using System;
using System.Collections.Generic;
using System.Numerics;
using AcDream.App.Rendering.Wb;
using AcDream.Core.Physics;
using AcDream.Core.World;
using DatReaderWriter.DBObjs;
using Xunit;

namespace AcDream.Core.Tests.Rendering.Wb;

public sealed class EntitySpawnAdapterTests
{
    // ── Happy-path: server-spawned entity ─────────────────────────────────

    [Fact]
    public void OnCreate_ServerSpawnedEntity_RegistersAnimatedEntityState()
    {
        var cache = new CapturingTextureCache();
        var adapter = MakeAdapter(cache);
        var entity = MakeEntity(id: 1, serverGuid: 0xDEAD0001u);

        var state = adapter.OnCreate(entity);

        Assert.NotNull(state);
        Assert.Same(state, adapter.GetState(0xDEAD0001u));
    }

    [Fact]
    public void OnCreate_ServerSpawnedEntity_SequencerIsNotNull()
    {
        var adapter = MakeAdapter();
        var entity = MakeEntity(id: 1, serverGuid: 0xDEAD0002u);

        var state = adapter.OnCreate(entity);

        Assert.NotNull(state!.Sequencer);
    }

    // ── Atlas-tier filter ─────────────────────────────────────────────────

    [Fact]
    public void OnCreate_ProceduralEntity_ReturnsNullAndRegistersNothing()
    {
        var cache = new CapturingTextureCache();
        var adapter = MakeAdapter(cache);
        // ServerGuid == 0 → atlas-tier, must not be processed here.
        var entity = MakeEntity(id: 2, serverGuid: 0u);

        var state = adapter.OnCreate(entity);

        Assert.Null(state);
        Assert.Null(adapter.GetState(0u));
        // No texture decode should have been triggered.
        Assert.Empty(cache.Calls);
    }

    // ── Palette-override texture decode ───────────────────────────────────

    [Fact]
    public void OnCreate_WithPaletteOverrideAndSurfaceOverrides_TriggersTextureCacheDecode()
    {
        var cache = new CapturingTextureCache();
        var adapter = MakeAdapter(cache);

        var palette = new PaletteOverride(
            BasePaletteId: 0x04001234u,
            SubPalettes: new[]
            {
                new PaletteOverride.SubPaletteRange(0x04002000u, 0, 2),
            });

        // Entity carries two parts each with one surface override.
        var entity = new WorldEntity
        {
            Id = 10,
            ServerGuid = 0xBEEF0001u,
            SourceGfxObjOrSetupId = 0x02000001u,
            Position = Vector3.Zero,
            Rotation = Quaternion.Identity,
            PaletteOverride = palette,
            MeshRefs = new[]
            {
                new MeshRef(0x01000010u, Matrix4x4.Identity)
                {
                    SurfaceOverrides = new Dictionary<uint, uint>
                    {
                        { 0x08000100u, 0u }, // surfaceId → origTex (0 = none)
                    },
                },
                new MeshRef(0x01000020u, Matrix4x4.Identity)
                {
                    SurfaceOverrides = new Dictionary<uint, uint>
                    {
                        { 0x08000200u, 0x05000300u }, // with origTex override
                    },
                },
            },
        };

        adapter.OnCreate(entity);

        // One call per surface-with-override: (0x08000100, null) and (0x08000200, 0x05000300).
        Assert.Equal(2, cache.Calls.Count);

        Assert.Contains(cache.Calls, c => c.SurfaceId == 0x08000100u
                                         && c.OrigTexOverride == null
                                         && c.Palette == palette);
        Assert.Contains(cache.Calls, c => c.SurfaceId == 0x08000200u
                                         && c.OrigTexOverride == 0x05000300u
                                         && c.Palette == palette);
    }

    [Fact]
    public void OnCreate_WithPaletteOverrideButNoSurfaceOverrides_DoesNotCallCache()
    {
        // Surfaces without SurfaceOverrides == null are decoded lazily at draw
        // time; the adapter only pre-warms what it knows at spawn time.
        var cache = new CapturingTextureCache();
        var adapter = MakeAdapter(cache);

        var entity = new WorldEntity
        {
            Id = 11,
            ServerGuid = 0xBEEF0002u,
            SourceGfxObjOrSetupId = 0x02000002u,
            Position = Vector3.Zero,
            Rotation = Quaternion.Identity,
            PaletteOverride = new PaletteOverride(0x04001235u, Array.Empty<PaletteOverride.SubPaletteRange>()),
            // MeshRef with NO SurfaceOverrides.
            MeshRefs = new[] { new MeshRef(0x01000011u, Matrix4x4.Identity) },
        };

        adapter.OnCreate(entity);

        Assert.Empty(cache.Calls);
    }

    [Fact]
    public void OnCreate_WithoutPaletteOverride_DoesNotCallCache()
    {
        var cache = new CapturingTextureCache();
        var adapter = MakeAdapter(cache);
        var entity = MakeEntity(id: 12, serverGuid: 0xBEEF0003u);

        adapter.OnCreate(entity);

        Assert.Empty(cache.Calls);
    }

    // ── OnRemove ─────────────────────────────────────────────────────────

    [Fact]
    public void OnRemove_ReleasesPerEntityState()
    {
        var adapter = MakeAdapter();
        var entity = MakeEntity(id: 20, serverGuid: 0xCAFE0001u);

        adapter.OnCreate(entity);
        Assert.NotNull(adapter.GetState(0xCAFE0001u));

        adapter.OnRemove(0xCAFE0001u);
        Assert.Null(adapter.GetState(0xCAFE0001u));
    }

    [Fact]
    public void OnRemove_UnknownGuid_NoOps()
    {
        var adapter = MakeAdapter();

        // Must not throw.
        adapter.OnRemove(0xDEADBEEFu);
    }

    // ── Multiple entities ─────────────────────────────────────────────────

    [Fact]
    public void OnCreate_MultipleEntities_EachGetsOwnState()
    {
        var adapter = MakeAdapter();
        var e1 = MakeEntity(id: 30, serverGuid: 0x11110001u);
        var e2 = MakeEntity(id: 31, serverGuid: 0x11110002u);

        var s1 = adapter.OnCreate(e1);
        var s2 = adapter.OnCreate(e2);

        Assert.NotNull(s1);
        Assert.NotNull(s2);
        Assert.NotSame(s1, s2);
        Assert.Same(s1, adapter.GetState(0x11110001u));
        Assert.Same(s2, adapter.GetState(0x11110002u));
    }

    [Fact]
    public void OnRemove_OnlyReleasesTargetGuid()
    {
        var adapter = MakeAdapter();
        var e1 = MakeEntity(id: 40, serverGuid: 0x22220001u);
        var e2 = MakeEntity(id: 41, serverGuid: 0x22220002u);

        adapter.OnCreate(e1);
        adapter.OnCreate(e2);
        adapter.OnRemove(0x22220001u);

        Assert.Null(adapter.GetState(0x22220001u));
        Assert.NotNull(adapter.GetState(0x22220002u));
    }

    // ── Helpers ───────────────────────────────────────────────────────────

    private static EntitySpawnAdapter MakeAdapter(ITextureCachePerInstance? cache = null)
    {
        cache ??= new CapturingTextureCache();
        return new EntitySpawnAdapter(cache, _ => MakeSequencer());
    }

    private static WorldEntity MakeEntity(uint id, uint serverGuid)
        => new WorldEntity
        {
            Id = id,
            ServerGuid = serverGuid,
            SourceGfxObjOrSetupId = 0x02000001u,
            Position = Vector3.Zero,
            Rotation = Quaternion.Identity,
            MeshRefs = new[] { new MeshRef(0x01000001u, Matrix4x4.Identity) },
        };

    private static AnimationSequencer MakeSequencer()
        => new AnimationSequencer(new Setup(), new MotionTable(), new NullAnimationLoader());

    // ── Mocks / stubs ─────────────────────────────────────────────────────

    /// <summary>
    /// Capture every call to GetOrUploadWithPaletteOverride so tests can
    /// assert without a live GL context.
    /// </summary>
    private sealed class CapturingTextureCache : ITextureCachePerInstance
    {
        public readonly record struct Call(uint SurfaceId, uint? OrigTexOverride, PaletteOverride Palette);
        public List<Call> Calls { get; } = new();

        public uint GetOrUploadWithPaletteOverride(
            uint surfaceId,
            uint? overrideOrigTextureId,
            PaletteOverride paletteOverride)
        {
            Calls.Add(new Call(surfaceId, overrideOrigTextureId, paletteOverride));
            return 1u; // Fake GL handle.
        }
    }

    private sealed class NullAnimationLoader : IAnimationLoader
    {
        public Animation? LoadAnimation(uint id) => null;
    }
}