using System;
using System.Linq;
using NUnit.Framework;

namespace Chernobyl.ComponentModel
{
    [TestFixture, Description("Tests for the TaskEnumerable type.")]
    public class TaskEnumerableTests : TaskTests
    {
        [Test, Description("A test to insure the TaskEnumerable.Canceled event " +
            "is raised and the TaskEnumerable.IsCanceled is true when all of " +
            "tasks contained by the TaskEnumerable are canceled.")]
        public void CancelAllTasksTest()
        {
            ITask[] tasks = new ITask[]
                                {
                                    new TestingTask(),
                                    new TestingTask(),
                                    new TestingTask()
                                };
            TaskEnumerable taskEnumerable = new TaskEnumerable(tasks);
            
            CanceledChecker canceledChecker = new CanceledChecker();
            taskEnumerable.Canceled += canceledChecker.OnCanceled;

            foreach (ITask task in tasks)
                task.Cancel();

            Assert.IsTrue(canceledChecker.OnCanceledInvoked,
                "TaskEnumerable.Canceled was not invoked even though all of " + 
                "the ITask instances it contains were canceled.");

            Assert.IsTrue(taskEnumerable.IsCanceled,
                "TaskEnumerable.IsCanceled is false even though all of " +
                "the ITask instances it contains were canceled.");
        }

        [Test, Description("A test that ensure the TaskEnumerable.ProgressPercentage " +
            "property is set to the proper value when one of its contained ITask " + 
            "instances makes a certain amount of progress.")]
        public void ProgressPercentageTest()
        {
            TestingTask containedTask = new TestingTask();
            ITask[] tasks = new ITask[]
                                {
                                    containedTask,
                                    new TestingTask(),
                                    new TestingTask(),
                                    new TestingTask()
                                };
            TaskEnumerable taskEnumerable = new TaskEnumerable(tasks);

            containedTask.SetProgressPercentage(100);

            Assert.AreEqual(25, taskEnumerable.ProgressPercentage,
                "One task of four was set to 100% progress completion but the " +
                "TaskEnumerable.ProgressPercentage was not 25%.");
        }

        /// <summary>
        /// A helper type used to check if the <see cref="TaskEnumerable.Canceled"/>
        /// event has been invoked.
        /// </summary>
        class CanceledChecker
        {
            public void OnCanceled(object sender, EventArgs e)
            {
                OnCanceledInvoked = true;
            }

            public bool OnCanceledInvoked { get; set; }
        }

        protected override ITask CreateIncompleteTask()
        {
            ITask[] tasks = new ITask[]
                                {
                                    new TestingTask(),
                                    new TestingTask(),
                                    new TestingTask()
                                };
            return new TaskEnumerable(tasks);
        }

        protected override ITask CreateCompleteTask()
        {
            TestingTask[] tasks = new[]
                                {
                                    new TestingTask(),
                                    new TestingTask(),
                                    new TestingTask()
                                };

            foreach (TestingTask task in tasks)
                task.SetProgressPercentage(100);

            return new TaskEnumerable(tasks);
        }

        protected override void MakeProgress(ITask task)
        {
            TaskEnumerable taskEnumerable = (TaskEnumerable) task;
            ((TestingTask)taskEnumerable.First()).SetProgressPercentage(50);
        }
    }
}