using System;
using System.Threading;
using UnitTestSharp;

namespace Glass.UnitTests
{
    public class TreeWalkGuardTests : TestFixture
    {
        public class BeginTests : TestFixture
        {
            public void EmptyContainer_Succeeds()
            {
                new TreeWalkGuard().Begin(new ControlContainer()).Dispose();
            }

            public void WellFormedNestedTree_Succeeds()
            {
                var root = new Control("root");
                root.CanvasChildren.Add(new Control("child"));
                root.CanvasChildren.Add(new Control("sibling")).CanvasChildren.Add(new Control("grandchild"));
                var controls = new ControlContainer();
                controls.Add(root);

                new TreeWalkGuard().Begin(controls).Dispose();
            }

            public void Cycle_Throws()
            {
                var parent = new Control("parent");
                var child = new Control("child");
                parent.CanvasChildren.Add(child);
                child.CanvasChildren.Add(parent);
                var controls = new ControlContainer();
                controls.Add(parent);

                CheckThrow(typeof(InvalidOperationException));
                new TreeWalkGuard().Begin(controls);
            }

            public void ControlAddedTwiceToTheSameParent_Throws()
            {
                var parent = new Control("parent");
                var child = new Control("child");
                parent.CanvasChildren.Add(child);
                parent.CanvasChildren.Add(child);
                var controls = new ControlContainer();
                controls.Add(parent);

                CheckThrow(typeof(InvalidOperationException));
                new TreeWalkGuard().Begin(controls);
            }

            public void ControlSharedBetweenTwoBranches_Throws()
            {
                var shared = new Control("shared");
                var first = new Control("first");
                var second = new Control("second");
                first.CanvasChildren.Add(shared);
                second.CanvasChildren.Add(shared);
                var controls = new ControlContainer();
                controls.Add(first);
                controls.Add(second);

                CheckThrow(typeof(InvalidOperationException));
                new TreeWalkGuard().Begin(controls);
            }

            public void MalformedTree_DoesNotClaimTheGuard()
            {
                var guard = new TreeWalkGuard();
                var malformed = new ControlContainer();
                var control = new Control("control");
                malformed.Add(control);
                malformed.Add(control);

                try
                {
                    guard.Begin(malformed);
                }
                catch (InvalidOperationException)
                {
                }

                guard.Begin(new ControlContainer()).Dispose();
            }

            public void MalformedTree_LeavesNoVisitedControlsBehind()
            {
                var guard = new TreeWalkGuard();
                var control = new Control("control");
                var malformed = new ControlContainer();
                malformed.Add(control);
                malformed.Add(control);
                var wellFormed = new ControlContainer();
                wellFormed.Add(control);

                try
                {
                    guard.Begin(malformed);
                }
                catch (InvalidOperationException)
                {
                }

                guard.Begin(wellFormed).Dispose();
            }

            public void WhileAWalkIsUnderway_Throws()
            {
                var guard = new TreeWalkGuard();
                var scope = guard.Begin(new ControlContainer());

                CheckThrow(typeof(InvalidOperationException));
                guard.Begin(new ControlContainer());
            }

            public void AfterTheScopeIsDisposed_Succeeds()
            {
                var guard = new TreeWalkGuard();
                guard.Begin(new ControlContainer()).Dispose();

                guard.Begin(new ControlContainer()).Dispose();
            }

            public void WhileAWalkIsUnderwayOnAnotherGuard_Succeeds()
            {
                var first = new TreeWalkGuard();
                var second = new TreeWalkGuard();
                using (first.Begin(new ControlContainer()))
                {
                    second.Begin(new ControlContainer()).Dispose();
                }
            }

            public void WhileAWalkIsUnderwayOnAnotherThread_Succeeds()
            {
                var guard = new TreeWalkGuard();
                Exception thrown = null;

                using (guard.Begin(new ControlContainer()))
                {
                    var thread = new Thread(() =>
                    {
                        try
                        {
                            guard.Begin(new ControlContainer()).Dispose();
                        }
                        catch (Exception exception)
                        {
                            thrown = exception;
                        }
                    });
                    thread.Start();
                    thread.Join();
                }

                CheckNull(thrown);
            }
        }
    }
}