using System.Collections.Generic;
using System.Numerics;
using AcDream.Core.Physics;
using DatReaderWriter.Types;

namespace AcDream.Core.Lighting;

/// <summary>
/// Routes <see cref="SetLightHook"/> animation hooks to the
/// <see cref="LightManager"/> — when a torch lights / extinguishes via
/// an animation frame, flip the corresponding
/// <see cref="LightSource.IsLit"/> latch. Per r13 §2 the hook is AC's
/// way of saying "this Setup's baked-in LightInfo is now active".
///
/// <para>
/// Registration: at entity spawn time the caller walks the Setup's
/// <c>Lights</c> dictionary and registers a <see cref="LightSource"/>
/// per <c>LightInfo</c>, tagging it with the owning entity id. When a
/// hook fires later, we look up every light tagged to that owner and
/// flip them all together (retail's SetLightHook is a per-setup
/// boolean, not per-light).
/// </para>
/// </summary>
public sealed class LightingHookSink : IAnimationHookSink
{
    private readonly LightManager _lights;

    // Index owner → the set of LightSource instances they registered.
    // Maintained lazily — populated on first RegisterLight for that owner.
    private readonly Dictionary<uint, List<LightSource>> _byOwner = new();

    public LightingHookSink(LightManager lights)
    {
        _lights = lights ?? throw new System.ArgumentNullException(nameof(lights));
    }

    /// <summary>
    /// Register a light with the manager + track it by owner so later
    /// SetLightHook / Unregister calls can reach it.
    /// </summary>
    public void RegisterOwnedLight(LightSource light)
    {
        System.ArgumentNullException.ThrowIfNull(light);
        _lights.Register(light);
        if (!_byOwner.TryGetValue(light.OwnerId, out var list))
        {
            list = new List<LightSource>();
            _byOwner[light.OwnerId] = list;
        }
        list.Add(light);
    }

    /// <summary>Drop every light tagged to this owner (despawn / unload).</summary>
    public void UnregisterOwner(uint ownerId)
    {
        if (!_byOwner.TryGetValue(ownerId, out var list)) return;
        foreach (var l in list) _lights.Unregister(l);
        _byOwner.Remove(ownerId);
    }

    /// <summary>
    /// Get the set of registered lights for an owner — exposed so
    /// callers can reposition them (torch on hand follows hand part).
    /// </summary>
    public IReadOnlyList<LightSource>? GetOwnedLights(uint ownerId)
    {
        return _byOwner.TryGetValue(ownerId, out var list) ? list : null;
    }

    public void OnHook(uint entityId, Vector3 entityWorldPosition, AnimationHook hook)
    {
        if (hook is not SetLightHook slh) return;
        if (!_byOwner.TryGetValue(entityId, out var list)) return;

        foreach (var light in list)
            light.IsLit = slh.LightsOn;
    }
}