using UnitTestSharp;

namespace Blacklight.SharpDX9.UnitTesting
{
    public class RefreshTallyTests : TestFixture
    {
        public class ObserveTests : TestFixture
        {
            public void FirstFrame_CountsNothing()
            {
                var tally = new RefreshTally();

                tally.Observe(presentCount: 5, presentRefreshCount: 100);

                CheckEqual(0L, tally.MissedRefreshes);
            }

            public void FramesOnConsecutiveRefreshes_CountNothing()
            {
                var tally = new RefreshTally();

                tally.Observe(presentCount: 5, presentRefreshCount: 100);
                tally.Observe(presentCount: 6, presentRefreshCount: 101);
                tally.Observe(presentCount: 7, presentRefreshCount: 102);

                CheckEqual(0L, tally.MissedRefreshes);
            }

            public void FrameThatSkipsARefresh_CountsOne()
            {
                var tally = new RefreshTally();

                tally.Observe(presentCount: 5, presentRefreshCount: 100);
                tally.Observe(presentCount: 6, presentRefreshCount: 102);

                CheckEqual(1L, tally.MissedRefreshes);
            }

            public void LongStall_CountsEveryRepeatedRefresh()
            {
                var tally = new RefreshTally();

                tally.Observe(presentCount: 5, presentRefreshCount: 100);
                tally.Observe(presentCount: 6, presentRefreshCount: 105);

                CheckEqual(4L, tally.MissedRefreshes);
            }

            public void SeparateMisses_Accumulate()
            {
                var tally = new RefreshTally();

                tally.Observe(presentCount: 5, presentRefreshCount: 100);
                tally.Observe(presentCount: 6, presentRefreshCount: 102);
                tally.Observe(presentCount: 7, presentRefreshCount: 105);

                CheckEqual(3L, tally.MissedRefreshes);
            }

            public void SeveralFramesBetweenCalls_CountOnlyTheRefreshesBeyondThem()
            {
                var tally = new RefreshTally();

                tally.Observe(presentCount: 5, presentRefreshCount: 100);
                tally.Observe(presentCount: 8, presentRefreshCount: 104);

                CheckEqual(1L, tally.MissedRefreshes);
            }

            public void DiscardedPresentAndRepeatedFrameInOneGap_CancelOut()
            {
                var tally = new RefreshTally();

                tally.Observe(presentCount: 5, presentRefreshCount: 100);
                tally.Observe(presentCount: 7, presentRefreshCount: 102);

                CheckEqual(0L, tally.MissedRefreshes);
            }

            public void SameFrameAgain_KeepsMeasuringFromWhenItWentUp()
            {
                var tally = new RefreshTally();

                tally.Observe(presentCount: 5, presentRefreshCount: 100);
                tally.Observe(presentCount: 5, presentRefreshCount: 100);
                tally.Observe(presentCount: 6, presentRefreshCount: 102);

                CheckEqual(1L, tally.MissedRefreshes);
            }

            public void PresentsDiscardedBeforeTheyWereShown_CountNothing()
            {
                var tally = new RefreshTally();

                tally.Observe(presentCount: 5, presentRefreshCount: 100);
                tally.Observe(presentCount: 8, presentRefreshCount: 101);

                CheckEqual(0L, tally.MissedRefreshes);
            }

            public void RefreshCounterWrapping_StillCountsTheGap()
            {
                var tally = new RefreshTally();

                tally.Observe(presentCount: 5, presentRefreshCount: uint.MaxValue);
                tally.Observe(presentCount: 6, presentRefreshCount: 1);

                CheckEqual(1L, tally.MissedRefreshes);
            }

            public void PresentCounterWrapping_StillCountsTheGap()
            {
                var tally = new RefreshTally();

                tally.Observe(presentCount: uint.MaxValue, presentRefreshCount: 100);
                tally.Observe(presentCount: 1, presentRefreshCount: 103);

                CheckEqual(1L, tally.MissedRefreshes);
            }

            public void StatisticsBeforeAnythingDisplayed_AreNotABaseline()
            {
                var tally = new RefreshTally();

                tally.Observe(presentCount: 0, presentRefreshCount: 0);
                tally.Observe(presentCount: 5, presentRefreshCount: 100);
                tally.Observe(presentCount: 6, presentRefreshCount: 102);

                CheckEqual(1L, tally.MissedRefreshes);
            }
        }

        public class RestartTests : TestFixture
        {
            public void GapAcrossTheRestart_IsNotCounted()
            {
                var tally = new RefreshTally();
                tally.Observe(presentCount: 5, presentRefreshCount: 100);

                tally.Restart();
                tally.Observe(presentCount: 6, presentRefreshCount: 200);
                tally.Observe(presentCount: 7, presentRefreshCount: 201);

                CheckEqual(0L, tally.MissedRefreshes);
            }

            public void KeepsTheCountSoFar()
            {
                var tally = new RefreshTally();
                tally.Observe(presentCount: 5, presentRefreshCount: 100);
                tally.Observe(presentCount: 6, presentRefreshCount: 102);

                tally.Restart();

                CheckEqual(1L, tally.MissedRefreshes);
            }
        }
    }
}