using System;
using System.Collections.Generic;

namespace Syntriax.Engine.Core;

public class ListPool<T> : IPool<List<T>>
{
    public Event<IPool<List<T>>, List<T>> OnReturned { get; } = new();
    public Event<IPool<List<T>>, List<T>> OnRemoved { get; } = new();

    private readonly Func<List<T>> generator = null!;
    private readonly Queue<List<T>> queue = new();

    public List<T> Get()
    {
        if (!queue.TryDequeue(out List<T>? result))
            result = generator();

        result.Clear();
        OnRemoved?.Invoke(this, result);
        return result;
    }

    public void Return(List<T> list)
    {
        if (queue.Contains(list))
            return;

        list.Clear();
        queue.Enqueue(list);
        OnReturned?.Invoke(this, list);
    }

    public ListPool(Func<List<T>> generator, int initialCapacity = 1)
    {
        this.generator = generator;
        for (int i = 0; i < initialCapacity; i++)
            queue.Enqueue(generator());
    }
}