using System.Collections.Immutable;
using System.Numerics;
using AcDream.Core.Physics;

namespace AcDream.Core.Tests.Physics;

public sealed class ShadowSetPositionCommitTests
{
    private const uint Landblock = 0xA9B40000u;
    private const uint Cell1 = Landblock | 0x0001u;
    private const uint Cell9 = Landblock | 0x0009u;

    [Fact]
    public void NoneRefreshesFrameWithoutChangingExactMembership()
    {
        var registry = RegisteredSingle();
        ulong version = registry.GetOwnerVersion(1u);
        var moved = new Vector3(14f, 12f, 50f);

        registry.CommitSetPosition(
            1u, moved, Quaternion.Identity, Cell1, 0f, 0f,
            PhysicsShadowCommitAction.None, []);

        ShadowEntry entry = Assert.Single(registry.GetObjectsInCell(Cell1));
        Assert.Equal(moved, entry.Position);
        Assert.Empty(registry.GetObjectsInCell(Cell9));
        Assert.Equal(version + 1UL, registry.GetOwnerVersion(1u));
    }

    [Fact]
    public void ReplaceDeduplicatesExactCellsAndPreserveRetainsThem()
    {
        var registry = RegisteredSingle();
        var replaced = new Vector3(36f, 12f, 50f);
        registry.CommitSetPosition(
            1u, replaced, Quaternion.Identity, Cell9, 0f, 0f,
            PhysicsShadowCommitAction.Replace,
            ImmutableArray.Create(Cell9, Cell9, 0u));

        Assert.Empty(registry.GetObjectsInCell(Cell1));
        Assert.Equal(replaced,
            Assert.Single(registry.GetObjectsInCell(Cell9)).Position);

        var preserved = new Vector3(38f, 12f, 50f);
        registry.CommitSetPosition(
            1u, preserved, Quaternion.Identity, Cell9, 0f, 0f,
            PhysicsShadowCommitAction.Preserve, []);
        Assert.Equal(preserved,
            Assert.Single(registry.GetObjectsInCell(Cell9)).Position);

        var emptyReplace = new Vector3(40f, 12f, 50f);
        registry.CommitSetPosition(
            1u, emptyReplace, Quaternion.Identity, Cell9, 0f, 0f,
            PhysicsShadowCommitAction.Replace, []);
        Assert.Equal(emptyReplace,
            Assert.Single(registry.GetObjectsInCell(Cell9)).Position);
    }

    [Fact]
    public void RecalculateUsesCanonicalFloodInsteadOfRetainedCells()
    {
        var registry = RegisteredSingle();
        var moved = new Vector3(36f, 12f, 50f);

        registry.CommitSetPosition(
            1u, moved, Quaternion.Identity, Cell9, 0f, 0f,
            PhysicsShadowCommitAction.Recalculate, []);

        Assert.Empty(registry.GetObjectsInCell(Cell1));
        Assert.Equal(moved,
            Assert.Single(registry.GetObjectsInCell(Cell9)).Position);
    }

    [Fact]
    public void SuspendedPreserveRestoresExactRowsAndConsumesReceipt()
    {
        var registry = RegisteredSingle();
        Assert.True(registry.Suspend(1u));
        Assert.Equal(0, registry.TotalRegistered);
        Assert.Equal(1, registry.SuspendedRegistrationCount);
        var moved = new Vector3(15f, 12f, 50f);

        registry.CommitSetPosition(
            1u, moved, Quaternion.Identity, Cell1, 0f, 0f,
            PhysicsShadowCommitAction.Preserve, []);

        Assert.Equal(1, registry.TotalRegistered);
        Assert.Equal(0, registry.SuspendedRegistrationCount);
        Assert.Equal(moved,
            Assert.Single(registry.GetObjectsInCell(Cell1)).Position);
    }

    [Fact]
    public void SuspendedReceiptCopiesAcrossCollisionRootAndClearsOnTeardown()
    {
        var source = RegisteredSingle();
        Assert.True(source.Suspend(1u));
        var destination = new ShadowObjectRegistry();

        Assert.False(destination.RefreshRetainedOwnerFrom(
            source, 1u, Landblock, out ulong version));
        Assert.Equal(source.GetOwnerVersion(1u), version);
        Assert.Equal(1, destination.RetainedRegistrationCount);
        Assert.Equal(1, destination.SuspendedRegistrationCount);

        destination.CommitSetPosition(
            1u, new Vector3(16f, 12f, 50f), Quaternion.Identity,
            Cell1, 0f, 0f, PhysicsShadowCommitAction.None, []);
        Assert.Single(destination.GetObjectsInCell(Cell1));
        destination.Deregister(1u);
        Assert.Equal(0, destination.RetainedRegistrationCount);
        Assert.Equal(0, destination.SuspendedRegistrationCount);
        destination.Clear();
        Assert.Equal(0, destination.TotalRegistered);
    }

    [Fact]
    public void MultiPartNoneRefreshesEachPartFromRootTransform()
    {
        var registry = new ShadowObjectRegistry();
        IReadOnlyList<ShadowShape> shapes =
        [
            Shape(0x01000001u, new Vector3(1f, 0f, 0f)),
            Shape(0x01000002u, new Vector3(0f, 1f, 0f)),
        ];
        registry.RegisterMultiPart(
            2u, new Vector3(12f, 12f, 50f), Quaternion.Identity,
            shapes, 0u, EntityCollisionFlags.None, 0f, 0f, Landblock,
            Cell1);
        Quaternion rotation = Quaternion.CreateFromAxisAngle(
            Vector3.UnitZ, MathF.PI / 2f);
        var root = new Vector3(14f, 12f, 50f);

        registry.CommitSetPosition(
            2u, root, rotation, Cell1, 0f, 0f,
            PhysicsShadowCommitAction.None, []);

        ShadowEntry[] entries = registry.GetObjectsInCell(Cell1)
            .Where(entry => entry.EntityId == 2u)
            .OrderBy(entry => entry.GfxObjId)
            .ToArray();
        Assert.Equal(2, entries.Length);
        Assert.Equal(root + Vector3.Transform(shapes[0].LocalPosition, rotation),
            entries[0].Position);
        Assert.Equal(root + Vector3.Transform(shapes[1].LocalPosition, rotation),
            entries[1].Position);
    }

    private static ShadowObjectRegistry RegisteredSingle()
    {
        var registry = new ShadowObjectRegistry();
        registry.Register(
            1u, 0x01000001u, new Vector3(12f, 12f, 50f),
            Quaternion.Identity, 1f, 0f, 0f, Landblock,
            seedCellId: Cell1, isStatic: false);
        return registry;
    }

    private static ShadowShape Shape(uint gfxObjId, Vector3 local) => new(
        gfxObjId,
        local,
        Quaternion.Identity,
        1f,
        ShadowCollisionType.BSP,
        0.25f,
        0f);
}