#region CPL License
/*
Nuclex Framework
Copyright (C) 2002-2017 Nuclex Development Labs

This library is free software; you can redistribute it and/or
modify it under the terms of the IBM Common Public License as
published by the IBM Corporation; either version 1.0 of the
License, or (at your option) any later version.

This library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
IBM Common Public License for more details.

You should have received a copy of the IBM Common Public
License along with this library
*/
#endregion

#if !NO_CONCURRENT_COLLECTIONS

using System;
using System.Threading;
using System.Collections.Generic;

#if UNITTEST

using NUnit.Framework;

namespace Nuclex.Support.Threading {

  /// <summary>Unit Test for the thread runner class</summary>
  [TestFixture]
  internal class ThreadRunnerTest {

    #region class DefaultDisposeRunner

    /// <summary>Implementation of a thread runner to check default dispose behavior</summary>
    private class DefaultDisposeRunner : ThreadRunner {

      /// <summary>Reports an error</summary>
      /// <param name="exception">Error that will be reported</param>
      protected override void ReportError(Exception exception) { }

      /// <summary>Called when the status of the busy flag changes</summary>
      protected override void BusyChanged() { }

    }

    #endregion // class DefaultDisposeRunner

    #region class DummyRunner

    /// <summary>Implementation of a thread runner used for unit testing</summary>
    private class DummyRunner : ThreadRunner {

      /// <summary>Initializes a new dummy thread runner</summary>
      public DummyRunner() : base() {
        this.completionGate = new ManualResetEvent(initialState: false);
      }

      /// <summary>Immediately frees all resources used by the instance</summary>
      public new void Dispose() {
        base.Dispose(100);

        if(this.completionGate != null) {
          this.completionGate.Dispose();
          this.completionGate = null;
        }
      }

      /// <summary>Waits for the task for complete (all of 100 milliseconds)</summary>
      /// <returns>True if the task completed, false if it continues running</returns>
      public bool WaitForCompletion() {
        return this.completionGate.WaitOne(100);
      }

      /// <summary>How often the status of the busy flag has changed</summary>
      public int BusyChangeCount {
        get { return this.busyChangeCount; }
      }

      /// <summary>Error that has been reported the last time a task was run</summary>
      public Exception ReportedError {
        get { return this.reportedError; }
      }

      /// <summary>Reports an error</summary>
      /// <param name="exception">Error that will be reported</param>
      protected override void ReportError(Exception exception) {
        this.reportedError = exception;
      }

      /// <summary>Called when the status of the busy flag changes</summary>
      protected override void BusyChanged() {
        ++busyChangeCount;
        if((busyChangeCount >= 2) && (base.IsBusy == false)) {
          this.completionGate.Set();
        }
      }

      /// <summary>Last error that was reported in the thread</summary>
      private Exception reportedError;
      /// <summary>Number of times the busy state of the runner has changed</summary>
      private int busyChangeCount;
      /// <summary>Triggered when the busy event has performed a double flank</summary>
      private ManualResetEvent completionGate;

    }

    #endregion // class DummyRunner

    #region class DummyTask

    /// <summary>Dummy task that can be executed by a thread runner</summary>
    private class DummyTask : IDisposable {

      /// <summary>Initializes a new dummy task</summary>
      /// <param name="delayMilliseconds">How long the task shoudl take to execute</param>
      public DummyTask(int delayMilliseconds) {
        this.startGate = new ManualResetEvent(initialState: false);
        this.delayMilliseconds = delayMilliseconds;
      }

      /// <summary>Immediately releases all resources owned by the instance</summary>
      public void Dispose() {
        if(this.startGate != null) {
          this.startGate.Dispose();
          this.startGate = null;
        }
      }

      /// <summary>Waits for the task to start (all of 100 milliseconds)</summary>
      /// <returns>True if the start started, false if it didn't</returns>
      public bool WaitForStart() {
        return this.startGate.WaitOne(100);
      }

      /// <summary>Sets the task up to fail with the specified error</summary>
      /// <param name="error">Error the task will fail with</param>
      public void FailWith(Exception error) {
        this.error = error;
      }

      /// <summary>Runs the task with no arguments</summary>
      public void Run() {
        this.startGate.Set();

        ++this.executionCount;
        Thread.Sleep(this.delayMilliseconds);
        if(this.error != null) {
          throw this.error;
        }
      }

      /// <summary>Runs the task with one argument</summary>
      /// <param name="firstArgument">First argument passed from the runner</param>
      public void Run(float firstArgument) {
        this.startGate.Set();

        ++this.executionCount;
        this.firstArgument = firstArgument;
        Thread.Sleep(this.delayMilliseconds);
        if(this.error != null) {
          throw this.error;
        }
      }

      /// <summary>Runs the task with two argument</summary>
      /// <param name="firstArgument">First argument passed from the runner</param>
      /// <param name="secondArgument">Second argument passed from the runner</param>
      public void Run(float firstArgument, string secondArgument) {
        this.startGate.Set();

        ++this.executionCount;
        this.firstArgument = firstArgument;
        this.secondArgument = secondArgument;
        Thread.Sleep(this.delayMilliseconds);
        if(this.error != null) {
          throw this.error;
        }
      }

      /// <summary>Runs the task with no arguments</summary>
      /// <param name="cancellationToken">Token by which cancellation can be signalled</param>
      public void RunCancellable(CancellationToken cancellationToken) {
        this.startGate.Set();

        ++this.executionCount;

        if(delayMilliseconds == 0) {
          Thread.Sleep(0);
        } else {
          if(cancellationToken.WaitHandle.WaitOne(delayMilliseconds)) {
            this.wasCancelled = cancellationToken.IsCancellationRequested;
            cancellationToken.ThrowIfCancellationRequested();
          }
        }
        if(this.error != null) {
          throw this.error;
        }
      }

      /// <summary>Runs the task with one argument</summary>
      /// <param name="firstArgument">First argument passed from the runner</param>
      /// <param name="cancellationToken">Token by which cancellation can be signalled</param>
      public void RunCancellable(float firstArgument, CancellationToken cancellationToken) {
        this.startGate.Set();

        ++this.executionCount;
        this.firstArgument = firstArgument;

        if(delayMilliseconds == 0) {
          Thread.Sleep(0);
        } else {
          if(cancellationToken.WaitHandle.WaitOne(delayMilliseconds)) {
            this.wasCancelled = cancellationToken.IsCancellationRequested;
            cancellationToken.ThrowIfCancellationRequested();
          }
        }
        if(this.error != null) {
          throw this.error;
        }
      }

      /// <summary>Runs the task with two argument</summary>
      /// <param name="firstArgument">First argument passed from the runner</param>
      /// <param name="secondArgument">Second argument passed from the runner</param>
      /// <param name="cancellationToken">Token by which cancellation can be signalled</param>
      public void RunCancellable(
        float firstArgument, string secondArgument, CancellationToken cancellationToken
      ) {
        this.startGate.Set();

        ++this.executionCount;
        this.firstArgument = firstArgument;
        this.secondArgument = secondArgument;

        if(delayMilliseconds == 0) {
          Thread.Sleep(0);
        } else {
          if(cancellationToken.WaitHandle.WaitOne(delayMilliseconds)) {
            this.wasCancelled = cancellationToken.IsCancellationRequested;
            cancellationToken.ThrowIfCancellationRequested();
          }
        }
        if(this.error != null) {
          throw this.error;
        }
      }

      /// <summary>How many times the task was run</summary>
      public int ExecutionCount {
        get { return this.executionCount; }
      }

      /// <summary>Whether the task was cancelled by the runner itself</summary>
      public bool WasCancelled {
        get { return this.wasCancelled; }
      }

      /// <summary>What the first argument was during the last call</summary>
      public float FirstArgument {
        get { return this.firstArgument; }
      }

      /// <summary>What the second argument was during the last call</summary>
      public string SecondArgument {
        get { return this.secondArgument; }
      }

      /// <summary>Last error that was reported in the thread</summary>
      private Exception error;
      /// <summary>Triggered when the task has started</summary>
      private ManualResetEvent startGate;
      /// <summary>How long the task should take to execute in milliseconds</summary>
      private int delayMilliseconds;
      /// <summary>How many times the task has been executed</summary>
      private volatile int executionCount;
      /// <summary>Whether the task has been cancelled</summary>
      private volatile bool wasCancelled;
      /// <summary>First argument that was passed to the task</summary>
      private volatile float firstArgument;
      /// <summary>Second argument that was passed to the task</summary>
      private volatile string secondArgument;

    }

    #endregion // class DummyRunner

    /// <summary>Verifies that the thread runner has a default constructor</summary>
    [Test]
    public void CanBeDefaultConstructed() {
      using(new DummyRunner()) { }
    }

    /// <summary>Checks that the runner sets and unsets its busy flag</summary>
    [Test]
    public void BusyFlagIsToggled() {
      using(var runner = new DummyRunner()) {
        int busyFlagChangeCount = runner.BusyChangeCount;
        Assert.IsFalse(runner.IsBusy);

        runner.RunInBackground((Action)delegate() { });
        Assert.IsTrue(runner.WaitForCompletion());

        Assert.GreaterOrEqual(busyFlagChangeCount + 2, runner.BusyChangeCount);
        Assert.IsFalse(runner.IsBusy);
      }
    }

    /// <summary>Lets the thread runner run a simple task in the background</summary>
    [Test]
    public void CanRunSimpleTaskInBackground() {
      using(var task = new DummyTask(0)) {
        using(var runner = new DummyRunner()) {
          runner.RunInBackground(new Action(task.Run));

          Assert.IsTrue(runner.WaitForCompletion());
          Assert.IsNull(runner.ReportedError);
        }

        Assert.AreEqual(1, task.ExecutionCount);
        Assert.IsFalse(task.WasCancelled);
      }
    }

    /// <summary>
    ///   Checks that the thread runner is able to pass a single argument to a task
    /// </summary>
    [Test]
    public void CanPassSingleArgumentToSimpleTask() {
      using(var task = new DummyTask(0)) {
        using(var runner = new DummyRunner()) {
          runner.RunInBackground(new Action<float>(task.Run), 12.43f);

          Assert.IsTrue(runner.WaitForCompletion());
          Assert.IsNull(runner.ReportedError);
        }

        Assert.AreEqual(1, task.ExecutionCount);
        Assert.AreEqual(12.43f, task.FirstArgument);
        Assert.IsFalse(task.WasCancelled);
      }
    }

    /// <summary>
    ///   Checks that the thread runner is able to pass two arguments to a task
    /// </summary>
    [Test]
    public void CanPassTwoArgumentsToSimpleTask() {
      using(var task = new DummyTask(0)) {
        using(var runner = new DummyRunner()) {
          runner.RunInBackground(new Action<float, string>(task.Run), 98.67f, "Hello");

          Assert.IsTrue(runner.WaitForCompletion());
          Assert.IsNull(runner.ReportedError);
        }

        Assert.AreEqual(1, task.ExecutionCount);
        Assert.AreEqual(98.67f, task.FirstArgument);
        Assert.AreEqual("Hello", task.SecondArgument);
        Assert.IsFalse(task.WasCancelled);
      }
    }

    /// <summary>
    ///   Verifies that an error happening in a simple task is reported correctly
    /// </summary>
    [Test]
    public void SimpleTaskErrorIsReported() {
      using(var task = new DummyTask(0)) {
        var error = new InvalidOperationException("Mooh!");
        task.FailWith(error);

        using(var runner = new DummyRunner()) {
          runner.RunInBackground(new Action(task.Run));

          Assert.IsTrue(runner.WaitForCompletion());
          Assert.AreSame(error, runner.ReportedError);
        }

        Assert.AreEqual(1, task.ExecutionCount);
        Assert.IsFalse(task.WasCancelled);
      }
    }

    /// <summary>Lets the thread runner run a cancellable task in the background</summary>
    [Test]
    public void CanRunCancellableTaskInBackground() {
      using(var task = new DummyTask(100)) {
        using(var runner = new DummyRunner()) {
          runner.RunInBackground(new CancellableAction(task.RunCancellable));
          Assert.IsTrue(task.WaitForStart());
          runner.CancelAllBackgroundOperations();

          Assert.IsTrue(runner.WaitForCompletion());
          Assert.IsNull(runner.ReportedError);
        }

        Assert.AreEqual(1, task.ExecutionCount);
        Assert.IsTrue(task.WasCancelled);
      }
    }

    /// <summary>
    ///   Checks that the thread runner is able to pass a single argument to a task
    ///   that can be cancelled
    /// </summary>
    [Test]
    public void CanPassSingleArgumentToCancellableTask() {
      using(var task = new DummyTask(100)) {
        using(var runner = new DummyRunner()) {
          runner.RunInBackground(new CancellableAction<float>(task.RunCancellable), 12.43f);
          Assert.IsTrue(task.WaitForStart());
          runner.CancelAllBackgroundOperations();

          Assert.IsTrue(runner.WaitForCompletion());
          Assert.IsNull(runner.ReportedError);
        }

        Assert.AreEqual(1, task.ExecutionCount);
        Assert.AreEqual(12.43f, task.FirstArgument);
        Assert.IsTrue(task.WasCancelled);
      }
    }

    /// <summary>
    ///   Checks that the thread runner is able to pass two arguments to a task
    ///   that can be cancelled
    /// </summary>
    [Test]
    public void CanPassTwoArgumentsToCancellableTask() {
      using(var task = new DummyTask(100)) {
        using(var runner = new DummyRunner()) {
          runner.RunInBackground(
            new CancellableAction<float, string>(task.RunCancellable), 98.67f, "Hello"
          );
          Assert.IsTrue(task.WaitForStart());
          runner.CancelAllBackgroundOperations();

          Assert.IsTrue(runner.WaitForCompletion());
          Assert.IsNull(runner.ReportedError);
        }

        Assert.AreEqual(1, task.ExecutionCount);
        Assert.AreEqual(98.67f, task.FirstArgument);
        Assert.AreEqual("Hello", task.SecondArgument);
        Assert.IsTrue(task.WasCancelled);
      }
    }

  }

} // namespace Nuclex.Support.Threading

#endif // UNITTEST

#endif // !NO_CONCURRENT_COLLECTIONS