using System;
using UnitTestSharp;

namespace Susurrus.UnitTests
{
    public class VoiceTableTests : TestFixture
    {
        public class CtorTests : TestFixture
        {
            public void StartsEmpty()
            {
                VoiceTable table = new VoiceTable(3);

                CheckEqual(3, table.Capacity);
                CheckEqual(0, table.ActiveCount);
            }

            public void ZeroCapacity_Throws()
            {
                CheckThrow(typeof(ArgumentOutOfRangeException));
                new VoiceTable(0);
            }
        }

        public class AcquireTests : TestFixture
        {
            public void HandsOutTheLowestFreeSlotFirst()
            {
                VoiceTable table = new VoiceTable(3);

                CheckEqual(0, table.Acquire().Slot);
                CheckEqual(1, table.Acquire().Slot);
                CheckEqual(2, table.Acquire().Slot);
            }

            public void FirstUseOfASlot_IsGenerationOne()
            {
                CheckEqual(1, new VoiceTable(1).Acquire().Generation);
            }

            public void CountsTheVoiceAsActive()
            {
                VoiceTable table = new VoiceTable(3);

                table.Acquire();

                CheckEqual(1, table.ActiveCount);
            }

            public void WhenEverySlotIsInUse_ReturnsNone()
            {
                VoiceTable table = new VoiceTable(2);
                table.Acquire();
                table.Acquire();

                CheckEqual(Voice.None, table.Acquire());
                CheckEqual(2, table.ActiveCount);
            }

            public void ReusingASlot_AdvancesItsGeneration()
            {
                VoiceTable table = new VoiceTable(1);
                Voice first = table.Acquire();
                table.Release(first);

                Voice second = table.Acquire();

                CheckEqual(first.Slot, second.Slot);
                CheckEqual(first.Generation + 1, second.Generation);
            }

            public void ReleasedSlots_AreReusedMostRecentFirst()
            {
                VoiceTable table = new VoiceTable(3);
                Voice zero = table.Acquire();
                Voice one = table.Acquire();
                table.Acquire();
                table.Release(zero);
                table.Release(one);

                CheckEqual(1, table.Acquire().Slot);
                CheckEqual(0, table.Acquire().Slot);
            }
        }

        public class IsActiveTests : TestFixture
        {
            public void AnAcquiredVoice_IsActive()
            {
                VoiceTable table = new VoiceTable(2);

                CheckTrue(table.IsActive(table.Acquire()));
            }

            public void None_IsNotActive()
            {
                VoiceTable table = new VoiceTable(2);
                table.Acquire();

                CheckFalse(table.IsActive(Voice.None));
            }

            public void AReleasedVoice_IsNotActive()
            {
                VoiceTable table = new VoiceTable(2);
                Voice voice = table.Acquire();
                table.Release(voice);

                CheckFalse(table.IsActive(voice));
            }

            public void AVoiceWhoseSlotWasReused_IsNotActive()
            {
                VoiceTable table = new VoiceTable(1);
                Voice old = table.Acquire();
                table.Release(old);
                Voice current = table.Acquire();

                CheckFalse(table.IsActive(old));
                CheckTrue(table.IsActive(current));
            }

            public void AVoiceFromASlotThisTableDoesNotHave_IsNotActive()
            {
                VoiceTable table = new VoiceTable(1);
                table.Acquire();

                CheckFalse(table.IsActive(new Voice(slot: 5, generation: 1)));
            }
        }

        public class ReleaseTests : TestFixture
        {
            public void FreesTheSlot()
            {
                VoiceTable table = new VoiceTable(2);
                Voice voice = table.Acquire();

                CheckTrue(table.Release(voice));
                CheckEqual(0, table.ActiveCount);
            }

            public void ReleasingTwice_ChangesNothingTheSecondTime()
            {
                VoiceTable table = new VoiceTable(2);
                Voice voice = table.Acquire();
                table.Release(voice);

                CheckFalse(table.Release(voice));
                CheckEqual(0, table.ActiveCount);
            }

            public void ReleasingAStaleVoice_LeavesTheNewOneRunning()
            {
                VoiceTable table = new VoiceTable(1);
                Voice old = table.Acquire();
                table.Release(old);
                Voice current = table.Acquire();

                CheckFalse(table.Release(old));
                CheckTrue(table.IsActive(current));
            }

            public void ReleasingNone_ChangesNothing()
            {
                VoiceTable table = new VoiceTable(2);
                table.Acquire();

                CheckFalse(table.Release(Voice.None));
                CheckEqual(1, table.ActiveCount);
            }

            public void ReleasingAFullTableThenAcquiring_WorksAgain()
            {
                VoiceTable table = new VoiceTable(1);
                table.Release(table.Acquire());

                CheckFalse(table.Acquire().IsNone);
            }
        }

        public class VoiceAtTests : TestFixture
        {
            public void ReturnsTheVoiceInAnActiveSlot()
            {
                VoiceTable table = new VoiceTable(2);
                Voice voice = table.Acquire();

                CheckEqual(voice, table.VoiceAt(voice.Slot));
            }

            public void ReturnsNoneForAFreeSlot()
            {
                VoiceTable table = new VoiceTable(2);
                Voice voice = table.Acquire();
                table.Release(voice);

                CheckEqual(Voice.None, table.VoiceAt(voice.Slot));
            }

            public void NegativeSlot_Throws()
            {
                CheckThrow(typeof(ArgumentOutOfRangeException));
                new VoiceTable(2).VoiceAt(-1);
            }

            public void SlotPastTheEnd_Throws()
            {
                CheckThrow(typeof(ArgumentOutOfRangeException));
                new VoiceTable(2).VoiceAt(2);
            }
        }
    }
}