using System.Collections.Generic;
using System.Numerics;
using AcDream.App.Rendering.Vfx;
using AcDream.Core.Physics;
using AcDream.Core.Vfx;
using AcDream.Core.World;
using DatReaderWriter.Types;
using Xunit;
using DatPhysicsScript = DatReaderWriter.DBObjs.PhysicsScript;

namespace AcDream.Core.Tests.Rendering.Vfx;

public sealed class EntityScriptActivatorTests
{
    /// <summary>Recording sink so we can assert which hooks the runner fires.</summary>
    private sealed class RecordingSink : IAnimationHookSink
    {
        public List<(uint EntityId, Vector3 Pos, AnimationHook Hook)> Calls = new();
        public void OnHook(uint entityId, Vector3 worldPos, AnimationHook hook)
            => Calls.Add((entityId, worldPos, hook));
    }

    private static DatPhysicsScript BuildScript(params (double time, AnimationHook hook)[] items)
    {
        var script = new DatPhysicsScript();
        foreach (var (t, h) in items)
            script.ScriptData.Add(new PhysicsScriptData { StartTime = t, Hook = h });
        return script;
    }

    private static WorldEntity MakeEntity(uint serverGuid, Vector3 position) =>
        new()
        {
            Id = serverGuid,
            ServerGuid = serverGuid,
            SourceGfxObjOrSetupId = 0x02000001u,
            Position = position,
            Rotation = Quaternion.Identity,
            MeshRefs = System.Array.Empty<MeshRef>(),
        };

    private record Pipeline(
        ParticleSystem System,
        ParticleHookSink Sink,
        PhysicsScriptRunner Runner,
        RecordingSink Recording);

    private static Pipeline BuildPipeline(params (uint id, DatPhysicsScript script)[] scripts)
    {
        var registry = new EmitterDescRegistry();
        var system = new ParticleSystem(registry);
        var hookSink = new ParticleHookSink(system);          // for activator's StopAllForEntity
        var recording = new RecordingSink();                  // for runner's hook dispatch
        var table = new Dictionary<uint, DatPhysicsScript>();
        foreach (var (id, s) in scripts) table[id] = s;
        var runner = new PhysicsScriptRunner(
            id => table.TryGetValue(id, out var s) ? s : null,
            recording);
        return new Pipeline(system, hookSink, runner, recording);
    }

    [Fact]
    public void OnCreate_WithDefaultScript_FiresRunnerWithEntityGuidAndPosition()
    {
        var p = BuildPipeline(
            (0xAAu, BuildScript((0.0, new CreateParticleHook { EmitterInfoId = 100 }))));
        var activator = new EntityScriptActivator(p.Runner, p.Sink, _ => 0xAAu);
        var entity = MakeEntity(serverGuid: 0xCAFEu, position: new Vector3(1, 2, 3));

        activator.OnCreate(entity);

        Assert.Equal(1, p.Runner.ActiveScriptCount);
        p.Runner.Tick(0.001f);
        Assert.Single(p.Recording.Calls);
        Assert.Equal(0xCAFEu, p.Recording.Calls[0].EntityId);
        Assert.Equal(new Vector3(1, 2, 3), p.Recording.Calls[0].Pos);
    }

    [Fact]
    public void OnCreate_WithoutDefaultScript_DoesNothing()
    {
        var p = BuildPipeline();   // no scripts registered
        var activator = new EntityScriptActivator(p.Runner, p.Sink, _ => 0u);
        var entity = MakeEntity(serverGuid: 0xCAFEu, position: Vector3.Zero);

        activator.OnCreate(entity);

        Assert.Equal(0, p.Runner.ActiveScriptCount);
        Assert.Empty(p.Recording.Calls);
    }

    /// <summary>
    /// Persistent emitter: TotalDuration=0 and TotalParticles=0 prevent
    /// auto-finish; InitialParticles=1 ensures a particle spawns at t=0
    /// without waiting for the Birthrate timer; Lifespan=999f keeps that
    /// particle alive far past the test horizon.
    /// </summary>
    private static EmitterDesc BuildPersistentEmitterDesc() => new()
    {
        DatId          = 100u,
        Type           = ParticleType.Still,
        EmitterKind    = ParticleEmitterKind.BirthratePerSec,
        MaxParticles   = 4,
        InitialParticles = 1,
        TotalParticles = 0,   // 0 = no particle-count cap
        TotalDuration  = 0f,  // 0 = no time-based finish
        Lifespan       = 999f,
        LifetimeMin    = 999f,
        LifetimeMax    = 999f,
        Birthrate      = 0.5f,
        StartSize      = 0.5f,
        EndSize        = 0.5f,
        StartAlpha     = 1f,
        EndAlpha       = 1f,
    };

    [Fact]
    public void OnCreate_SetsEntityRotationForHookOffsetTransform()
    {
        // The CreateParticleHook's Offset is in entity-local frame; the sink
        // needs the entity's rotation to transform it to world space. If the
        // activator forgets SetEntityRotation, the offset goes off in world
        // axes — visual symptom: portal swirls misaligned to the portal stone.
        // This test verifies the seed happens by checking the spawned particle's
        // world position matches the rotated offset, not the unrotated offset.

        var registry = new EmitterDescRegistry();
        registry.Register(BuildPersistentEmitterDesc());

        var system = new ParticleSystem(registry);
        var hookSink = new ParticleHookSink(system);

        // Hook offset = (1, 0, 0) in entity-local frame.
        var hookOffset = new Frame
        {
            Origin = new Vector3(1f, 0f, 0f),
            Orientation = Quaternion.Identity,
        };
        var script = BuildScript(
            (0.0, new CreateParticleHook { EmitterInfoId = 100u, Offset = hookOffset }));
        var table = new Dictionary<uint, DatPhysicsScript> { [0xAAu] = script };
        var runner = new PhysicsScriptRunner(
            id => table.TryGetValue(id, out var s) ? s : null,
            hookSink);

        var activator = new EntityScriptActivator(runner, hookSink, _ => 0xAAu);

        // Entity rotated 90° around world-Z (yaw left); local +X maps to world +Y.
        var entityRotation = Quaternion.CreateFromAxisAngle(
            Vector3.UnitZ, MathF.PI / 2f);
        var entity = new WorldEntity
        {
            Id = 0xCAFEu,
            ServerGuid = 0xCAFEu,
            SourceGfxObjOrSetupId = 0x02000001u,
            Position = Vector3.Zero,
            Rotation = entityRotation,
            MeshRefs = System.Array.Empty<MeshRef>(),
        };

        activator.OnCreate(entity);
        runner.Tick(0.001f);
        system.Tick(0.001f);

        // Find the live particle. With the rotation applied, world position of
        // the local-(1,0,0) offset should be approximately world-(0,1,0). Without
        // the rotation seed (the bug), it would be world-(1,0,0).
        var live = system.EnumerateLive().FirstOrDefault();
        Assert.NotNull(live.Emitter);
        var worldPos = live.Emitter.Particles[live.Index].Position;
        Assert.InRange(worldPos.X, -0.01f, 0.01f);
        Assert.InRange(worldPos.Y,  0.99f, 1.01f);
    }

    [Fact]
    public void OnRemove_StopsScriptsAndEmitters()
    {
        // For this test we need the runner to dispatch into the REAL
        // ParticleHookSink so OnRemove's sink.StopAllForEntity has a live
        // emitter to kill. This is the only observable way to verify the
        // call had effect without subclassing the sealed sink.
        var registry = new EmitterDescRegistry();
        registry.Register(BuildPersistentEmitterDesc());

        var system  = new ParticleSystem(registry);
        var hookSink = new ParticleHookSink(system);

        var script = BuildScript((0.0, new CreateParticleHook { EmitterInfoId = 100u, Offset = new Frame() }));
        var table  = new Dictionary<uint, DatPhysicsScript> { [0xAAu] = script };
        var runner = new PhysicsScriptRunner(
            id => table.TryGetValue(id, out var s) ? s : null,
            hookSink);  // runner dispatches into real sink, not RecordingSink

        var activator = new EntityScriptActivator(runner, hookSink, _ => 0xAAu);
        var entity = MakeEntity(serverGuid: 0xCAFEu, position: Vector3.Zero);

        activator.OnCreate(entity);
        runner.Tick(0.001f);  // fires the CreateParticleHook → spawns emitter

        Assert.True(system.ActiveEmitterCount > 0,
            "Setup precondition failed: emitter should be alive after the hook fires.");

        activator.OnRemove(0xCAFEu);

        Assert.Equal(0, runner.ActiveScriptCount);
        // sink.StopAllForEntity marks the emitter Finished; system.Tick reaps it.
        system.Tick(0.01f);
        Assert.Equal(0, system.ActiveEmitterCount);
    }
}