using System.Collections.Generic;
using System.Linq;
using System.Numerics;
using AcDream.Core.Physics;
using Xunit;

namespace AcDream.Core.Tests.Physics;

public class ShadowObjectRegistryMultiPartTests
{
    private const uint LbId = 0xA9B40000u;
    private const float OffX = 0f;
    private const float OffY = 0f;

    private static IReadOnlyList<ShadowShape> DoorShapes() => new[]
    {
        new ShadowShape(
            GfxObjId:      0u,
            LocalPosition: new Vector3(0f, 0f, 0.018f),
            LocalRotation: Quaternion.Identity,
            Scale:         1.0f,
            CollisionType: ShadowCollisionType.Cylinder,
            Radius:        0.100f,
            CylHeight:     0.200f),
        new ShadowShape(
            GfxObjId:      0x010044B5u,
            LocalPosition: Vector3.Zero,
            LocalRotation: Quaternion.Identity,
            Scale:         1.0f,
            CollisionType: ShadowCollisionType.BSP,
            Radius:        2.0f,
            CylHeight:     0f),
        new ShadowShape(
            GfxObjId:      0x010044B6u,
            LocalPosition: Vector3.Zero,
            LocalRotation: Quaternion.Identity,
            Scale:         1.0f,
            CollisionType: ShadowCollisionType.BSP,
            Radius:        2.0f,
            CylHeight:     0f),
        new ShadowShape(
            GfxObjId:      0x010044B6u,
            LocalPosition: Vector3.Zero,
            LocalRotation: Quaternion.Identity,
            Scale:         1.0f,
            CollisionType: ShadowCollisionType.BSP,
            Radius:        2.0f,
            CylHeight:     0f)
    };

    [Fact]
    public void RegisterMultiPart_FourShapes_AllShareEntityId()
    {
        var reg = new ShadowObjectRegistry();
        const uint doorEntityId = 0x000F4244u;

        reg.RegisterMultiPart(
            entityId:        doorEntityId,
            entityWorldPos:  new Vector3(132.6f, 17.1f, 94.08f),
            entityWorldRot:  Quaternion.Identity,
            shapes:          DoorShapes(),
            state:           0x10008u,
            flags:           EntityCollisionFlags.None,
            worldOffsetX:    OffX,
            worldOffsetY:    OffY,
            landblockId:     LbId);

        int found = 0;
        foreach (var entry in reg.AllEntriesForDebug())
        {
            if (entry.EntityId == doorEntityId) found++;
        }
        Assert.True(found >= 4,
            $"Expected at least 4 entries for door entity (one per shape); found {found}");
    }

    [Fact]
    public void RegisterMultiPart_EmptyShapeList_NoOp()
    {
        var reg = new ShadowObjectRegistry();
        reg.RegisterMultiPart(
            entityId:       0x1u,
            entityWorldPos: Vector3.Zero,
            entityWorldRot: Quaternion.Identity,
            shapes:         System.Array.Empty<ShadowShape>(),
            state:          0u,
            flags:          EntityCollisionFlags.None,
            worldOffsetX:   OffX, worldOffsetY: OffY, landblockId: LbId);

        Assert.Equal(0, reg.TotalRegistered);
    }

    [Fact]
    public void Deregister_RemovesAllParts()
    {
        var reg = new ShadowObjectRegistry();
        const uint doorEntityId = 0x000F4244u;
        reg.RegisterMultiPart(doorEntityId, new Vector3(132.6f, 17.1f, 94.08f),
                               Quaternion.Identity, DoorShapes(), 0x10008u,
                               EntityCollisionFlags.None, OffX, OffY, LbId);

        reg.Deregister(doorEntityId);

        Assert.Equal(0, reg.TotalRegistered);
        foreach (var entry in reg.AllEntriesForDebug())
            Assert.NotEqual(doorEntityId, entry.EntityId);
    }

    [Fact]
    public void UpdatePhysicsState_PropagatesEtherealToAllParts()
    {
        var reg = new ShadowObjectRegistry();
        const uint doorEntityId = 0x000F4244u;
        reg.RegisterMultiPart(doorEntityId, new Vector3(132.6f, 17.1f, 94.08f),
                               Quaternion.Identity, DoorShapes(), 0x10008u,
                               EntityCollisionFlags.None, OffX, OffY, LbId);

        reg.UpdatePhysicsState(doorEntityId, 0x1000Cu); // 0x10008 | 0x4

        int updated = 0;
        foreach (var entry in reg.AllEntriesForDebug())
        {
            if (entry.EntityId != doorEntityId) continue;
            Assert.Equal(0x1000Cu, entry.State);
            updated++;
        }
        Assert.True(updated >= 4, $"Expected all parts updated, only {updated} were");
    }

    [Fact]
    public void RegisterMultiPart_PartsAcrossMultipleCells_AllCellsListed()
    {
        var reg = new ShadowObjectRegistry();
        // Two shapes 30m apart in X — must span two outdoor 24m cells.
        var shapes = new[]
        {
            new ShadowShape(0u, new Vector3(  0f, 0f, 0f), Quaternion.Identity, 1f,
                            ShadowCollisionType.Cylinder, 1f, 2f),
            new ShadowShape(0u, new Vector3(30f, 0f, 0f), Quaternion.Identity, 1f,
                            ShadowCollisionType.Cylinder, 1f, 2f),
        };
        reg.RegisterMultiPart(0x1u, new Vector3(12f, 12f, 50f), Quaternion.Identity,
                               shapes, 0u, EntityCollisionFlags.None, OffX, OffY, LbId);

        // Part 1 at world (12, 12) → cell (0,0) = LbId | 1
        // Part 2 at world (42, 12) → cell (1,0) = LbId | 9
        var entriesIn1 = reg.GetObjectsInCell(LbId | 1u);
        var entriesIn9 = reg.GetObjectsInCell(LbId | 9u);
        Assert.Contains(entriesIn1, e => e.EntityId == 0x1u);
        Assert.Contains(entriesIn9, e => e.EntityId == 0x1u);
    }

    [Fact]
    public void Register_SingleShapeCompat_Unchanged()
    {
        var reg = new ShadowObjectRegistry();
        reg.Register(42u, 0x01000001u, new Vector3(12f, 12f, 50f),
                     Quaternion.Identity, 1f, OffX, OffY, LbId);

        Assert.Equal(1, reg.TotalRegistered);
        Assert.Single(reg.GetObjectsInCell(LbId | 1u),
                      e => e.EntityId == 42u);
    }

    [Fact]
    public void UpdatePosition_MovesAllPartsWithEntity()
    {
        var reg = new ShadowObjectRegistry();
        const uint movingEntityId = 0xA1u;

        var shapes = new[]
        {
            new ShadowShape(0u, new Vector3(0f, 0f, 0f), Quaternion.Identity, 1f,
                            ShadowCollisionType.Cylinder, 0.5f, 1f),
            new ShadowShape(0u, new Vector3(1f, 0f, 0f), Quaternion.Identity, 1f,
                            ShadowCollisionType.Cylinder, 0.5f, 1f),
        };
        reg.RegisterMultiPart(movingEntityId, new Vector3(10f, 10f, 50f),
                               Quaternion.Identity, shapes, 0u,
                               EntityCollisionFlags.None, OffX, OffY, LbId);

        // Move entity to (50, 10, 50). Parts should be at (50, 10, 50) and (51, 10, 50).
        reg.UpdatePosition(movingEntityId,
                           new Vector3(50f, 10f, 50f), Quaternion.Identity,
                           OffX, OffY, LbId);

        Vector3 expectedPart0 = new(50f, 10f, 50f);
        Vector3 expectedPart1 = new(51f, 10f, 50f);
        var atNew = reg.AllEntriesForDebug().Where(e => e.EntityId == movingEntityId).ToList();
        Assert.Equal(2, atNew.Count);
        bool found0 = atNew.Any(e => Vector3.Distance(e.Position, expectedPart0) < 0.01f);
        bool found1 = atNew.Any(e => Vector3.Distance(e.Position, expectedPart1) < 0.01f);
        Assert.True(found0 && found1,
            "Expected both parts at new world positions (50, 10, 50) and (51, 10, 50)");
    }

    [Fact]
    public void Deregister_ClearsEntityShapesCache_NoStaleUpdatePositionRebuild()
    {
        // A6.P4 door fix (2026-05-24) regression: after Deregister, a stray
        // UpdatePosition with the same entityId must NOT resurrect the entity
        // via the _entityShapes path. The Deregister cleanup added in Task 4
        // (which folded Task 6 into the multi-part registration commit) clears
        // _entityShapes[entityId] alongside the cell-list cleanup.
        var reg = new ShadowObjectRegistry();
        const uint doorEntityId = 0x000F4244u;
        reg.RegisterMultiPart(doorEntityId, new Vector3(132.6f, 17.1f, 94.08f),
                               Quaternion.Identity, DoorShapes(), 0x10008u,
                               EntityCollisionFlags.None, OffX, OffY, LbId);

        reg.Deregister(doorEntityId);

        // Stray UpdatePosition should be a no-op now (no entry to find AND
        // no _entityShapes entry to rebuild from).
        reg.UpdatePosition(doorEntityId, new Vector3(200f, 200f, 50f),
                           Quaternion.Identity, OffX, OffY, LbId);

        Assert.Equal(0, reg.TotalRegistered);
    }
}