using MoonTools.ECS;
using System;

namespace Nerfed.Runtime.Scene.Streaming;

/// <summary>
/// A centralized cleanup system for slowly destroying chunk entities to avoid frame stutters.
/// </summary>
public class ChunkTeardownSystem : MoonTools.ECS.System
{
    private readonly Filter _unloadedFilter;

    // Adjustable limit to prevent massive stutters when unloading chunks.
    public int MaxEntitiesToDestroyPerFrame { get; set; } = 250;

    public ChunkTeardownSystem(World world) : base(world)
    {
        _unloadedFilter = FilterBuilder
            .Include<ChunkUnloadPendingTag>()
            .Build();
    }

    public override void Update(TimeSpan delta)
    {
        int destroyed = 0;

        foreach (var entity in _unloadedFilter.Entities)
        {
            if (destroyed >= MaxEntitiesToDestroyPerFrame) break;

            Destroy(entity);
            destroyed++;
        }
    }
}