null || !x.equals(y)))
            {
                threadFailed = true;
                assertEquals(x, y);
            }
        }

        /**
         * threadFail with message "should throw exception"
         */
        public void threadShouldThrow()
        {
            //try
            //{
            threadFailed = true;
            fail("should throw exception");
            //}
            //catch (AssertionFailedError e)
            //{
            //    e.printStackTrace();
            //    throw e;
            //}
        }

        /**
         * threadFail with message "Unexpected exception"
         */
        public void threadUnexpectedException()
        {
            threadFailed = true;
            fail("Unexpected exception");
        }

        /**
         * threadFail with message "Unexpected exception", with argument
         */
        public void threadUnexpectedException(Exception ex)
        {
            threadFailed = true;
            ex.PrintStackTrace();
            fail("Unexpected exception: " + ex);
        }

        /**
         * Wait out termination of a thread pool or fail doing so
         */
        public void joinPool(TaskScheduler exec)
        {
            try
            {
                exec.Shutdown();
                assertTrue(exec.AwaitTermination(TimeSpan.FromMilliseconds(LONG_DELAY_MS)));
            }
            // catch (SecurityException ok) // LUCENENET - not needed
            // {
            //     // Allowed in case test doesn't have privs
            // }
            catch (ThreadInterruptedException /*ie*/)
            {
                fail("Unexpected exception");
            }
        }


        /**
         * fail with message "should throw exception"
         */
        public void shouldThrow()
        {
            fail("Should throw exception");
        }

        /**
         * fail with message "Unexpected exception"
         */
        public void unexpectedException()
        {
            fail("Unexpected exception");
        }

        protected static readonly int zero = 0;
        protected static readonly int one = 1;
        protected static readonly int two = 2;
        protected static readonly int three = 3;
        protected static readonly int four = 4;
        protected static readonly int five = 5;
        protected static readonly int six = 6;
        protected static readonly int seven = 7;
        protected static readonly int eight = 8;
        protected static readonly int nine = 9;
        protected static readonly int m1 = -1;
        protected static readonly int m2 = -2;
        protected static readonly int m3 = -3;
        protected static readonly int m4 = -4;
        protected static readonly int m5 = -5;
        protected static readonly int m6 = -6;
        protected static readonly int m10 = -10;

        internal void ShortRunnable()
        {
            try
            {
                Thread.Sleep(SHORT_DELAY_MS);
            }
            catch (Exception e)
            {
                threadUnexpectedException(e);
            }
        }

        internal void MediumRunnable()
        {
            try
            {
                Thread.Sleep(MEDIUM_DELAY_MS);
            }
            catch (Exception e)
            {
                threadUnexpectedException(e);
            }
        }

        // LUCENENET TODO: Complete port
    }

    /// <summary>
    /// LUCENENET specific - fake support for an API that feels like ThreadPoolExecutor.
    /// </summary>
    internal static class JSR166TestCaseExtensions
    {
        /// <summary>
        /// LUCENENET specific - state to keep track of tasks.
        /// <see cref="LimitedConcurrencyLevelTaskScheduler"/> removes tasks from the list when they complete,
        /// so this class is needed to keep track of them.
        /// </summary>
        private class TaskState
        {
            private readonly TaskFactory _factory;
            private readonly List<Task> _tasks = new();

            public TaskState(TaskScheduler scheduler)
            {
                _factory = new TaskFactory(scheduler);
            }

            public void NewTask(Action action)
            {
                var task = _factory.StartNew(action);
                _tasks.Add(task);
            }

            public int ActiveCount => _tasks.Count(t => t.Status == TaskStatus.Running);

            public int CompletedCount => _tasks.Count(t => t.IsCompleted);

            public int TaskCount => _tasks.Count;

            public bool AllCompleted => _tasks.All(t => t.IsCompleted);

            public bool JoinAll(TimeSpan timeout) => Task.WhenAll(_tasks).Wait(timeout);
        }

        private static readonly ConditionalWeakTable<TaskScheduler, TaskState> _taskFactories = new();

        public static void Execute(this TaskScheduler scheduler, Action action)
        {
            if (!_taskFactories.TryGetValue(scheduler, out TaskState? state))
            {
                state = new TaskState(scheduler);
                _taskFactories.Add(scheduler, state);
            }

            state.NewTask(action);
        }

        public static bool AwaitTermination(this TaskScheduler scheduler, TimeSpan timeout)
        {
            if (_taskFactories.TryGetValue(scheduler, out TaskState? state))
            {
                return state.JoinAll(timeout);
            }

            return true;
        }

        public static int GetActiveCount(this TaskScheduler scheduler)
        {
            if (_taskFactories.TryGetValue(scheduler, out TaskState? state))
            {
                // Approximate the number of running threads, which shouldn't exceed the concurrency level
                return Math.Min(scheduler.MaximumConcurrencyLevel, state.ActiveCount);
            }

            return 0;
        }

        public static int GetCompletedTaskCount(this TaskScheduler scheduler)
        {
            if (_taskFactories.TryGetValue(scheduler, out TaskState? state))
            {
                return state.CompletedCount;
            }

            return 0;
        }

        public static int GetTaskCount(this TaskScheduler scheduler)
        {
            if (_taskFactories.TryGetValue(scheduler, out TaskState? state))
            {
                return state.TaskCount;
            }

            return 0;
        }

        public static void Shutdown(this TaskScheduler scheduler)
        {
            if (scheduler is LimitedConcurrencyLevelTaskScheduler lcl)
            {
                lcl.Shutdown();
            }
        }

        public static bool IsTerminated(this TaskScheduler scheduler)
        {
            if (scheduler is LimitedConcurrencyLevelTaskScheduler lcl
                && _taskFactories.TryGetValue(scheduler, out TaskState? state))
            {
                return lcl.IsShutdown && state.AllCompleted;
            }

            return false; // can't be shut down, so can't be terminated
        }
    }
}